module “strategy development” safe decommissioning of nuclear power plants project...
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MODULE “STRATEGY DEVELOPMENT”
SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 2
CONTENTS
1. Basic terminology
2. Decommissioning options2.1. Description of different options. Decommissioning strategy
2.2. Decommissioning options characterization, evaluation of the advantages/disadvantages of the different options
3. Selection of decommissioning option3.1. Consideration relating to different factors in the selection decommissioning option
3.2. Process of selection
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 3
TRAINING OBJECTIVES
Upon completion of training trainees should be able to: Identify the main terminology used in decommissioning –
decommissioning stages, start and final condition, methods and options etc.
Describe/explain the option of immediate decommissioning and safe disposal after final shut down.
Describe/explain the deferred dismantling decommissioning option. Identify the advantages and disadvantages of the different
decommissioning options.
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 4
TRAINING OBJECTIVES
Explain the considerations relating to RAW management system. Explain the considerations relating to radiological inventory and
ageing of the equipment. Explain the considerations relating to decommissioning costs, social
aspects and qualification level of the personnel. Explain the relations between radiation protection requirements,
release criteria, available technologies (tools, equipment, working methods, etc.) and decommissioning option/strategy selection.
Explain the process of decommissioning strategy/option selection.
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 5
MAIN TERMINOLOGY
OPERATION OF A NUCLEAR FACILITY -
All activities performed to achieve the purpose for which the nuclear facility was constructed
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MAIN TERMINOLOGY
FINAL SHUTDOWN –
The final phase of operation when main process equipment of the nuclear facility is shutdown for decommissioning and operations performed under operational modes are
completed
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MAIN TERMINOLOGY
END OF OPERATION –
State of the nuclear facility when all activities, performed to achieve the purpose for which the equipment was
designed, are irrevocably completed
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MAIN TERMINOLOGY
DECOMMISSIONING –
Administrative and technical actions taken to allow the removal of some or all of the regulatory controls from a
facility
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 9
MAIN TERMINOLOGY
LICENCE –
A legal document issued by the regulatory body granting authorization to perform special
types of activities
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MAIN TERMINOLOGY
DECOMMISSIONING OPTION –
The process/method for decommissioning by which
decommissioning purpose is achieved
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MAIN TERMINOLOGY
DECOMMISSIONING PHASE – in terms of time and contents it is a well-defined part of decommissioning of a nuclear facility or its component, with clearly defined initial and final state• Preparation to ensure safe enclosure • Safe enclosure• Preparation for decommissioning• Decommissioning of a nuclear facility or its components
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MAIN TERMINOLOGY
DECOMMISSIONING STAGE – a level reached during nuclear facility decommissioning• Stage “Nuclear facility storage under surveillance”• Stage ”Restricted release” (limited utilization of
site)• State ”Unrestricted release” (unlimited utilization
of the site – “green field”)
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MAIN TERMINOLOGY
CRITERIA FOR UNLIMITED UTILIZATION OF SITE OR UNRESTRICTED RELEASE OF MATERIALS FROM
CONTROL –
Levels of surface contamination of materials (sites), collective and relative dose rate do not exceed the value
of equivalent individual yearly dose
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MAIN TERMINOLOGY
DOCUMENTATION• Concept (strategy, options) for decommissioning• Plan for decommissioning or plan for decommissioning phase• Final decommissioning documentation
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DESCRIPTION OF DIFFERENT OPTIONS
Immediate decommissioning (immediate dismantling) Decommissioning following the safe enclosure (deferred
dismantling) Decommissioning under surveillance (storage of nuclear
facility under surveillance) Decommissioning with in situ entombment
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 16
DESCRIPTION OF DIFFERENT OPTIONS
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ADVANTAGES OF IMMEDIATE DISMANTLING
Access to information for status of a piece of equipment based on current operational documentation;
Utilizing specific experience on given facility; Keeping and using key staff familiar with specific site
conditions; Sufficient (in most cases) financial assurance, funds
assessed on basis of existing (during operation) conditions.
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DISADVANTAGES OF IMMEDIATE DISMANTLING
Need for using remote control mechanisms for dismantling;
Need for radiation protection; Need for long-term RAW storage in specialized storage
facility; Staff high collective equivalent dose; Financial losses related to applying costly dismantling and
transportation methods.
