Tuesday, December 02, 2014

To Jupiter and Beyond with Nuclear Energy

Sometimes, irony abounds:

When it comes to space travel, plutonium-238 is the perfect fuel: long-lasting and, as I'll explain later, relatively safe. Without it, we have no hope of going much further than Mars, after which it simply becomes too dark to rely on solar panels, the most common alternative power source in space. But the world is rapidly running out of plutonium-238.

Where’s the irony? Plutonium-238 is a byproduct of producing plutonium-239, which was used in nuclear weaponry. With the end of the cold war, and the dismantling of much of the nuclear arsenal, there’s no call for plutonium-239. It a case of undoubted progress blocking further progress.

Happily, that’s not the end of the story. The government is looking into another way of making plutonium-238. Sarah Zhang at Gizmodo explains the process:

The production plan, for now, involves hopping between no fewer than three DOE labs all over the country.

  • Idaho National Laboratory: The precursor material, neptunium-237, is extracted from nuclear reactor fuel.
  • Oak Ridge in Tennessee: A reactor irradiates neptunium-237 to make plutonium-238. The plutonium-238 and any remaining neptunium-237 are extracted to be used as fuel and recycled, respectively.
  • Los Alamos in New Mexico: Plutonium-238 is pressed into pellets and stored.

This is rather pleasing – no plutonium-239, so no undue proliferation concerns, further work in nuclear technology, another step en route to dilithium crystals for future starship usage. Sometimes, progress just can’t be stopped. Good story.

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