b'using a WIPP disposal criteria approved sorbent. A demonstration of this procedure was performed previously at the Analytical Laboratory using a 5 mm length tubular segment of an irradiated fuel rod from the H.B. Robinson plant. For fiscal year (FY)21, efforts focused on completing scale up activities and facility impact and safety analysis to support performing chemical defueling on larger samples in HFEF. Equipment has been procured and is pending installation and demonstration. Two micro-TIG welding systems have been designed, fabricated, and installed to perform the circumfer-ential welds and seal welds necessaryFigure 3. ATF-R experiment assembly being filled with water during assembly to attach new endcaps and set theprocess at HFEFdesired rod internal pressure prior to follow on experiments. These welding systems utilize the new hot cell penetration feed through that was installed to supply the utilities and control system for the welding operations. Assembly of the first experiment with previously irradiated fuel was enabled by the restoration of the HFEF-15 cask to service and significant new handling equipment and control systems, in addition to operational and facility readiness. Demonstration of this new capability was completed when the ATF-R experiment was assembled into the MARCH-SERTTA experiment vehicle and successfully transferred to the TREAT facility from HFEF. The transient irradiation of this experiment was subsequently performed on July 29th 2021, marking the first experiment with previously irradiated fuel of theFigure 4. Successful weld demonstrated on oxidized cladding during out of cell modern TREAT era. testing of circumferential welder2021|AFC ACCOMPLISHMENTS 143'