Preliminary Conceptual Neutronic, Thermal, and Mechanical Design for ²³⁸Pu ATR Targets

Pu-238 is a valuable heat source material used to manufacture radioisotope power systems (RPSs), which are needed to provide electrical power for space exploration and other missions. Before 1989, the United States Department of Energy (DOE) produced Pu-238 at the Savannah River Site in South Carolina in nuclear reactors that are now decommissioned. From 1989 through 2009, existing DOE inventories of Pu- 238 were supplemented by quantities of Pu-238 purchased from Russia; however, supplies available for purchase from Russia are limited. DOE has restored domestic production to meet future demand; otherwise, NASA will be in danger of not being able to use RPSs in future missions. The Pu-238 Supply Program has the objective of reestablishing the domestic capability for producing Pu-238. In order to meet the quantities of Pu-238 needed to support NASA space mission and other federal users the ATR is being considered as an important asset to achieve the desired production of the radioisotope. In order to determine the constraints and parameters needed to maximize the production of Pu-238 at ATR a preliminary conceptual design target design was performed. The preliminary conceptual design had two principal goals: 1. Perform a trade study to determine an ATR target length that maximizes production as well as minimize the need to modify ORNL's target. 2. Evaluate the selected preliminary design from the standpoint of the ATR nuclear safety basis. (authors)