Upstream Optioneering – ILW/LLW Opportunities

Upstream Optioneering – ILW/LLWOpportunitiesIdentification of potential opportunities for ILW/LLWboundary wastes introduced by changing disposal route

To: NDA RWMDate: June 2014From: AMEC

Your Reference: RWMD/04/065Our Reference: 201139-AA-0004/001/Issue 1

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Title Upstream Optioneering – ILW/LLW OpportunitiesIdentification of potential opportunities for ILW/LLW boundary wastes introduced bychanging disposal route

Prepared for RWM

Your Reference RWMD/04/065

Our Reference 201139-AA-0004/001/Issue 1

Confidentiality,copyright &reproduction

This report is submitted by Energy, Safety and Risk Consultants (UK) Limited(hereafter referred to as AMEC) in connection with a contract to supply goods and/orservices and is submitted only on the basis of strict confidentiality. The contentsmust not be disclosed to third parties other than in accordance with the terms of thecontract.

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Executive SummaryThis report explores the benefits and disbenefits of disposing of a number of waste streams in theUK Radioactive Waste Inventory (UKRWI) that are within the boundary of the LLW and ILWclassifications to a range of representative facility types that would be suitable for wastes fromacross a range of activity concentrations.

The selected facilities employ a range of engineered design features and would be located within arange of depths (from a surface location to geological disposal depths of up to 1,000 m). The studyconsiders a LLWR-type facility and a GDF-facility type rather than the actual LLWR / GDF inparticular. Similar arguments apply to the other facility types considered, namely a moreengineered surface facility (modelled on the facility at Centre de l’Aube in France, and a cavern-based facility at an intermediate depth of about 50 m of the surface represented by the SFR facilityin Sweden. The identification of these benefits and disbenefits, and how these are dependent uponthe properties of individual waste streams, are illustrated using a number of case studies, one foreach of the waste streams.

The case studies have been structured around the following boundary waste streams, and wereselected to explore a number of issues that will influence future decisions on routing boundarywastes: the mild steel and graphite wastes that would arise at final dismantling and site clearanceat the Trawsfynydd site; the relatively large volumes of concrete and blockwork that would arise atthe final decommissioning stage of various processing plants at Sellafield; and the organic sludgefrom one of the earliest fuel reception facilities at Sellafield.

The main stage of the assessment was conducted at an options workshop attended byrepresentatives from RWM Limited, Magnox and LLWR. The conclusions of the four case studiesare summarised as follows:

Mild steel waste from reactor dismantlingThis ILW stream is dominated by the presence of Ni-63, but the fraction of the total activity fromlong-lived C-14 (~8%) is sufficient to rule out disposal to the LLWR-type facility, and wouldchallenge a more robust surface facility unless the engineered features could provide adequateassurance of effective containment over a very long period. No credible period of interim storagecould be employed as part of an alternative strategy of surface disposal, and such an approachwould conflict with important elements of NDA strategy on risk reduction and the timelyachievement of agreed site end-states.

Graphite waste from reactor dismantlingThis ILW stream has a C-14 activity concentration several orders of magnitude above the disposallimit for LLWR. It is likely that this would also be the case for a more engineered surface facility asit seems improbable that extra engineered barriers could compensate for such a large C-14inventory. The long half-life of C-14 indicates that decay storage would not be a feasible strategyfor enabling future near surface disposal. Disposal below surface at depths sufficiently great toprevent the incorporation of radiologically significant quantities in plant biota would be the onlyfeasible option.

Sellafield processing plants demolition wasteThis relatively large waste stream comprises the concrete and brickwork from the demolition of anumber of processing plants at Sellafield. It contains a wide range of fission products, chieflyCs-137 and Sr-90, and at about 2070, which is when it is planned to arise, it will become LLW. Theworkshop concluded that this waste stream would be most effectively managed by means of large-scale segregation, followed by the consignment of increasingly active fractions to facilities mostsuited to accepting such material. It is to be expected that most of the waste volume would besuitable for some form of surface disposal as LLW or VLLW, with a relatively small fractionreserved for geological disposal.

Sellafield fuel storage pondThis stream is a low volume, relatively low activity organic sludge containing a range of activationand fission products. In the 2013 UK Radioactive Waste Inventory (UKRWI)1 it is recorded as

1 NDA, 2013 UK Radioactive Waste Inventory, February 2014.

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arising from the year 2013. The clear conclusion from the assessment is that surface disposal ofthis waste stream would be favoured over geological disposal, as none of the indications of relativeperformance oppose this inclination. This is the case even though the waste was classified as ILWin the 2013 UKRWI, and therefore geological disposal is assumed to be the default managementstrategy. It should be noted also that the waste contains no significant levels of potentiallyproblematic radionuclides such as Cl-36 or C-14 that could justify a more careful examination of therespective advantages and disadvantages of different routing options. For this waste streamtherefore, surface disposal would not appear to have any significant disadvantages whencompared with geological disposal and may be significantly cheaper.

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Contents1 Introduction 7

2 Identification of candidate boundary waste streams 92.1 Definition 92.2 Selection of boundary waste streams for study 92.3 Summaries of candidate streams 11

3 Metrics for assessing benefits and disbenefits of routingoptions 153.1 Discussion 153.2 Selection for study 15

4 Waste Disposal Facility Types – Routing Options 174.1 Management of Radioactive Waste in the UK 174.2 Waste Disposal Facilities – Routing Options 18

5 Assessment Approach 355.1 Introduction 355.2 Scoring scheme 35

6 Assessment Results 376.1 9G310 – Final Dismantling & Site Clearance: Mild Steel (Reactor) ILW

(Trawsfynydd) 376.2 9G311 – Final Dismantling & Site Clearance: Graphite ILW (Trawsfynydd) 436.3 2D137 – Miscellaneous Plants Final Decommissioning: Processing Plants,

Tanks, Silos, etc (Sellafield) 496.4 2F26 – LWR Pond Sludge (Sellafield) 54

7 Summary and conclusions 59

8 References 61

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TablesTable 1: Metrics for Assessment of Benefits and Disbenefits of Routing Options........................... 16Table 2: Radiological capacity values applicable to all waste consignments to LLWR.................. 20Table 3: Radiological capacity values applicable to upper stack position consignments ............... 21Table 4: A comparison of the waste concentration limits for CSFMA and LLWR [16, 18, 19]......... 25

FiguresFigure 1: Illustration of operation of LLWR Vault 9 .......................................................................... 19Figure 2: More engineered surface disposal facility (Centre de l’Aube) .......................................... 23Figure 3: Aspects of design, future state and operation of the CSFMA disposal facility ................ 24Figure 4: Cavern-based disposal facility at 50 m depth (SFR) ........................................................ 28Figure 5: Interiors of three of the types of openings at SFR ............................................................ 28Figure 6: Illustration of a generic GDF (with co-located sections for HLW and SF) ........................ 32Figure 7: Scoring scheme - relative performance of each routing option against each metric...... 36Figure 8: Assessment scores for stream 9G310.............................................................................. 41Figure 9: Assessment scores for stream 9G311.............................................................................. 47Figure 10: Assessment scores for stream 2D137............................................................................ 53Figure 11: Assessment scores for stream 2F26 .............................................................................. 57

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1 IntroductionThe Radioactive Waste Management Limited (RWM) of the Nuclear Decommissioning Authority isundertaking a study on the management of wastes around the LLW/ILW boundary. In particular thestudy addresses issues related to whether disposal of particular waste streams to a GeologicalDisposal Facility represents an optimised strategy. Four possibilities were identified as part of thisprogramme:

#18 Decay storage of short-lived ILW to allow disposal to near-surface facilities

#91 Waste management by safety case argument

#108 Implementation of new routes for tritiated desiccants

#136 Benefits and disbenefits of LLW/ILW disposal routes

A project comprising of four tasks has been undertaken to develop these possibilities further.

Task 1Preparation of an inventory of waste that is potentially amenable to diversion from geologicaldisposal.

Task 2Examination of the potential for application of existing policy and guidance regarding themanagement of radioactive waste by safety case argument and not by classification.

Task 3Summarising the work to establish solutions for the management of tritiated wastes.

Task 4Identification of opportunities for LLW/ILW boundary wastes.

The aim of this work package within NDA’s Upstream Optioneering initiative, Task 4, is to explorethe benefits and disbenefits of disposing of a number of waste streams in the 2013 UK RadioactiveWaste Inventory (UKRWI) [1] that are at the boundary of the ILW and LLW classifications1 to arange of representative facility types that would be suitable for wastes from across a range ofactivity concentrations. The selected facilities employ a range of engineered design features andwould be located within a range of depths (from a surface location to geological disposal at a depthof up to 1,000 m). The identification of these benefits and disbenefits, and how these aredependent upon the properties of individual waste streams, are illustrated using a number of casestudies.

This report is the deliverable from Task 4 within the overall project (Upstream Optioneering –ILW/LLW Opportunities) (RWM opportunity No. 136) and utilises the results of Task 1 (Preparationof an inventory of waste which is potentially suitable for diversion from a future geological disposalfacility (GDF) – RWM Opportunity No. 18) and is also related to work conducted under Task 2(Determining the suitability of boundary wastes for near-surface disposal – Opportunity No. 91).Together with the study to explore the optimum management approach for tritiated boundarywastes (Task 3 – Opportunity No. 108), these tasks are intended to inform the further developmentof NDA’s Strategy for radioactive waste management.

This report explores the potential ideas and options for the concept of “waste management bysafety case”2. It is acknowledged that currently, radioactive waste management in the UnitedKingdom is founded upon policy-defined waste classifications and that significant effort (in terms of

1 Low Level Waste (LLW) is defined as radioactive waste having a radioactive content not exceeding4 GBq/tonne of alpha and 12 GBq/tonne of beta/gamma activity; Intermediate Level Waste is defined as wastewith radioactivity exceeding the upper boundaries of LLW, but do not require heating to be taken into account[2]. A small fraction of LLW is deemed to be unsuitable for surface disposal at the Low Level WasteRepository (LLWR), due principally to the concentrations of specific radionuclides of concern such as Pu-239,C-14 and Cl-36.2 An approach to assuring the safety of waste disposal based upon scientific argument and justified inferencerather the classification of the wastes.

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detailed analysis, stakeholder consultation, changes to legislation / regulation / policy, sitepermitting and planning permission) would probably be required to implement any significantchange to established practices. This report considers a LLWR-type facility and a GDF-type facilityrather than the actual LLWR / GDF in particular. Similar arguments apply to other facility typesconsidered herein.

This report:

Identifies the candidate boundary waste streams that are used for the case studies, togetherwith the rationale for their selection.

Summarises the representative types of potential disposal facility (routing options) to which thewaste streams could – in theory at least – be consigned.

Presents and accounts for the set of metrics used for assessing the potential benefits anddisbenefits of the routing of each of the waste streams to each of the disposal facility types.

Outlines the main features of the case studies (one for each of the candidate waste streams)set up to identify these separate benefits and disbenefits, and whether these could reasonablysupport a view on the overall advantage or disadvantage of a routing option.

A workshop was held to review, confirm and where necessary, adjust the set of assumptionsadopted. At this meeting some of the preliminary results were discussed, and additional informationand insight provided to support the finalisation of the case studies.

Section 2 outlines the candidate waste streams that are used to illustrate the benefits anddisbenefits of different routing options.

Section 3 outlines the metrics that are used in the four case studies.

Section 4 summarises the relevant features of the disposal facility types in the case studies.

Section 5 summarises the assessment approach adopted.

Section 6 discusses the results of the case studies.

Section 7 presents the overall conclusions of the study.

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2 Identification of candidate boundarywaste streams

2.1 DefinitionThe Low Level Waste Repository’s (LLWR) guidance document within its National WasteProgramme [3] defines ILW/LLW cross-boundary wastes as ILW and LLW with a concentration ofspecific radionuclides that prohibits or significantly challenges its acceptability at existing andplanned future disposal facilities for LLW, that could be practicably be managed as LLW (on thebasis of radiochemical and physico-chemical properties) through application of some treatmentprocess or decay storage. The management of this waste in the UK is complicated by the inherentcharacteristics of the wastes and the challenge that may be imposed upon the radiological capacityof an LLW management and disposal facility.

The key issue with these wastes is that management decisions based purely upon the radiologicalcategorisation may be sub-optimal from the perspective of cost (as available information andfundamental considerations would suggest strongly that geological disposal is significantly moreexpensive than surface disposal), environmental consequences (some radionuclides give rise toimpacts that are disproportionate on the basis of activity alone) and volume (given the limitedcapacity of existing facilities that are currently not planned to receive such material). It is alsorecognised that were the current NDA strategy [4] to be implemented inflexibly, the management ofthese wastes may limit the range of routing opportunities in a manner that is not sufficientlybeneficial or optimal.

