Numerical Modeling of Heat and Mass Transfer Processes in the Transfer of Spent Nuclear Fuel from "Wet" to "Dry" Cask Storage

Abstract

The paper describes in brief the heat and mass transfer processes in the transfer of spent nuclear fuel of the RBMK-100 reactor from "wet" to "dry" cask storage. The algorithms are described and the results are presented of the "through" calculation of the heat and mass transfer processes in ampoules and in a metal-concrete cask at various stages of spent nuclear fuel management.Keywords: nuclear power plant, spent nuclear fuel, metal-concrete cask, vacuum drying, long-term storage of casks, computational modeling.Introduction. Storage of spent nuclear fuel (SNF) is an urgent problem for many countries with developed nuclear power industry. In the Russian Federation, as a result of many years of operation of nuclear power plants (NPP), an enormous amount of SNF has been accumulated, which is stored in both at-reactor cooling ponds and in separate spent fuel storage pools (SNFP) on the premises of the NPPs. The total volume of these storage pools is not intended for long-term "wet" storage of the full amount of accumulated fuel. An especially complicated situation was observed at NPPs with RMBK-1000 high-power channel reactors because of the limiting capacity of the at-plant SNF storages.In 2011, a unique event took place in nuclear power engineering of the Russian Federation -the Complex of SNF "dry" storage and management systems based on the dual-purpose (storage and transportation) metal-concrete transportpacking complex TUK-109 was put into trial-commercial operation at the Leningrad NPP. The creation of the Complex makes it possible to realize disposal of SNF from the site of the NPP for long-term storage or processing. The developed technology was subsequently unifi ed and extended to the Kursk and Smolensk NPPs.The present paper considers the heat and mass transfer processes in transferring spent nuclear fuel from "wet" to "dry" cask storage, describes the algorithms, and presents the results of their computational modeling.Formulation of the Problem. The transport-packing complex TUK-109 used for "dry" storage and transportation of SNF consists of a metal-concrete cask (MCC) and a damping housing (PDH) protecting the MCC against damages and seal failure in case of bad road accidents. Inside the MCC body, there is a case with 144 ampoules containing fuel element clusters (FEC).The process of transferring SNF from "wet" to "dry" cask storage includes the following technological stages [1]:

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