Decommissioning (technical knowledge/experience; national strategies / policies; main issues; future trends)

Transcription

1 Decommissioning (technical knowledge/experience; national strategies / policies; main issues; future trends) Michele Laraia, IAEA World Nuclear University- Summer Institute 2008 Ottawa, Canada, 18 July 2008

2 Contents Decommissioning: the global overview (number of facilities, policies and strategies, trends) Planning issues Organization and management issues Technological issues Safety issues Integration of decommissioning constraints into new projects Case study No.1 : The preliminary decommissioning plan; how good is good enough? Case study No. 2: Identifying decommissioning stakeholders

3 Decommissioning a safety-oriented IAEA definition The administrative and technical actions taken to allow the removal of some or all of the regulatory controls from a nuclear facility (except for a repository or for certain nuclear facilities used for the disposal of residues from the mining and processing of radioactive material, which are closed and not decommissioned ).

4 Decommissioning (IAEA Safeguards Glossary, 2001) Decommissioned facility is an installation or location at which residual structures and equipment essential for its use have been removed or rendered inoperable so that it is not used to store and can no longer be used to handle, process or utilize nuclear material See Tajikistan reactor never operated but still subject to safeguards provisions

5 A broader vision of decommissioning The two main objectives of decommissioning are to render the site permanently safe and to recover it, as far as practicable, for reuse (TRS # 444, WNA 2006)

6 A frequent confusion Decommissioning addresses to the chemical, physical and mechanical processes in removing structures and components of a nuclear facility Environmental remediation addresses the cleanup and recovery to other uses of radioactively contaminated land and waters (restoration aims at reaching pristine conditions). Removal is often out of question (e.g. million tons of uranium mill tailings) The technical literature is often ambiguous on these terms Site remediation may include elements of decommissioning (the buildings) and the environment This lecture mostly addresses decommissioning, not ER.

7 Status of the Decommissioning of Nuclear Facilities around the World* Nuclear Power Plants Operating: 446 Under construction: 45 Shutdown, under decommissioning: 107 Decommissioned: 14 Research reactors and critical assemblies Operating: 288 Under construction: 9 Shutdown, under decommissioning: 119 Decommissioned: 404 * various IAEA sources,

8 Status of the Decommissioning of Nuclear Facilities around the World* Fuel cycle facilities (uranium milling, uranium conversion/recovery, uranium enrichment, fuel fabrication/heavy water production, fuel reprocessing) Operating: 423 Under construction: 19 Shutdown, under decommissioning: 297 Decommissioned: 192 Medical, research and industrial facilities: ~ Cold war legacy Total decommissioning liability for the period up to 2050 of about $ 1000 billion ($ 1 trillion)!!! Note these were 2005 $, not today s!!! *various IAEA sources

9 Status of the Decommissioning of Nuclear Facilities around the World* W Not to mention NORM*- contaminated facilities and sites Even approx numbers for NORM facilities are hard to estimate, since they depend on regulations still in evolution *Naturally Occurring Radioactive Material

10 Reasons for Decommissioning Uneconomical Operation Technical Obsolescence Conclusion of Research Program Safety Considerations Change in Governmental Policy Others - Accident, etc.

11 Decommissioning-related activities during the lifecycle of a nuclear facility State Design, Construction & Start-up Phase Operating Phase Shutdown Pre- decommissioning Phase Safe Enclosure Preparation Safe Enclosure Period Final Decommissionin g Phase Source Term Final Activities Initial Decommissioning Plan Ongoing Decommissioning Plan Final Decommissioning Plan Removal/ Defuelling. Waste Site Preparation Initial Dismantling Surveillance & Maintenance Dismantling. Final Survey & License Conditioning termination

12 Decommissioning Strategies Ideally planning for decommissioning should be started at the facility design stage and not after the facility has been permanently shutdown Cost/benefit evaluation should be used to determine the best strategy The sooner the better: early planning will allow timely allocation of funding and infrastructure

