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

2. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
CONTENTS
1. Basic terminology
2. Decommissioning options
2.1. Description of different options. Decommissioning strategy
2.2. Decommissioning options characterization, evaluation of the advantages/disadvantages of the different options
3. Selection of decommissioning option
3.1. Consideration relating to different factors in the selection decommissioning option
3.2. Process of selection
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

3. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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 , Programme “Leonardo da Vinci”

4. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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 , 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
Operation of a nuclear facility (nuclear power plant) – it is all activities targeting at achieving the purpose for which the nuclear power plant was constructed. It comprises maintenance, refueling, inspections during operations and other works related to that.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

6. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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
Final shutdown – final phase of operation when main process equipment of the nuclear facility is shutdown for decommissioning and the operations, performed under operational modes are completed. In different cases, especially for nuclear power plants that have several power units, final shutdown means gradual/phased shutdown of power units and separation of process equipment.
One of those actions is the removal of spent fuel from the reactor into the spent fuel pool within the operating limits and conditions and ensuring its cooldown and later its replacement to an interim spent fuel storage facility for a long-term storage.
The initial manipulation of operational radioactive waste is foreseen to be performed simultaneously with taking the fuel out of the reactor. Deferring dismantling and disassembly of separate components of contaminated process equipment minimum to the time for shutdown, at the initial period may result at the beginning to abrupt decrease in the volumes of generated radioactive waste thus decreased exposure of site staff (fission of short-term radionuclides, mainly corrosion products).
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

7. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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
End of operation – state of the nuclear facility when all types of activities, performed to achieve the purposes for which it was designed, are irrevocably completed. The nuclear facility is not in a given regulated operational mode and does not contain any nuclear materials or spent fuel. Operational license is replaced by a decommissioning license (in Bulgaria it is called “a permit”). Usually, final shutdown coincides with the beginning of decommissioning.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

8. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
MAIN TERMINOLOGY
DECOMMISSIONING –
Administrative and technical actions taken to allow the removal of some or all of the regulatory controls from a facility
Decommissioning – administrative and technical actions that are taken to allow the removal of some or all of the regulatory controls (the end storage facility that is to be “shutdown” and not “decommissioned”). Decommissioning follows the phase of final shutdown. The activities cover decontamination, dismantling, removal of radioactive substances, components or structures. These are implemented to gradually and systematically decrease radiological hazard and are undertaken on the basis of preliminary planning and safety assessment needed for the implementation of these works.
Decommissioning is inevitably accompanied by generation of both huge quantities of radioactive waste and conventional waste. The radioactive waste usually have forms that distinguish them from types of materials and waste generated at the operational phase. Considering safety precautions, generation of radioactive waste needs to be maintained as low as reasonably achievable. Possible operational consequences should also be eliminated or reduced to a minimum extent during decommissioning.
Decommissioning is a long-term process that usually takes several years or decades depending on the selected decommissioning option. Nuclear facility decommissioning options can be within the range of immediate dismantling and removal of all radioactive materials from a given site, to the option of safe enclosure and deferred dismantling, implemented throughout phases distributed in time and with the help of different techniques and conditions. Different factors influence the selection of an option, including time factor and economic factors, and especially the status of the radioactive waste management system at the phase of final shutdown.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

9. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
MAIN TERMINOLOGY
LICENCE –
A legal document issued by the regulatory body granting authorization to perform special types of activities
Licence – a legal document issued by the regulatory body granting authorization to perform special types of activities related to selection of site, design, equipment, commissioning and decommissioning.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

10. MAIN TERMINOLOGY DECOMMISSIONING OPTION –
The process/method for decommissioning by which decommissioning purpose is achieved
Decommissioning option – the process/method for decommissioning by which decommissioning purpose is achieved.
Decommissioning option - various decommissioning strategies that may be considered when decommissioning is being planned. A variety of factors, such as timing and the availability of technologies, will influence which decommissioning strategy is ultimately chosen.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

11. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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
Decommissioning phase – in terms of time and contents it is a well-defined part of decommissioning of a nuclear facility or its component with a clearly defined initial and final state. Different works can be simultaneously performed on different technological sections.
Preparation for safe enclosure – activity for equipping buildings (rooms) and sites for safe enclosure with protection barriers, it is carried out decontamination on the appropriate level and dismantling of equipment for conditioning, storage or disposal of radioactive waste that have been generated during that activity.
Safe enclosure – a phase at which the buildings and sites ensuring safe enclosure comply with the requirements for controlled site and no work is being implemented on the equipment (or on its component), excluding repair activities. All needed tests are performed at that time, including barrier leakage tests.
Preparation for decommissioning – activities for decontamination and dismantling of process system equipment, decontamination of sites, radiation monitoring and assessment of sites subject of decommissioning, conditioning, storage or disposal of radioactive waste that was generated during the implementation of that activity.
Decommissioning of a nuclear facility or its component – actions (after assessment of radiation situation) for dismantling of remaining equipment or its components is performed, demolition of sites and conditioning, storage or disposal of radioactive waste generated during that activity.
The activities that are performed simultaneously on particular components of a nuclear facility can meet the definitions for different decommissioning phases. Quite often at the first decommissioning phase the reactor is prepared for safe enclosure and simultaneously the unneeded components are decommissioned. At the phase of safe enclosure, it is quite often to dismantle and decommission the components that are not ensuring safe enclosure. Operations for management of radioactive and conventional waste, generated during decommissioning, are carried out at all phases.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

12. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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”)
Decommissioning stage – it is a level reached in decommissioning of a nuclear facility. Since particular components of the nuclear facility can be at a different level of decommissioning, the stage of decommissioning relates to the reactor. IAEA documents identify three phases:
1. “Nuclear facility storage under surveillance” stage – the decommissioning of the nuclear facility is irrevocable, radioactive waste is processed and there are no nuclear materials in the nuclear facility.
2. “Restricted release” stage (decommissioning with limitation, limited utilization of site) – a part of the area is released from regulatory control or dismantling of equipment is deferred.
3. “Unrestricted release” stage (decommissioning without limitation, unlimited utilization of the site – “green field”) – the whole site is released from regulatory control and is not a subject to regulatory control. This stage is the completion of decommissioning.
Thus decommissioning phases are periods of time prior and post reaching the second stage of decommissioning during which specified scope of work is implemented.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

13. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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
The criteria for the unrestricted utilization of the site or unlimited release of materials from control – the levels of surface contamination of materials (sites), collective and relative activity (dose) do not exceed the value of individual equivalent yearly dose of 0.01 mSv.
Clearance level - A value, established by a regulatory body and expressed in terms of activity concentration and/or total activity, at or below which a source of radiation may be released from regulatory control.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

14. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
MAIN TERMINOLOGY
DOCUMENTATION
Concept (strategy, options) for decommissioning
Plan for decommissioning or plan for decommissioning phase
Final decommissioning documentation
Documentation – nuclear facility decommissioning is accompanied from preparation of works till their completion by documentation. We are going to present only the main terms in this part:
Concept (strategy, options) for decommissioning – the concept for decommissioning is explained in the decommissioning documentation which is usually updated every years and incorporates the technical possibilities and financial assurance of decommissioning.
Plan for decommissioning or plan for decommissioning phase – safety documentation that is submitted by the operator and which formulates the priority and logical sequence for the implementation of the activities (decontamination, dismantling, demolition and generated waste and materials management) to accomplish the set final or phase state of decommissioned nuclear facility. It describes the initial and final state of the nuclear facility and activity, planned for given phase, including the impact of the facility on staff and environment. It covers issues related to financing of planned works and assessment of spent fuel and radioactive waste storage facility capacity in compliance with the decommissioning strategy and schedule.
The decommissioning plan or the plan for a separate decommissioning phase contains the analysis of possible emergency events and their consequences. A constituent part of the decommissioning plan or the plan for a decommissioning phase is the result of radiation monitoring upon final nuclear facility shutdown or during previous decommissioning phase and also a draft of a program for radiation monitoring after decommissioning or after a given decommissioning phase is completed.
Final decommissioning documentation – contains the assessment of all activities performed during decommissioning, detailed description of final status of the site, and the results from the final radiation monitoring.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

