PREPARATION OF DECOMMISSIONING RMBK

The decision to shut down the three remaining units of the Chernobyl NPP after the 1986 accident has been followed up by an extensive set of preparatory measures to facilitate their decommissioning. The options considered for the decommissioning of the NPPs are in general identical for all kinds of reactors, with some modifications reflecting the particular type of the reactor. For RBMK reactors they are as follows:

• Extended shutdown – the reactor is transferred to the permanent shut down state, the control systems are disabled, however they remain in the rector core together with the fuel;
• Defueling, decontamination, draining and drying – the fuel, the operational media and the radioactive waste are removed from the facility and an extensive decontamination program is carried out;
• Isolation and decommissioning of the turbine hall and the ancillary facilities – it means, in fact, the removal of all inactive equipment from the site and , if required, the demolition of the buildings outside the reactor block;
• Removal of primary circuit – all equipment and pipelines outside the reactor core are removed for decontamination and disposal;
• Reactor core removal – the final step, when all reactor internals have been removed and only the concrete biological shielding is left at the site.

Option 2 was selected for reactors 1, 2 and 3 of ChNPP. It comprised the removal of fuel and radioactive waste from the site, as well as the draining of all systems, isolation of penetrations from the reactor building and sealing of reactor block, leaving only engineered penetrations. The reactor was placed under appropriate care and maintenance.

The drafting of a decommissioning plan for all three ChNPP units, considering the Ukrainian national rules and the international standards, was covered by this project. The results can be considered as the principal document for planning and implementation of all decommissioning activities, including the management of radioactive waste generated during the decommissioning.

The overall objective of this project was to contribute to a safe and sound decommissioning of Units 1, 2 and 3 of Chernobyl NPP.

The specific objective of the project was to prepare a decommissioning plan for three ChNPP reactors, considering the Ukrainian national needs and requirements and also the international standards. The activities involved the identification and the assessment of various decommissioning options, recommendation and justification of the most preferred option and the preparation of documents to be submitted to the Ukrainian authorities to obtain the necessary licenses for decommissioning.

Achievements (With reference to the TORs)

The complete decommissioning plan, prepared within this project, comprises of 15 documents (in total about 2000 pages). It was split into an Introduction and ten sections, covering:

• Ukrainian political, legal and nuclear regulatory situation in relation to the ChNPP decommissioning;
• Systematic description of the Units 1, 2 and 3 and the ancillary facilities at the ChNPP site with the special emphasis to the issues related to the decommissioning;
• Radiological and otherwise hazardous inventories;
• Decision-analysis techniques used in the selection of the decommissioning strategy;
• Discussion of the actions aimed in the implementation of the decommissioning steps;
• Identification and quantification of the waste arising for selected decommissioning strategy;
• Technical means for monitoring of the personnel and the environment during decommissioning;
• Model for the executive management structure and management arrangements appropriate for the decommissioning
• Suitable model for the documentary system and the safety approval system to demonstrate that the decommissioning will be managed in a safe and an efficient manner;
• Estimation of the resources and the funding requirements for planned decommissioning strategy.

A set of supporting documents, facilitating an implementation of the individual steps of the decommissioning plan was also prepared, covering the details of the spent fuel management, the radioactive graphite waste management, an estimation of the radioactive inventory, the operational and the decommissioning waste management, the radiation protection, the technical specification of the equipment, etc.

On the request of the EC, additional problems raised by the Beneficiary during the presentation of project results had to be resolved. Therefore the original project was extended to perform an additional task entitled "provision of expert services to support the EC in achieving an agreed implementation strategy for the decommissioning of the reactors 1, 2 and 3 of ChNPP" (working abbreviation ISDRC). Subsequently the additional studies were performed by the contractor in the aim to clarify some key aspects of the decommissioning plan as an aid to prompt and effective implementation of the decommissioning. A special emphasis was given to the tasks, proposed by EBRD to be implemented via EBRD Nuclear Safety Account funding.

The decommissioning plan, the supporting documentation and the ISDRC report represent a valuable contribution to the preparation and the implementation of the decommissioning activities starting from the licensing till the practical dismantling activities related to selected decommissioning option.

Comments

(Quality of the results, Lesson learned, Recommendations for follow-up)

The final report is comprehensive, properly and in sufficient details describing all achievements and results of the contractor. The project results are presented in three volumes of the documentation: Decommissioning plan, Supporting documentation and ISDRC report. The project results are a valuable basis for further decommissioning activities.

The project fully met the objectives, stated in the relevant section of the ToR.

Further Information

Further information on the project results can be found in the Final report (available in the JRC Petten archive) and sought from the beneficiary organizations.

The Project Final report is available at the JRC-IE archive.