Back End of the Fuel Cycle(i)

2014

Jongwon CHOI

Principal Researcher

Contents

4. Back End of the Fuel Cycle

4.1 Spent Fuel Management

4.2 Spent Fuel Storage

4.3 Reprocessing

4.4 High-Level Waste Management

4.5 Low-Level Waste Management

2

4.1 Spent Fuel Management

What is Spent Nuclear Fuel?

“Spent nuclear fuel, occasionally called used nuclear fuel in some

countries, is nuclear fuel that has been irradiated at a nuclear power

plant. It is no longer useful in sustaining a nuclear reaction to

produce electricity.”

Nuclear Fuel Assembly consists

of the nuclear fuel material (Uranium)

and cladding, mainly zirconium alloy,

and structural support materials.

3

4.1 Spent Fuel Management

SF is radioactive Irradiation during reactor operation

– Actinides : U, Pu, Am, Np, Cm

– FPs (less than ~ 5% of fuel mat’l): Cs, Sr, I, Tc

– Activation Products resulted from the fuel structural mat’l like Zirconium

Alloy, Inconel and Stainless Steel

Radioactive decay characteristics of SF

- Radioactivity: the spontaneous decay of an unstable atomic nucleus,

giving rise to the emission of radiation

- Radiotoxicity: the adverse health effect of a radionuclide due to its

radioactivity

- Decay heat: the heat released as a result of radioactive decay

4

Composition of SF

5

95.6% : Uranium (reprocessed U is reusable in the existing NPP ?)

Fresh Fuel Spent Fuel

100% U

~ ~

45GWd/tU

FP

TRU

3% : Stable or short-lived FPs

0.3% : Cs & Sr (high heat generation rate)

0.1% : I2 & Tc (Long lived FPs)

0.1% : Long-lived actinides

0.9% : Pu (reusable fuel mat’l, but need to be internationally accepted)

HLW

Decay Characteristics of SF

6

General Characteristics of SF

- high radiation: α, β, γ-ray

- high residual decay heat

- high radiotoxicity

⇒ decrease with respect to time !!

Main parameters for SF manage.

facility design and SA

⇒ FPs dominate for around 300 yrs

after that then actinides dominate

※ Decay heat: Major parameter to

determine storage method and

disposal area, etc.

Decay Characteristics of SF

7

Radiotoxicity quantifies the effect of exposure (hazard)

- Effectively assumes complete release and uptake

Fission products dominate in short-term

- Fall well below the original toxicity after 200 years

Am-241 dominates in the 1,000 year time frame

Pu-239 and Pu-240 dominate in the 10,000 to 100,000 time

Np-237 dominates the long-term (>105 years) hazard

- Comes primarily from Am-241 decay

- Am-241 results from Pu-241 decay (and Cm-245 decay)

Repository environment will impact radiological risk

- All material is contained for ~10,000 years

- Plutonium moves slowly, FP quickly through environment

- Long-lived fission products (Tc-99 and I-129) dominate early

- Maximum dose results from Np-237 in long-term

SF Structure and Radionuclides

8

Schematic Cross-section of SF

※ Fuel integrity is important for

storage and disposal safety:

operation/handling history,

oxidative environment, crud

thickness, storage temperature, etc.

Methods of SF Management

9

Storage to decrease radiation and decay heat of SF

Not final solution but temporary

Storage is necessary to cool SF before disposal or reprocessing.

Storage technology is commercially available at present.

(some R&Ds for LTS is necessary)

Disposal to isolate HLW in the deep geological formation

Different Options from each countries deep geological conditions

Finland(2000) and Sweden(2009) decided the final disposal site.

Reprocessing to recover the reusable fuel materials like Pu/U

to be used for new nuclear fuel

UK, France, Russia, Japan

Storage Medium and Cooling Method

- Wet: Water

- Dry: Air, He

Location

- AR : Reactor site

- AFR : Away From Reactor site

Key Technologies for SF Storage

- Nuclear Criticality and Radiation Shielding

- Thermal Analysis

- Structural Analysis

- Accident Analysis

- Retrievability after Storage and Compatibility to next option

4.2 SF Storage

10

11

Key Issues for SA

General items to be considered at design phase

site operation sys.