15. 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
Immediate decommissioning (immediate dismantling)
Dismantling of a given equipment is performed immediately after activity decrease of short-term radionuclides. The main characteristic of immediate dismantling of a nuclear facility is the short final deadline for decommissioning. Immediate dismantling is used in the cases that foresee further utilization of the site (for instance for a new nuclear facility, etc.) or when a single nuclear facility is decommissioned and future deficit of staffing with qualified specialists is possible.
Decommissioning following the safe enclosure (deferred dismantling)
Characteristic feature of this option is the deferred dismantling and delayed demolition of equipment and buildings of the nuclear facility. The reason for this choice is the insufficient capacity or lack of storage facilities, lack of technical means for remote control dismantling, insufficient capacity of the technology for processing and conditioning of radioactive waste, insufficient capacity of radioactive waste storage facility or insufficient financing.
Decommissioning under surveillance (storage of nuclear facility under surveillance)
It is characterized with deferred dismantling of the chosen nuclear facility equipment without separating those components from the remaining equipment that is subject to dismantling. The access to these rooms is controlled only organizational measures. The active protective systems are in operation, minor repair of equipment that shall be used in the future is performed, staff costs are considerably higher than the costs for safe enclosure. At the worst, this option is close to the option “Custodial SAFSTOR” or to the immediate decommissioning with extended implementation of the works.
Decommissioning with in situ entombment
It is characterized with such a level of nuclear facility or its components safety assurance that allows for keeping it on its original place. This option is used quite rarely and when applied, after some time a re-assessment of the option is made and standard methods are applied. A typical example for that is the Chernobyl NPP shield (sarcophagus).
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

16. DESCRIPTION OF DIFFERENT OPTIONS
EWN – Energiewerke Nord GmbH
Germany
Hypothetical consideration
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

17. 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.
Immediate decommissioning (immediate dismantling)
Immediate dismantling is chosen by countries that have well-developed nuclear program and are leaders in nuclear facility decommissioning and have accumulated the needed experience in this field.
The advantages of the immediate dismantling are as follows:
Access to information for the status of a given piece of equipment on the basis of the current operational documentation;
Utilizing specific experience for a given facility;
Key personnel kept and utilized because they are familiar with the specific site conditions; and
In most cases sufficient financing which is formed on the basis of the existing operational conditions.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

18. 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.
Immediate dismantling has the disadvantage of using mechanisms of remote control and fragmentation of the equipment, because this equipment has a high dose rate.
Due to the specifics of the works for processing, conditioning and transportation, dismantled equipment parts require radiation protection between the different steps of RAW management, transportation to the storage facility including. Some of the radioactive waste must not be stored in surface (on the ground surface) storage facility. That is why they require long-term storage in a special newly-erected storage facility. All manipulations of equipment (waste) that has high doses result in high staff collective equivalent dose.
The amount allocated for the option of immediate dismantling covers the financial savings from both avoiding long-term operation and repair of equipment and storage of the information for that equipment on one hand, on the other hand financial losses related to utilizing costly methods for dismantling, fragmentation and transportation are also included. One of the main parameters of the chosen dismantling option is that part of the material that needs to be stored (disposed) and the part of material that is released from control.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

19. 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.
Decommissioning with safe enclosure (deferred dismantling)
The scope and duration of safe enclosure are defined primarily by the insufficient capacity of the above-mentioned technologies or by the possibility to accrue means to finance decommissioning costs, in case those funds have not been raised on time or in needed amount in accordance with the international requirements during the operation of the nuclear facility. Usually the subject of conditioning that ensures safe storage until final dismantling is the reactor and its adjacent components as well as primary circuit equipment, including buildings. During deferred dismantling, staff have restricted access to equipment and perform a minimum number of actions with the exception of needed repair.
The advantages of this option are as follows:
Provision of time for development of a complex system for radioactive waste management;
Using of nuclide half life period – especially of Co-60 which is one of the most active sources – it allows for decrease of collective doses and application of remote control mechanisms for fragmentation and equipment dismantling;
Provides time for development of new technologies and enhancement of decommissioning economy including raising special funds for financing of works;
Provides time needed for development of rules for low radioactive waste management, including recycling or release some materials from control into environment.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

