Preliminary Safety Assessment of Liquid Deuterium Premoderator Container for Ultra-Cold Neutron Source at WWR-K Reactor (AlSUN)

This paper presents a preliminary safety assessment of the liquid deuterium premoderator container developed for the AlSUN ultra-cold neutron source, integrated into the thermal column of the WWR-K reactor. Analytical calculations were conducted to evaluate the container’s response under three categories of hypothetical accident scenarios: (1) reactor power control and cryostat cooling failures, (2) breaches in the vacuum insulation, and (3) a stoichiometric deuterium–air detonation as a beyond-design-basis residual-risk bound. Key thermodynamic parameters—including temperature and pressure evolution—were tracked in each scenario to characterize the transient system behavior. The resulting profiles were then used to estimate mechanical stresses on the container walls, considering the thermomechanical properties of the materials used in its construction. Special attention was given to the structural integrity of Aluminum Alloy 5056, assessing its performance under extreme thermal and mechanical loads. These findings support the selection of Aluminum Alloy 5056 and inform future, more comprehensive studies employing advanced simulation tools.