Current status of ChNPP power units
Nowadays, the Chernobyl NPP proceeds to completion of the shutdown stage and comes to the stage of final shutdown and preservation, and performs the following tasks:
-Maintaining the Units in safe condition;
-Removal of nuclear fuel from the Units;
-Removal of operating media and potentially hazardous substances from the systems and equipment;
-Final stoppage of systems and components;-Removal of accumulated radioactive waste (RAW) from the Units;
-Carrying out a Comprehensive Engineering and Radiation Survey (CERS);
-Dismantling of equipment being external to reactor facilities;
-Reconstruction of life support systems for decommissioning;
-Development of decommissioning documentation;
-Creation of decommissioning infrastructure.
Releasing the Units from nuclear fuel is a basic factor specifying duration of the shutdown stage. In the beginning of March 2010, fresh nuclear fuel was transported to Russia (at the amount of 68 fresh fuel assemblies and 3 fuel elements).
Due to a delay in construction and commissioning of new dry-type ISF-2, the removal of SNF from the Units to the available ISF-1 was commenced in 2006 in order to mitigate the risks during work performance related to decommissioning and Shelter transformation into ecologically safe system, and to reduce the expenses for maintaining the Units in safe condition as well. Prior to placing additional SNF at ISF-1, SSE ChNPP has performed a large scope of work on re-assessing safety of the existing storage facility. According to the results of safety re-assessment, an ISF-1 Safety Improvement Plan was developed and implemented successfully. Performance of high-priority actions regarding this Plan (primarily, reconstruction of transport-process equipment) enabled SSE ChNPP to obtain a License for ISF-1 Operation and start SNF removal from the Units.
Removal of spent nuclear fuel (SNF) from the Units is carried out in three stages:
-Stage 1, i.e. transportation of spent nuclear fuel from Unit 3 to ISF-1;
-Stage 2, i.e. transportation of fuel (except for damaged one) from Units 1 and 2 to ISF-1;
-Stage 3, i.e. Units 1 and 2 will be released from damaged nuclear fuel.
In September 2010, Stage 1 was implemented successfully, i.e. Unit 3 was completely released from nuclear fuel. The works on removing conditioned nuclear fuel from ChNPP Unit 2 were completed in November 2012, and from Unit 3 – in September 2013. Damaged NF is stored in the fuel storage pools of these Units using special-purpose casks of different configuration produced by own efforts.
It is planned that till the end of 2014 an issue of safe management and storage of damaged nuclear fuel will be solved, and fuel storage pools of Units 1 and 2 will be released completely.
In spite of lack of experience in decommissioning of large-scale industrial nuclear facilities, a large amount of work is performed on ChNPP site:
-Comprehensive Engineering and Radiation Survey of Units 1, 2 and 3 is performed;
-Operating life of Units 1 and 2 systems and components involved in RAW and SNF management process is extended (Unit 1 – till 2017, Unit 2 – till 2018. Activities on extending operating life of Unit 3 systems and components were carried out in 2010-2011);
-Dismantling of facility systems and components, external to the reactor facilities, being not related to safety and not required for operations during subsequent decommissioning stages;
-A large volume of normative and technical documentation for decommissioning is developed, Design of Final Shutdown and Preservation of ChNPP Units is developed, as well as Project of ChNPP Cooling Pond Decommissioning;
-Over 240 process systems are released from operating media and potentially hazardous substances;
-More than 430 systems and 1,550 separate components are finally stopped constituting about 65% of total amount of ChNPP process equipment and 98.8% of systems and components, which could be finally stopped till complete removal of fuel.