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Design Calculations of VPVR/M Research Reactor Spent-Fuel Cask

Abstract To support the transport of spent nuclear fuel from Czech research reactors of Russian origin back to the Russian Federation, a special VPVR/M transport cask was designed at SKODA JS, Czech Republic. In 2007, the shipment of 16 VPVR/M casks with EK-10 fuel of 10 wt% 235U, IRT-2M fuel of 80 wt% 235U, and IRT-2M fuel of 36 wt% 235U expended at the LVR-15 research facility since 1957 was realized. The VPVR/M cask was designed for all fuel types used in Russian research reactors of similar designs, which were built in many countries outside of Russia. A revised version of the ORIGEN 2.2 code was used for depletion calculations of 35 types of irradiated fuel. Shielding analyses of the VPVR/M cask were performed using the DORT code with the revised BUGLE-96 multigroup cross-section library based on ENDF/B-VI Release 3. The criticality of the cask loaded with the highest-reactivity fuel was evaluated with the MCNP code using the DLC-200 cross-section data library using the fresh fuel approach. The isotopic inventory of IRT-3M fuel of 36 wt% 235U burned up to 184 MWd/kg U was identified as the bounding value. The sources of gamma rays for shielding calculations, neutron sources for shielding and criticality calculations, and heat sources were consequently evaluated. The original design of the cask was optimized with respect to the minimum weight needed for the conservation of the required shielding properties. In compliance with the regulatory requirements for spent-fuel storage and transport casks, the subcriticality of the system met the criticality safety criterion of keff < 0.95 for all the fuel types evaluated. The cask fulfilled Czech safety criteria as well as International Atomic Energy Agency regulations for subcriticality, shielding, heat cooling, and structure requirements.