b'3.4 FUEL SAFETY TESTINGCharacterization of The Metallic Foam for Source Term AnalysesPrincipal Investigator: F. G. Di Lemma, INLTeam Members/ Collaborators: K. Wright, A. Winston, L. Capriotti, C. Jensen and D. Wachs (INL)volatile fission products are believed to accumulate, also where fuel failures have been found to occur under failure-limits testing of Experimental Breeder Reactor (EBR)-II pin designs in Transient Reactor Test Facility (TREAT). Detailed understanding of this structure is still lacking but is needed to support transient fuel performance and source term determination analyses, mandatory for licensing of new nuclear fuel forms.Project Description: For the first time, the foam structure formed in certain metallic fuel pins is analyzed in detail using advanced characterization techniques, now available in the Irradiated Materials Figure 1. The EPMAU nder the Department ofCharacterization Laboratory (IMCL) instrument scientist (Ms.Energy (DOE) Advancedat Idaho National Laboratory (INL). A Karen E. Wright) performing aFuels Campaign (AFC),U-Pu-Zr metallic fuel pin, irradiated sample loading operation onfuel safety research for metallic fastto 11.09% peak burnup in EBR-II an irradiated sample. and subjected to an overpower reactor fuels has recently become aevent in the OPT-1 experiment major focus. Knowledge of fission(1992), was selected to assess the products transport behavior inevolution of microstructure and the nuclear fuel is crucial to achieving achemical form of fission products mature technology that can be usedafter a transient. This irradiated rod by reactor designers. This researchunderwent a moderate overpower applies advanced characterizationramp of 32% over a 5-minute techniques to evaluate the behaviorperiod and represents a first step to (e.g., chemical composition, fissionreviving detailed studies of transient product migration and microstructuralirradiation performance of metallic evolution) of the metal foamfuels since the early 1990s. These structure found in certain metallicexams will aid detailed understanding fuel pins. The foam structure formsof transport and potential release at the top of the fuel column wheremechanisms following unexpected 220 2019|AFC ACCOMPLISHMENTS'