13 After final shutdown, in a lack of plans for decommissioning

14 Decommissioning Strategies (ctd( ctd) Former IAEA decommissioning strategies Stage 1 - Preservation Stage 2 - Partial Dismantling Stage 3 - Full Dismantling USA decommissioning strategies DECON - Immediate Dismantling SAFSTOR - Safe Enclosure & Deferred Dismantling ENTOMB - In-Situ Disposal

15 Decommissioning Strategies (ctd( ctd) Decommissioning starts with the implementation of the decommissioning strategy and ends with the release of the site typically strategies are *: immediate dismantling deferred dismantling (Safe Enclosure) entombment * As defined in IAEA literature

16 Decommissioning Strategies (ctd( ctd) Variants on Deferred Dismantlement Safe enclosure duration Short Medium Long <15 years years >40 years Active and passive variants of safe enclosure A number of factors influence the approach Combinations of different features of each option Can opt out of Safe Enclosure at a future point in time

17 Decommissioning Strategies (ctd( ctd) An emerging decommissioning strategy: continuous decommissioning Start immediately, continue for a relatively long time depending on availability of resources Example: Rancho Seco NPP, USA

18 Factors Impacting Selection of a Strategy Legislative and regulatory requirements Spent fuel management strategy Waste arising and national waste management strategy Finances Condition of the facility radiologically and structurally Planned future use of the site Availability of technology Retention of operating staff and records

19 Factors Impacting Selection of a Strategy (ctd) Societal considerations - environment, employment and public perception Interactions with other countries national nuclear programs Experience and expertise to manage complex projects

20 Financial Factors Now many countries have some form of funding mechanism in place Private versus State owned facilities can impact timing Premature shutdown for NPP is still an open issue and limits options if it occurs Long term assurances of funding availability (see 135-yr deferred dismantling strategy in the UK)

21 Radiological Factors Dose rate level reductions taper off after years for most reactors (Co-60 controlling decay) Some longer-lived isotope issues may still present themselves (Cs-137, Sr-90) Lower worker occupational exposures in in research reactors make deferred dismantling really not very practical Remote operations may be used to reduce doses in immediate dismantling cases Prevailing α emitters e.g. at nuclear fuel cycle plants- render deferral useless or counterproductive ( Pu to Am decay)

22 Waste Management Factors Lack of waste disposal sites / inability to site new facilities. Escalating disposal costs Spent fuel management issues Deferral strategies may allow lowering of waste disposal categorization for some waste streams HLW >>>LLW, LLW >>>exempt Large decommissioning waste volumes may tax the disposal site ability to handle Waste storage can be an acceptable alternative to disposal (e.g. at Greifswald NPP, Germany) Ongoing search for new, additional waste management resources ( e.g. VLLW, conditional disposal, smelting and recycle see new Studsvik plant in UK etc)

23 Land Use Factors Many successes in reuse of both research reactor and NPP sites USA Land costs are at a premium in some countries Japan prescribes immediate dismantling by law Bound to become even more of an issue with stakeholders and involve them more in future decision making. Generally, stakeholders favor early dismantling and site reuse

24 CLOSING THE NUCLEAR LOOP REDEVELOPMENT! CONSTRUCTION SITING OPERATION AND NOW? DECOMMISSIONING

25 Vaporsphere Vaporsphere at atargonne National National Laboratory, Laboratory, USA: USA: from from nuclear nuclear facility facility to to warehouse warehouse

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27 Fort St Vrain,, USA: from nuclear power plant to gas fired power plant

28 The ORNL Graphite Reactor Museum

29 Specific Strategies Specific Strategies Factors favoring Immediate Dismantlement Decommissioning funds are available and costs are known Low-level waste disposal sites are available Experience of facility personnel and proven technologies are available Minimizes future regulatory uncertainty Minimizes near-term impact to the local economy Presents positive public perception Eliminates corporate liability sooner and makes site available for re-use Allows for earlier license termination Examples of fully dismantled NPPs (Maine Yankee, Big Rock Point, Trojan etc USA; Niederaichbach, Germany; JPDR, Japan)

