MODULE “STRATEGY DEVELOPMENT” SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”

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


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.


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.


MAIN TERMINOLOGY

OPERATION OF A NUCLEAR FACILITY -

All activities performed to achieve the purpose for which the nuclear facility was constructed


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


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


MAIN TERMINOLOGY

DECOMMISSIONING –

Administrative and technical actions taken to allow the removal of some or all of the regulatory controls from a

facility


MAIN TERMINOLOGY

LICENCE –

A legal document issued by the regulatory body granting authorization to perform special

types of activities


MAIN TERMINOLOGY

DECOMMISSIONING OPTION –

The process/method for decommissioning by which

decommissioning purpose is achieved


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


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”)


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


MAIN TERMINOLOGY

DOCUMENTATION• Concept (strategy, options) for decommissioning• Plan for decommissioning or plan for decommissioning phase• Final decommissioning documentation


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


DESCRIPTION OF DIFFERENT OPTIONS


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.


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.


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.


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.


TYPES OF DEFERRED DISMANTLING

Custodial SAFSTOR Passive SAFSTOR Hardened SAFSTOR


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, ...


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.


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).


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


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.


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.


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.


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.


HUMAN AND TECHNICAL RESOURCES

Availability of experienced personnel; Availability of needed documentation; Development of computer science technologies.


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.


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)

Documents

MODULE “STRATEGY DEVELOPMENT” SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”