Mobile helium cooling loop system for in-reactor PAHR experiments

One objective of the PAHR program at Sandia Laboratories is to better simulate the decay heating of debris beds and molten pools by using the Annular Core Pulse Reactor (ACPR) operated in its steady-state mode to fission heat UO2 fueled PAHR experiment capsules. Safe performance of these typically long duration, elevated temperature PAHR experiments within the ACPR first necessitated the development of a unique system for cooling, control, and diagnostics of the PAHR experiment capsule. The experimental equipment arrangement of the mobile helium cooling loop (HCL) system connected through piping to the PAHR debris bed capsule located at the bottom of the 23 cm diameter by 7 m long dry experiment tube penetrating the core region of the pool-type ACPR reactor is described. The mobile HCL system uses low pressure helium gas to remove heat at rates up to 20 kW that was fission generated within the sealed capsule containing UO2 and molten sodium