SKODA VPVR/M cask for spent nuclear fuel from research reactors

The LVR-15 research reactor at Nuclear Research Institute Rez plc was designed in 1957. The original fuel type was EK-10 with 10% enrichment and of Russian origin. Subsequently, in 1974, the inner parts of the reactor were reconstructed for the utilizing of a highly enriched uranium (HEU) fuel, namely, the Russian IRT-2M fuel assemblies (FA) with 80% 235U enrichment. From 1989 to 1996, the reactor was rebuilt to be operated at higher power, up to 15 megawatts (MW). The type of FA was retained but the enrichment was changed to 36 % with the use of the IRT-2M fuel type. The transformation took several reactor cycles using gradually different mixed core configurations. Since 1998, the reactor has been operated only with the IRT-2M (36%) FA. The policy for spent fuel management in NRI is based on using three facilities for spent fuel assemblies from the LVR-15 reactor. The first one, the current at-reactor (AR) facility, is a pond in the reactor hall next door to the reactor. The second one is the away from reactor (AFR1) pond in the reactor auxiliary building. The third facility, (AFR2), is a pond at the institute's high-level waste storage (HLWS) facility. During the time period of the former Soviet block, several different types of research reactors were designed and operated, mostly utilizing HEU of Soviet origin. There have been seventeen countries with research reactors operating on Soviet- or Russian-supplied fuel . Belarus, Bulgaria, China, Czech Republic, DPRK, Egypt, Germany, Hungary, Kazakhstan, Latvia, Libya, Poland, Romania, Serbia and Montenegro, Ukraine, Uzbekistan and Vietnam. FA enrichment varies from 2% to 90% 235U. In 2004, the U.S. and Russian Federation signed an agreement concerning the repatriation of Russian-origin high-enriched uranium (HEU) research reactor fuel to Russia. The primary goal of the Russian Research Reactor Fuel Return (RRRFR) program is to eliminate highly enriched uranium (HEU) stockpiles and persuade eligible countries to convert their research reactors from HEU to low enriched uranium (LEU). Under the RRRFR program, Russia has agreed to take back spent and fresh fuel from research reactors so long as the reactor operators agree to convert the reactors to operate on LEU or shut down. So far, eight shipments have repatriated Russian-origin fresh HEU fuel under the RRRFR program, from Serbia, Romania, Bulgaria, Libya, Uzbekistan, the Czech Republic, and Latvia. The SKODA VPVR/M cask had to fulfill safety requirements mandated by legislation regarding shielding quality, subcriticality and thermal cooling. Sources of gamma rays, neutron sources, heat sources and isotope inventory were determined by the program ORIGEN. The revised version of ORIGEN incorporates updates of the reactor models, cross sections, fission product yields, decay data, and decay photon data, as well as the source code. Shielding calculations of the SKODA VPVR/M cask were provided by the program DORT in one-dimensional (1D) and/or two-dimensional (2D) geometries. A revised multigroup cross-section library (BUGLE-96, based on ENDF/B-VI Release 3) used in these calculations was produced for light water reactor shielding and reactor pressure vessel dosimetry applications. The cross-section processing methodology is the same as that used for producing BUGLE-93 and is consistent with ANSI/ANS 6.1.2. According to the legislation requirements for the storage and transport casks for the spent fuel, the subcriticality of the system has to meet the requirement of keff ≤ 0.95. The MCNP program for system criticality calculations was used in the mode KCODE with the DLC-200 pointwise cross-section data library. All calculations were done for the fuel with maximum multiplication capability, i.e. fresh fuel. The Skoda VPVR/M cask of the B(U)F type, identification designation CZ/048/B(U)F.96, meets the applicable International Atomic Energy Agency regulations, as well as applicable international transport regulations which refer to these IAEA regulations. The Skoda VPVR/M cask, identification designation CZ/048/B( U)F.96, is intended for road and rail transport, inland waterways and sea transport of 36 undamaged fuel assemblies (FA) with spent nuclear fuel (SNF) from research nuclear reactors or 36 stainless containers with damaged FA and/or with fuel elements from damaged FA and/or with parts of fuel elements from damaged FA. The cask can also be used to store: - 36 undamaged FA; - 36 stainless containers with damaged FA; - 36 stainless containers with fuel elements or parts of damaged FA. The cask manufacturer is SKODA JS a. s