2.2 Selection of boundary waste streams for studyTo highlight a number of key issues that can be expected to influence the suitability of alternativerouting options for boundary wastes, a number of worked examples (Case Studies) have beenformulated, mostly centred on waste streams that are on the borderline between classification asILW and LLW (in that they will decay from ILW to LLW during the period of time covered by theUKRWI – up to about 2300), but with one exception involving more long-lived activity.

The identification of waste streams within the UKRWI that may be suitable for some form ofdiversion from the current default route for ILW of a future geological disposal facility to others ofmore appropriate design and location was undertaken as part of Task 1 of this overall project [5], towhich reference was therefore made.

The main characteristics of waste streams that will be relevant to possible future decisions on theirmost appropriate routing – whether a confirmation of the current position or an amendment to this –are as follows:

Volume, noting that

- higher volume streams would probably provide a greater potential benefit from re-routing,particularly as large volumes may present challenges to current facility capacities,whereas

- it would probably be easier to implement some opportunities for the lower volumestreams,

Half-life (longer-lived streams may be less suitable for re-routing),

Significant radionuclides (some may be judged to be less suitable for near-surface disposalthan others),

Physical/chemical characteristics (the presence of specific harmful substances such as heavymetals or certain types of organic materials may lead to challenges for one or more of theconsidered disposal routes),

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Heterogeneity (whether waste streams are essentially mixed in nature – e.g. MiscellaneousActivated Components (9F25-27), comprising mild steel, graphite and stainless steels,insulation and PVC sheeting – and others much more uniform in nature such as cooling pondfurniture (2F15), comprising only boronated stainless steel vessels). This may mean thatmixed streams may require more effort to segregate, but that this may be justified by better oreasier disposal.

With these characteristics in mind, the 247 waste streams within the UKRWI that were identified inthe Task 1 Report as sufficiently near to the border between ILW and LLW to merit areconsideration of their default disposal route were examined with the above factors in mind, and inconsultation with RWM Limited, Magnox and LLWR, the following four streams were selected forthis task. 1, 2

Stream 1: 9G310 – Final Dismantling & Site Clearance: Mild Steel (Reactor) ILW(Trawsfynydd)

This is a substantial waste stream that arises at Final Site Clearance (FSC) and is fairlyrepresentative across all the Magnox reactors in the UK with steel pressure vessels. It comprises avariety of mild steel items.

Stream 2: 9G311 – Final Dismantling & Site Clearance: Graphite ILW (Trawsfynydd)

This stream, which is likely to be reasonably representative across the Magnox and AGR fleets,represents an important and potentially problematic waste type for NDA, namely high volumereactor graphite containing significant concentrations of the long-lived radionuclide C-14. Incontrast to the other waste streams it remains within the category of ILW at the end of the period ofinterest (c. 2300). At the outset it was emphasised that the assessment of this stream shouldacknowledge that NDA has recently published a Strategic Position Paper [7] on the management ofgraphite. Building upon recent documents on different aspects of graphite management thisstrategic assessment concluded that no sufficient case for changing the baseline strategy forreactor graphite from geological disposal has been put forward, though it fully acknowledges that arange of technical and regulatory factors may in specific situations support an alternative approach.

Stream 3: 2D137 – Miscellaneous Plants Final Decommissioning: Processing Plants,Tanks, Silos, etc (Sellafield)

This stream would result from the final stages of demolition of a range of facilities on the Sellafieldsite, and would comprise concrete, bricks and blockwork. It is a relatively poorly characterisedstream, comprising items over a relatively wide range of sizes – some large blocks of buildingstructure may be present. As a very high volume stream (12,500 m3) it could represent a significantopportunity if diverted from the current default (geological) disposal strategy.

Stream 4: 2F26 – LWR Pond Sludge (Sellafield)3

This stream is a relatively low activity organic sludge. It was considered a challenging waste butone whose consideration may highlight significant potential opportunities that could be appliedmore widely.

The timescales for arising of these four waste streams presented in the following tables are basedupon current planning assumptions. These are subject to change as the NDA strategy forradioactive waste management evolves with time.

1 It was acknowledged within the Task 1 Report that the selection criteria for these waste streams werenecessarily cautious, and hence it may well be possible in future to justify consideration of a larger set ofwaste streams possible diversion from geological disposal.2 The initial proposal was to include dessicants, as a group if possible (3J04, 3K04, 3N04, 4B06 and 9H02).However, as the Task 3 Report [6] concludes, washing these wastes to remove the tritium content has metwith considerable success, so this treatment approach may well become the baseline strategy, therebylowering the activity concentration of these streams to levels considerably below the ILW threshold. It wasdecided to replace this stream with 9G311 for the reasons given below.3 Comprises mainly algae, guano and objects inadvertently dropped into pond.

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0

200

400

600

800

1000

1200

1400

2013 2038 2043 2052 2063 2069 2075 2088 2095 2102 2113 2138 2163 2188 2213 2238 2263 2288 2313

Decay Year

Volu

me

(m3 )

VLLWLLWILW

2.3 Summaries of candidate streamsThe following information is taken from the UKRWI (2013) [1] and the accompanying Waste Data Sheets. The decay information is taken from theTask 1 Report [5].

Stream 1: 9G310 – Final Dismantling & Site Clearance: Mild Steel (Reactor) ILW (Trawsfynydd)

WasteStream ID

Waste Stream Description Volumes and timescales ofarising

Adverse physical /chemical characteristics? Radionuclides / decay Summary comment

9G310

Final Dismantling & SiteClearance : Mild Steel(Reactor) ILW(Trawsfynydd)

1200 m3

Arises between 2069-2088,ILW until 2288-2313

None.A variety of mild steel items

At 2088:Ni-63 (90%), C-14 (8%), Ni-59(2%)

Medium/longer termarising and becomesLLW over longer term

Packaging assumption

Waste is expected to be encapsulated in a cementitious grout within suitable waste containers (e.g. 4 m box [ILW] for GDF (default) or ½ HeightDisposal Container TC01 [LLW] for LLWR).

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0

500

1000

1500

2000

2500

3000

3500

4000

2013 2038 2043 2052 2063 2069 2075 2088 2095 2102 2113 2138 2163 2188 2213 2238 2263 2288 2313

Decay Year

Volu

me

(m3 )

VLLWLLWILW

Stream 2: 9G311 – Final Dismantling & Site Clearance: Graphite ILW (Trawsfynydd)

WasteStream ID

Waste Stream Description Volumes and timescales of arising Adverse physical /chemical characteristics? Radionuclides / decay Summary comment

9G311 Final Dismantling & siteClearance : Graphite ILW,Trawsfynydd

3400 m3

Arisings begin 2075. Maximumvolume reached by 2088Remains ILW at 2313

Graphite blocks and othergraphite components.

At 2088C-14 (94%), H-3 (3%), Ni-63(2%), Cl-36 (0.2%)

Remains ILW overrelevant timescales

Packaging assumption

Waste is expected to be encapsulated in a cementitious grout within suitable waste containers (e.g. 4 m box [ILW] for GDF (default) or ½ HeightDisposal Container TC01 [LLW] for LLWR).

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0

2000

4000

6000

8000

10000

12000

14000

2013 2038 2043 2052 2063 2069 2075 2088 2095 2102 2113 2138 2163 2188 2213 2238 2263 2288 2313

Decay Year

Volu

me (

m3 )

VLLWLLWILW

Stream 3: 2D137 – Miscellaneous Plants Final Decommissioning: Processing Plants, Tanks, Silos, etc (Sellafield)

WasteStream ID

Waste Stream DescriptionVolumes and timescales of arising

Adverse physical /chemical

characteristics?Radionuclides /

decay Summary comment

2D137 Miscellaneous Plants – Finaldecommissioning: ProcessingPlants, Tanks, Silos, etc(Sellafield)

12,500 m3

Arisings begin 2043 and reach maximum by 2088. Theinitial (low volume) arisings at 2043 are ILW, whichdecays to LLW by 2052. At about 2063 the main wasteretrieval campaign commences, giving rise to ILWcategory material. This decays to LLW by 2069.

Concrete, bricks,blockwork

At 2088Cs-137 (40%),Sr-90 (7%)

Relatively poorlycharacterised stream. Maycontain large items.Medium term arising justabove ILW threshold anddecays over short term toLLW

Default packaging assumption (GDF)

Waste is expected to be encapsulated in a cementitious grout within suitable waste containers (e.g. Sellafield 3 m3 box).

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0

5

10

15

20

25

30

35

40

45

2013 2038 2043 2052 2063 2069 2075 2088 2095 2102 2113 2138 2163 2188 2213 2238 2263 2288 2313

Decay Year

Volu

me

(m3 )

VLLWLLWILW

Stream 4: 2F26 – LWR Pond Sludge (Sellafield)

WasteStream

ID

Waste StreamDescription Volumes and

timescales of arisingAdverse physical /

chemicalcharacteristics?

Radionuclides / decay Summary comment

2F26 LWR PondSludge, Sellafield

39 m3

Arisings begin 2013.Max volume reachedat/before 2050. LLWby 2038

Algae, debris andguano (organic sludge).Slightly alkaline, notoxidising or reducing.

At 2052Ni-63 (35%), Cs-137 (29%),Co-60 (2%),Pa-233 (2%),Np-237 (2%), Sr-90 (1%),

Early arising lowvolume stream,becoming LLW overshort term

Default packaging assumption (GDF)

Not yet established in UKRWI. Waste is assumed to be encapsulated in cementitious grout within suitable waste containers, or possibly subject to aform of conditioning and possibly pre-treatment to prevent organic material remaining biologically active or capable of supporting microbial activity withinthe waste containers.

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3 Metrics for assessing benefits anddisbenefits of routing options

3.1 DiscussionThe core of any optioneering process, whether conducted at a higher (strategic) or lower (moredetailed, technical) level, involves considering or assessing the positive and negative aspects of eachof the potential routing options against an agreed set of metrics or attributes. These are factors that,when considered as a consistent set, cover the full range of regulatory and wider stakeholderconcerns.

In this assessment these factors would need to cover specific aspects such as the costs and costsavings of each routing option; their overall operational and post-closure safety implications; theacceptability of the specified wastes at each of the disposal facilities; the consistency of suchproposed disposal with the current NDA strategy as it relates to the management of these wastes; andwhether the disposal facilities being proposed would be available at the time of the waste arising.

As this is essentially a technical appraisal undertaken at a preliminary stage of an overall decision-making process, no attempt has been made to assign relative significances to the individual benefitsand disbenefits in a formal way, which would be required as part of an exercise to develop an overallranking of the specified approaches. The intention, rather, is that the information made available in thisstudy can be used to support a further, more detailed examination of the opportunities presented by awider range of potential disposal routes than would be indicated by an informed interpretation of NDAwaste management strategy and the more limited disposal options currently available.

3.2 Selection for studyThe preliminary set of metrics generated for this study was developed from work undertaken by LLWR[3]. These in turn were based upon previous work undertaken in the context of the assessment of BestAvailable Techniques (BAT) [8] and the NDA’s own guidance on business cases and valuemanagement [9]. This set was reviewed and amended during the workshop. The finalised set ispresented below as Table 1.

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Table 1: Metrics for Assessment of Benefits and Disbenefits of Routing Options

No. Metric Description / Scope

1Cost – segregation,packaging and interimstorage

The relative measure of unit cost of actions that would or may be requiredahead of the disposal of waste stream at each facility. The costs ofretrieval have not been taken into account as these will be commonacross the options.

2 Cost – disposal The relative measure of the unit cost of disposal.

3 Disposability / WasteAcceptance

Measure of acceptability of waste stream for disposal followingconditioning and packaging taking into account radiological and otherfactors. For two of the routing options (the default surface disposal facilitymodelled on LLWR and a deep disposal facility modelled on the proposedUK GDF) specific information and guidance can be provided. For theother, currently more speculative, routing options relative indications areproposed on the basis of whether they are surface, near-surface or atdepth, the engineered features likely to be provided, and values in forceat analogous overseas facilities.

The disposability of a suitably packaged waste stream to a defaultsurface facility (represented by the LLWR) is taken to be sufficientlyrepresented by its compatibility with the current numerical and qualitativeWAC.

The disposability of a waste stream to a GDF located at a depth of 200 to1,000 m will not be subject to activity constraints. Packaged waste willneed to conform to the Waste Package Specification [10] prior toacceptance.

This metric also covers the issue of information and judgements on wastecomposition uncertainty and variability.

4Schedule / Timing –requirement forinterim storage

This metric provides a measure of whether the disposal facility type wouldbe available to receive the waste once it arises. The base assumptionadopted is that interim storage would be at the site of origin, though it isacknowledged that central or regional storage facilities may provided indue course.

