DOE steps up plutonium production for future space exploration

February 23, 2021, 12:02PMNuclear News

This high-resolution still image is from a video taken by several cameras as NASA’s Perseverance rover touched down on Mars on February 18. Credits: NASA/JPL-Caltech

NASA’s Perseverance rover, which successfully landed on Mars on February 18, is powered in part by the first plutonium produced at Department of Energy laboratories in more than 30 years. The radioactive decay of Pu-238 provides heat to radioisotope thermoelectric generators (RTGs) like the one onboard Perseverance and would also be used by the Dynamic Radioisotope Power System, currently under development, which is expected to provide three times the power of RTGs.

Idaho National Laboratory is scaling up the production of Pu-238 to help meet NASA’s production goal of 1.5 kg per year by 2026, the DOE announced on February 17.

HFIR is producing: Pu-238’s half-life of nearly 88 years is ideal for deep-space travel, but the nation’s supplies have been dwindling since the closure of production reactors at Savannah River Laboratory in the late 1980s. The DOE, in partnership with NASA, reestablished U.S. domestic plutonium production at Oak Ridge National Laboratory’s High Flux Isotope Reactor (HFIR) in 2015 and has been consistently increasing its capabilities. ORNL can now produce up to 700 grams of Pu-238 each year by irradiating target pellets made of neptunium oxide mixed with aluminum metal. .

Target assembly for production of plutonium-238. Photo: INL

INL targets: Idaho National Laboratory is working to qualify several positions within the Advanced Test Reactor (ATR) to maximize its production of Pu-238. Seven targets containing neptunium pellets were loaded into the ATR in July 2019, and another seven-target assembly was recently loaded. The seven targets will be irradiated in the reactor over 55 to 58 days, and once the irradiation is complete, the targets will be sent to ORNL to extract the Pu-238 and confirm the quality and quantity of the material.

INL expects to generate around 30 grams of Pu-238 from its first two irradiation campaigns. [PR1] ATR is scheduled for renovations that will take the reactor off line for six to nine months, starting in April 2021.

Stephen Johnson, director of INL’s Space Nuclear Power and Isotope Technologies Division, said, “INL, together with ORNL, will provide the Pu-238 heat source material to power NASA’s missions for decades to come.”

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