Current status of ChNPP power units
From 2003 to 2015 Chornobyl NPP was at the shutdown stage, during which the following activity was performed:
- Units maintenance in safe condition;
- Nuclear Fuel removal from Units;
- emptying of systems and equipment from operating media and potentially hazardous substances;
- final shutdown of systems and components;
- accumulated radioactive waste (RAW) removal from Units;
- Comprehensive engineering and radiation survey (CERS)
- dismantling of equipment external with regard to reactor installations;
- Reconstruction of life support systems for decommissioning;
- decommissioning documentation development;
- infrastructure creation for decommissioning
Nuclear fuel removal from units was the main factor, determining the shutdown stage duration. In early March 2010 fresh nuclear fuel (in total 68 fresh fuel assemblies and 3 fuel elements 3) was transported to Russia.
Due to the delay in new dry type ISF-2 construction and commissioning, in order to reduce risks during decommissioning and Shelter object transformation into ecologically safe system, and to reduce costs for units maintenance in safe state transportation of spent nuclear fuel (SNF) from units to existing storage facility ISF-1 was started in 2006. Prior to place additional spent fuel in ISF-1 ChNPP performed a lot of work on existing storage safety reassessment. "ISF-1 Safety Improvement Plan" was developed and successfully implemented based on the results of the safety reassessment. Implementation of the Plan (primarily reconstruction of transportation and technological equipment) has allowed to ChNPP to obtain the license to operate ISF-1 and to start spent fuel transportation from Units.
SNF was removed from Units in three stages:
- first stage - spent fuel transportation from Unit 3 to ISF-1;
- second stage – Units 1 and 2 spent fuel (except damaged) was transported to ISF-1;
- third stage – units 1 and 2 are free of the damaged nuclear fuel.
First stage was successfully implemented in September 2010, Unit 3 was completely released from nuclear fuel. Work on ChNPP Unit 1 release from standard spent fuel was completed in November 2012, at Unit 1 - in September 2013. Damaged nuclear fuel in cooling pools of these Units is stored in a special different configurations canisters, manufactured by ChNPP.
During 2015 - early 2016, the problem of damaged nuclear fuel safe management and storage was resolved and cooling pools of Units 1 and 2 were completely released.
Despite the lack of experience in major industrial nuclear facilities decommissioning, a lot of works were performed at ChNPP site:
- comprehensive engineering and radiation survey at Units 1,2,3;
- term of Units 1, 2 systems and elements operation involved in RAW and SNF Management was extended for 10 years (Unit 1 – till 2017, Unit 2 – till 2018). Work on Unit 3 systems and components operation extension was performed within 2010-2011).
- dismantling of systems and components external to the nuclear reactor not influencing the safety and not necessary at the later stage of decommissioning is started;
- large amount of normative and technical documentation for decommissioning tasks, draft design of ChNPP Units Final shutdown and Preservation, design for Chernobyl cooling pond decommissioning were developed;
- more than 240 technological systems has been exempt from working media and potentially harmful substances;
- more than 430 systems and 1,550 pieces of individual equipment and components were finally shutdown, that represents about 65% of all systems and components and 98.8% of the systems and components that can be finally shutdown until the complete removal of fuel.
Current status of ChNPP power units
Since April 2015 SSE "Chornobyl NPP" is at the stage of Final Shutdown and Preservation. The main objectives of FS and P stage are:
- Dismantling of equipment and systems being external to reactor and not affecting the safety and not need to perform work on the next stages;
- strengthening of barriers preventing the spread of radioactive substances into the environment;
- reliable preservation of parts of installations which aren’t subject to dismantling;
- creating conditions for the temporary controlled storage of radioactive materials.