The metric also covers any practicable storage period that may berequired to allow the activity content of the waste to decay sufficiently tofall to a level generally consistent with the actual or expected wasteacceptance criteria (and hence justified by the supporting safety case).

5 Requirement forwaste processing

This metric relates to the need for, and resulting technical challengesinvolved in, segregating the waste stream, followed by any treatment andconditioning for packaging ahead of disposal in the specified facility type.

It covers the availability and technical maturity of the necessarytechnology, feasibility for particular wastes, flexibility, and availability ofresources (people and/or infrastructure).

It also covers the possible production of secondary waste.

6 Compatibility withNDA strategy

This metric serves to highlight issues that may indicate potentiallyavoidable departure from NDA strategy. Notable concerns include:

i. Possible impact on planned end-states and the institutional controlperiod for the originating site (such as, from delays in delicensingcaused by the inability to remove wastes in accordance with lifetimeplan) and the disposal facility.

ii. Compatibility with current volume & radiological capacities of thedisposal facilities – i.e. a measure of whether the disposal is anappropriate use of the facility provision.

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4 Waste Disposal Facility Types – RoutingOptions

4.1 Management of Radioactive Waste in the UKThis sub-section of the report summarises the current arrangements for the management of thevarious categories of solid radioactive waste in the UK outside Scotland, for which a differentmanagement policy is in force.1

4.1.1 Low Level WasteLow Level Waste (LLW) is defined formally in the Government policy document [2] as: “Radioactivewaste having a radioactive content not exceeding four gigabequerels per tonne (GBq/te) of alpha or12 GBq/te of beta/gamma activity”. Operational LLW in the UK requiring disposal is super-compactedto reduce its volume and sent for disposal at the LLWR, where it is encapsulated in cement andpackaged in large steel containers. These are then placed in an engineered vault a few metres belowthe surface. LLW from decommissioning activities which requires disposal, which typically comprisesmetallic items and structures, along with brick and concrete structural materials, is generally size-reduced as appropriate and grouted directly into the steel containers.2

4.1.2 Higher Activity WastesHigher Activity Wastes (HAW) is defined in the UK as wastes and comprising Intermediate LevelWaste (ILW) – “with radioactivity levels exceeding the upper boundaries for low-level wastes, butwhich do not require heating to be taken into account in the design of storage or disposal facilities”,and High Level (or Heat Generating) Waste (HLW) – “in which the temperature may rise significantlyas a result of their radioactivity, so that this factor has to be taken into account in designing storage ordisposal facilities” [2]. The latter comprises the highly radioactive products from reprocessing andspent fuel. ILW, which is of concern in this study, arises mainly from the reprocessing of spent fuel andfrom general operations and maintenance at nuclear sites, and comprises a wide range of items,ranging from metal items such as fuel cladding and reactor components, to sludges from the treatmentof radioactive liquids. Typically, ILW is packaged for disposal by encapsulation in cement in highly-engineered 500 litre stainless steel drums or in higher capacity steel or concrete boxes.

Government policy for waste arising in England and Wales is that HAW will be disposed of to a futuregeological disposal facility (GDF), in which radioactive waste will be isolated deep inside a suitablerock formation to ensure that no harmful quantities of radioactivity ever reach the surface environment.Such disposal is internationally recognised as the preferred approach for the long-term managementof higher activity radioactive waste.

HAW also includes a small fraction of the total volume of LLW that cannot be disposed to a surfacefacility in the UK, due principally to the concentration of specific radionuclides (those with long half-lives or other undesirable radiological properties). Current plans for waste arising in England andWales are that it would be disposed of in a GDF in a similar way as HAW.

1 This policy states that the long term management of HAW that arises in Scotland currently is storage in nearsurface facilities, with the option of retrieval kept open ahead of any future decision on final disposal. Thisdifference means that this study will currently have very limited relevance to decisions on managing some formsof wastes that arise in Scotland that are within the boundary of ILW and LLW classifications.2 A similar strategy is being adopted for the near-surface LLW disposal facility at Dounreay Site RestorationLimited in Scotland.

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4.2 Waste Disposal Facilities – Routing OptionsThe four case studies in this work involve the examination of the specific benefits and disbenefits ofrouting the four candidate waste streams outlined in Section 2.3 to each of four disposal facility typesin turn. These are as follows:

Option A – a surface disposal facility designed for LLW with the characteristics and features of thecurrent LLWR,

Option B – a more engineered surface facility modelled on the facility at Centre de L’Aube inFrance operated by ANDRA that was designed for LLW and some short-lived ILW,

Option C – a cavern-based disposal facility located in the region of 50 m of the surfacerepresented by the SFR operated by SKB (Swedish Nuclear Fuel and Waste ManagementCompany) and suitable for LLW and most ILW,

Option D – a geological disposal facility of the illustrative design presented by RWM Limited forthe UK that would be located between depths of 200 m and 1,000 m and capable of managing allwaste types.

As far as the availability these disposal facilities is concerned, for the purposes of this study it isassumed that a surface disposal facility of the type represented by LLWR (Option A) will be availableover the entire period over which the waste streams arise, but some consideration will be taken of thefact that such a facility or facilities will have limitations on their volumetric capacity as they aredesigned primarily to accept LLW.

Analogously, for disposal facilities of the general types represented by Options B-D, it is assumed thattheir development in the UK has been agreed in principle and that they will be made available to wasteproducers within a few decades.

To facilitate the appraisal and comparison of the benefits and disbenefits of the routing optionsreported later in this report in Section 6, general comments against each of the metrics are providedwithin the overviews of each facility type.

4.2.1 Option A – Disposal to an engineered surface facility for LLWRepresented by LLWRSummary of main features [11, 12, 13]

The LLWR is the UK’s principal facility for the disposal of solid low-level radioactive waste. For the first36 years of operation, disposals were by tumble tipping of drummed, bagged and loose wastes intosuccessive trenches within the ‘consented area’. During disposals, the waste was covered by soil atthe end of each day and periodically, a hardcore layer was placed to facilitate tipping operations.

From 1987 onwards, disposal operations were upgraded and remedial work was carried out on thetrenches. An engineered, concrete disposal vault was constructed (Vault 8), which allowed the orderlyemplacement of containerised waste within an engineered concrete structure according to moremodern disposal standards. The introduction in 1995 of waste monitoring and high-force compactionat the WAMAC (Waste Monitoring and Compaction Plant) facility on the Sellafield site significantlyimproved the waste loading of the ISO containers. Some of these received before 1995 were sentback to WAMAC for the waste to be compacted. In the light of decisions taken by the regulators andplanning authorities, a detailed analysis and associated rationale was developed and a preferred‘Modular Vault’ design adopted for the construction of Vault 9, whose construction was completed in2010. This is intended to serve as a baseline design for future vaults.

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Figure 1: Illustration of operation of LLWR Vault 9

The compacted and non-compacted wastes are grouted within steel half-height (or third-height) ISOcontainers, which are then stacked within the engineered structure. The vaults are constructed on aconcrete base with an underlying drainage layer and concrete walls. The structure is below groundlevel. Vaults are surrounded by surface water drains, which collect rainwater from the surface of thevault base slab whilst a drainage blanket under the slab and perimeter drains collect groundwater frombeneath and around the vault. The principal means of leachate containment is the naturally occurringclay layer at about 5 m below ground level.

Once disposal operations are complete the entire area of vaults and trenches will be closed insequence from north to south with a unified multi-layered barrier system, comprised of a highlyengineered, single dome final cap, cut-off wall and associated engineering. This will be constructed instrips across each vault and the adjacent area of the trenches, as soon as practicable after closure ofeach vault.

The cap is designed to provide the best practicable impermeable barrier to infiltration of rainwater andto intrusion, and to maintain its functions for as long as possible. The potential effects of wastedegradation and subsidence have been assessed and it has been concluded that the resultantdifferential settlements will be small and consistent with sufficient long-term performance.

Costs – segregation, packaging and interim disposal

As the UK currently has a disposal facility for LLW in the form of LLWR, and is assumed always tohave a similar facility, no significant period of interim storage would be required for wastes to bedisposed of to the facility other than for any decay storage that might be required. In some cases thereare also likely to be waste segregation costs, but these will vary from disposal site to disposal site andare borne by the waste producer and hence not included here. Indications of the current costs of thelarge mild steel containers can be inferred from the latest LLWR Service Price List [14]. On the basisof the model facilities employed in this preliminary assessment for more engineered near-surfacedisposal and geological disposal it is concluded that these were likely to be significantly less expensiveper unit volume of waste than the more robust containers that would be used in more engineeredsurface facilities and those fabricated from stainless steel that would be appropriate for geologicaldisposal, though it has to be admitted that the benefits of more robust engineered features and adeeper disposal location may permit the reverse assumption to be adopted.

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Costs – disposal

The current costs of disposal are dependent on whether waste is packaged in a standard containerand whether it has been compacted. The standard volume charge for 2013/14 is ~£3k/m3 [14], withadditional radioactivity charges levied on a per MBq basis. Higher rates for radioactivity content applyto specified radionuclides.

Disposability / Waste acceptance

The (low level) waste accepted currently is required to conform to the Waste Acceptance Criteria(WAC) [15]. These have very recently been updated in line with the radiological capacity valuespublished in the LLWR Environmental Safety Case (ESC) [16]. The WAC specify a range ofradiological, physical and chemical restrictions on materials and packages for disposal. These are tobe taken as applying in addition to the overarching (EA Permit) activity limits of 4 GBq/t for alpharadionuclides and 12 GBq/t for beta/gamma radionuclides. Radionuclide and radionuclide groupconcentration and/or activity limits are in force at the consignment, vault and facility level. Wastesinclude packing materials, paper, protective clothing, electric cables, scrap metals and tools, as well asreactor wastes and other materials.

Radiological aspects: Overarching EA Permit activity limits for waste are 4 GBq/t (alpha) and 12 GBq/t(beta/gamma). Following 2011 ESC additional, radionuclide specific limits (radiological capacityvalues) are being applied to waste consignments (effectively each ISO container) [16]. These are to beapplied using the ‘sum of fractions’ approach to ensure that the total impact of all radionuclides isappropriately accounted for.1

Table 2: Radiological capacity values applicable to allwaste consignments to LLWR

RadionuclideRadiological Capacity

Values (GBq t-1)Radionuclide

Radiological CapacityValues (GBq t-1)

Nb-94 0.22 Np-237 1.2

I-129 70 Pu-239 1.4

Ag-108m 1.1 Pu-240 1.6

Ra-226 0.26 Pu-241 240

Th-229 0.54 Pu-242 1.5

Th-230 0.45 Pu-244 0.58

Th-232 0.11 Am-241 8.1

Pa-231 0.28 Am-242m 60

U-233 4.2 Am-243 1.1

U-234 16 Cm-245 0.85

U-235 2.1 Cm-246 1.9

U-236 21 Cm-248 0.099

U-238 9.4 Others* 300* ’Others’ excludes radionuclides with half-lives less than 3 months

1 The ‘sum of fractions’ approach involves dividing the inventory of each radionuclide by its radiological capacityand ensuring that the sum of all the contributions evaluated in this way is less than 1.

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Table 3: Radiological capacity values applicable toupper stack position consignments

RadionuclideRadiological Capacity

Values (GBq t-1)Radionuclide

Radiological CapacityValues (GBq t-1)

H-3 290 U-234 0.060

C-14 0.012 U-235 0.065

Cl-36 0.0023 U-236 1.7

Ni-63 77 U-238 0.37

Sr-90 0.51 Np-237 0.046

Zr-93 210 Pu-238 0.97

Nb-94 0.0054 Pu-239 0.41

Mo-93 0.84 Pu-240 0.41

Tc-99 0.076 Pu-241 12

Ag-108m 0.0064 Pu-242 0.43

I-129 0.32 Pu-244 0.024

Cs-135 5.4 Am-241 0.42

Cs-137 0.15 Am-242m 0.36

Pb-210 0.25 Am-243 0.054

Ra-226 0.00011 Cm-242 190

Ac-227 0.57 Cm-243 0.86

Th-229 0.029 Cm-244 29

Th-230 0.00031 Cm-245 0.10

Th-232 0.0031 Cm-246 0.49

Pa-231 0.020 Cm-248 0.0031

U-233 0.27 Others* 300*’Others’ excludes radionuclides with half-lives less than 3 months

These values are in addition to those in the previous table and such wastes will be managed using acapacity management and emplacement strategy.

Any intent to dispose of waste materials that breach these WAC, even for a short period of timefollowing emplacement, would be subject to prior agreement/authorisation by LLWR, the EA and NDA.

The current Lifetime Plan for LLWR does not make provision for the disposal of material which isnominally ILW at the time of arising, nor of specified LLW that would breach the current WAC (e.g.reactor graphite). Accordingly, acceptance of such additional waste for disposal at the facility cannotbe guaranteed, though in the light of the modest volumes involved and the nature of the wastes thatwould be considered for diversion from the current assumption of geological disposal, is unlikely topose a major challenge.