20. 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.
The disadvantages of this option are as follows:
Loss of specific experience of staff for given nuclear facility at the end of the period for safe enclosure;
Costs for financing of nuclear facility professional information maintenance;
Ageing of key equipment and barriers, financial costs for equipment repair;
Public support;
Continuous shrinking of the site;
Issues related to prognosis for rising costs;
Changes in legislation towards more rigorous rules for RAW management and release of materials in environment.
Since many of the above-listed parameters from international practice considerably change, it is necessary to reconsider national strategies for decommissioning and modification of the decommissioning option with safe enclosure. Generally the time for safe storage is decreased from 100 to 30 years, while for equipment it is provided only for the reactor and its auxiliary systems, instead of the entire primary circuit. Thus time and scope are close to the immediate dismantling parameters when the reactor and its auxiliary systems (reactor pit, core, etc.) are the last to be dismantled, prior to demolition of the reactor building.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

21. TYPES OF DEFERRED DISMANTLING
Custodial SAFSTOR
Passive SAFSTOR
Hardened SAFSTOR
Many types of safe enclosure are utilized worldwide, and in the USA those are as follows:
"Custodial SAFSTOR" – safe storage in the state in which the given component was at the time of final shutdown. It is characterized with low level of cleaning and decontamination until the phase of safe enclosure, staff performs activities, the active process protection systems are operated and maintained (ventilation, …). Radiation monitoring is assured and staff is allowed restricted access to the nuclear facility equipment.
"Passive SAFSTOR" – (passive safe storage) characterized with considerable decrease of equipment activity prior to the phase of safe enclosure when there is no need of the operation of the active process protective systems. Only physical protection and violations identification are electronically provided. Status and minor maintenance work related to preservation of barrier integrity are periodically controlled.
"Hardened SAFSTOR" – (hardened safe storage) is characterized with such cleaning of nuclear facility and such protective containment (barrier) which is impossible or of low probability to be violated. Barrier violations can be identified, minor repair is targeting the preservation of barrier integrity. Status is periodically monitored in small scope.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

22. 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, ...
The choice of the decommissioning option is defined by a number of parameters as follows:
Requirements of legal documents (acts, rules, standards) and regulatory bodies;
Expected costs for decommissioning;
Spent fuel management strategy;
Infrastructure for radioactive waste management;
Criteria for release from control;
Social and economic parameters, social concerns about suggested decommissioning activity;
Nuclear facility status and the ageing process of the facility;
Radiological assessment,...
When choosing a preferable option each parameter needs to be analyzed in accordance with the special parameters of the nuclear facility decommissioning.
The following items shall review the parameters that significantly influence the choice of strategy.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

23. 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.
All those requirements influence to a certain extent the choice of decommissioning strategy (option). Certain options can be either completely eliminated or limited. In many countries the in situ entombment decommissioning type is absolutely forbidden. Quite often the time provided for decommissioning is limited to safe enclosure. The criteria values for release of materials and site from control are defined by the law.
The criteria values for storage of waste in storage facilities of different type are one of those parameters that are most often object to influence, because the ratio between waste and materials of medium, low and very low activity, that can be released from control, is changed on the basis of the latter parameters. As it is proved by practice, the greater part of waste, generated during decommissioning, can be dumped as conventional industrial waste upon some control. More than 90% of the concrete, used for the construction of water-pressurized water reactors, is not considered radioactive waste.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

