The effect of the number of spent fuel casks on the dose of the outer part of the hall concrete wall

The management of high radioactive spent nuclear fuel (SNF) from research and power reactors has become a key topic of discussion in the nuclear communities. Metal casks are used for the management and disposal of spent fuel and all types of radioactive waste worldwide. The spent fuel assemblies-contained casks are stored in interim storage facilities. The present study aims to show the neutronic behavior and neutron/gamma dose rates of a designed hall for storage of the casks as a current technical, economic, safe and flexible solution, adaptable to any long and short-term SNF storage strategy. The hall structure was considered as ordinary concrete with an internal dimension of ۵×۶×۵ m۳. The concrete wall thickness was discussed to keep the dose rate limit of ۱۰ μSv/h (neutron and gamma) at its external side when ۲۵ casks are available inside the hall. ORIGEN and MCNPX computational codes were used to model the storage hall contained ۲۵ Tehran Research Reactor spent fuel casks. The carried out calculations showed ۳۰ cm thickness would fulfil total gamma and neutron dose rate limitation after the external surface of the concrete wall. When the hall contains ۲۵ casks (any contains ۱۶ ۵۵%-burnup ۱۰-years cooled spent fuel assembly), maximum gamma and neutron dose rates at the external surface of the hall are ۳.۴۵ nSv/h and ۳.۴۵ μSv/h, respectively. In addition, the carried out calculations showed natural circulation of air could powerfully remove the deposited heat of neutron and gamma rays.

Keywords:

Spent fuel cask , Gamma and neutron dose rate , interim storage hall , MCNPX simulation