Non-radiological aspects: Waste accepted at LLWR must conform with a number of restrictions onliquid content, voidage, reactivity and chemical toxicity. In particular, any disposed materials must notinvalidate any of the assumptions made in the ESC regarding the post-closure performance of thefacility as a whole.

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Schedule / Timing – requirement for interim storage

It is assumed in this study that there would be no restrictions on the availability of an LLWR-typefacility for the disposal of wastes deemed to be acceptable.

Requirement for waste processing

Physical, chemical and thermal techniques may be used to ensure that an appropriate and acceptablewasteform is produced that conforms to the WAC. Size reduction of large items may be required insome cases. The ISO containers used are grouted at LLWR to ensure that a robust wasteform isproduced that provides protection to the waste and minimises the voidage within the containers.

Compatibility with and effect on NDA strategy

The potential advantages and disadvantages arising from a proposal to dispose of waste within theboundary of the LLW and ILW classifications will depend largely on the radionuclide inventory (half-life, etc) and volume of the individual waste streams. The issues may include the possible impact onthe current end-state requirement for LLW, or the timescale for its achievement, together with how thenecessarily limited volumetric capacity of the facility would be managed.

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4.2.2 Option B – Disposal to a more engineered surface disposal facility suitable forboth LLW and some ILWRepresented by the CSFMA facility at Centre de L’AubeSummary of main features [17, 18, 19]

In this case it is assumed that a more engineered disposal facility for LLW and material wastestowards the lower boundary of ILW has been authorised for construction in the UK and would be madeavailable in due course. For this work, the representative design and other characteristics of such afacility are based on the example of the CSFMA at the Centre de l’Aube in France, which currentlyaccepts short-lived low- and intermediate-level waste (and more limited amounts of longer-livedradionuclides), mainly from the nuclear power industry and the activities of the French atomic energycommission (CEA). It also includes waste from hospitals, research and university laboratories. In thefuture, waste from clean-up and dismantling of nuclear facilities may be disposed of at the Centre del’Aube.

Following the example of the CSFMA, the waste would be disposed of at surface in reinforcedconcrete vaults with walls approximately 30 cm thick. The cells within the CSFMA vaults are 25 metressquare and 8 metres high. The facility has about 400 above ground concrete vaults and, depending onwaste type, after filling with waste packages they are back-filled with either gravel or concrete, and arethen topped with a concrete slab and sealed with an impermeable coating. Each vault can take 2,500–3,500 m3 of waste. Finally, the cell will be capped with a several metres thick layer of clay, to ensurethe exclusion of water. The CSFMA is designed to accommodate 1,000,000 m3 of waste.

The main types of waste packages used are, steel drums and concrete or steel boxes. The waste isembedded in a concrete matrix, thus a waste package is composed of 15–20% radioactive waste and80–85% embedding matrix.

Containment in the packages is provided by the waste matrix (homogeneous waste) which forms adiffusion barrier. The minimum thickness for the concrete envelope is calculated as that needed toprovide mechanical strength and containment for a few hundred years.

Figure 2: More engineered surface disposal facility (Centre de l’Aube)

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Figure 3: Aspects of design, future state and operation ofthe CSFMA disposal facility

(a) Concrete disposal vaults (b) Artist’s impression of (c) Grouting of the wastecompleted set of vaults drums within disposal

vault

General waste acceptance criteria that apply to all packages that are delivered provide requirementson the physical-chemical properties of the waste: e.g. no free liquid, inert matter. They focus on theradiological characterisation of the package, particularly on the identification of radionuclides that maybe present. A list of 143 nuclides has been established. The dose rates of all waste packages aremeasured to detect waste that could contain higher quantities of activity than have been taken intoaccount in the safety assessment. Activity limits are derived from the safety scenarios, see below, andsome limits are prescribed to avoid “hot spots” in the repository.

Another key aspect is the identification and control of materials that might have a chemical impact.These materials are partly identified from regulations relevant for non-radioactive repositories, e.g.lead, boron, nickel, chrome (total and oxidised form), antimony, selenium, cadmium, mercury,beryllium, arsenic, free cyanides, ammonia and asbestos. These materials must be quantified,generally using typical chemical spectra for waste. This inventory provides data to perform chemicalimpact calculations.

In common with other operational surface and near-surface facilities, the safety case for the CSFMArequires that following the termination of the institutional control and monitoring period (no more than300 years). At that time, safety should no longer rely on the artificial barriers but on wider issues suchas the level of rainfall at the site and how surface water would be managed. Scenarios are derived thatinclude normal and abnormal situations (intrusion for instance).

Costs – segregation, packaging and interim disposal

As this type of facility in the UK would be designed for wastes that exceed the current activityconcentration limits for a facility such as LLWR, it is likely that higher specification and hence moreexpensive waste containers would be used.

As indicated earlier in this section, this type of facility would be made available within a few decades,and so waste that is intended to be routed to it arising in the near future would require interim storagein the intervening period. Judgements on the relative significance of such costs have been based uponthe current version of the NDA Waste Lifecycle Cost Calculator and Norms [20].

Costs – disposal

Information on the disposal costs for the representative facility at Centre de l’Aube is difficult to secure.An NEA review [21] in 1999 provided indications of the various costs associated with the constructionand operation of LLW repositories across a number of states. These covered a range of near-surfacefacilities, together with geological repositories of various designs. Notwithstanding that the costs ofdisposal may or may not also include provisions to cover construction as well as operation, from theinformation provided it is clear that disposal of boundary wastes to more engineered facilities such asthe CSFMA will be significantly more expensive than for a facility such as the LLWR. The NEA reportwould suggest a factor of about two.


It is recognised that the current WAC for CSFMA should only be used as indicative values, as ananalogous facility in the UK would set need to its own values based on the waste, site/location and

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regulatory factors relevant to the UK. A notable difference is that the CSFMA is located in a lessdensely populated and more arid region than the LLWR. This will tend to reduce the unit impact of thedisposal of some radionuclides. Mindful of these and other differences, some concentration limits inforce at the CSFMA and LLWR are reproduced below to provide some background to theconsideration of the differences introduced by the level of engineered barriers provided in surfacedisposal facilities.

Table 4: A comparison of the waste concentration limits for CSFMA and LLWR [16, 18, 19]

RadionuclideActivity limit perpackage CSFMA

(Bq/g) and (GBq/t)Equivalent LLWR

value (GBq/t)

H-3 2.0 105 (200) 290

C-14 9.2 104 (92) 0.012

Cl-36 5.0 (0.005) 0.0023

Fe-55 6.1 109 (6.1 106) 12

Co-60 1.3 108 (1.3 105) 12

Ni-59 1.1 105 (110) 12

Ni-63 3.2. 106 (3200) 12

Se-79 5.5 104 (55) 12

Sr-90 6.0 106 (6000) 0.51

Nb-94 - 0.0054 & 0.22 1

Tc-99 4.4 104 (44) 0.076

Pd-107 3. 105 (3000) 12

Ag-108m 1.4 103 (1.4) 0.0064 & 1.1 1

Sb-125 5.1 108 (5.1 105) 12 & 701

I-129 1.4 103 (1.4) 0.32

Cs-135 2.6 105 (26) 5.4

Cs-137 3.3 105 (33) 0.15

Sm-151 4.5 105 (45) 12

Total alpha(after 300 y) 3.7 103 (3.7) 4 2

The radionuclide-specific values are, as expected in a number of cases, significantly or considerablygreater than the corresponding values for LLWR.

As far as radiological capacity is concerned, a surface disposal facility of this type in the UK wouldmost likely be constructed to dispose of wastes that would be unacceptable at LLWR.3

1 Depending on whether package is placed in upper level of stack or not.2 A number of lower, nuclide-specific values (e.g. for Pu-239), have also been published.3 Such a facility could also of course be designed and sized to accommodate wastes that are currently acceptableat LLWR.

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No surface disposal facility with more developed engineered features than the LLWR has beenconstructed in the UK. As indicated previously, it is assumed in this study that the provision of such afacility has been agreed in principle and will be made available to waste producers within a fewdecades. Waste that arises before this time would therefore require interim storage.


As this facility would be designed to provide a greater level of containment of radionuclides over thelong-term, and have a greater degree of physical robustness, it is possible that the waste streamsselected for disposal may require a greater degree of processing/treatment than would be the case fora less engineered facility. The other comments made on Option A are also applicable here.


The current NDA strategy makes no specific reference to the concept of more engineered surfacefacilities for the specific purpose of disposing of solid radioactive wastes. The availability of a widerrange of disposal facilities in the UK could be argued as strengthening national policy as more of thematerial within the 2013 UKRWI would be assigned to facilities designed specifically (i.e.proportionately) to receive it. In addition, it would both reduce the burden on existing facilities andpotentially reduce the volume of wastes destined for geological disposal. An end-state that meets theexpectations of stakeholders would be agreed following the necessary consultations.

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4.2.3 Option C – Disposal to a Cavern-Based Disposal Facility located in the regionof 50 m of the surface suitable for LLW and most ILWRepresented by the SFR facility operated by SKB at Forsmark

Summary of main features [17, 22, 23]

In this case it is assumed that a below-surface facility at a depth of a few tens of metres within anestablished geological horizon for a variety of ILW had been authorised for construction in the UK andwould be made available in due course. For this work, the representative design and othercharacteristics of such a facility are based on the example of the Swedish Final Repository (SFR),mainly for operational waste from the nuclear industry, but which in future will also acceptdecommissioning wastes.

The Swedish repository is designed for short-lived low and intermediate level waste (spent ionexchange resins and scrap metal from the refurbishment of nuclear plant) and currently has a capacityof 63,000 m3, comprising four rock caverns and one silo. The caverns differ in terms of their designand expected long-term performance, and are located at different depths. Although the waste isclassified as short-lived, it also contains radioactive substances with a very long half-life. SKB isrequired to demonstrate the future performance of the facility over tens of thousands of years.

The SFR is located 50 metres beneath the seabed in crystalline bedrock. At present, the area abovethe repository is covered by the sea. However, the ongoing shore-level displacement (the land risingafter the latest glacial period) at the site will lead to substantial changes of the geohydrologicalconditions and the surface ecosystem during the next coming 10,000 years. This is considered in thesafety assessments.

The SFR consists of four 160-metre-long rock vaults, plus a rock cavern with a 50-metre-high concretesilo. Two access tunnels connect the facility to the ground surface.

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Figure 4: Cavern-based disposal facility at 50 m depth (SFR)

A 50 m high concrete silo surrounded by a clay buffer contains intermediate level waste (ILW) holdingabout 90% of the total activity content in SFR. The waste in the silo is solidified with cement orbitumen in containers of steel or concrete (moulds and drums). The containers are embedded inconcrete in the shafts in the silo, acting as the first barrier. The next barrier is the silo’s concrete wall,which is nearly one metre thick. Between the outer wall of the silo and the rock, which also acts abarrier, is a thick layer of bentonite clay. The impervious clay prevents groundwater from flowingthrough the silo. It also acts as a filter and captures any radionuclides that might escape from the siloand protects the silo from movements in the rock.

The remaining 10% of the activity will be disposed of in four more simple rock caverns. One of the fourrock caverns (BMA) is also used to dispose of some intermediate level waste where the external dosefrom the wastes is such that radiation shielding is required. The packages consist mainly of moulds ordrums, and the vault consists of a number of storage compartments. The caverns for BTF and BLAare used to dispose of low-level waste.

Low level waste mainly consisting of protective clothing is deposited in standard ISO freightcontainers in one of the four rock vaults (BLA).

The load bearing structural parts of the BMA vault are founded on solid rock. The bottom slab isfounded on a base of rock levelled with gravel. The bottom slab, walls and floor structures are made ofin situ cast reinforced concrete. The walls and roof of the rock vault are lined with shotcrete. Aprefabricated concrete lid is put in place after the compartments are filled with waste. The lids provideradiation shielding and fire protection. Another concrete layer is cast on top of the prefabricated lids togive the structure added stability and tightness. BMA has three barriers; the waste package, thecompartment structures and the surrounding rock.

Figure 5: Interiors of three of the types of openings at SFR

(a) Top of ILW silo (b) Rock cavern for ILW (BMA) (c) Rock cavern for LLW (BLA)

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In summary, the SFR facility has been designed to accommodate a range of individual types of wastesin the LLW-ILW range and that a variety of types of openings and engineered barriers are used asappropriate.

Costs – segregation, packaging and disposal

The waste containers that would be employed for this type of facility in the UK would probably berequired to have a higher specification than is currently in use for surface disposal, and following thepractice at a proposed UK GDF may be constructed using stainless steel, which is significantly moreexpensive.

