b'4.4 CAPABILITIES/CORE FUNCTIONS OF R&D CAMPAIGNFinal Design of the LOCA Test Commissioning Series in TREATPrincipal Investigators: Klint AndersonTeam Members/ Collaborators: Charles Folsom, Clinton Wilson, Changhu Xing, Kelly Ellis, Robert Armstrong, Leigh Ann Astle, Nicolas Woolstenhulme, Colby JensenThe completed design ofT he unexpected closure ofto release water from the upper the Halden Boiling Watercapsule containing a fuel specimen the LOCA test device willReactor (HBWR) eliminatedinto an expansion tank below allow the U.S. to performthe only in-reactor Loss of Coolant(Figure 1). The approach will fill critical safety testing forAccident (LOCA) testing capabilitythe in-pile LOCA testing gap left studying and advancingavailable in the western world. by HBWR and adds capability to LWR fuel for the U.S.This capability would have beenstudy stored-energy heating effects nuclear energy fleet. key in continued research aboutresulting in temperature ramp rate Fuel Fragmentation Relocationeffects, never evaluated before on and Dispersal (FFRD). To helpirradiated LWR fuels. These behav-eliminate this major capability gap,iors are expected to play important and ultimately support the lightroles in FFRD, the primary chal-water reactor (LWR) Industryslenge to extending the regulatory goal for achieving higher burnupsburnup limit beyond 62 GWd/t. The and evaluating new fuel design atTWIST capsule design provides a various development stages, a LOCAstate-of-the-art instrumentation testing device is critical. After a fewpackage to collect relevant time-years of engineering studies, a newdependent data for post-test analysis in-reactor LOCA testing device forof the experiment. Figures 2 and 3 the Transient Reactor Test facilityshow the instrumentation package (TREAT) was developed. The finalincluded in the commissioning design for this device has beentest design including options to completed, out-of-reactor prototypemeasure either the fuel centerline testing is underway, and plans are intemperature or rodlet pressure. The place to perform in-reactor commis- design accommodates rodlets with sioning tests next year. fueled lengths ranging from 25 to 50 cm. An out-of-reactor prototype Project Description:was designed as a part of this same The Transient Water Irradiationeffort and is being utilized to inform System in TREAT (TWIST) capsulefabrication, assembly, and testing provides a controlled environmentconditions for future LOCA tests in in which a blow-down event canTWIST (Figure 4). Final design of the be simulated by actuating a valve 152 2022|AFC ACCOMPLISHMENTS'