Nuclear spacecraft fuel could really blast off soon

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Mar 28, 2017

An epic blastoff in nuclear spacecraft fuel seems about to happen. Plutonium 238 (Pu-238), which sounds like the kind of radioactive stuff that makes people glow green in sci-fi movies, could be seeing a literal boom in production by 2020.

Pu-238 degrades into uranium-234, and the heat produced by that decay process is converted into electricity by the radioisotope thermoelectric generators (RTGs) in spacecraft. NASA has used RTGs for some of its most groundbreaking spacecraft, including both Voyager probes, both Viking Mars landers, the New Horizons Pluto probe and the Cassini Saturn orbiter that recently wowed us with unprecedented images of Saturn and its moons. Now Technical Solutions Management (TSM) wants to start a public-private partnership with NASA and the U.S. Department of Energy (DOE) to generate massive quantities of this isotope before the already vanishing supply is diminished even further.

TSM CEO Billy Shipp believes the project "could establish a redundancy in the production of plutonium; it could potentially increase capacity, if the [NASA] missions needed increased capacity, and as a result, it could minimize the programmatic risk overall to the space program."

Contributing their efforts to Pu-238 production will be Canadian Nuclear Laboratories (CNL), Ontario Power Generation (OPG), and the DOE’s Pacific Northwest National Laboratory (PNNL). New technology for producing neptunium-237 “targets” was recently developed by the PNNL, which will ship these targets to a CNL lab that will assemble them into reactor bundles intended for the OPG’s Darlington Reactor. Irradiation of these bundles will generate plutonium-238. They will then be returned to CNL to be taken apart and chemically processed.

While some disagree that our stores of Pu-238 are disappearing at a rate that would make the situation dire anytime soon (even though we really only have enough for up to four deep space missions), the project helmed by TSM is meant to be in collaboration with the DOE’s current Pu-238 production, just one tentacle of the overall process rather than a complete takeover. Shipp and his colleagues plan to start official discussions with NASA soon and submit a funding proposal to the DOE for the project’s upcoming second phase. Phase two will involve reactor bundle qualification, after which a comprehensive flowchart of Pu-238 production will be developed and presented. TSM is shooting for a yield of at least 11 pounds of Pu-238 per year—which could possibly rocket to double that.

While NASA appears to be mostly in favor of TSM’s proposition (you can never have enough reactor sources), the decision ultimately stands with the DOE. A go-ahead from the government agency could mean aiming for some astronomical goals ahead. TSM has prospects beyond backing up the radioactive plutonium supply, as in bolstering the nation’s entire supply of nuclear fuel and even making more advanced planetary exploration possible.

“Our desire is to have a fully integrated plutonium-238 mission for DOE that we're just a part of," said Shipp. He feels TSM is “highly confident from both a regulatory base as well as a technical base that this [project] will go forward.”