Recovery of Plutonium-244 from the Mark-18A Targets at Savannah River Site

In recent years, the Department of Energy – National Nuclear Security Administration (DOENNSA) Office of Nuclear Material Integration (NA-532) has tasked Savannah River Site (SRS)/Savannah River National Laboratory (SRNL) to develop a process to recover plutonium from the Mark-18A (MK-18A) targets. The Mk-18A plutonium isotopics are unique, and contain the world’s remaining, unseparated supply of plutonium-244. The current accessible inventory of plutonium-244 was recovered in the early 1970’s at Oak Ridge National Laboratory (ORNL) from twenty-one Mk-18A targets. The demand for plutonium-244 is growing beyond the current inventory as increasing demands for nuclear proliferation monitoring and mixed oxide fuel production all benefit from the use of plutonium-244 in analytical analysis. Today, sixty-five Mk-18A targets are currently stored in SRS’s L-Basin. A large, multidisciplinary team has been established at SRNL (with additional support for ORNL staff) to develop the method to recover the valuable plutonium at SRNL and ship the radiological material to ORNL. The targets will be removed one at a time for transportation from L-Basin to SRNL in a newly designed onsite transportation cask. Once received into SRNL, the targets will be loaded into SRNL’s shielded cell facility, where they will be processed to recover the plutonium for future isotopic purification at ORNL. The remaining high burn-up actinides (higher isotopic distribution of Am, Cm and Cf) will also be sent to ORNL for future programs. During the development of the process flowsheet at SRNL, the main focus is to ensure its practicality for operation with maximum recovery of plutonium-244. Additional considerations in the design are meeting the current facility authorization basis, controlling potential off-site releases in unmitigated accident scenarios, minimizing worker exposure and meeting a purity specification for shipment of radiological materials to ORNL. At this time, the first Mk-18A target is expected to be received in SRNL late-2020.