24. 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).
Structures of costs for decommissioning:
Activity after final shutdown (radioactive waste processing);
Maintenance activities (еspecially in cases of long-term storage under surveillance) and control;
Dismantling, decontamination, treatment of contaminated soils;
Radioactive waste management (processing and conditioning, storage and disposal, transportation including);
Others (documentation development, licensing process, quality assurance).
Nuclear facility decommissioning is generally associated with considerably huge costs. The option ensuring safe enclosure allows to split those costs in long periods of time and decrease yearly costs which is of great importance in case of insufficient financial means for the “green lawn” decommissioning option. Extension of safe enclosure term, on the other hand leads to a total financial cost increase as a result of increased costs for maintenance and monitoring. Thus the issue of raising funds for decommissioning of nuclear facilities shall always be one of the assessing parameters when choosing an option for safe enclosure, while the period for safe storage has a counter effect on the extent of costs.
Costs for safe enclosure in the course of years usually are not one of the assessing parameters for the safe storage amount. “Timeless” safe enclosure can eventually mean transfer of responsibility for the nuclear facility decommissioning financial costs to the future generations.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

25. 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
Decommissioning of a nuclear facility does not considerably impact the strategy for spent fuel management. Removal of radioactive waste, including the spent fuel from the nuclear facility prior to commence the actions related to decommissioning, is considered one of the main safety requirements by most of the countries. In some of the cases failure to solve the issue of spent fuel storage in interim storage facilities during nuclear facility decommissioning, considerably impacts the implementation of activity schedule.
For isolated nuclear facilities where spent fuel is stored in a pool on the site, the further treatment of that fuel impacts the term for release of site from control, thus on completion of decommissioning.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

26. 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.
The possibility in terms of time for phase processing of all waste directly depends on complexity and capacity of the radioactive waste management system thus influencing the choice of a decommissioning option. Accessibility and capacity of technologies decrease the duration of different decommissioning phases.
Sufficiency of capacity of different technologies for radioactive waste management defines the status of operational waste especially in case their processing and conditioning were deferred while in the future it would require part of technology capacity to process the waste that were generated during operation.
This also applies for the systems for processing of waste generated by several nuclear facilities (within the site, country, or internationally – for instance melting of radioactive metal). A very important factor as well is to provide a continuous flow of waste. Otherwise waste is piled in the narrow places during processing, conditioning, storage or release from regulatory control, which results in additional costs for erection of storage facilities.
In case of insufficiency of certain facilities (buildings) for storage of all categories of radioactive waste, then:
It is possible to leave the nuclear facility or part of it in state of “storage under surveillance”;
It is possible to process and store waste in interim storage facilities or containers.
Safe storage assurance should not be an alternative to the decision for continuous storage as compared to radioactive waste disposal.
Quite often a short-term strategy is utilized, based on the possibility to reduce the volume of transitional radioactive waste which level of activity might become lower during their monitored storage and become lower than the acceptance criteria for storage facility disposal or release from regulatory control.
Different problems may occur during storage of re-cycled radioactive waste. It is important the requirement for acceptance of re-cycled waste for disposal in the storage facility that is to be erected in the future. Otherwise, the necessity of re-packing or re-conditioning of waste in the future shall additionally expose staff to radiation and shall increase costs. The strategy for separate dismantling and storage of large-sized components is of a specific importance for decommissioning.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

27. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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.
When choosing different decommissioning strategies for a nuclear facility, the following needs to be considered:
Local population employment status not only for the nuclear facility but for the surroundings as well;
Environmental issues (land price, characteristics of the technical site landscape, the possibilities to use the site);
Influence on local infrastructure, especially on activities directly connected with nuclear facility (transport, supply of provisions, etc.);
Existing risk and how it is understood and accepted by the population.
Social and economic aspects shall be the decisive parameter in choosing the decommissioning option, especially for regions with poorly developed industry, for an isolated nuclear facility and in case of simultaneous decommissioning of all facilities on a site. In such case the additional costs to maintain employment in that region shall be high.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