As for the conceptual, more engineered, surface disposal facility discussed in the previous section thistype of facility would be made available within a few decades, and so waste that is intended to berouted to it arising in the near future would require interim storage in the intervening period.Judgements on the relative significance of such costs have been based upon the current version ofthe NDA Waste Lifecycle Cost Calculator and Norms [20].

Costs – disposal

As in the previous case for the more engineered surface facility, specific information on disposal costsfor a facility such as SFR as a representative facility located within a few tens of metres of the surfaceis difficult to secure, and where such costs are available, the allocation of costs between construction(not considered in this study), operation and final closure does not appear to be consistent acrossfacility types.

A high level consideration of the factors affecting the operation of geological and near-surface disposalfacilities implies strongly that disposing of wastes even a few tens of metres underground would besignificantly costlier than disposing on or near the surface, even if the latter are engineered to asignificantly greater degree than LLWR.


No package-specific activity limits could be obtained for SFR. Facility limits available are thosepublished in 2010 [22] and reproduced below. These limits appear to be independent of one another,and therefore would not be applied using the ‘sum of fractions’ approach commonly used elsewhere(e.g. at LLWR).

Nuclide Half-life(year)

Total activity limit (Bq)

BLA BMA BTF Silo3H 12.3 — — — 1.3 1014

14C 5.7 103 2.6 109 2.9 1011 1.3 1011 6.8 1012

55Fe 2.7 2.3 1012 1.0 1014 1.7 1013 7.1 1014

59Ni 7.5 104 2.3 1010 1.0 1012 1.5 1011 6.8 1012

60Co 5.2 5.8 1012 2.6 1014 4.0 1013 1.8 1015

63Ni 100 1.9 1012 8.8 1013 1.5 1013 6.3 1014

90Sr 28.8 7.1 1010 6.5 1012 2.7 1012 2.5 1014

94Nb 2.0 104 2.3 107 1.0 109 1.5 108 6.8 109

99Tc 2.1 105 1.1 108 8.8 109 3.6 109 3.3 1011

106Ru 1.0 2.1 109 1.7 1011 6.2 1010 6.1 1012

129I 1.6 107 6.4 105 4.7 107 2.2 107 1.9 109

134Cs 2.3 2.6 1011 2.2 1012 1.1 1013 8.1 1014

135Cs 3.0 106 6.4 106 5.3 108 2.2 108 1.9 1010

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Nuclide Half-life(year)

Total activity limit (Bq)

BLA BMA BTF Silo137Cs 30. 2 1.4 1012 1.3 1014 5.3 1013 4.9 1015

238Pu 87.7 4.7 108 3.1 1010 1.7 1010 1.2 1012

239Pu 2.4 104 1.9 108 1.2 1010 6.9 109 3.8 1011

240Pu 6.6 103 2.9 108 1.9 1010 1.1 1010 7.8 1011

241Pu 14.4 1.5 1010 9.4 1011 5.4 1011 4.2 1013

241Am 433 3.8 108 2.4 1010 1.3 1010 1.0 1012

244Cm 18.1 4.4 108 2.8 109 1.5 109 1.2 1011

Total activity 1.2 1013 6.0 1014 1.4 1014 9.2 1015

Comparison with the corresponding facility capacity values available for LLWR [16] shows that theindividual radionuclide limits for SFR are in most cases considerably lower. This would appear to be atvariance with the expectation that as a disposal facility located at approximately 50 m depth could beexpected to accept waste with activity concentrations that are much greater than the correspondingvalues for surface facilities such as LLWR and (to a lesser degree) more engineered surface variants.This argument would be based upon the greater isolating properties of the surrounding rock and amore favourable hydrogeological environment. The engineered barrier system may also be morerobust. The reasons for the unexpectedly low declared radiological capacities are unclear. It seemspossible that they are driven by the nature of the wastes destined for the repository.

As in the previous case, it is not appropriate to apply the precise numerical WAC for an exampleoverseas facility too strictly, which in this case can be only be inferred as only facility limits seem to bepublished, as they will be dependent upon many factors unrelated to the performance of the facility.For the purposes of this study it is assumed that a UK disposal facility located at an intermediate depthof 50 m within a geological context suitable for the long-term containment radioactive waste wouldhave significantly higher numerical WAC than either a surface facility similar to LLWR or one that hasmore engineered features such as the CSFMA.


No below-surface disposal facility of any description has been constructed in the UK. As indicatedpreviously, it is assumed in this study that the provision of such a facility has been agreed in principleand will be made available to waste producers within a few decades. Waste that arises before thistime would therefore require interim storage.


From publically available information there would appear to be no significant differences between thepackaged waste forms that are generally acceptable at facilities situated at depths typified by SFR andthe more engineered near-surface disposal facilities. As this facility will be designed to provide agreater level of containment of radionuclides over the long-term, and have a greater degree of physicalrobustness, it may be reasonable to assume that the waste streams selected for disposal at a futureUK facility of this type may require a greater degree of processing/treatment than is currently the casefor surface disposal. As in the cases of Options A and B, waste may need to be grouted (orconditioned in some other way) prior to dispatch to ensure conformance with the WAC, but as thefacility itself would provide the necessary degree of structural integrity, grouting for this purpose alonewould probably not be necessary.


The current NDA strategy specifies that higher activity wastes will be managed by means of geologicaldisposal, which is assumed to involve constructing an engineered facility, ‘typically between 200 and

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1,000 metres underground’, but the exact depth will depend on the site geology. For planningpurposes, a minimum depth of 200 m is specified [24].

The availability of a wider range of disposal facilities in the UK may be expected to strengthen nationalpolicy as more of the material within the 2013 UKRWI would be assigned to facilities designedspecifically (i.e. proportionately) to receive it. In addition, it would both reduce the burden on existingfacilities and lead some lowering of the required provision for wastes currently identified for deeper,geological disposal. A facility located at 50 m depth could be located within the footprint of a ‘NationalGDF’, or co-located to allow any processing, reception and other facilities to be shared. An end-statethat meets the expectations of stakeholders would be agreed following the necessary consultations.

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4.2.4 Option D – Disposal to a proposed Geological Disposal Facility located at adepth of 200 m – 1,000 m and able to accommodate all waste typesRepresented by a GDF design proposed by NDA RWM Limited

Summary of main features [24, 25]

The UK Government’s Strategy as set out in a 2008 White Paper [2] is to manage HAW (comprisingILW, High Level Waste (HLW)/Spent Fuel (SF) and LLW unsuitable for near-surface disposal) in thelong-term through geological disposal. This will involve constructing an engineered facility (GDF),typically between 200 and 1,000 metres underground to isolate the wastes from the environment andensure the radioactivity is sufficiently contained so that it will not be released back to the surface inunacceptable amounts that may cause harm to people and living things.

Figure 6: Illustration of a generic GDF (with co-located sections for HLW and SF)

A GDF will utilise a series of barriers working together to isolate the wastes and contain theradionuclides associated with the wastes. The typical barriers found in a multi-barrier geologicaldisposal system include:

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The waste form

This is the form into which waste is conditioned to make itsuitable for disposal. ILW is typically cemented into a solidblock within its waste container, for some ILW a resin is usedinstead of cement; HLW is turned into glass andencapsulated within a stainless steel container.

The waste containerProvides a physical barrier and enables the waste to betransported and handled safely during interim storage andthen for emplacement in a GDF.

The buffer or backfillThe material that is placed immediately around the wastecontainers providing physical protection of the wastecontainers and in some cases a chemical barrier.

Mass backfill The material used to fill the excavated access tunnels, shaftsor drifts in a disposal facility.

Sealing systems Complements the mass backfill and controls the movementof fluids along the excavated access tunnels, shafts or drifts.

The natural geologicalbarrier

The host rock in which the facility is constructed and itssurrounding rocks.

A geological disposal facility will be designed to accept waste packages that comply with the GenericWaste Package Specifications [26], and sized accordingly.

Prior to operating a geological disposal facility, WAC will be established for all wastes to be emplacedin a geological disposal facility. Even though such a disposal facility would only accept wastes thatcomply with the WAC, as the facility itself will be designed with reference to the range of wastes thatare required to be accepted, in practice this is unlikely to impose any further restrictions on thedisposal of boundary wastes, in addition to the restrictions in place for HAW.

Costs – segregation, packaging and disposal

The waste containers that would be employed for this type of facility in the UK would be required tohave a higher specification than is currently in use for surface disposal, and most would beconstructed using stainless steel, which is significantly more expensive.

As for the conceptual disposal facilities discussed in the previous two sub-sections, this type ofrepository would be made available within a few decades, and so waste that is intended to be routedto it arising in the near future would require interim storage in the intervening period. Judgements onthe relative significance of such costs have been based upon the current version of the NDA WasteLifecycle Cost Calculator and Norms [20].

Costs – disposal

Ahead of undertaking a more specific assessment of the costs of disposing of the waste streams ofparticular interest, a high level consideration of the factors affecting the provision of geological andnear-surface facilities leads to the conclusion that disposing of wastes within geological formations atdepth would be significantly costlier than disposing nearer the surface, even if such facilities areengineered to a significantly greater degree than the current LLWR.


As indicated above, waste to be disposed at a GDF must comply with the Waste PackageSpecifications [26]. As such, appropriate packaging arrangements consistent with these have been orwill be used, whether these have been proposed by the waste producer and endorsed by NDA, orotherwise assumed by NDA. Waste acceptance at a geological disposal facility is likely to pose theleast challenge among the set of facility types considered in this study.

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No geological disposal facility of any description has been constructed in the UK. As indicatedpreviously, it is assumed in this study that the provision of such a facility has been agreed in principleand will be made available to waste producers within a few decades. Waste that arises before thistime would therefore require interim storage.


As far as processing/treatment and packaging are concerned, the statements for disposal ofradioactive waste at a lower depth than is currently proposed by the NDA also apply here.


The current NDA strategy [4] specifies that HAW will be managed by means of geological disposal,which will be by means of an appropriately engineered facility, ‘typically between 200 and 1,000metres underground’, but the exact depth will depend on the site geology. As the wastes of concern inthis study are currently at the lower boundary of the definition of ‘higher activity’ and many will haveundergone radioactive decay to a sufficient degree so that it no longer qualifies as such, the NDA islikely to support a more flexible application of its Strategy by reviewing such wastes that are currentlyplanned to be consigned to a national GDF with a view to considering other, more appropriatedisposal routes.

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5 Assessment Approach5.1 Introduction

As indicated in the Introduction, the case studies which form the focus of this study are intended toidentify and then evaluate the range of benefits and disbenefits of disposing of each of the candidateboundary waste streams presented in Section 2 to each of the facility types summarised in Section 4.

Following work to collate information on the waste streams and representative disposal facilities andprepare briefing information, the main stage of the assessment was undertaken in a facilitatedworkshop held at RWM Limited, attended by participants from RWM Limited, LLWR Ltd, Magnox Ltdand AMEC. As a group, these were able to bring a broad range of knowledge and expertise on themanagement of a wide range of radioactive wastes, both in the UK and wider afield, and therefore tothe assumptions and constraints that would or may be relevant if alternatives to the current decisionson disposal were to be explored.

At this early stage of the consideration of the opportunities for boundary wastes that could be realisedby re-routing it is neither possible nor appropriate to undertake a more sophisticated optioneering andconsultation process to explore the widest possible range of implications of the different routingoptions. The case studies have therefore been restricted to generating high level indications of thelikely relative performance – whether advantageous or disadvantageous – of each routing optionagainst each metric in turn. These indications were based upon the consensus view of the participantsat the workshop. No formal attempt was made within the assessment to integrate the separatemeasures of the benefits and disbenefits into an overall measure of favourability for each disposalroute, though some tentative conclusions may be justified.

5.2 Scoring schemeThe scoring scheme used in this study is as illustrated graphically in Figure 7. The following relativescale centred on the LLWR (taken as the representative of a surface disposal facility for LLW in theUK) was employed to record the performance of each routing option against each metric: Neutral, oras a Minor, Moderate or Major Advantage or Disadvantage. Decisions on whether one routing optionwould provide a benefit or a disbenefit on the issue of the cost of disposal or the need for wasteprocessing prior to packaging were based upon available information (numerical or qualitative) wherepossible, and where this approach was not possible, sufficiently recorded expert judgements wereapplied.

LLWR was set as the reference point for this exercise due to the fact that substantially moreinformation for it is available on issues such as its waste acceptance criteria and the costs of disposalthan for the other facility types, which are at the present time conceptual. For each waste stream andeach of the attributes, disposal options are compared against the reference point to establish if theyrepresent an advantage or a disadvantage and the justification for that assessment was recorded.

