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 Concentration System, comprising A2 of the above list, was delivered.

The Concentration system is purposed for the deep concentration by evaporation with the output of crystallized salt residue after concentration process:

• concentrat from the LRW tanks (concentrated solution of salts, which are not crystallized during Evaporator Concentrate cooling and are placed under the crystallized residue deposit) with 90% Boric Acid content (this content is calculated for NaBO2), preliminarily purified from radio nuclides;
• salt crystallized deposit solution from the LRW tanks, preliminarily purified from radio nuclides

The concentration system consists of the following functional equipment groups:

• equipment group of evaporator concentrate collecting consisting of evaporator concentrate collecting tanks and pumps;
• equipment group of concentration by evaporation;
• equipment group of the steam condensation, condensate collecting and pumping, non- condensed gases removal;
• equipment group of salt separation;
• isolation and control valves;
• electrical equipment and I&C

Scope of supply

The scope of supply includes the complete design, manufacture, supply and supervision for installation and commissioning of the LRW concentration system described above. 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 3 May 2005. The Provisional Acceptance Certificate was signed on 23 December 2005. The Final Acceptance Certificate was signed on 9 October 2006.