ÚJD SR

In the Slovak Republic we do have more than 40 years of experience concerning nuclear fuel management. First fuel for nuclear power plant A-1 in Jaslovske Bohunice was assembled from Soviet supplies (all spent fuel was re-exported back to Russian Federation). At present company SE,a.s. takes care of management of both fresh nuclear fuel as well as spent nuclear fuel for NPP Bohunice V-2, NPP Mochovce and in the same way does it company JAVYS, a.s. for NPP V-1 and Interim Spent Fuel Storage Facility.

The fresh fuel after being supplied to the NPP is carefully examined and cleaned in fresh fuel storage facility. The fresh fuel is stored in plastic sleeves to prevent its pollution. The storage facility has to be designed so that in any possible emergency situation the creation of so called critical assembly would be prevented. Before fresh fuel loading the fuel is placed in containers T-12 and is transferred to the reactor hall where the container is put to the shaft No. 1 or to the universal nest. By means of refuelling machine it is then loaded to the reactor. In the reactor the fuel is used for some 3 to 5 years depending on its enrichment. Through the fission of 235U by thermal neutrons we obtain from the fuel in the reactor the heat, which is then transferred in the turbo-generator to the electric energy. After 3 up to 5 years majority of 235U is fissured resulting in form of fission products. Besides the spent nuclear fuel contains further fission products which were not in the fresh fuel and which do not exist in the nature. These are so called trans-uranes; particularly 239Pu, 241Am and further are well known. The fission products and trans-uranes which are in the spent nuclear fuel are in majority radioactive. Therefore during the management of spent nuclear fuel strict provisions against radiation have to be observed. These are ensured so that the handling of spent nuclear fuel is performed under water. Spent nuclear fuel is then stored from 3 to 7 years in the spent fuel storage pool, which is situated in proximity of the shaft No.1 and reactor itself. Due to radioactive decay of fission products and trans-uranes the heat is generated in the spent nuclear fuel. This heat is called residual heat. This residual heat is immediately after spent fuel removal from the reactor very high and decreases exponentially with a time. The heat is removed from the spent fuel storage pool by means of cooling system. The spent nuclear fuel contains also after reactor uploading fission products 235U and 239Pu and other and therefore the storage facility has reliably to guarantee that the critical assembly will not be generated. After prescribed time of storage the fuel is transported to the Interim Spent Fuel Storage Facility. In the storage facility the fuel is stored in containers KZ-48, the design and material used assure the sub-criticality of spent fuel. Containers are placed in pools under water level. The water serves at the same time as the shielding and medium for residual heat removal from the fuel. It is planned at present that the spent nuclear fuel would be stored in interim storage up to 2050. Besides storage it is possible to place the spent nuclear fuel to depositories for permanent deposition or it is possible to process it in the reprocessing factories.

Modified: 29.7.2016 11:10