Decommissioning in the Russian Federation:29 October 1999
As part of a TACIS project, Munich based TÜV Energie Consult was commissioned to support Russian regulators on decommissioning the country’s nuclear power stations. In a working group together with Gosatomnadzor, a strategy has been developed to address the challenges. by GERHARD RIEGG
There are 29 nuclear power plants in operation within the Russian Federation (RF). Four old NPPs (two units at Novovoronezh and two units at Beloyarsk) have been shut down for some years. Another nine plants should reach the end of their design life by the year 2005. However, before the design life expires, operators should carry out a study considering the options both of extending their plant’s operational life and of decommissioning. Safety issues are of supreme importance, but social and economic factors should also be taken into account.
In the RF decommissioning cannot start until after the spent fuel is removed from the unit. Gosatomnadzor also needs to issue a licence to the plant operator. Requirements to ensure nuclear safety during decommissioning are currently being defined.
The resolution of a number of concerns connected with decommissioning, such as common requirements for operational and decommissioning waste, implementation of interim storage and plans for final repositories, as well as funding of decommissioning activities, are at different stages of development. The decommissioning of new nuclear power plants has, at least, been resolved as an operator must submit a document proving that payments are being made into a decommissioning fund to get a licence.
The main decommissioning concept consists of a post operational phase of about four years after final shut down. Over the next five years, a plant will be prepared for safe enclosure, which will last 30 to 50 years; the plant can then be totally dismantled.
The table at right lists the 29 operating NPPs and the four that have been permanently shutdown.
NUCLEAR PROGRAMME STATUS
The design lifetime for VVER and RBMK reactors is 30 years. However, operators are conducting intensive tests and carrying out analyses and other actions with the goal of extending this period.
The investigations address the issues of neutron embrittlement of VVER pressure vessels and replacement of RBMK pressure tubes. For example, there has been a major study of the reactor vessels at Novovoronezh, and the results have shown that the lifetime of VVER reactor vessels could be extended to 45 years.
Four first generation reactors, the AMB100 and AMB200 at Beloyarsk (which were forerunners to the RBMK reactor), and two VVER-type reactors at Novovoronezh, have been shut down for several years. The following diagrams indicate the scale of the problem The main problem at Beloyarsk 1 and 2 preventinge actual decommissioning is providing safe interim storage of spent fuel. At the moment the spent fuel is in wet storage pools; plans for dry interim storage sites outside the power plant units are being implemented by the operator. The concept was developed in 1995 by Rosenergoatom. Research and development is underway to provide the transport packaging cask.
Due to damaged fuel elements, particularly at the coolant channels, there are particles of nuclear fuel inside the reactor cores which have been located and measured. Measures to ensure the safe enclosure of the reactor cores, making use of the graphite moderator, must be undertaken. Systematic registration of the activity inventory of both units must also be conducted.
At Novovoronezh work on partial dismantling of equipment in the turbine hall has started. The off-site transport of all fuel elements from Novovoronezh 1 and 2 for reprocessing will be completed within a year. The operator carried out extensive surveys of the radiological condition of the plant. The systems and plant components which are no longer necessary for the decommissioning were identified. Documents for the preparatory phase of the safe enclosure are being created.
In terms of licensing these four units are still in the (post)-operational stage, as in Russia decommissioning of a NPP can only begin after fuel elements have been removed. So far no application for licensing decommissioning activities has been made. The lack of normative documents for decommissioning has been quoted as one of the main reasons.
THE LEGAL SITUATION
After the fall of the Soviet Union atomic energy legislation was remodelled and the Board of Atomic Energy restructured1.
The Nuclear Energy Law [20.10.95], which has been effective since 1995, means it is obligatory to obtain a licence for any decommissioning activity. Decom- missioning of individual plants must also be approved by the government.
The 1995 Nuclear Energy Law also demands that when building a NPP decommissioning has to be considered. As a result technical rules for new NPPs are laid down, eg the use of appropriate material like steel with a low content of cobalt and the need to consider dismantling during the plant’s construction. The financing of future decommissioning has only been guaranteed in recent years by the creation of decommissioning funds which involve a 1.3% rate increase to consumers’ bills.
Another requirement is that at least five years before the end of a NPP’s design lifetime the operator must submit a plan for decommissioning2..
