engleski

Radiation Dose rates in the Vicinity of the NPP Krško Reracked Spent Fuel Pool in Real Case Scenarios

Recent activities focused on spent fuel management in the NPP Krško lead to the spent fuel pool capacity increase by reracking. The purpose of the capacity increase was to assure a safe storage of spent fuel assemblies in the existing spent fuel pool during the plant lifetime. In the first reracking phase, the capacity has been increased from 828 locations to 1694 locations for spent fuel assemblies placement, providing enough locations for spent fuel assemblies storage up to the year 2023, i.e. 40 years plant lifetime. The reracking has been performed by combining old and new high-density racks. Three old modules have been eliminated and 9 new modules have been placed in the empty part of the pool. Plans exist for the second reracking phase that would increase the capacity up to 2319 locations as a necessity for the eventual extension of the plat lifetime beyond the year 2023. In this paper we have investigated the reracking impact on radiation dose rates in the vicinity of the spent fuel pool at the end of the plant lifetime. Real case scenario of spent fuel pool loading has been assumed by taking into account the actual number of spent fuel assemblies, their reactor history, isotopic inventory and time spent in the pool prior to the end of the plant lifetime. Two possible plant lifetimes (40 years and 50 years), as well as 12-month fuel cycle length and 18-month fuel cycle length management strategies leading to four different scenarios have been investigated. The radiation dose rates have been calculated using SAS3 sequence of the SCALE code package and QAD-CGGP code. The spent fuel inventory has been calculated by ORIGEN2-PC code. The calculated radiation dose rates have been compared to the dose limits in 10 CFR 20 for the restricted work area.

reracking; spent fuel pool; radiation dose rates; SCALE; QAD-CGGP; ORIGEN2-PC

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