Background

Kola NPP consists of four VVER-440 power units and comprises two special buildings where liquid radioactive waste (LRW) storage vessels are located. These two special buildings were constructed during the 1st construction stage (Units 1 and 2) and 2nd construction stage (Units 3 and 4) respectively. Accumulated LRW is temporarily stored in stainless steel tanks. It has to be processed in such a way as to allow for safe long-term storage, transportation and final disposal of such waste.

It has been decided to renovate the Liquid Radioactive Waste Treatment Unit (LRWTU) at Kola NPP in order to create a complex of process systems, installations and equipment for handling and treatment of waste which has been accumulated up to the present time and in future. This will be done by means of solidification to reduce the initial amount of waste and conditioning for controlled safe storage and further final disposal.

The complete LRWTU includes the following sub-systems, units and equipment (see the block diagram of the complete LRWTU in the attached diagram):

• А1 – dissolution and extraction of salts (R1.01/94G);
• А2 – concentrating (R1.01/96C);
• А3 – cementation of waste ion-exchange resins and sludge (R1.01/04A Lot 3);
• А4 – extraction of liquid radioactive waste from storage tanks (R1.01/94G);
• А5 – removal of radionuclides from evaporator concentrate solutions (R1.01/04A Lot 5/1 and R1.01/04A Lot 5/2);
• Transport/process equipment for handling the solidified waste (R1.01/04A Lot 1);
• Radiation control (monitoring) equipment (R1.01/04A Lot 2);
• Auxiliary systems and units;
• Solidified waste storage facility.

Several of the above systems and components of the LRWTU have been provided through the Tacis programme, as indicated in the above list (see projects R1.01/94G, R1.01/96C, R1.01/04A Lots1-5). Project R1.01/04A Lot 4 comprised the supply of valves for installation at the connections between the different process systems. A feasibility study was also performed in the framework of project R1.6/91.

Objectives

Under the present contract, a Liquid Radioactive Waste Removal System, comprising items A1 and A4 of the above list, was delivered.

The LRW removal system deals with:

• dissolution and/or wash-out of liquid radioactive waste stored in the tanks of the Liquid Waste Storage Facilities (LWSF) in the form of salt solution (evaporator concentrate) and crystallized sedimentation (deposit), spent filter-materials and floor drain sludge
• pumping of resultant solutions and/or pulps and sludge over to the plants of further LRW processing.

The LRW removal system in more detail is designed for:

• Removing of salt solutions (decontat) from evaporator concentrate tanks of LWSF-1 and LWSF-2 and transferring of decontat for further processing;
• Dissolving of crystallized salt deposits formed during storage time of evaporator concentrate in the tanks of LWSF-1 and LWSF-2 and transferring of resultant solutions for further processing;
• Washing-out and removing of spent sorbents and sludge out of sorbent tanks and sump tanks of LWSF-1 and LWSF-2 and transferring of resultant pulp for further processing.

Scope of supply

The scope of the Supply comprises two complete sets of LRW removal systems, each consisting of:
• submersible pumps for circulation and out-pumping of salt solutions, pulp, sorbents and sludge;
• device, ensuring wash-out of crystallized salt deposit, spent sorbents and sludge - jet mixer;
• heaters of salt solution;
• isolation and control valves;
• electrical equipment and I&C.

The scope of supply includes the design, manufacture, supply and supervision for installation and commissioning of the components of LRW removal systems. It also includes the provision of documentation, acceptance testing, certification, assistance to the End User in licensing and the required training of KNPP personnel.

Results

The equipment was delivered on 17.12.2004. The Final Acceptance Certificate was signed on 30 November 2006.