30 Completed projects: Maine Yankee, USA

31 Specific Strategies (ctd( ctd) Factors favoring Deferred Dismantlement Funds not available for immediate dismantlement Smaller radioactive waste volumes Lower staff radiation exposures More time to resolve waste management issues (e.g. graphite at Vandellos NPP) Avoid industry learning curve Some areas may be able to be immediately reused Benefit from technology enhancements Multi-unit sites Examples of NPPs in Safe Enclosure: (Barsebaeck, Sweden; Humboldt Bay, USA; all Magnoxes, UK; Vandellos, Spain).

32 Vandellos Vandellos Safestore: Safestore: former former workshops workshops at at the the base base of of the the reactor reactor are are being being used used for for the the Mestral Mestral Technological Technological Centre Centre

33 Specific Strategies ( Specific Strategies (ctd ctd) Factors favoring Entombment Used only in rare instances Geographic location remote sites Governmental controls may be practical Limited funding and resources available quick and easy solution Examples: earlier US reactors, Georgia IRT However Waste disposal site created Creates longer term liability / monitoring requirement Presents burden to future generation

34 Georgia reactor: before and after entombment

35 Specific arguments for Greifswald to go to immediate dismantling Need to re-employ exceedingly large operational staff (thousands of workers) in an economically depressed region. Prompt decision on decommissioning strategy allowing reemployment of key staff. Availability of waste disposal facility at the beginning of the decommissioning project. Funds made available by State. Full set of clearance criteria harmonized to international standards. Difficulty of installing safe storage for WWERs (no secondary containment).

36 Multiple Plant Sites Multiple plant sites will typically wait until all the facilities are ready for decommissioning to gain an efficiencies of scale before decommissioning any one unit Examples fr USA Dresden 1, Peach Bottom 1, Indian Point 1, Millstone 1 In some cases there may be co-located on a common site old retired units in Safe Storage awaiting dismantling and new operating units of a next generation design

37 Strategy Trends Technologies are generally readily available for immediate dismantling Trends are based on country specific drivers ex. waste disposal site availability at reasonable cost Major obstacles: Lack of funding Lack of waste management & disposal facilities (e.g. UK) Life extension practices for NPP; fewer decommissioning projects in the near future

38 Trend: regardless of a preference for immediate dismantling ( IAEA s preferred strategy), still some 50% of recently shutdown NPPs opt for delayed dismantling EVOLUTION OF NPP DECOMMISSIONING STRATEGY 35 Entombment N of NPP Units and before Strategy under consideration Strategy changed from safe enclosure to dismantling Safe enclosure pursued Safe enclosure achieved Dismantling underway Dismantling completed Shutdown date

39 Current issues and challenges for the future* - Planning for Decommissioning Decommissioning policies, strategies and plans Lack of clarity in energy and decommissioning policies Missing decommissioning strategies for multi-facilities sites Peer review of decommissioning policies, strategies and plans Planning the transition from operation to decommissioning. Lack of regulation to carry out the transition Restructuring the organization (e.g. privatization, funding issues) Preservation of knowledge and competence * Issues in red arbitrarily selected for discussion.

40 Current issues and challenges for the future - Planning for Decommissioning (cont d) Documentation Lack of guidance on initial/ ongoing decommissioning plans. Harmonization of national legislation with EU directives and IAEA (e.g. EIA standards). Funding Insufficient funding can cause decommissioning delays. Deferral by default. Accurate cost estimates should be performed (e.g. using the EC/IAEA/NEA guidelines). More harmonization needed. Funding mechanisms should be periodically reviewed. Funding mechanisms should not hinder fair competition (EU concerns). Internal funds? Segregated funds? To what extent can these funds be used before decommissioning?

41 The Cintichem case: from 25 M$ to 100 M$. Characterize! Characterize! Characterize! Do not miss leakage migrating from plant basement, to foundation, to bedrock, to groundwater Later can be too late.

