Mark-18A Target Processing: A New Capability for Target and Fuel Processing in the U.S.

A new processing capability is being developed at the Savannah River National Laboratory (SRNL) to enable processing of irradiated Mark-18A (Mk-18A) targets. These targets, initially containing plutonium-242 starting material, were fabricated at the Savannah River Site (SRS) in the 1960s and irradiated in the SRS high-flux K Reactor to produce californium-252 (Cf-252). Twenty-one of the 86 original targets were processed at the Oak Ridge National Laboratory (ORNL) in the 1970s to recover Cf-252, plutonium-244 (Pu-244), and heavy curium (Cm-246–248). The other 65 Mk-18A targets, containing the U.S. supply of Pu-244 and heavy curium, have remained in storage in L Basin at SRS. The motivation for this National Nuclear Security Administration (NNSA) Office of Environment, Safety, and Health (NA-ESH-12) funded program is to stand up a facility at SRNL to process the remaining Mk-18A targets to recover Pu-244 and heavy curium. This multi-year engineering and research and development effort culminates in a new lab-scale processing capability at SRNL which meets the need to separate and recover vital Mk-18A products and creates opportunities for additional fuel and target processing particularly for materials that cannot be feasibly processed anywhere else (e.g., in the SRS H Canyon reprocessing facility). Moreover, this mission meets the growing need of establishing a strong workforce in nuclear materials processing.  Targets will be transported individually from L Basin to the Shielded Cells Facility at SRNL where they will be cut, dissolved, chemically separated, and converted to plutonium oxide and americiumcurium oxide products respectively. Both of these products will be packaged and shipped separately to ORNL for further processing. The first Mk-18A target is expected to be received and processed at SRNL in the fall of 2024.  This presentation will include a brief history and description of the Mk-18A targets, the general target processing strategy, a description of the new processing line and the flowsheet, and an updated facility processing status.