28. 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.
The characteristics of radionuclide remaining inventory in the nuclear facility at the beginning of decommissioning works impact the choice of safe enclosure of its components or of another option. In case of facility surface contamination or activation of the material by the lon-term radionuclides, the deferred dismantling shall have no results in terms of decrease of the dose rate. The long-term safe storage compared to the relatively short period of operation of the facility shall increase the possibility for structure ageing and shall pose the need of minor repair or reconstruction of the barriers preventing the release of radionuclides into environment.
This also relates to the systems used to provide safe storage at the final decommissioning phase (ventilation systems, process supply systems, cranes, etc.). Continuous integrity of those systems is a safety requirement and its provision may result in considerable rise of costs. The above-mentioned also immediately impacts the period, scope and type (form) of safe storage.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

29. 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.
The interests of the owner and expected development and utilization of the site also influence to a considerable extent the time schedule for the decommissioning of the different sites, especially from point of view of the following:
Utilizing the site for the erection of another nuclear facility (this parameter has a particular influence on decommissioning in Japan);
Utilization of nuclear facility decommissioning components for another facility on the site or simultaneous decommissioning activities of several facilities on one and the same site;
Optimization of costs in time considering the interrelation with another facility belonging to the same owner.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

30. HUMAN AND TECHNICAL RESOURCES
Availability of experienced personnel;
Availability of needed documentation;
Development of computer science technologies.
The availability of experienced staff is an advantage for immediate decommissioning; it considerably lowers radiation loading and training costs for those workers. In case of the long-term safe enclosure, the skills of the decommissioning staff may be either lost or decreased to a lower level. A new staff needs to be trained prior to continuing the activities under decommissioning and high level of nuclear and radiation safety must be ensured which causes new costs and issues. All operational and technical documentation needs to be maintained, the operational records and the description of the modifications implemented on the nuclear facility during previous decommissioning phases.
Due to the rapid development of the computer science technologies, this issue is technically and economically very demanding and costly, while at the same time dismantling, demolition and waste treatment technologies are being continuously developed and enhanced and the costs for those activities are going down with time.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

31. 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.
The decommissioning process is time-consuming and depending on the selected options continues for decades. The intensity and character of the activities performed are different in terms of time and requirement for professional qualification of the workers, staffing and provision of equipment and materials.
The issue of financing the process of decommissioning which requires to know the financial cost not only in its absolute value, but its allocation in time is very important. On the basis of that knowledge, a specific method could be later applied to finance the process of decommissioning (based on the decommissioning fund) and could be planed the phase distribution in time and disbursement of financial means of the fund.
A sufficient scope of qualified data is needed to plan that process – the assessment of the different options for that process and selection of an optimum decommissioning option may be done on the basis of those data. The assessment of decommissioning parameters is one of the main scope of decommissioning planning process. The rest of the steps from nuclear facility decommissioning option selection depend on the results of that assessment (decommissioning method, selection of technologies, RAW management, financing scheme, etc.).
The main objective of the assessment of the decommissioning process is to create a data base on the basis of which would be possible to prepare, provide for and implement the process of nuclear facility decommissioning in a safe, economically efficient and timely manner.
During decommissioning of a nuclear facility, safety is associated with safe performance of all the works (all activities), with the minimum impact on staff and meeting all limit values for gaseous and liquid releases and the limit values for the materials released during the process. The safety for the future is achieved by the safe treatment and disposal of the RAW and the safe treatment of toxic waste.
The economic aspect is associated with the development of an optimum decommissioning in terms of financial costs and an optimum scheme for the financing of the process. The financial assessment of the process is related to the main activities at the preparatory phase of project.
The time aspect is related to the development of an optimized decommissioning method in time. Depending on the selected option, the period of time needed for the implementation of the decommissioning activities, might be within the span of years to decades (more than 100 years). The time aspect is also related to coordination of needs and personnel, technological equipment, materials for the process, the capacity for processing, conditioning, storage and disposal of the RAW, etc.
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”

32. Project BG/04/B/F/PP-166005, Programme “Leonardo da Vinci”
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)
Project BG/04/B/F/PP , Programme “Leonardo da Vinci”