The Mochovce Final Treatment Center for Liquid Radioactive Waste Introduced to Active Trial Operation

Abstract

The Final Treatment Centre (FTC) for Mochovce Nuclear Power Plant (NPP) have been designed for treatment and final conditioning of radioactive liquid and wet waste produced by named NPP equipped with Russian VVER-440 type of reactors. Treated wastes comprise radioactive concentrates, spent resin and sludge. VUJE Inc. as an experienced company in field of treatment of radioactive waste in Slovakia has been chosen as main contractor for technological part of FTC. During the realisation of project the future operator of Centre required the contractor to solve the treatment of wastes produced in the process of NPP A-1 decommissioning. On the basis of this requirement the project was modified in order to enable manipulations with waste products from A-1 NPP transported to Centre in steel drums. The initial project was prepared in 2003. The design and manufacture of main components were performed in 2004 and 2005. FTC civil works started in August 2004. Initial non-radioactive testing of the system parts were carried out from April to September 2006, then the tests of systems started with model concentrates and non-radioactive resins. After the processes evaluation the radioactive test performed from February 2007. A one-year trial operation of facility is planned for completion during 2007 and 2008. The company JAVYS, Inc. is responsible for radioactive waste and spent fuel treatment in the Slovak republic and will operate the FTC during trial operation and after its completion. This Company has also significant experience with operation of Jaslovske Bohunice Treatment Centre. The overall capacity of the FTC is 820 m3/year of concentrates and 40 m3/year of spent resin and sludge. Bituminization and cementation were provided as main technologies for treatment of these wastes. Treatment of concentrate is performed by bituminization on Thin Film Evaporator with rotating wiping blades. Spent resin and sludge are decanted, dried and mixed with bitumen in blade homogeniser. The bitumen product is discharged into 200dm3 steel drums. Drums with bitumen product or drums originated from A-1 NPP are loaded into Fibre Reinforced Concrete containers (FRC) and grouted with cement. Cement grout is prepared from the mixture of cement, additive and radioactive over-concentrate. By formulating the cement grout with evaporator concentrates the maximum radioactivity is fixed in cement matrix and volume of final waste product is minimized. A batch mixer with rotating blades is used to produce the cement grout. The grouted FRC containers are stored in the expedition hall and after 28 days of curing are transported to final disposal. After the start of routine operation, the FTC provides treatment for all liquid and wet LLW produced from the operation of the Mochovce NPP. The final product of the FTC is a FRC loaded with bitumen product in drums and filled with radioactive cement product. This container meets all limits for final disposal in the National Radioactive Waste Repository at Mochovce. This paper introducing the main parts of FTC and describes the technological procedures including the basic technological parameters for both used technologies, their working capacity and the overall waste flow. The evaluation of experience gained in the phases of Centre construction and commissioning and partially trial operation as well is a part of this paper (Evaluation of completion works process and time schedule, testing of systems using model media, radioactive testing and trial operation).