A 1997 Russian government resolution – “Regulation of licensing activity on utilisation of nuclear energy [14.07.97]” – and a Gosatomnadzor rule – “Requirements regarding form and contents of documents to ensure nuclear safety and radiation protection of nuclear installations, storage facilities, radiation sources and/or applied activities [01.11.97]” – both describe the basic procedures and the engineering process for licensing. Rosenergoatom, as the plant operator, must provide the following documents and reports:
• Programme on decommissioning.
• Report of the results of a plant and site survey (such as engineering and radiation conditions).
• Report on the safety analysis.
• Programme and schedule on dismantling equipment and systems.
• Quality assurance programme for NPP decommissioning.
• Instruction on accident elimination during NPP decommissioning.
• Measures to protect personnel in case of accidents during decommissioning.
• Instruction on operating equipment and systems which takes into account the dismantling stages according to the dismantling programme.
• Design of materials and equipment needed for NPP decommissioning according to the co-ordinated Gosatomnadzor RF list.
• Instruction on registration and control of radioactive waste generated during decommissioning.
• Certificate on changes in physical protection related to decommissioning.
• Certificate on the final declaration of inventory of nuclear materials.
The requirements on the contents and form of the respective documents have not been determined in detail. Thus operators are uncertain about the depth of information demanded of the documents mentioned above. These requirements will be issued by Gosatomnadzor and from then on will be mandatory.
In the course of the TACIS project general framework rules about basic requirements and procedures were established by Gosatomnadzor3, with the assistance of TÜV, and discussed with various committees from the licensing authorities, institutes and the operator in the RF.
With the creation of this rule and the ensuing definition of the requirements for the individual licensing documents, the often quoted problem of the lack of normative documents will be eliminated.
QUESTIONS ON DECOMMISSIONING
The main unresolved issues include: Funding. One problem is that so far the costs of decommissioning have not been determined. For NPPs which have been shut down there is no financial backup to cover decommissioning. With the economically tense situation in Russia it remains unclear what priority is being given to decommissioning.
Spent fuel. The management of spent VVER nuclear fuel elements at the Mayak reprocessing plant is based on tried and tested technology. Reprocessing of RBMK spent fuel requires technical development. The spent fuel elements from RBMK-reactors (totalling 6500 Mg) and of the EGP-reactors (around 110 Mg) will be stored temporarily on-site or in regional stores.
Radwaste. Radioactive waste from NPPs in operation are transported to on-site storage for solid and liquid waste. The storage of nuclear waste from decommissioning has not been taken into account in the construction of these stores. The storage facilities are regarded as temporary interim storage. A final repository for radioactive waste does not exist in the RF.
To resolve some of these problems, a government resolution dated 23 October 1995 initiated the programme “Management of radioactive waste and spent fuel, utilisation and disposal for 1996 - 2005”. The main purposes of this programme are:
• To establish revised rules for safe management of radioactive waste.
• To create technologies and technical institutions for collection, treatment, interim storage and transport of radioactive waste and spent nuclear material.
• To create guidelines for construction of interim stores and final repositories for radioactive waste and nuclear material, to ensure reliable isolation from the biosphere.
Safe enclosure, also called supervised long-term storage, was chosen as the preferred option for the decommissioning of NPPs in the RF. Sufficient surveys and plans must now be conducted to address the following:
• Implementing safe enclosure for the various reactor types.
• Requirements of activity barriers and their maintenance for long periods of time.
• Construction behaviour of buildings over several decades.
• Surveillance and control of safe enclosures.
CONCEPTS FOR DECOMMISSIONING
The operator and the operating institutions of the RF favour safe enclosure as a concept for decommissioning.
The concept can be divided into the following parts:
Stage 0. Preparatory stage for decommissioning. Duration: 3-4 years.
• Removal of fuel elements.
• Realisation of decommissioning project.
• Provision of licensing documents.
Stage one. Preparation of safe enclosures. Duration: 5 years.
• Dismantling of systems no longer in use.
Stage two. Safe enclosure. Duration: 30 - 50 years (100 years also considered).
• Surveillance and control of safe enclosure and preparation for complete dismantling of the plant during the last 5 years of safe enclosure.
Stage three. Complete dismantling. Duration: 5 years.
• Removal of all plant from the site and, if the site is still required, preparation for thenew use.
At the moment documents and detailed concepts are being prepared by plant operators for the preparatory stages of decommissioning and safe enclosure. For the realisation of stages 2 and 3 no precise concepts exist. It may be assumed that nuclear sites will not be released from authority control. It is more realistic to assume that at such sites, especially considering the employment situation, nuclear facilities will continue to exist in some form.