It is important to bear in mind that structuring the comparative assessment in this way is entirely apractical consideration, and should not be interpreted as implying that the LLWR or other surfacefacility for which it is a representative would necessarily be the default routing option for any of thewaste streams.

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Minor Moderate Major

Referencepoint

Neutral

Advantage

Disadvantage

Figure 7: Scoring scheme - relative performance of each routing optionagainst each metric

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6 Assessment Results

6.1 9G310 – Final Dismantling & Site Clearance: Mild Steel(Reactor) ILW (Trawsfynydd)

Packaging assumption – Waste is expected to be encapsulated in a cementitious grout withinsuitable waste containers (e.g. 4 m box [ILW] for GDF (default) or ½ Height Disposal Container TC01[LLW] for LLWR).

6.1.1 Option scores1. Costs – packaging, segregation and interim storage

The distribution of pre-disposal unit costs across the considered facility types is a function of therespective packaging cost, the need for interim storage to permit compliance of this waste stream withthe facility acceptance criteria, and the associated need to re-package the waste during this time.

Disposal Option Comment Score on relativescale

A Default SurfaceFacility

Interim storage would be required aswaste not expected to meet WAC untilaround 2313

Waste likely to need re-packagingseveral times during this interim storageperiod of >200 years; interim store willneed to be replaced (likely store lifetime~100-150 years)

Reference point

B More EngineeredSurface Facility

Interim storage would be required, butlikely to be shorter than Option A as theWAC is likely to be less restrictive.

May need to be repackaged during thistime but with lower frequency due to ashorter expected duration of interimstorage; interim store may need to bereplaced

Minor advantage

C Facility situated at~50 m

Would be no requirement for interimstorage as waste conforms with WAC(assumed to be similar for radionuclidesconcerned compared with deeper GDF)

Packaging would probably be morerobust than for surface disposal(reflecting general practice, see below),but this would only need to be carried outonce

Major advantage

DFacility situatedbetween 200 m and1,000 m

No requirement for interim storage aswaste conforms with WAC as it is beinggenerated from decommissioning

Packaging would probably be morerobust than for surface disposal (in thiscase stainless steel, reflecting currentcurrent provision for possibleretrievability), but this would only need tobe carried out once.

Major advantage

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2. Costs – disposal

The most significant factor in determining the relative unit costs was judged to be whether the facilityhas been excavated within a suitable geological formation, or located on the surface. The former willhave much greater all-round operating and maintenance costs. The relative scores reflect this.


A Default SurfaceFacility Baseline operating costs Reference point


Operating costs/unit cost of disposal notsignificantly increased from a lessengineered surface facility

Neutral


A facility of this type would significantlybe costlier to operate than one in thenear-surface environment as workingunderground requires significantlygreater provisions to ensure adequateaccess, a safe working environment andoperability (e.g. maintenance).

Moderatedisadvantage


Although costs of disposing of waste tothis type of facility will be higher than forOption C, the difference does not justifyrecording a more unfavourablejudgement on the coarse scoringscheme employed.


3. Disposability / waste acceptance

The main issue impacting upon the acceptability of this waste stream across the representative facilitytypes is the relatively high quantity of the long-lived C-14, which following microbial conversion into amobile organic form, can be transported rapidly through the near surface environment. The facilityrepresented by Option B would be likely to result in lower impacts per unit disposal, but not markedlyso when compared to the other two disposal facilities, situated at about 50 m depth (Option C), andbetween 200 m and 1,000 m (Option D). The much higher level of the much shorter half-life and lessradiotoxic nuclide Ni-63 would pose much less of a challenge.



Waste stream is significantly abovecurrent WAC until 2200. High level ofC-14 in waste stream exceeds theconsignment capacities by two orders ofmagnitude for the entire period underconsideration

Reference point


It may be possible to engineer a nearsurface facility in the UK to permit therequired C-14 activity. There is someuncertainty as to whether thecorresponding levels of C-14 in this wastestream inventory (3 GB/t) would bepermitted in a near surface facility in theUK, though this level is well within theWAC for CSFMA.

Minor advantage

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This type of facility is much more likely tobe able to accept this waste stream,though this would be dependent on thelocation and precise design of therepository.

Major advantage


This waste stream is unlikely to pose anychallenges from its radionuclide content. Major advantage

4. Schedule & timing – requirement for interim storage

The determining factor in this case would be the fact that the necessary length of interim storage at thesite of origin would be prohibitively long and therefore could not be provided for the two surface-basedfacilities.



Unfeasibility long interim storage timewould be required for this facility type aswaste stream would be above WAC forabout 200 years hence.

Reference point


The situation here would approximate tothat above. Neutral


Interim storage would not be requiredahead of a facility type becomingavailable as waste will almost certainlybe within facility WAC

Major advantage


Interim storage would not be requiredahead of a facility type becomingavailable as waste will be within facilityWAC

Major advantage

5. Requirement for waste processing

All of the options perform similarly against this metric as the considerations of size-reduction andconditioning are common to all the facility types.



No suggestion that segregation or sizereduction would be required, groutingcould occur at this type of surface facility

Reference point


No suggestion that segregation or sizereduction would be required, groutingwould be required at originating site

Neutral


No suggestion that segregation or sizereduction would be required, there maybe no requirement to grout for a GDFtype facility, if required, grouting wouldbe at originating site

Neutral

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Neutral

6. Compatibility with NDA strategy

The main issues here are the fact that as C-14-bearing ILW, the waste would, on the basis of currentassessments, not be acceptable at a surface facility similar to the current provision, and this positionmay not differ significantly even if a much higher degree of engineered features were to be provided.The substantial delay on disposal that would otherwise ensue would impact unacceptably upon thetimescale for achieving the agreed end-states for Options A and B.



As ILW, disposal of this waste stream toa LLWR-type of facility is at variance withcurrent NDA strategy. This would conflictwith current strategy in that any disposalwould need to be delayed substantially.The volume of this additional wastestream (just under 1200 m3) would beunlikely to pose a significant challenge toa LLWR-type facility.

Reference point


The availability of a more engineeredsurface facility in the UK would providegreater flexibility in waste routing, wouldprovide a more ‘fit-for purpose’ repositoryand assist in reducing the pressure onthe limited capacity of other facilities(surface or at depth) less suited or over-engineered for this type of waste. It islikely that the levels of C-14 in this wastestream will still rule out surface disposalin the UK.

Minor advantage


As above, but more favoured as facilitywould be much more suitable inaccommodation the C-14 content.

Major advantage


Fully compatible with current NDAstrategy. Major advantage

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6.1.2 Results and discussionThe distribution of scores of the options against the set of metrics for this waste stream is presented inFigure 8 below.

Figure 8: Assessment scores for stream 9G310

This summary makes clear that in the considered view of the experts at the workshop, the two optionsfor this stream involving disposal at about 50 m (C) and between 200 m and 1,000 m (D), have agreater number and more pronounced benefits than the two surface disposal options (A & B). Fromthe wide set of metrics considered in this study the only aspect of the performance of the deeperdisposal options that compared less favourably than the surface disposal options is, predictably, theirunit cost of disposal. This reflects the more onerous working environment that would be present atdepth, from both an engineering and maintenance of safety perspective.

This overall pattern of benefits and disbenefits is a direct consequence of the fact that for the period oftime over which waste management decisions and actions can be planned with a reasonable degreeof confidence, this waste stream will probably remain unsuitable for surface disposal. This follows ondirectly from the fact that the main disposal challenge presented by this stream arises from thepresence and level of the long-lived and radiologically significant radionuclide C-14, with the higherlevels of the shorter-lived and less significant radionuclide Ni-63 exerting lower order of challenge. Theworkshop concluded that as this stream is very likely to exceed the WAC of a surface facility in the UK,unless the level of engineered features (in the case of Option B) could provide adequate reassuranceof effective containment of this potentially mobile radionuclide over a sufficiently long period of time forthe effects of decay to reduce the hazard to a sufficiently low level. It is important to note that nocredible period of interim storage could be employed as part of an alternative strategy of surfacedisposal, and such an approach would conflict with important elements of NDA strategy on riskreduction and the timely achievement of agreed site end-states. In terms of the risk presented post-closure, the other disposal facilities, one situated at about 50 m, and the other between 200 m and1,000 m, also benefit from the fact that they would be at a very much lower risk from human intrusion,in contrast to the surface disposal facilities.

It is noted that the workshop was of the view that the advisability of disposal of this waste streambelow the surface at the current planning basis for the UK (200 m to 1,000 m) or at a depth

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approximating to that of the current SFR facility of about 50 m would be similar. This is because theworkshop believed that the operational costs of such facilities would be broadly similar, and that thecontainment afforded to the C-14 content would be assessed as being sufficient even at the shallowerdepth of 50 m. Hence assuming that a facility similar to that outlined here as Option C would be madeavailable in the UK, the workshop expected there would not be any aspect of the NDA strategy thatwould influence whether it would be preferable to route this waste stream via Option C or Option D.

6.1.3 Wider implications of the conclusions on possible management of wastestream 9G310The original intention in this study was to explore how the assessment of the benefits and disbenefitsof a number of routing options for waste stream 9G310 could be applied more widely by examiningsimilar waste streams. However, an examination of the other waste streams within Waste Group 1(Activated Metals) as defined in the Task 1 Report [5] revealed that the only other sizeable stream ofthis type that arises as ILW and subsequently decays to LLW over the period of interest of the study(to just beyond the year 2300) arises from a currently operating reactor of a very different design(PWR). As such, its irradiation history will be very different to that of wastes from Trawsfynydd and theother Magnox plants, which in turn will influence the distribution of radionuclides present in the wasteand the overall activity levels.

Although the information available the information available for this study does not provide a firm basisfor applying the conclusions of this part of the assessment for stream 9G310 to activated steel andmetallic waste streams from decommissioned reactors more generally, similar considerations andconclusions are expected to apply from a disposability perspective independently of the constraintadopted here of decay to LLW within 300 years of arising.

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6.2 9G311 – Final Dismantling & Site Clearance: Graphite ILW(Trawsfynydd)Packaging assumption – Waste is expected to be encapsulated in a cementitious grout withinsuitable waste containers (e.g. 4 m box [ILW] for GDF (default) or ½ Height Disposal Container TC01[LLW] for LLWR).

6.2.1 Option scores

1. Costs – packaging, segregation and interim storage

The distribution of pre-disposal unit costs for this waste stream is similar to that for 9G310, justified bymuch the same reasoning. The only difference that was felt to justify a change from the scoreassigned to 9G310 was that the admittedly improved performance of the more engineered facility isstill likely to be insufficient to justify a period of interim storage that is tractable given the much higherconcentrations of the problematic nuclide C-14. In effect, unless extraordinary measures are takenwith respect to geology, depth and engineered features to ensure that the risk from transport pathwaysand human intrusion are acceptably low, no form of disposal of waste at or within a few metres of thesurface with this level of C-14 is likely to be acceptable.



An unfeasible period of interim storagewould be required, waste would need tobe re-packaged a large number of times

Reference point


An unfeasible period of interim storage islikely to be required (but theoreticallyless than for Option A), and incomparison to the above would need tobe repackaged less frequently due to aslightly higher robustness.

In contrast to the previous assessment,these small advantages were not judgedto be sufficient to justify a morefavourable score than the default.

Neutral


Would be no requirement for interimstorage as waste conforms with WAC.

Packaging would probably be morerobust than for surface disposal(reflecting general practice, see below),but this would only need to be carried outonce

Major advantage


Would be no requirement for interimstorage as waste conforms with WAC.

Packaging would probably be morerobust than for surface disposal (in thiscase stainless steel, reflecting currentprovision for possible retrievability), butthis would only need to be carried outonce.

Major advantage

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The relative disposal costs for this waste stream across the considered options were agreed to be thesame as for stream 9G310.




Operating costs/unit cost of disposal notsignificantly increased from a lessengineered surface facility

Neutral


A facility of this type would besignificantly costlier to operate than onein a near-surface environment asworking underground requiressignificantly greater provisions to ensureadequate access, a safe workingenvironment and operability (e.g.maintenance).



As for disposal facility at 50 m depth Moderatedisadvantage


The workshop concluded that the scores assigned for this waste stream across the disposal optionswould be the same as for stream 9G311. More so than for the metallic waste stream, and following onfrom statements made earlier, the determining factor is that the C-14 concentration in the wasteexceeds the likely WAC for the surface disposal facility by a significant margin, thereby effectivelyprecluding routing to either of the first two options.



Waste stream exceeds the current b/gWAC by approaching an order ofmagnitude up to 2313. More significantly,the concentration of C-14, whichdominates the waste activity, exceeds thecorresponding level of 0.012 GBq/t bynearly four orders of magnitude. Wastestream remains ILW for duration of study.