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DEFERRED DISMANTLING - ADVANTAGES
Provide time for development of complex system for RAW management;
Decrease collective doses; Limited utilization of remote control mechanisms for
fragmentation and dismantling of equipment; Provide time needed for development of new
technologies; Enhancement of decommissioning economy; Provide time for development of management rules for law
activity waste.
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DEFERRED DISMANTLING - DISADVANTAGES
Loss of staff specific experience for given nuclear facility; Costs for financing maintenance of professional information for
nuclear facility; Ageing of a key importance piece of equipment and barriers, financial
costs for equipment maintenance; Public support; Continuous shrinking of site; Issues related to prognosis for rising costs; Changes in legislation towards more rigorous rules for RAW
management and release of materials in environment.
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TYPES OF DEFERRED DISMANTLING
Custodial SAFSTOR Passive SAFSTOR Hardened SAFSTOR
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PARAMETERS INFLUENCING THE CHOICE OF DECOMMISSIONING OPTION
Requirements of legal documentation (acts, rules and standards) and authorities;
Expected costs for decommissioning; Spent fuel management strategy; Infrastructure for radioactive waste management; Criteria for release from control; Social and economic parameters; Nuclear facility status and facility ageing process; Radiological assessment, ...
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REQUIREMENTS OF ACTS, RULES, STANDARDS AND REGULATORY BODIES
Some options may be completely rejected or limited. The values of criteria for release of materials or site from
control are defined by law. Criteria values for waste storage in facilities of different
type are stipulated by the law.
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DECOMMISSIONING COSTS
Activities after final shutdown (RAW processing); Maintenance work and control; Dismantling, decontamination, treatment of contaminated
soils; RAW management (processing and conditioning, storage
and disposal, transportation including); Others (documentation development, licensing process,
quality assurance).
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SPENT FUEL MANAGEMENT STRATEGY
Removal of spent fuel – main safety requirement Spent fuel disposal in interim storage facilities Utilization of spent fuel pool for wet storage of spent fuel
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RADIOACTIVE WASTE MANAGEMENT SYSTEM
Capacity of RAW management system; Accessibility and capacity of technologies; Provision of continuous flow of waste; In case of insufficient RAW storage facilities:
• leave nuclear facility or part of it under in state “storage under surveillance”;
• process and store waste in interim storage facilities or containers.
Develop a short-term strategy for reduction of transitional RAW volume;
Store re-cycled RAW.
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SOCIAL AND ECONOMIC PARAMETERS AND PUBLIC OPINION ABOUT DECOMMISSIONING OPTIONS
Local population employment; Environmental issues:
• Price of the land;• Characteristics of technical sites landscape;• Possibilities to use the site.
Influence on local infrastructure especially on activities directly connected with the nuclear facility:• Transportation;• Supply of provisions, ...;
Understanding and acceptance of existing risk by population.
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NUCLEAR FACILITY PARAMETERS AND AGEING PROCESSES
Parameters of remaining radionuclide inventory in the nuclear facility;
Structure ageing; Necessity of minor maintenance of barriers against
radionuclide release in environment.
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OWNER’S INTERESTS AND EXPECTED DEVELOPMENT AND UTILIZATION OF SITE
Utilization of site for erection of another nuclear facility; Utilization of decommissioned nuclear facility components
for another facility on site or simultaneous decommissioning activities on several facilities on one site;
Optimization of costs in time considering the interrelation with another facility of the same owner.
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 30
HUMAN AND TECHNICAL RESOURCES
Availability of experienced personnel; Availability of needed documentation; Development of computer science technologies.
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DESCRIPTION OF PROCESS FOR CHOOSING DECOMMISSIONING STRATEGY
The process is assured with:• Workers with different professions and needed qualification;• Equipment and materials;• Financial means;• Sufficient scope of qualified data.
Evaluation of decommissioning parameters and selected option;
Planning of the process; Preparation, provision for and implementation of
decommissioning process considering the following:• Safety aspect;• Economic aspect;• Time aspect.
Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci” 32
REFERENCES
Decommissioning of Nuclear Power Plants and Research Reactors, Safety Guide, SS № WS-G-2.1 (1999)
Organization and Management for the Decommissioning of Large Nuclear Facility, TRS № 399 (2000)
Decommissioning of Nuclear Facilities Other than Reactors, TRS № 386 (1998)
The Decommissioning of WWER-Type Nuclear Power Plants, IAEA-TECDOC-1133 (2000)
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