Issues in Long-term assessment of Uranium site remediation fileupdated every 3 years [2007-2009],...

Issues in Long-term assessment of Uranium site remediation

Marie-Odile GALLERAND

2012 BIOPROTA Workshop

21-24 May 2012

Nancy, FRANCE

Issues in LT assessment of U site remediation – 22 May 2012 –MO.Gallerand – BIOPROTA Workshop

� Context of Long Term studies in the field of former uranium mine site

� Main issues


� Regulatory context

� Requirements from the National Plan for the Management of radioactive

Materials and Waste (PNGMDR)

� Recommendations from the GEP (Pluralist Expert Group)

Context of Long Term studies in the field of former uranium mine sites


Autunite Mining site

BNI regulation Framework :

� All the installations of the fuel cycle

AUTHORITIES : Nuclear safety Authority (ASN)

ICPE regulation Framework :

� Tailings disposals

Mining code regulation Framework :

� Mine sites

AUTHORITIES : Ministry of environment and ASN

Uranium mines Nuclear installations



Public Health code


At national level

� The mining code� Set the rules for Uranium ore mining works and facilities

� Is complemented by two decrees� 1980 General Rules applicable to mining and quarrying industries

(RGIE)� 1990 Specifies technical rules relative to environmental protection :

management of radioactive materials ; discharge authorisation ; environment monitoring and control

� completed by additional requirements :� the Environment Code (for ICPE)

� the Public Health Code (protection of the population) � based on EURATOM directive and include the (ICRP) principles

At local level

� National regulations give rise to compliant local regulations taken

by the local authorities (Prefect)




Beginnings to consider the post-closure situation of the mine sites

� In 1980 and 1993, and 1999 the ministry of environment issued several documents to define fundamental concepts applicable to the final closure of mill tailings disposals and give the objectives and technical requirements for long term

� in 2001, in support of the recommendations of the ministry, methodological documents have been prepared by institutional technical supports (IRSN and BRGM)

Méthodologie d’évaluation de la stabilité des digues à

stériles uranifères -Application à deux sites

pilotes

2001

Méthodologie d’évaluation de la stabilité des digues à

stériles uranifères -Application à deux sites

pilotes

2001

Expertise de la méthode COGEMA d’identification et de caractérisation des groupes de référence associés aux anciens sites miniers

2001

Expertise de la méthode COGEMA d’identification et de caractérisation des groupes de référence associés aux anciens sites miniers

2001











� Instituted by the Program Law n°2006-739 dated 28 June 2006 that provides a framework for the sustainable management of radioactive materials and waste

� Drawn up under the auspices of ASN (pluralistic working group ASN, MEDDTL, DGEC, environmental associations, representatives of elected officials, control and evaluation authorities, radioactive waste producers and managers –operators-)

� updated every 3 years [2007-2009], [2010-2012], [2013-2015], …

� Review the existing management methods for radioactive materials and waste

� Report the estimated needs for storage/disposal facilities and specify the necessary capacities of the facilities and the duration of the storage

� For the radioactive waste with no definitive management method, determine the objectives to be reached through Research and Studies

Plan implemented by decree a



Focussed on the long term impact of the tailings disposals[2007- 2009]

� 17 disposals, of which 11 enclosed with dams

dam

� First assessment expected by the end of 2008, to be delivered to the ministries of energy and environment by Areva

�mechanical and geochemical behaviour of the tailings (within the disposal)

� long term stability of the dams

� long term impact of the uranium mill tailings disposals

Requirement(Article 10)



Scope broadened to the impact of the former U mine sites in general

and in particular the impact resulting from the re-use of waste rock in

the public domain and the long term impact of the waste rock piles

~230 sites

[2010- 2012]

Waste rock pile

Remediated site (landscaping with waste rock)




The way to promote a shared understanding of the situations around the

former uranium mine sites

�http://www.gep-nucleaire.org

� set up in 2005 by the French ministries of health, environment and industry� work initially focused on the Limousin former uranium mine site issues

Groupe d’Expertise PluralisteGroupe d’Expertise Pluraliste




�http://www.gep-nucleaire.org

Groupe d’Expertise PluralisteGroupe d’Expertise Pluraliste

� Improve dialogue between (local) stakeholders

� Provide methodological tools for impact assessments

� Formulate recommendations to improve the risk management and the surveillance network

� Generalise the recommendations to all sites,and consider the long terms issues

Main assignments


�To renovate and clarify the institutional and legal framework forthe management of the former uranium mine sites

� Question of the transfer of responsibilities (Areva → Authorities)

� Revising the mining regulations to be more relevant to post-remediation situations

�To promote efforts directed at the improvement of knowledge on the sites; to continue the studies and research and to broaden their scope

� Understanding of the processes

� Question of developing a predictive capacity in relation to the evolution of key phenomena(hydrogeology, hydrochemistry, exhalation and transfer of radon, accumulation of radioactivity in sediments, aging of milling residues…)