Reference point


It may be possible to engineer a nearsurface facility in the UK to permit therequired C-14 activity, There is someuncertainty as to whether thecorresponding levels of C-14 in this wastestream inventory (~88 GB/t) would bepermitted in any near surface facility inthe UK.

Neutral


This type of facility is much more likely tobe able to accept this waste stream,though this would be dependent on thelocation and precise design of therepository.

Major advantage

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This waste stream is unlikely to pose anychallenges from its radionuclide content. Major advantage


The justification for the relative scores is as for waste stream 9G310.



Unfeasibility large interim storage timerequired for this facility type Reference point


Unfeasibility large interim storage timerequired for this facility type Neutral


Interim storage would not be requiredahead of a facility type becomingavailable

Major advantage


Interim storage would not be requiredahead of a facility type becomingavailable

Major advantage


The justification for the relative scores is as for waste stream 9G310.



No suggestion that segregation or sizereduction would be required, groutingcould occur at this type of surface facility

Reference point


No suggestion that segregation or sizereduction would be required, groutingwould be required at originating site

Neutral


No suggestion that segregation or sizereduction would be required, there maybe no requirement to grout for a facilitysituated at ~50 m, if required, groutingwould be at originating site

Neutral



Neutral

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The relative scores for the four options in general follows the arguments presented for stream 9G310.The significantly higher level of C-14 in this waste stream, however, would strengthen the negativeassessment against both of the surface facility types.



As long-lived ILW containing mainlyC-14, disposal of this waste stream to aLLWR-type of facility would conflictstrongly with current NDA strategy. Thesizeable volume of this additional wastestream (~3400 m3) may impact uponmanagement of the lifetime plan of aLLWR-type facility.

Reference point


Although the engineered features andlocation of a future UK facility willimprove its expected performanceconsiderably with respect to a LLWR-type facility, it is likely that no surfacefacility in the UK could be justified forgraphite wastes with a C-14 approachingfour orders of magnitude in excess of thecurrent surface facility limit.

Neutral


As above, but in the light of the C-14content it would be more favoured as thefacility would be more suitable.

Major advantage


Current baseline NDA strategyMajor advantage

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Figure 9: Assessment scores for stream 9G311

The results of the assessment for the graphite waste stream from Trawsfynydd that arises at the FinalDismantling and Site Clearance phase of decommissioning are very similar to those for the mild steelstream. As for the previous case, the two options for this stream involving disposal at depth (C & D)have a greater number and also more pronounced benefits than the two surface disposal options (A &B), with the unit cost of disposal as the only metric that would disfavour deep disposal.

For this stream the higher concentration of C-14 in the graphite waste means that it would remain wellwithin the category of ILW over any practicable schedule for final disposal, with the radiotoxicity of thisradionuclide compounding the challenge faced by a surface disposal facility, regardless of its design.The very long half-life of the radionuclide means that no feasible period of interim storage would allowdisposal for a facility at the surface.

As previously, and following the same reasoning, the workshop was of the view that the advisability ofthe disposal of this waste stream would be insensitive as to the whether the facility were to be locatedat the current planning basis for the UK (200 m to 1,000 m) or at a depth of approximating to that ofthe current SFR facility of about 50 m. Both would be sufficient in ensuring adequate containment forC-14 and neither would be subject to any significant risk from intrusion.

6.2.3 Wider implications of the conclusions on possible management of wastestream 9G311An examination of the 2013 UKRWI [1] reveals that total volume of graphite waste from the NDAestate will amount to approximately an order of magnitude larger than that arising from Trawsfynyddalone, and although the irradiation histories will vary, the dominant radionuclide in each case is C-14,which will be present at levels considerably above the ILW threshold.

Leaving aside the possibility of managing this waste by some form of treatment to reduce its C-14content ahead of some form of surface disposal [27], there would appear to be no reasons to amend

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the conclusions of the above assessment were it to be extrapolated from waste stream 9G311 to thereactor graphite that will arise in the UK as a whole other than to note that it would be more importantto ensure that sufficient provision be made for the much larger volumes of waste involved in thecandidate facilities. This impact will clearly be most significant if disposal were to be considered to anexisting facility.

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6.3 2D137 – Miscellaneous Plants Final Decommissioning:Processing Plants, Tanks, Silos, etc (Sellafield)

Packaging assumption – Waste is expected to be encapsulated in a cementitious grout withinsuitable waste containers (e.g. Sellafield 3 m3 box).


This large volume waste stream is known to be significantly heterogeneous in physical andradiological composition and has not yet been well characterised. The waste will range from ILW toLLW and below, with a greater proportion toward the lower levels. The Sellafield site strategy asreflected in the packaging assumption presented in the 2013 UKRWI would suggest strongly thatsome of the material may contain alpha activity. Waste intended to be routed to a surface facilitysimilar to LLWR would need to be segregated to remove the expected small fraction of the materialthat exceeds the WAC (this is unlikely to be an issue for the other waste facility types), though in thelight of the large initial volume of this stream, some segregation would also be appropriate for all thedisposal routes so that their capacities can be optimised. Some of the material for disposal maycontain hazardous non-radioactive contaminants such as lead and asbestos, which would present aparticular challenge to some or all of the surface facilities.



For LLWR-type facility some interimstorage may be required before wastecan be accepted. In the light ofuncertainties in waste streamcomposition it may also be necessary touse waste containers more robust thanthe standard mild steel designs.

Reference point


Lower costs from interim storage withsimilar waste containers to the abovebeing appropriate. May be possible forwaste to be accepted without any interimstorage being necessary.

Moderate advantage


Waste could be accepted with no interimstorage as waste conforms with WAC,but the packaging would probably bemore onerous than for surface disposal(reflecting general practice, see below)

Neutral


Waste could be accepted with no interimstorage as waste conforms with WAC,but would require more onerous packingrequirements, (e.g. stainless steel),reflecting current provision for possibleretrievability.

Neutral

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As in the case of the previous two streams the most significant factor in determining the relative unitcosts was judged to be whether the facility has been excavated within a suitable geological formation,or located on the surface. The former will have much greater all-round operating and maintenancecosts. The relative scores reflect this.




Operating costs/unit cost of disposal notsignificantly increased from a LLWR typefacility

Neutral







The scores assigned for this waste stream across the disposal options are determined by the fact thatno facility other than represented by Option A would require any interim storage to ensureconformance with the WAC and that the two disposal facilities at depth will be subject to low or verylow risks from human intrusion or coastal erosion.



Waste is likely to conform to current WACvery soon after it is planned to arise.Significant uncertainty in wastecomposition may lead to rejection of aproportion of waste.

Reference point


Could accommodate waste without needfor interim storage. Minor advantage


Could accommodate waste without needfor interim storage, there is also lessrequirement for segregation. Very muchlower risks from human intrusion than fora near-surface facility, e.g. site re-development scenarios.

Moderate advantage


Could accommodate waste without needfor interim storage, there is also lessrequirement for segregation. Negligibleintrusion risk

Moderate advantage

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The disposal options perform very similarly against this metric, with the only minor difference beingthat some interim storage to allow radioactive decay would probably be required for a small proportionof the waste if it were consigned to a LLWR-type facility. All of the other options would be able toaccommodate the waste as it arises.



Interim storage at the LLWR-type facilitywill be required until the waste becomesLLW, although this not a significantperiod of time

Reference point


It is assumed that a facility of this typecan be constructed by 2060-2070 andaccommodate waste arises as it arises,therefore there is no requirement forinterim storage

Minor advantage


It is assumed that a facility of this typecan be constructed by 2060-2070 andaccommodate waste as it arises,therefore there is no requirement forinterim storage

Minor advantage


It is assumed that a facility of this typecan be constructed by 2060-2070 andaccommodate waste as it arises,therefore there is no requirement forinterim storage

Minor advantage


The disposal options perform very similarly against this metric and were therefore all given the same(neutral) score. As the 2013 UKRWI assumes that a 3 m3 box would be default container (presumablybecause of the possibility of some alpha contamination being present, as noted earlier), and becauseof the large volume of this waste stream, transportation (to a processing facility) would be an issue assoon as the likely location of currently conceptual disposal facilities are known.



The waste will comprise rubble and alsolarger items that may not be consideredsuitable to size-reduce. Somecharacterisation and segregation may berequired due to the heterogeneity ofwaste stream

Reference point

B More EngineeredSurface Facility As above

Neutral

C Facility situated at~50 m As above

Neutral


As aboveNeutral

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Disposing of significant quantities of material within the LLW category by geological disposal andwhich would otherwise be suitable for surface disposal conflicts with NDA strategy. Uncertainties in thecomposition of this waste stream led the workshop to recognise that it was not appropriate to allocatescores to the individual options in this case. In reality not all of the waste would be allocated to onefacility – a range may be involved, each accepting waste for which it was suitable. In reality therefore,it was decided likely that following segregation, the waste material may be able to be resolved into anumber of sub-categories: material suitable for special landfill, material suitable for surface disposal(i.e. Option A only or both Options A & B), and a much smaller remaining faction being consigned to afacility at greater depth as necessary.

In the light of the above no scores were allocated against this metric1 for this waste stream



Not scored – refer to accompanying commentary




1 Note that the scores allocated against the other metrics are still considered meaningful as they illuminate thetechnical issues associated with the various disposal options.

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6.3.1 Results and discussionThe distribution of scores of the options for this waste stream against all of the metrics apart fromCompatibility with NDA strategy is presented in Figure 10 below.

Figure 10: Assessment scores for stream 2D137

For the reasons given in the final section of how the waste stream 2D137 is likely to perform againstthe metric Compatibility with NDA strategy, this relatively large volume waste stream would be mosteffectively managed by means of large-scale segregation, followed by the consignment of increasinglyactive fractions to facilities more suited to accepting such material. It is to be expected that most of thewaste volume would be suitable for some form of surface disposal as LLW or VLLW, with a relativelysmall fraction reserved for geological disposal.

The scores in the above graphic are broadly similar to the two previous waste stream assessments,with geological disposal having higher costs but showing advantages by not requiring any interimstorage (for radioactive decay) and having less restrictive WAC.

It is interesting to note that one possibility that may be worth revisiting would be to dispose of thewhole stream to an engineered surface facility. The WAC would be sufficiently high in all likelihood,and this approach could dispense with the need for any segregation and hence the cost, risk andcomplexity introduced by this operation.

6.3.2 Wider implications of the conclusions on possible management of wastestream 2D137Unlike 9G310 and 9G311, the characteristics of this stream are not shared with other waste streams inthe 2013 UKRWI. Although it shares some outward similarity with the bulk concrete waste streamsthat will arise at Magnox sites at the final demolition stage of decommissioning (from reactor and non-reactor structures), 2D137 originates from a range of facilities that were involved in reprocessing, andhence the origin and levels of the activity contained will be entirely different (notably, the Magnoxstreams will contain virtually no fission products).

201139-AA-0004/001/Issue 1 Page 54 of 62

6.4 2F26 – LWR Pond Sludge (Sellafield)

Default packaging assumption – not specified in 2013 UKRWI. Waste is assumed to beencapsulated in cementitious grout within suitable waste containers, or possibly subject to anotherform of conditioning and possibly pre-treatment to prevent organic material remaining biologicallyactive or capable of supporting microbial activity within the waste containers.


The issue of ensuring that the wasteform would not be capable of supporting any significant microbialactivity (as is presently the case) is common to the disposal options. The judgement of the workshopwas that conditioning the waste in a cementitious medium may generate a sufficiently high pH toeliminate this risk. Whether this would be the case or not, it was considered appropriate to assumethat a form of processing could be applied quite straightforwardly across the disposal options toeliminate this issue. This metric therefore does not discriminate between the options.



It is assumed that all waste can bepackaged on arising Reference point

B More EngineeredSurface Facility As above Neutral

C Facility situated at~50 m As above Neutral


As above Neutral


The relative disposal costs for this waste stream across the considered options were agreed to be thesame as for the previous cases.




Operating costs/unit cost of disposal notsignificantly increased from a LLWR typefacility

Neutral






201139-AA-0004/001/Issue 1 Page 55 of 62


As the waste stream would be acceptable at all of the potential disposal facilities the option scores forthis metric for Options B to D were set to be the same as for the reference, Option A.



Waste is likely to conform with currentWAC very soon after arising (mostlybefore 2038).

Reference point


There would be no issues withacceptability of this waste in this facilitytype.

Neutral



Neutral



Neutral


The workshop determined that all disposal options would perform very similarly against this metric.The need to process the waste into a form suitable for disposal (which would be the same for alloptions) would reduce the need for some interim storage that would otherwise be required before thefacilities represented by Options B-D, and also permit the waste to decay sufficiently to be able to bedisposed to a LLWR-type facility (Option A).