42 Current issues and challenges for the future - Decommissioning Organization Cultural change from operation to decommissioning Operators motivation and mentality (e.g. a research reactor staff). Sequence of one-off operations in a changing environment instead of routine. Loss of knowledge. Training and providing necessary information. Leadership and adaptation of procedures. Improve the record keeping. Social issues Loss of jobs. Early planning of alternative employment incl. site reuse. Early identification and involvement of the stakeholders

43 Current issues and challenges for the future - Decommissioning Organization (cnt d( cnt d) Organization structure Change of responsibilities. Interactions operator contractors regulators. Promotion of international exchange of expertise and lessons learned. Clearly define objectives, functions and responsibilities Early planning of interactions, regular exchange of information. Transparency. Project Management Lack of experience with operators and regulators. Difficulty to estimate contingencies. Control of compliance with plans and schedules. Learning by doing, dissemination of experience, focus on key issues. Adopting cost estimating, risk and contingency management techniques. Regular monitoring and follow up of the plans and schedules.

44 Final shutdown Post operation Preparation of Safe Enclosure Waiting Period Dismantling 4 years 3 years 40 years 4 years 26/3/1997 1/3/ /12/ Fig.1 Decommissioning Phases Dodewaard

45 Director Head of NPP Support Security Quality Assurance Operations Maintenance Technical Support Fig. 2 Dodewaard: organization during normal operation

46 Director Head of NPP Assistant Head NPP Security Quality Assurance Communication Operations and Maintenance Decommissioning Personnel and Support Fig. 3 Dodewaard: organization during post-operational phase

47 Director Head of NPP Assistant Head NPP Security Quality Assurance Communication Decommissioning Personnel and Support Fig. 4 Dodewaard: organization during preparation for safe enclosure

48 Current issues and challenges for the future - Decommissioning technologies Decontamination If, when, how and what to decontaminate. Effluent treatment (e.g. decontamination solutions). Cost - benefit analysis before any decision. Decontamination is not cure-all. Dismantling Sequence and timing of dismantling. Logistics. Maintenance experience for large equipment, similar decommissioning projects, early planning.

49 Current issues and challenges for the future - Decommissioning technologies (cnt d( cnt d) Waste and material management Secondary waste management. Categorization and segregation of material. Management of special and toxic materials (e.g. graphite, Be, Na, crystallized boric acids, asbestos). Comprehensive information on different technologies and drawbacks. Training of staff, proper technology and criteria to help sorting and treat different waste streams. R&D programs, IAEA to promote international solutions for special waste management. Criteria for selection of technology Not sufficient clarity of the criteria for selection of decommissioning technology. Cost benefit analysis (e.g. economics), characterize only as needed, waste acceptance criteria, etc. Characterization in mixed α β γ fields Characterization at close-to-clearance levels

50 Current issues and challenges for the future - Decommissioning Safety Safety case Definition of a set of licensing documents required for D&D. Evolution of safety issues during the decommissioning process and their associated documents. Lack of experience in developing safety assessments. Optimize and give flexibility to the licensing process. Reflect the changes in the decommissioning process. Training and dissemination of experience (e.g. safety assessment). Preliminary vs. final decommissioning plans.

51 Current issues and challenges for the future - Decommissioning Safety (cnt d( cnt d) Radiological vs. non radiological risks Possible lack of communication between different regulatory bodies. Establish legislation and early dialog between the different regulatory bodies. How to balance radiological and non radiological hazards. Develop adequate methodology to take into account both types of hazards. Definition of responsibilities.

