The US Department of Energy (DOE) manages an inventory of materials that contains a range of long-lived radioactive isotopes that were produced from the 1960s through the 1980s by irradiating targets in production reactors at the Savannah River Site (SRS) to produce special heavy isotopes for DOE programmatic use, scientific research, and industrial and medical applications. During the late 1960s, one of the production reactors was configured to operate in a very high flux mode, and >8 kg of 242Pu plutonium contained in Mark-18A (Mk-18A) targets was irradiated to produce 252Cf for use in neutron source applications. Twenty-one targets were processed at the Oak Ridge National Laboratory (ORNL) to recover the 252Cf, heavy curium (i.e., curium rich in 246Cm through 248Cm), and 244Pu. Sixty-five of the Mark-18A targets were not processed and are currently in wet storage at SRS. DOE’s Office of Nuclear Materials Integration (ONMI) established a Mk-18A Target Material Recovery Program (MTMRP) to separate and preserve the unique materials in these targets. Evaluations are also under way to determine whether additional rare long-half-life fission product isotopes present in the targets in much smaller quantities, such as 93Zr, can be economically recovered. These evaluations include assessment of the quality, value, and demand of the materials; process modifications required to facilitate recovery; and the incremental costs for their recovery from the Mk-18A targets.