b'High Burnup Fuel Loss-of-Coolant Accident Experiment DesignPrincipal Investigator: Robert ArmstrongTeam Members/Collaborators: Colby Jensen, Klint Anderson, Charles Folsom, David KamermanT he U.S. nuclear industry isof increased enrichment and higher aiming to extend the licensedburnup, fuel management strategies burnup limit of nuclear fuelthat were not previously viable, such in light water reactors (LWRs) fromas extending operating cycle length, 62 GWd/t up to approximatelyare now attainable. Such a transition 75 GWd/t. To increase regulatoryhas both economic and safety benefits burnup limits, a licensing basis isas less frequent outages keep reactors required to ensure all regulatoryrunning and reduces the dose expo-requirements are met. The highestsure to outage workers and potential priority research and developmentfor outage-related events.need to support burnup extension,As part of the licensing basis for as determined by the Collaborativeburnup extension, the behavior Research on Advanced Fuel Technol- of HBu fuel during a LOCA must ogies Fuel Performance and Testingbe addressed. To investigate the Technical Experts Group, is thebehavior of HBu fuel during Design behavior of high burnup (HBu) fuelBasis Accidents including LOCA, the during a loss-of-coolant accidentAdvanced Fuels Campaign (AFC) has (LOCA) due to a phenomenon thatdeveloped an experiment vehicle has been termed fuel fragmentation,known as the Transient Water relocation, and dispersal (FFRD).Irradiation System in TREAT (TWIST). While an impressive amount of inte- After a series of fresh fuel commis-gral-type and separate-effect experi- sioning tests, HBu LOCA experiments ments studying HBu fuel behaviorwill be performed in TWIST. These under LOCA conditions havetests are a part of the AFC Integral been performed to date, data gapsLOCA test plan which also includes regarding FFRD remain. To addressfurnace tests to be performed in the needs required for burnupthe Severe Accident Test Station at extension, integral LOCA experi- Oak Ridge National Laboratory.ments on HBu fuel to be performed in the Transient Reactor Test FacilityOne of the main objectives of HBu (TREAT) at Idaho National Labora- LOCA testing in TWIST will be tory have been designed. to assess FFRD under conditions representative of large break LOCAs Project Description: (LBLOCAs). In a pressurized water Enabled through the combinationreactor (PWR) LBLOCA, the coolant of increased fuel enrichment andin the core rapidly begins to void extending the licensed fuel burnupfollowing break initiation. This results limit, the U.S. nuclear industry aimsin a drop in the ability to remove to enhance the economic efficiencyheat from the fuel rods. Core coolant and safety of LWRs. Through the usevoiding also causes the reactor to go 108 2023|AFC ACCOMPLISHMENTS'