Criticality safety assessment of a cask for IRT-2000 spent fuel interim storage at Kozloduy NPP AFR basin

The problem of providing conditions for interim storage of spent nuclear fuel from the research reactor IRT-2000, Sofia at the Away-from-reactor (AFR) basin of the NPP Kozloduy is presented in this paper. The aim of the work is to find a technical solution of the problem and to ground this solution from the nuclear safety point of view. The technical possibility for using the WWER-440 spent fuel transport cask including basket with 19 tight panels for interim storage of all spent fuel assemblies from IRT-2000 Sofia is analysed. For criticality safety analysis two world well-known and used program systems (MCNP4B H SCALE4.4) have been applied. The results obtained show that for all analysed configurations the values of Keff are less than 0.34, which is in compliance with the nuclear safety requirements. Also the economical assessment of the proposed variant is given. (author)