LAUSR

Abstract This study presents the development of a new integral-type rack design, characterized by the use of gadolinium (Gd)-containing structure materials that enhances the capacity of spent fuel (SF) pool storage by exploiting the high neutron absorption capability of Gd. Appropriate types and contents of Gd-based neutron-absorbing materials are selected for the new design through parametric studies. For high-reactivity fuels (region I of SF storage pools), neutron-absorbing material composed of Gd 0.7 at% with Eu 2.73 at% is found to be an optimal neutron absorber whereas for low-reactivity fuels (region II of SF storage pools), a composition of Gd 0.7 at% with Eu 8.38 at% is found to be optimal. A criticality safety analysis shows that the newly designed racks are more subcritical than conventional racks for both regions I and II. The additional reactivity margin yielded by the new integral-type design can be used to reduce the pitch of the rack while maintaining equivalent subcriticality compared to conventional rack design. This study demonstrates the potential of Gd-based neutron absorbers in structure materials for increasing the total amount of fuel assemblies that can be stored in a SF storage pool.