b'stress evolution during rapid powerfabrication, (3) TREAT testing forFigure 1. Photographs of (a) cold transient. Possible alteration of theCr-coated cladding tubes, (4) mate- spray coating system used for the Cr damage/failure phenomena of therial characterization and mechanicalcoating deposition and (b) sections of Zircaloy-4 cladding tube before and coated cladding under RIAs due totest after TREAT testing, and (5)after Cr coating depositionthe chemical interactions and phaseanalysis of data and modeling of transformations must be importantfailure mechanism of Cr-coated in future licensing and commer- cladding tubes. In the first stage cialization. Success of the proposedof the project, the test matrix for research will generate valuableTREAT testing was established to experimental data for the responsedemonstrate potential late phase of Cr-coated Zr-alloy cladding tubeshigh temperature RIA failures such under RIA conditions, which thenas cladding ballooning and burst, can be compared with future experi- oxidation embrittlement, and mental results of irradiated highcladding melting by adjusting the burn-up Cr-coated Zr-alloy claddingtarget peak cladding temperature, tubes currently being irradiated attotal energy deposited, and cladding commercial reactors. The result ofinternal pressure. A total of six RIA this project will be used for antici- tests are planned: two uncoated pated licensing applications to theZr-alloy cladding as a reference test, U.S. Nuclear Regulatory Commissionthree CS Cr-coated Zr-alloy cladding, (NRC), thereby accelerating deploy- and one PVD Cr-coated Zr-alloy ment of Cr-coated ATF concepts incladding. Sections of Zircaloy-4 clad-U.S. commercial light water reactording tubes were coated at the UWM (LWR) fleets. using the cold spray deposition facility as Figure 1. The as-deposited Accomplishments: CS Cr-coated cladding was polished To achieve the objective of thisto achieve the smooth surface research, five primary task areasroughness and it was confirmed have been identified: (1) sampleusing Scanning Electron Microscopy fabrication for TREAT testing, (2)(SEM) photography as shown in irradiation capsule design andFigure 2. Several uncoated Zircaloy-4 2023|AFC ACCOMPLISHMENTS 121'