Decommissioning tasks

According to the requirements of General provisions of Safety assurance during Nuclear Power Plants and Research Nuclear Reactors decommissioning, the following tasks should be performed during ChNPP decommissioning:
1. Safety assurance during Units 1,2,3 decommissioning.
2. Protection of the personnel, population and environment against harmful influence ionizing radiations and protection of the future generations.
3. Bringing of power units 1,2,3 in a condition excluding possibility of subsequent use of this power installations for the purposes for which they have been constructed.
4. Performance of a complex of measures to achieve at the territory occupied by units 1,2,3 and auxiliary constructions, conditions which as much as possible reduce restriction for utilization of this territory. That stipulates:
- Step-by-step liberation fro9m ionizing radiation sources, subject to the control;
- A cancellation of restrictions and reductions of the radiation control in supervision zone and in sanitary - protective zone of ChNPP.

The Chornobyl NPP Decommissioning Concept outlines the following strategy for the ChNPP decommissioning:
- deferred dismantling (SAFSTOR method, as per the internationally accepted classification);
- early removal of FC;
- dismantling of lifting equipment in CH;
- reconstruction of CH marquees;
- dismantling of external structures;
- cooling of primary circuit (PC) and reactors, up to 50 years;
Engineering structures dismantling and ChNPP site cleanup are not decommissioning activities, they shall be considered within the framework of activities for mitigation of the accident consequences and recovery of the Exclusion Zone.

The following are the major tasks of the Chornobyl NPP at the shutdown stage:
- maintain safe condition of power units 1,2,3 and existing spent nuclear fuel storage facility;
- develop the infrastructure needed to manage spent nuclear fuel and radioactive waste at the Chornobyl NPP industrial site;
- remove nuclear fuel from the power units;
- complete construction and commissioning of the following:
- the second storage facility for spent nuclear fuel;
- liquid radioactive waste treatment plant;
- industrial complex for solid radioactive waste management;
- develop and approve the following projects:
- for the phase of Units 1,2,3 final shutdown and mothballing;
- for reconstruction of transport and process sectors at the existing spent nuclear fuel storage facility;
- for the damaged nuclear fuel management;
- for the cooling pond decommissioning;
- upgrade the infrastructure facilities (power supply network, heat and water supply, fire suppression system, telecommunications, etc.);
- remove working media and potentially hazardous substances from systems and equipment;
- finally shutdown, decommission, and partially dismantle some systems and elements at the power units;
- accomplish the comprehensive engineering and radiation survey (CERS);
- implement administrative and technical measures for management, operation, maintenance, and repairs of the systems that shall be in further operation, ensure safety monitoring.

At the stage for the Chornobyl NPP power units’ final shutdown and mothballing the following major activities shall be implemented:

- dismantle external (with regard to a nuclear reactor) systems and elements of the facilities that do not impact safety and shall not be required at further stages;
- improve the barriers that prevent from release of radioactivity into the environment;
- safely mothball those parts of the facilities that are not subject to dismantling;
- ensure conditions to allow temporary monitored storage of radioactive substances at the facilities;
- collect and condition the radioactive waste accumulated during the abovementioned activities, transfer the radioactive waste to specific enterprises.

During the reactor facilities cooling phase the following major activities shall be implemented:

- operation of the systems and elements ensuring safe storage of the radioactive substances contained in the mothballed facilities;
- periodical survey of a mothballed facility condition;
- dismantling of equipment that was not subject to mothballing;
- collection and conditioning of the radioactive waste accumulated during the abovementioned activities, transfer of the radioactive waste to special enterprises.

The following are planned for a phase of the reactor facilities dismantling:
- dismantle and remove systems and elements, which contamination level exceeds the removal levels, with the objective to dispatch them for interim storage in radioactive waste storage facilities;
- collect and condition the radioactive waste accumulated during the abovementioned activities, transfer the radioactive waste to special enterprises;
- execute final radiation survey of a site with the objective to confirm that the decommissioning activities are complete.

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