SSC &

Design

criteria

Structural

analysis

Thermal

analysis

Shielding

analysis

Criticality

analysis

Confine-

ment

Conceptual design

Accident Tech. Spec.

evaluation

Function Test

of Components Radiation

Protection QA D&D

Radwaste

Storage

*SSC : Structures, Systems and Components

Regulations and guides

- IAEA Safety Series No. 116

- 10CFR72, - ANSI/ANS 57.9

- Regulatory Guide 3.48, NUREG-1536,1567

Wet Storage

Water at least 2.5 m deep is both an effective shield and good

heat –transfer medium while SF is storing in pool storage

Role of Water

- Radiation shielding

- Protection of radioactive contamination

- Dissipation of decay heat

- Good visibility for SF handling and monitoring for nuclear material SG

Spacing : nuclear and cooling

- sub-critical : Keff < 0.95

- temperature of pool water < ~71℃

Material of storage rack

- Borated Stainless steel

- Boral or Boraflex

12

Dry storage : cooling by air or inert gas

- Cask type: metal container or concrete cask

- Vault type

- Dry well

- Concrete Silo type

Advantages

- low maintenance and high reliability

- low arising of secondary wastes

- reduced corrosion over long periods

- easier decommissioning

SF is stored in the concrete or metal container or concrete facility.

SF has been successfully dry-stored for several decades since 1980s.

Longest license period is 60 years in the US.

Dry Storage

13

14

Dry Storage System in Commercial

Vault Metal Cask Concrete Cask H-Concrete Module

Storage method Model Capacity Burnup Cooling time Heat load

Metal Cask NAC-S/T 26 PWR 35 GWd/tU 5y 26 kW

Concrete Silo VSC-24 24 PWR 40 GWd/tU 5y 26 kW

Concrete Module

NUHOMS-24P 24 PWR 40 GWd/tU 5y 26 kW

Vault MVDS 50000 MAGNOX 5 GWd/tU 150 day -

AFR Dry Spent Fuel Storage in World (IAEA NFCIS 2007-4-9)

In Operation

Construction Awaiting License

Planned Standby Other Total

44 15 1 13 1 2 76

Advantage Disadvantage

Wet

▶plentiful const./op experience ▶proven tech. on S/G ▶small land for facility op ▶available for various fuel types : even short cooling time for AR

▶ operation RWs impact on facility cost ▶keep on op after full reception of SF for cooling and maintenance ▶high utility cost ▶high radiation exposure

D

r

y

Metal

Cask ▶proven technology (plentiful construction or fabrication and op experience) ▶good for extensibility for storage facility at AR and/or AFR. ▶no op RW ▶Passive cooling ▶Low radiation exposure

▶high cost for storage Cask ▶impossible to monitor during op ▶high cladding temperature

Concrete

Silo

▶impossible to investigate SF during op ▶low storage density▶high cladding temp. ▶some issues for LT integrity of concrete ▶comparatively low PA

Vault ▶no experience for PWR SF ▶impossible to investigate SF during op ▶low storage density▶Low PA

Dry Well ▶good extensibility ▶no op RW ▶Passive cooling

▶comparatively great site ares ▶impossible to investigate SF during op ▶high cladding temperature

Concrete

Cask

▶good extensibility ▶comparatively low Cask cost ▶no op RW

▶low heat conductivity of concrete ▶some issues for LT integrity of concrete ▶thermal limit for inner concrete wall

Comparison of Storage Technology

Metal Cask Vault (MVDS)

Concrete Cask

SF Storage Method

Module (NUHOMS)

Low Cost

Good Expandability

High Cost

Good Cooling Eff.

No Case for LWR

Low Cost

Ready Expandability

Transportable for

short distance

High Cost

Good Expandability

Flexibility in

storage system

Metal Cask is preferable option for countries carrying out SF reprocessing

Vault concept has been used in the US, UK, France

The US has been developing a Concrete Cask with high structural safety

since 911 accident.