52 Some good examples of bad practices

53 Current issues and challenges for the future - Decommissioning Safety (cnt d( cnt d) Clearance and site release criteria Introduction of harmonized clearance levels. Use of RS-G-1.7, as a basis for improving harmonization. Consider adoption of conditional release criteria for materials and sites Economics/practicability of current release criteria. D&D with limited resources Develop graded approach methodologies focusing on the most relevant safety related issues. Minimize decommissioning costs when having limited resources

54 Integration of decommissioning constraints into new projects Lessons learned from complete decommissioning projects Decommissioning practitioners to talk to designers Be realistic: a plant is not designed to be decommissioned The time factor: design is followed by year operation and perhaps as many years of safe enclosure

55 INFORMATION SOURCES (CTD) Experienced technical and management staff members that have performed decommissioning of nuclear facilities regulators, operators and contractors Often lessons learned are detailed in project final reports and in some instances specific reports on lessons learned Site visits to units or facilities in decommissioning is another useful way to learn what others have done in similar situations Do not trust vendors blindly

56 INFORMATION SOURCES (CTD) Dedicate resources to track projects as they are happening In addition, there are some sources of lessons learned available on the Internet (e.g. the DOE programme)

57 A BASIC PROBLEM IN TRANSFERRING DECOMMISSIONING LESSONS LEARNED TO DESIGNERS AND BUILDERS OF NEW FACILITIES Decommissioners and designers/builders belong to different categories, well distinct in space, time, organizations, professional / contractual interests and motivations A conscious effort is needed by an independent / overarching authority to establish and enforce the link

58 A FEW SELECTED CRITERIA TO REVIEW DESIGN/CONSTRUCTION IN THE LIGHT OF DECOMMISSIONING Decide on scope of decommissioning e.g. what is going to be left behind following decommissioning (foundations, discharge pipes, etc.) Avoid considering unproven decommissioning technologies let someone else test or evaluate and ready the new technology. Keep it simple! Do not reinvent the wheel! Maintain a strong document control system including effective retrieval and prompt disposition of unneeded records. Flag decommissioning-related records!

59 A FEW SELECTED CRITERIA TO REVIEW DESIGN/CONSTRUCTION IN THE LIGHT OF DECOMMISSIONING (CTD) As built drawings are often not accurately as built and other documentation may be lacking Time is money tackle a problem with the biggest equipment space constraints allow to be used Facility maintenance is a critical activity also for eventual decommissioning. What is good for maintenance and repair is also good for D&D Do not overlook the issues of: Groundwater contamination Soil contamination Know what is underground Hence: waterproof coatings on floors and walls

60 A FEW SELECTED CRITERIA TO REVIEW DESIGN/CONSTRUCTION IN THE LIGHT OF DECOMMISSIONING (CTD) Evaluate options for large intact component removal versus size reducing larger items Understand the packaging and disposal requirements even at the design stage Make provisions to maintain detailed and accurate records on the contents of your waste packages

61 Large items Decommissioning waste US Ecology, Richland France PWR Vessel Head, laube, France

62 A FEW SELECTED CRITERIA TO REVIEW DESIGN/CONSTRUCTION IN THE LIGHT OF DECOMMISSIONING (CTD) Closely evaluate (cost/benefit analysis) any and all opportunities to decontaminate material for release or to recycle/reuse decommissioning projects Be ready to face changes of: the reference decommissioning strategy; the future destination of the site. Be ready to face the evolution of: the legal framework; the financing of the decommissioning project; the waste fees.

63 Case Study No. 1: the preliminary decommissioning plan (PDP) : how good is good enough? The PDP is to prove that end-of-life decommissioning can be done in a safe, cost-effective and timely manner The PDP should be in place at the design and construction stage The PDP should be a living document: it should evolve in detail until the final, ready-for-action plan is implemented Prime goal of the PDP: collecting decommissioning funds during operation, hence funding mechanisms to be described in the PDP What more contents? How should the PDP evolve? Who should be in charge? What may change the assumptions of the PDP?

64 Case study No. 2: Identifying decommissioning stakeholders A stakeholder is a person or entity that affects / is affected by decommissioning Traditional stakeholders: operator & regulator D&D stakeholders: contractors, funding bodies, Ministries and other policy-makers Other stakeholders: local communities, trade unions, shareholders More stakeholders? How to involve stakeholders?

65 Website on IAEA activities missioning/