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posted by martyb on Friday October 20 2017, @04:09PM   Printer-friendly
from the non-glowing-assessment dept.

A Government Accountability Office report has found that the U.S. is unlikely to produce enough Plutonium-238 for NASA missions about a decade from now. The isotope has been used in radioisotope thermoelectric generators (RTGs) on missions such as Voyager, Cassini, and the Mars Science Laboratory:

Another GAO report notes: "[...], DOE currently maintains about 35 kilograms (kg) [77 pounds] of Pu-238 isotope designated for NASA missions, about half of which meets power specifications for spaceflight. However, given NASA's current plans for solar system exploration, this supply could be exhausted within the next decade."

[...] To address the plutonium problem, in 2011 NASA provided funding to the Department of Energy (DOE) to restart domestic production of the substance. The program is called the Pu-238 Supply Project. So far, the Project has produced ∼3.5 ounces (100 grams) of Pu-238. DOE identified an interim goal of producing 10 to 17.5 ounces (300 to 500 grams) of new Pu-238 per year by 2019. The goal is to produce 1.5 kilograms of new Pu-238 per year—considered full production—by 2023, at the earliest.

GAO is questioning the Supply Project's ability to meet its goal of producing 1.5 kilograms of new Pu-238 per year by 2026. For one thing, the oversight agency's interviews with DOE officials revealed that the agency hasn't perfected the chemical processing required to extract new Pu-238 from irradiated targets to meet production goals.

Only one DOE reactor is currently qualified to make Pu-238:

NASA's plutonium will be produced at two of these reactors, but only one of them is currently qualified to make Pu-238. GAO reported that initial samples of the new Pu-238 did not meet spaceflight specifications because of impurities. However, according to DOE, the samples can be blended and used with existing Pu-238.


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  • (Score: 0) by Anonymous Coward on Friday October 20 2017, @11:41PM (2 children)

    by Anonymous Coward on Friday October 20 2017, @11:41PM (#585478)

    There's reason for caution. 238Pu is an alpha emitter with a half-life of about 88 years. That's slow enough that if it became dispersed in the environment, it could make its way into people's bodies before much of it had decayed. But it's fast enough that, should the plutonium remain in someone's body, much of it would decay during the person's lifetime. It has a much greater activity than an identical amount of 239Pu. Alpha particles emitted within someone's body travel a very short distance before they are absorbed, hence essentially all of their energy is deposited in neighboring cells.

    Robert Park, who should know, told me ~20 years ago that NASA's RTGs are designed to survive a launch failure without dispersing their plutonium (he was talking about the ones used in the Apollo program). I have no idea whether that's changed for the worse. Even if it has, it's small potatoes compared to having ICBMs on alert or having several damaged reactors at Fukushima.

  • (Score: 2) by takyon on Saturday October 21 2017, @01:43AM

    by takyon (881) Subscriber Badge <{takyon} {at} {soylentnews.org}> on Saturday October 21 2017, @01:43AM (#585519) Journal

    https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Plutonium_power_source [wikipedia.org]

    Had there been any malfunction causing the probe to collide with the Earth, NASA's complete environmental impact study estimated that, in the worst case (with an acute angle of entry in which Cassini would gradually burn up), a significant fraction of the 33 kg of plutonium-238 inside the RTGs would have been dispersed into the Earth's atmosphere so that up to five billion people (i.e. almost the entire terrestrial population) could have been exposed, causing up to an estimated 5,000 additional cancer deaths over the subsequent decades (0.0005 per cent, i.e. a fraction 0.000005, of a billion cancer deaths expected anyway from other causes; the product is incorrectly calculated elsewhere as 500,000 deaths). However, the chance of this happening were estimated to be less than one in one million.

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  • (Score: 2) by c0lo on Saturday October 21 2017, @06:50AM

    by c0lo (156) on Saturday October 21 2017, @06:50AM (#585587)

    should the plutonium remain in someone's body, much of it would decay during the person's lifetime.

    I doubt it, that person's life will be much shorter.

    Alpha particles emitted within someone's body travel a very short distance before they are absorbed, hence essentially all of their energy is deposited in neighboring cells.

    Deposited is the wrong term to use. Destruction by radiolysis [wikipedia.org] it's what actually happens.
    As an example of the effects, see Alexander Litvinenko [wikipedia.org].
    The high majority of Polonium isotopes [wikipedia.org] decays on α and β channels.