Dry Storage Method

16

From Store FUEL Vol. 12 No. 152 Ux

Consulting, April, 2011

Unit: assembly

17

Independent SF Storage Installations

in US

Table “Dry CASK Storage in the US.” March

3, 2009, STOREFUEL, 11-127(UXC)

SF Dry Storage in US (2007)

38 Sites : Cask Storage

13 Sites : Cask ordered

6 Sites: purchasing

878 Casks stored (10,686

MT, 2007. 3)

55,630 MT (2006)

• Consortium of 8 Utilities

• 1997- License Application

• 2006- Approved

• Strong against of Utah

Private Fuel Storage(PFS)

18

Facility Capacity(t) Storage Method Status Remarks

Hanford - K Basins 2100 AFR wet spent fuel storage (from NPPs) In operation(1950) Laboratory

Idaho CPP-603, CPP-666 small AFR wet spent fuel storage (from NPPs) In operation(1952) Laboratory

Morris Reprocessing Plant Site 750 AFR wet spent fuel storage (from NPPs) Stand by(1984) Commercial

Savannah River (SRS) small AFR wet spent fuel storage (from NPPs) In operation Laboratory

West Valley Reprocessing

Plant Site 27 AFR wet spent fuel storage (from NPPs) In operation(1966) Commercial

Wet Storage Facility (AFR)

Facility Capacity(t) Storage Method Status Remarks

Actinide Packaging and

Storage Fac. (APSF) 2001 AFR Dry MVDS Planned Laboratory

Arkansas NPP Site ISFSI 150 AFR Dry cask, PWR In operation(1997) Commercial

Big Rock Point NPP Site small AFR Dry cask, BWR Planned Commercial

Calvert Cliffs NPP Site 1112 AFR Dry NUHOMES-24P, PWR In operation(1992) Commercial

Davis Besse NPP Site ISFSI 360 AFR Dry NUHOMES-24P, PWR In operation(1995) Commercial

Dresden NPP Site 70 AFR Dry cask, BWR Under construction Commercial

Duane Arnold NPP Site small AFR Dry cask, BWR Planned Commercial

Fort St. Vrain NPP Site ISFSI 15.4 AFR Dry MVDS, HTGR In operation(1992) Commercial

H.B. Robinson NPP Site ISFSI 26 AFR Dry NUHOMES-7P, PWR In operation(1986) Commercial

Dry Storage Facility (AFR) – 1/2

SF Storage Facilities in US

19

Facility Capacity(t) Storage Method Status Remarks

Hanford-Canister StorageBuilding 2300 AFR Dry Cask Underconstruction(03) Laboratory

Idaho CPP-603 IFSF, CPP-749 270 AFR Dry wells In operation(75) Laboratory

Idaho TAN-607 demonstration small AFR Dry cask In operation(75) Pilot plant

McGuire NPP Site small AFR Dry cask, PWR Planned(00) Commercial

North Anna NPP Site ISFSI 840 AFR Dry TN-32, PWR In operation(98) Commercial

Oconee NPP Site ISFSI 380 AFR Dry NUHOMS-24P, PWR In operation(90) Commercial

Owl Creek NPP Site 40000 AFR dry storage Planned(04) Commercial

Oyster Creek NPP Site 190 AFR Dry NUHOMES-52B,BWR Planned Commercial

Palisades NPP Site ISFSI 233 AFR Dry cask, PWR In operation(93) Commercial

Peach Bottom NPP Site small AFR Dry, BWR In operation(00) Commercial

Point Beach NPP Site ISFSI 447 AFR Dry cask, PWR In operation(95) Commercial

Prairie Island NPP Site ISFSI 724 AFR Dry cask, PWR In operation(94) Commercial

Private Fuel Storage LLC 40000 AFR Dry cask Planned(03) Commercial

Rancho Seco NPP Site ISFSI 202 AFR Dry NUHOMS-MP187, PWR Planned Commercial

Surry NPP Site ISFSI 808 AFR Dry cask, PWR In operation(86) Commercial

Susquehanna NPP Site 343 AFR Dry NUHOMS-52B, BWR In operation Commercial

TMI-2, Debris at Idaho 130 AFR Dry NUHOMS In operation(99) Commercial

Trojan NPP Site ISFSI 359 AFR Dry cask, PWR Under construction Commercial

Dry Storage Facility (AFR) – 2/2

SF Storage Facilities in US

20

Surry ISFSI pad 1 Surry ISFSI pad 2

Surry ISFSI pad 1 and 3 Surry ISFSI pad 3

SF Storage Facilities in US

21

22

2 Central Interim Storage Facilities

Ahaus & Gorleben

6 Temporary Storage Facilities (5 to 8 years)

15 On-site Interim Storage Facilities

at Nuclear Power Plants

SF Storage in Germany

Current Storage Facilities in Germany

First central storage facilities: Ahaus and Gorleben (1983)

