b'Figure 3. Rendering of the prototype fixture concept to weld thermocouples to the surface of rodlet claddingcell, to mitigate the risk of a depres- spindle speeds, and drilling bit surization event within the cell. profile. Holes were successfully As a potential alternative to thedrilled in a two-pellet stack with the methods developed by Halden todiameter of the hole being approxi-cryogenically stabilize the fuel formately 0.063 (See Figure 2).drilling operations, INL in FY2021A conceptual design of a modular began developing a methodologyfixture to enable welding of ther-to drill centerline holes withoutmocouples to the cladding surface cryogenic stabilization. Originallywas completed. This is a critical step this methodology was developed anddue to the difficulty of handling is still in use today by the Commis- loose wires remotely in the hotcell sariat a lenergie atomique (CEA)environment. The conceptual in France. In FY2021, INL success- fixture, shown in Figure 3. This fully developed a method to drilldesign allows for the wires to be pre-centerline holes in fresh sintered UO 2 placed in the holder prior to entry fuel pellets. In FY2022, efforts wereto the hotcell and is also compatible made to adapt this methodologywith the remote circumferential to drilling fresh pre-cracked pelletsweld system previously installed. in an attempt to simulate crackedThis design incorporates a heat sink irradiated fuel. Optimization wasto minimize weld affected area and performed using cordierite as a enables accurate angular positioning surrogate fuel pellet, which wasof the thermocouple-rodlet interface bonded to a tube, and then pre- relative to the tungsten electrode. A cracked in a vice to a pre-determinedprototype is currently being fabricated force. Optimization of the methodand testing will begin in FY2023.included variation of the feedrates, 2022|AFC ACCOMPLISHMENTS 151'