� Knowledge on the chemical toxicity

�To extend the effort of remediation in order to put in place systems as robust as possible for the long term

�…



(selection)

Final report issuedSept.15, 2010

Long term issues highlighted by the GEP with specific questions linked to the transfer of responsibility of the tailings disposals to the public body within a few years, and the concern of the remediation of the sites in case of any failure/dysfunction


� Context of Long Term studies in the field of former

uranium mine site

� Main issues

Main issues


� Consideration regarding the long term impact assessment in the field of

uranium mine remediated site

� Long term main issues



Backfilled Open pitOpen pit + dam Depression + ring damThalweg + dam

Topsoil

Waste rock

Tailings

Vegetation

disposal cover structure

Type of tailings disposals in France

Main issues/general considerations

Source term

238U : ~ 3-14 TBq

226Ra : ~ 40-110 TBq


Current potentially

exposed populations

Mining works Remediated site

?

Environmental measurements(water, air, sediments, food chain)

Scenario(1 reference)

Radiological impact (dose)

Calculated environmental concentration

Hypothetical

exposed

populations

Scenarios(1 reference;5 altered)

Initial referenceconditions(background levels)

Methodology of the impact assessment

Current situation Long term situation(s)



SC1 : standard conditions

SC2 : Integrity failure of the cover

SC3 : Integrity failure of the dams

SC4 : Residence building over the disposal (cover intact)SC5 : Digging works within the disposal (road yard)SC6 : Residence building over the disposal (cover totally broken)

Natural evolution scenario

Altered evolution scenarios




Timescale, occurrence and scenarios - Doctrine

te te + ∆tDemonstrated efficiency period

Surveillance

active guaranteed Not guaranteed

SC2, SC3

SC4, SC5

SC1

Radiological impact assessment/Respect of the dose limit

Reference scenario

Altered scenarios

ts

SC6

Evaluation of radiological impact/ altered scenarios probability




Main issues

Hydro(geo)chemistry of the tailings disposals and the sites in general

Stability of the dams over a few ten thousands years

Radon modelling Water treatments (discharges)

Management of radioactive materials (sediments)


Main issues

Hydro(geo)chemistry of the tailings disposals and the sites in general

▌The tailings are supposed to evolve naturally into a chemical

and mineralogical form limiting the U and Ra mobility,

whatever the scenario may be

No sufficient demonstrative data- continue the characterisation studies- implement geochemical models- demonstrate the validity of the models for all the disposals

Tailings sampling from Bellezane disposal


Main issuesStability of the dams over a few ten thousands years

▌The dams are supposed to be robust structures, the stability

of which is guaranteed, even in case of extreme climatic

events or large earthquake occurrences

- Middle to long term stability not demonstrated- Absence of assessment of the radiological impact which could follow a

suspension of surveillance and/or maintenance process- Need to revise the probability of hazards accumulations


Main issues

Radon modelling

▌Radiological impacts : < 1 mSv/y for the reference situation < a few ten mSv/y for highly altered situations

Need to compare the computed radiological exposure values with the surveillance results, particularly indoor radon concentration. The calculated indoor radon dose for the altered scenario “house built over the tailings disposal” is very small and not consistent with indoor radon concentration effectively observed in some dwellings in France (in particular in Region with high radon potential)

Need to improve the modelling of :-Radon emanation and transport within the soil-Radon entry into the building (advection/diffusion through a (cracked) concrete slab)-Radon accumulation in the building

Apply the modelling to situation where houses are built over a waste rock pile or a former site landscaped with waste rockCompare the results with observed radon concentration measured in building or industrial platforms whose base is made of waste rock

Need to study the relevance and feasibility of a reinforcement of the cover over the tailings disposals (to limit radon exposure over a few 10 thousands years)


Main issues

Water treatments

(discharges)

10 « chemical » treatment plants over 14

��

�

�


Main issues

Water treatments

(discharges)

3 « passive » treatment plants (limestone drains)

1 « chemical/passive »configuration (lime/ion exchange resin)

Areva Researches in progress

�Bark biosorption

�Membrane filtration

�Wetlands

Enhancement of existing processes

� Limestone drains (clogging)


Main issues

Water treatments (discharges)

� Need to study the evolution of the mine water quality� Is the current treatment efficient? What if the discharge limits are lowered?� What are the positive/negative points of the treatments?� Can we imagine to replace the physico-chemical treatment by a more “passive” one?� Do the current discharge standard limits ensure that the radiological and chemical impacton (Human) and Ecosystems is negligible/acceptable? What if the treatment is stopped?

Management of radioactive materials (sediments)

� What are the processes that lead to the accumulation of radioactivity from the former U mine site and tailings disposal into the sediments of downstream waterpond?

� What is the fate of these sediments over the long term and the corresponding impact on ecosystem? on human health according to the potential use?

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