First on-site storage facilities:

Jülich research center (1993)

Interim Storage North (1999)

At-reactor storage facilities after German nuclear phase out decision 2001

BAM, IAEA TM on VLTS, 2011

WTI

STEAG

Underground Tunnel

23

24

Facility Capacity Storage Method Status Remarks

Greifswald NPP Site, ZAB -

Zwischenlager 560

AFR wet spent fuel storage

(from NPPs) In operation(1985) Commercial

Karlsruhe 55 AFR wet spent fuel storage

(from NPPs)

Shutdown

(1971-1990) Pilot plant

Wet Storage (AFR)

Facility Capacity Storage Method Status Remarks

Ahaus Central Interim Storage 4200 AFR Dry cask, LWR, THMR,

MTR In operation(1992) Commercial

Biblis NPP Site, Brennelement-

Zwischenlager 1400 AFR Dry interim storage

Under

construction(2005) Commercial

Biblis NPP Site, Interim Storage

(Temporary) 280 AFR Dry interim storage In operation(2002) Commercial

Brokdorf On-Site Storage Facility 100 cask-

bund. AFR Dry interim storage

Under

construction(2005) Commercial

Brunsbuettel NPP Site Interim Storage

(Temporary) 140 AFR Dry interim storage

Awaiting

license(2005) Commercial

Brunsbuettel On-site Storage Facility 450 AFR Dry interim storage Under construction Commercial

Gorleben Central Interim Storage AFR dry spent fuel storage In operation(2005) Commercial

Grafenrheinfeld On-site Storage Facility

(KKG BELLA) 88 cask-bund.

AFR dry spent fuel storage (from

NPPs)

Under

construction(2005) Commercial

Dry Storage (AFR) - 1/2

SF Storage in Germany

Facility Capacity Storage Method Status Remarks

Greifswald NPP Site ZLN Dry Storage

585 AFR Dry cask, WWER In operation(1999) Commercial

Grohnde On-site Storage Facility 100 cask-

bund. AFR Dry interim storage Underconstruction(2005) Commercial

Gundremmingen On-site Storage Facility

2250 AFR Dry interim storage Under construction(2005) Commercial

Isar On-site Storage Facility (KKI BELLA)

152 cask-bund.

AFR Dry interim storage Under construction(2005) Commercial

Juelich Research Center, AVR Storage

8 AFR Dry cask, LWR,

HTR In operation(1993) Commercial

Kruemmel NPP Site Interim Storage (Temporary)

120 AFR dry SF storage Under construction(2004) Commercial

Kruemmel On-site Storage Facility 800 AFR dry SF storage Under construction(2005) Commercial

Lingen On-site Storage Facility 1250 AFR dry SF storage In operation(2002) Commercial

Neckarwestheim NPP Site (GKN) 1600 AFR Dry cask Under construction(2006) Commercial

Philippsburg NPP Site ISFSF 1600 AFR Dry cask,

PWR/BWR Under construction(2006) Commercial

Pilot Conditioning Gorleben (PKA) 35 AFR dry SF storage Stand by Pilot plant

Dry Storage (AFR) - 2/2

SF Storage in Germany

25

Germany - Storage Cask Types

• CASTOR® V/19 and V/52 for LWR Spent Fuel

• CASTOR® Ic, IIa for LWR Spent Fuel (older design)

• CASTOR® HAW 20/28 CG

• CASTOR® HAW 28M

• TN 85

• TS 28

• CASTOR® THTR/AVR

• CASTOR® MTR2

Sources:

GNS

Areva - TN International

FZ Jülich

BAM, IAEA TM on VLTS, 2011 26

AFR at Ahaus

AFR at Gorleben

Cooling System

AR (WTI)

SF Storage Facilities in Germany

27

Facility Capacity Storage Method Status Remarks

Rokkasho Spent Fuel

Storage 3000

AFR wet spent fuel storage

(from NPPs) In operation(1999) Commercial

Tokai Spent Fuel Storage 140 AFR wet spent fuel storage

(from NPPs) In operation(1997) Commercial

Facility Capacity Storage Method Status Remarks

Fukushima Daiichi NPP Site

SFSF 408 AFR Dry cask, BWR In operation(1995) Commercial

Tokai II Power Station Cask

Custody Building 915 canister AFR Dry cask, BWR In operation(2001) Commercial

Mutsu ISFSI 3000 AFR Dry cask planned(2001) Commercial

Wet Storage (AFR)