Processing/packaging would beundertaken on arising. Reference point


Neutral


Neutral


As aboveNeutral

201139-AA-0004/001/Issue 1 Page 56 of 62


As noted earlier, the (as yet undetermined) method that would be adopted to prepare the raw wastefor disposal would be the same across all options, which therefore score identically. As it wouldprovide an opportunity to reduce the disposed volume of this stream considerably, the potential ofincineration of the sludge as a viable treatment option was noted as worthy of further consideration.



Waste would be retrieved as sludge andsome segregation carried out to removeobjects above a specified size.Encapsulation using cementitious orother encapsulant method suited toorganic material would be required

Reference point


Neutral


Neutral


As aboveNeutral


This relatively low volume waste stream decays to LLW a short time after it arises. As geologicaldisposal of such material would be at variance with NDA strategy, even though it is a waste streamthat is exceptional as far as its provenance and composition is concerned, the workshop assignedrelative minor negative scores to Options C & D.



Although waste is in the category of ILWat the start of the period of arising, itdecays to LLW within a few years, sothat within 10-20 years it falls to LLW.Subject to the conditioned wasteformconforming with the non-radiologicalaspects of the WAC, consignment to aLLWR-type facility is likely to be regardedas in accordance with current NDAstrategy.

Reference point


Following on from the above, no furtheradvantages or disadvantages of note inthe context of the overall strategy wouldarise from disposal to a more engineeredsurface facility.

Neutral


Given that waste would not qualify asILW for more than a few years afterarising (and before conditioning),disposal to a deeper facility wouldprobably be regarded as not entirely inkeeping with the main thrust of NDAstrategy.

Minor disadvantage

201139-AA-0004/001/Issue 1 Page 57 of 62



Given that waste would not qualify asILW for more than a few years afterarising (and before conditioning),disposal to a deeper facility wouldprobably be regarded as not entirely inkeeping with the main thrust of NDAstrategy.

Minor disadvantage


Figure 11: Assessment scores for stream 2F26

The clear conclusion that emerges from the consideration of the relative performance of the routingoptions against the set of metrics is that surface disposal of this waste stream would be favoured overdisposal at depth, as none of the indications of relative performance are in opposition to this trend.This is the case even though the waste was classified as ILW in the 2013 UKRWI, and thereforegeological disposal is assumed to be the default management strategy.

The relative favourability of surface disposal is due principally to the higher unit costs of disposal; witha secondary reason being that disposal of material that would clearly be in the category of LLW at thetime of disposal would not be in accordance with NDA strategy. It should be noted also that the wastewould contain no significant levels of radionuclides such as Cl-36 or C-14 that would justify a morecareful examination of the respective advantages and disadvantages of different routing options due totheir much higher impact per unit activity that is disposed. For this waste stream therefore, surfacedisposal would not appear to have any significant disadvantages when compared with disposal atdepth.

201139-AA-0004/001/Issue 1 Page 58 of 62

The above assessment suggests strongly that the default disposal strategy for this waste streamshould be reconsidered in due course as surface disposal would provide a sufficient level of safetywhilst providing significant cost savings.

6.4.2 Wider implications of the conclusions on possible management of wastestream 2F262F26 is a low volume stream and has little resemblance to any other sludge arisings in the 2013UKRWI. Accordingly no discussion on the wider implications of routing decisions for this stream canbe offered.

201139-AA-0004/001/Issue 1 Page 59 of 62

7 Summary and conclusionsThis report explores the benefits and disbenefits of disposing of a number of waste streams in the UKRadioactive Waste Inventory (UKRWI) that are broadly within the classification of ILW/LLW boundarywastes to a range of representative facility types that would be suitable for wastes from across a rangeof activity concentrations.

The selected facilities employ a range of engineered design features and would be located within arange of depths (from a surface location to geological disposal at up to 1,000 m). The study considersa LLWR-type facility and a GDF-facility type rather than the actual LLWR / GDF in particular. Similararguments apply to the other facility types considered, namely a more engineered surface facility anda cavern-based disposal facility located at/within 50 m of the surface. The identification of thesebenefits and disbenefits, and how these are dependent upon the properties of individual wastestreams, are illustrated using a number of case studies, one for each of the waste streams.

The case studies have been structured around the following boundary waste streams:

9G310 – Final Dismantling & Site Clearance: Mild Steel (Reactor) ILW (Trawsfynydd)

9G311 – Final Dismantling & Site Clearance: Graphite (Reactor) ILW (Trawsfynydd)

2D137 – Miscellaneous Plants Final Decommissioning: Process Plants, Tanks, Silos, etc(Sellafield)

2F26 – LWR Pond Sludge (Sellafield)

The representative types of disposal facilities are as follows:

Default surface facility – a facility designed for LLW with the characteristics and features of thecurrent LLWR (Option A),

More engineered surface facility – a facility modelled on the facility at Centre de L’Aube in Franceoperated by ANDRA that was designed for LLW and some short-lived ILW (Option B),

A disposal facility located at about 50 m depth – a cavern-based facility represented by the SFRoperated by SKB and suitable for LLW and most ILW (Option C),

A geological disposal facility that would be located between depths of 200 m and 1,000 m andcapable of managing all waste types (Option D).

The main stage of the assessment was conducted at an options workshop attended byrepresentatives from RWM Limited, Magnox Ltd and LLW Repository Ltd. The conclusions of the fourcase studies are summarised as follows:

9G310

This ILW stream decays to LLW at about 2300. It is dominated by the presence of Ni-63, but the levelof the small fraction (~8%) of the long-lived C-14 is sufficient to rule out disposal to the LLWR-typefacility, and would challenge a more robust surface facility unless the engineered features couldprovide adequate assurance of effective containment over a very long period (to permit significantradioactive decay of this nuclide to take place). No credible period of interim storage could beemployed as part of an alternative strategy of surface disposal, and such an approach would conflictwith important elements of NDA strategy on risk reduction and the timely achievement of agreed siteend-states. In terms of the risk presented post-closure, the disposal facilities at about 50 m depth andbetween 200 m and 1,000 m also benefit from the fact that they would be subject to very much lowerrisks human intrusion, unlike the disposal facilities much nearer to the surface.

9G311

This ILW stream comprises mainly C-14, with an activity concentration of the order of 90 GBq/tonne.Its long half life would mean that this situation would persist for very many thousands of years. As forthe previous case, the two options for this stream involving disposal at increasing depth (C & D) havea greater number and also more pronounced benefits than the two surface disposal options (A & B),with the unit cost of disposal as the only metric that would disfavour deep disposal.

201139-AA-0004/001/Issue 1 Page 60 of 62

The factor of overwhelming importance in precluding surface disposal would be that the concentrationof the long-lived nuclide C-14 in the graphite waste is judged to be unacceptable from the perspectiveof post-closure risk. In effect, unless extraordinary measures are taken with respect to geology, depthand engineered features to ensure that the risk from transport pathways and human intrusion areacceptably low, no form of near-surface disposal of waste with this level of C-14 is likely to beacceptable.

2D137

This relatively large waste stream comprises the concrete and brickwork from the demolition of anumber of processing plants at Sellafield. It contains a wide range of fission products, chiefly Cs-137and Sr-90, and at about 2070, which is when it is planned to arise, it will become LLW. The workshopconcluded that this waste stream would be most effectively managed by means of large-scalesegregation, followed by the consignment of increasingly active fractions to facilities most suited toaccepting such material. It is to be expected that most of the waste volume would be suitable for someform of surface disposal as LLW or VLLW, with a relatively small fraction reserved for geologicaldisposal.

The outcome of the options assessment in this case is broadly similar to those from the two previouswaste streams, with disposal at depth having higher costs but showing advantages by not requiringany interim storage (for radioactive decay) and having less restrictive WAC. The results suggest thatone possibility that may be worth revisiting would be to dispose of the whole stream to an engineeredsurface facility. The WAC would be sufficiently high in all likelihood, and this approach could dispensewith the need for any segregation and hence the risks introduced by this operation.

2F26

This stream is a low volume, relatively low activity organic sludge containing a range of activation andfission products. In the 2013 UKRWI [1] it is recorded as arising from the year 2013. The clearconclusion from the assessment is that surface disposal of this waste stream would be favoured overdisposal at depth, as none of the indications of relative performance are in oppose this inclination. Thisis the case even though the waste was classified as ILW in the 2013 UKRWI, and therefore geologicaldisposal is assumed to be the default management strategy.

The relative favourability of surface disposal is due principally to the higher unit costs of disposal; witha secondary reason being that disposal of material that would clearly be in the category of LLW at thetime of disposal would not be in accordance with NDA strategy. It should be noted also that the wastewould contain no significant levels of potentially problematic radionuclides such as Cl-36 or C-14 thatcould justify a more careful examination of the respective advantages and disadvantages of differentrouting options. For this waste stream therefore, surface disposal would not appear to have anysignificant disadvantages when compared with disposal at depth.

The above assessment suggests strongly that the default disposal strategy for this waste streamshould be reconsidered in due course as surface disposal would provide a sufficient level of safetywhilst providing significant cost savings.

201139-AA-0004/001/Issue 1 Page 61 of 62

8 References1 NDA, 2013 UK Radioactive Waste Inventory, February 2014.

2 Managing Radioactive Waste Safely: A Framework for Implementing Geological Disposal, Cm7386, June 2008.

3 LLWR Ltd, National Waste Programme: Guidance on decision making for management of wastesclose to the LLW and ILW categorisation boundary that could potentially cross the LLW boundary,NWP/REP/016, Issue 2, February 2013.

4 NDA, Strategy, April 2011.

5 AMEC, Upstream Optioneering – LLW/ILW Opportunities: Preparation of an inventory of wastepotentially suitable for diversion from geological disposal, 201139-AA-0001/001, Issue 1, March2014.

6 AMEC, Upstream Optioneering – LLW/ILW Opportunities: The management of tritiated wastes,201139-AA-0003/001, Issue 1, AMEC, May 2014.

7 NDA, Higher Activity Wastes: Strategic Position Paper on the Management of Waste Graphite,January 2014.

8 Nuclear Industry Safety Directors Forum, Best Available Techniques (BAT) for the Managementof the Generation and Disposal of Radioactive Wastes – a Nuclear Industry Code of Practice,Issue 1, December 2010.

9 NDA, NDA Guidance and Expectations for Business Cases and Value Management, EGG08, Rev8, March 2013.

10 NDA, Generic Waste Package Specification, Nirex Report N/104, Issue 2, 2007.

11 LLWR Ltd, The 2011 ESC: Environmental Safety Case – Main Report, LLWR/ESC/R(11)10016,May 2011.

12 LLWR Ltd, The 2011 ESC: Engineering Design, LLWR/ESC/R(11)10020, May 2011.

13 LLWR Ltd, The 2011 ESC: Site History and Description, LLWR/ESC/R(11)10018, May 2011.

14 LLWR Ltd, Service Price List, WSC-SPR-LIS, Version 3.3, August 2013.

15 LLWR Ltd, Waste Acceptance Criteria – Low Level Waste Disposal, WSC-WAC-LOW, Version 4,March 2014.

16 LLWR Ltd, The 2011 ESC: Waste Acceptance, LLWR/ESC/R(11)10026, May 2011.

17 SKB, International perspective on repositories for low level waste, Report R-11-16, December2011.

18 Andra, Specifications d’Acception des Colis de Dechets Radioactifs au Centre de l’Aube (I.N.B.No. 149), Specifications Generales & Specification d’Evaluation et de Declaration desCaracteristiques Radioactives, ACO.SP.ASRE.99.002.B, 1999.

19 S Voinis and J L Maillard, Waste Acceptance Criteria for LLW, Centre de l’Aube, Andrapresentation SUR.TR.ASSN.09.0086, 2009.

20 NDA, Waste Lifecycle Cost Calculator and Norms, Technical Note #LL18776758, Version 3,December 2013.

21 NEA, Low-level Radioactive Waste Repositories: An Analysis of Costs, 1999.

22 STUK (Finnish Radiation and Nuclear Safety Authority), Evaluation of the radioactive wastecharacterisation at the Olkiluoto nuclear power plant, STUK-YTO-TR162, March 2000.

23 C Lindberg, Swedish Experience from Siting, Construction and Operation of RW DisposalFacilities, CEG Workshop on Isolation and Disposal of Radioactive Waste, 28-30 June 2006.

201139-AA-0004/001/Issue 1 Page 62 of 62

24 NDA, Geological Disposal: Summary of generic designs, NDA/RWMD/054, December 2010.

25 NDA, An overview of the Generic Disposal System Safety Case, NDA/RWMD/010, December2010.

26 NDA, Geological Disposal: Generic Waste Package Specification, NDA Report no.NDA/RWMD/067, March 2012.

27 NDA, Higher Activity Wastes: Strategic Position Paper on the Management of Reactor Graphite,SMS/TS/D1-HAW-6/003/PP, Doc ID: 21082797, January 2014.

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