|System fot Radioactive Waste Treatment|
At present, liquid and solid radioactive waste generated during NPP operation is treated at the conditioning facilities of NPP and stored in special storages of liquid and solid radioactive wastes.
Liquid radioactive wastes treatment
Liquid radwaste or so called floor drains are radwaste, water used for decontamination of equipment and premises of radiologically controlled area, regeneration solutions, and ion-exchanger flushing waters for liquid radwaste treatment facilities. Floor drains and special laundry waters are delivered for treatment to liquid radwaste treatment facilities №3 and №7 to purify floor drains against radioactive contamination, mechanical and chemical admixtures in order to reduce the bulk of radioactive waste.
When designing the floor drains purification systems (TR) following basic requirements were taken into account:
• To ensure purification from mechanical admixtures using deposition method;
• To purify from mechanical admixtures using filtration method on pre-filters;
• To perform single-stage distillation with further condensation and deaeration of secondary steam;
• To perform deep evaporation from ion-exchanging admixtures after distillation and deaeration as a final phase to obtain pure distillate.
Purification of all types of waters delivered to special water treatment facility №3 is carried out in order to recycle the water in plant process.
In course of operation of special water treatment facilities concentrated floor drains (still bottoms), spent filtering materials and sludge are generated.
Still bottoms and filtering materials are dumped and stored in the system for liquid radwaste storage.
Currently, in order to get solidified and provide free storage capacities still bottoms are subject to treatment at deep evaporation unit UGU-1-500. Solidified radwaste is called molten salt stored at KhNPP solid radwaste storage.
TACIS project U1.04/93A “Treatment of Backlog of Radioactive Waste Water” implemented technology for purification of floor and sludge waters, as well as used filtering materials through centrifugation system. Equipment of leading European manufacturers has been supplied by “AnsaldoNucleare” company in the frame of technical assistance.
Radioactive Water and Still Bottoms Generation Regulations have been developed and reference levels for liquid radwaste generation have been established to reduce the volume of liquid radwaste. In the frame of reconstruction and modernization program KhNPP implements measures aimed at minimization of liquid radwaste generation.
Solidified radioactive wastes treatment
After conditioning, still bottom is directed to the installation of deep evaporation UGU-1-500 for further concentration. This installation is designed for treatment of liquid salt concentrates (still bottoms) that are formed in the process of evaporation of radioactive drainage waters of Water treatment facilities of KhNPP. The output salt concentrate – molten salt after UGU-1-500 is placed into metal 200-l containers-drums where it is cooled generating solidified still bottom.
The product of centrifugation is dewatered filtering material and sludge loaded into drums and stored in cages of Solid Radioactive Waste Storage Facility (SRWSF) compartments.
At Khmelnitsky NPP, containers-drums are stored in the storage of solid radwaste. Drums filled with molten salt fall under periodical inspection. Due to its characteristics (dissolving capability in case of water ingress) molten salt shall not be subject to final disposal.
Handling with radioactive oil
Spent radioactive oil is subject to burning at special facility for incineration of radioactive oil installed at the workshop of special auxiliary building, the facility design provides for the purification of flue gases on special ventilation filters and has adequate operation permit.
Solid radwaste treatment
The solid radwaste is generated mainly upon the completion of preventive and corrective maintenance at the plant. Wastes are sorted by their aggregative state (solid or liquid) and by their activity (contaminated and non-contaminated). Contaminated wastes are sorted by groups of activity. Damp wastes are dried in place of generation; they are sorted and packed according to their activity. Packed wastes are transported to temporary waste storage. Plant-generated waste is transferred in shipping casks on a special vehicle from the locations where it is collected to the SRWSF, Special Auxiliary Building. Mass, activity, accounting of radwaste including their registration in accounting log and database in SRWSF, Special Auxiliary Building, then the wastes are unloaded from shipping cask into the cell.
Khmelnitsky NPP has put into effect and is implementing the “Comprehensive Radwaste Management Programme for NNEGC “Energoatom”, 2012-2016 that establishes measures to reduce the amount of RW generation, as well as capital measures and modernization measures. Implementation of this program resulted in the development of design for radwaste treatment complex for KhNPP and obtaining of positive expert conclusions for the design, and participation in activities on testing liquid radwasate treatment technologies.
“Comprehensive Radwaste Management Programme for NNEGC “Energoatom” PM-D.0.18.174-16 for the period from 2017 to 2021 has been put into force by the directive of NNGEC Energoatom №927-r dated 12.10.2016r.
Creation of radwaste treatment complex to be commissioned in 2021 remains the key capital measure of the Program. Construction and commissioning of radwaste treatment complex will allow for treatment to bring the waste to the state suitable for long-term storage and shipment for disposal to dedicated radwaste handling facilities.
KhNPP submitted proposals on the measures to be carried out in the frame of National Targeted Environmental Program over the period 2018-2027 currently developed.