Dry Storage (AFR)

SF Storage in Japan

28

1st Candidate Site for AFR Storage

Mutsu city

Metal Cask Storage by

Tokyo Electric Power

Company

Metal Cask(Fukushima) Storage Building

at Tokai Daini

SF Dry Storage in Japan

29

Mutsu interim storage facility (AFR)

≪Schematic diagram of storage facility≫ ≪Key specifications of facility ≫

Approx. 130 m

Approx. 60 m

Approx. 30 m

Storage capacity: 3,000 tU

Storage system: dry metal

cask (dual purpose system)

Storage period: 50 yrs

Key dimensions of storage

building

• Length : Approx. 130 m

• Width : Approx. 60 m

• Maximum height: Approx. 30

m

• Ceiling height:Approx. 15 m

• Thickness of wall and roof

surrounding the storage area:

1m

Operation starts in 2012

Implementing entity: RFS

SF Storage Facility in Japan

30

Secured additional storage capacity

by adopting dry storage since 1991

Allocated a space within the Wolsong site boundary

for installation of concrete silos

Storage Density : 254.1 kg/m2

Year Installed No. of silos

1992 60

1998 80

2002 60

2005 100

Total 300

SF Dry Storage in Korea

* Each silo contains 540 fuel bundles

31

Central Interim Storage Facility (CLAB) in Sweden

Graphic art: Mats Jerndahl

Clab

Forsmark/SFR

Barsebäck

Ringhals

Clab 2 increases the capacity

from 5,000 to 8,000 tonnes

In the unloading pool

the fuel assemblies are

lifted out and placed in

a storage canister

32 m

Oskarsham

32

33

Swedish Transportation Ship

34

Storage Concept of SF

900

m 530

m

Canisters room

Outlet

baffle

Inlet

stack

Handling area

Inlet

stack

Outlet stack

(46 m)

Interim storage bunker

(110 m x 42 m)

110 m Storage Concept of SF at semi-underground

SF Storage Concept in France(CEA)

Interim Dry Storage Facilities

Axpo

ZWILAG

ZWIBEZ @ Beznau NPP

ZWILAG interim storage facility

SF Storage in Switzland (1/2)

35

Axpo

ZWILAG

HLW storage hall @ ZWILAG

IAEA seal

Hotcell for SF (un)loading ZWILAG

SF Storage in Switzland (2/2)

Reactor-Site

Dry storage containers-OPG

Vaults-Hydro Québec

Silos-NBP, AECL

Casks in Rock Caverns Casks and Vaults in Storage Chambers

Surface Modular Vaults Casks and Vaults in Storage Buildings

Centralized Extended Storage

SF Storage in Canada

37

4.3 Reprocessing

What is Reprocessing?

To recover useful constituents of fuel for reuse

– Weapons (Pu)

– Energy (Nuclear Fuel)

For waste management

– Condition fuel

for optimized

disposal

– Recover long-lived

radioactive elements

for transmutation

38

Reprocessing - History

It began during Manhattan Project to recover Pu-239 (US)

– first, separated microgram quantities of Pu in 1942 using bismuth-

phosphate precipitation process

– Process scaled to kilogram quantity production at Hanford in 1944

: A scale-up factor of 109 !

Solvent extraction processes followed to allow concurrent

separation and recovery of both U and Pu and

Reprocessing transitioned from defense to commercial use

– Focus on recycle of U & Pu

– Waste management

20 g of plutonium

hydroxide 1942

39

Purex Process

Tributyl phosphate(TBP) used as the extractant in a hydrocarbon

diluent (dodecane or kerosene)

– Developed by Knolls Atomic Power Lab. and tested at Oak Ridge in 1950-

1952

– Used for Pu production plant at Savannah River in 1954 (F-canyon)

(H-canyon facility begin operation in 1955 and is still operational in 2008)

– Replaced REDOX process at Hanford in 1956

– Modified PUREX used in Idaho beginning in 1953 (first cycle)

40

Aqueous separation process

The PUREX process will be used to describe the basics on how solvent extraction is used to separate U and Pu from dissolved fuel

– Principles are similar for many other solvent

extraction processes (e.g. separation of FPs or

TRU) which use other extractants

Solvent extraction in aqueous reprocessing : PUREX (Plutonium Uranium REdox Extraction)

The differential and controllable distribution of ions

between two immiscible liquid phases:

i) Aqueous phase concentrated and dilute nitric acid

ii) Organic phase typically kerosenelike hydrocarbons

- Actinide ions are typically water soluble.

- Under certain conditions the ions may associate with

organic, predominantly nonpolarcomplexing agents.

- The formed complexes are far more soluble in

organic solvents than the bare ions.

One standard complexing agent : TBP

41

PUREX Process – Basic Principle

42

The PUREX solvent is typically 30 vol% TBP in a

hydrocarbon diluent (dodecane or kerosene)

The extracting power of TBP is derived

mainly from its phosphoryl oxygen atom

coordinating to metal ions:

TBP is classeextractant i.e. it will only

extract electroneutral complexes into the organic

phase d as a neutral e.g.

U and Pu Separation

43

As a general rule only metal ions in the +4 and +6 oxidation

states are extracted, this means that all other species

present are rejected

This leads to an effective separation

of U & Pu away from nearly all other

species in dissolved nuclear fuel.

PUREX Process

SF is first chopped into small pieces

dissolved in nitric acid solvent extraction

with TBP U and Pu separated from the

rest of the FPs and MAs U and PU are

separated in multistage extraction cycles and

purified.

The dual phase character of the PUREX

method can be made clear by distingushing

the aqueous (solid) and organic (dotted) paths

as in the adjacent flow chart.

Today, this method gives a 99.9 %

separation of U and Pu.

Out of proliferation concern, Pu can be co-

precipitated with U to avoid the separation of

pure Pu.

The waste stream, the liquid HLW, contains

FPs, MAs and APs and is processed and

vitrified, i.e. mixed with glass material to form

a borosilicate glass and encapsulated in a

stainless steel container.

44

THORP Reprocessing Flowsheet

45

Commercial Plant in the US

West Valley, NY

– First plant in US to reprocess commercial SNF

– Operated from 1966 until 1972

– Capacity of 250-300 MTHM/yr

– Shutdown due to high retrofit costs associated with changing

safety and environmental regulations and construction of larger

Barnwell facility

Barnwell, SC

– 1500 MTHM capacity

– Construction nearly completed- startup testing was in progress

– 1977 change in US policy on reprocessing stopped construction

– Plant never operated with spent nuclear fuel

46

Commercial-scale application

of the PUREX process

47

France

– Magnox plant in Marcoule began operation in 1958 (~400 MT/yr)

– Magnox plant in La Hague began operation in 1967 (~400 MT/yr)

– LWR oxide plant (UP2) began in La Hague in 1976 (800 MT/yr)

– LWR oxide plant (UP3) began in La Hague in 1990 (800 MT/yr)

UK

– Windscale plant for Magnox fuel began in 1964 (1200-1500 MT/yr)

– THORP LWR oxide plant began in 1994 (1000-1200 MT/yr)

Japan

– Tokai-Mura plant began in 1975 (~200 MT/yr)

– Rokkasho plant currently undergoing hot commissioning (800 MT/yr)

Russia

– Plant RT-1, – Began operation in 1976, 400 MT capacity

– Variety of headend processes for LWR, naval fuel, fast reactor fuel

USA

– West Valley(1st commercial plant, 1966-1972): 250-300 MT Capacity,

Shutdown due to high costs associated with regulations

– Barnwell (1500 MT capacity) never operated with SF

– 1977 change in US policy on reprocessing

Fuel-cycle flow sheet

for 1000-Mwe LWR

48

PUREX Process – advantages and disadvantages Advantages

– Continuous operation/ High throughput

– High purity and selectivity possible – can be tuned by flowsheet

– Recycle solvent, minimizing waste

Disadvantages

– Solvent degradation due to hydrolysis and radiolysis

– Dilute process, requires substantial tankage and reagents

– Historical handling of high-level waste

– Stockpiles of plutonium oxide

49

Thank you for your attention!

Continue to Part II

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