Author Topic: Wired article on Pu-238 production for space missions  (Read 24672 times)

Offline Steven Pietrobon

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Re: Wired article on Pu-238 production for space missions
« Reply #40 on: 03/27/2014 05:33 AM »
Thanks cartman, but SNAP-10A is a nuclear reactor, not a radioisotope thermolelectric generator (RTG).
« Last Edit: 03/27/2014 05:47 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #41 on: 03/27/2014 04:35 PM »
Total Non-NASA Missions:  8 (APL  9)
Number of Non-NASA RTGs: 10 (APL 11)


I talked to Ralph. He miscounted. Your number is right.

Offline vulture4

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Re: Wired article on Pu-238 production for space missions
« Reply #42 on: 03/28/2014 01:06 PM »
During the decadal survey we commissioned a study on small fission power reactors. I'm attaching it here.

In all honesty, we did this because John Casani requested it and Casani is a legend (and nice guy). But I think there was little support for it among the planetary science community. At the very least they wanted the Pu-238 production line restarted so that they could consider missions that had been proposed in the recent past. Small fission reactors would be nice to have for more ambitious planetary missions, but there are no realistic missions that could use them that anybody could foresee in the next several decades.

Thanks, a very interesting study. Still, spacecraft reactor designs have been around for decades. If power requirements increase even moderately (i.e. for nuclear electric propulsion) isn't there a point where it makes sense to pursue reactor development? The alternative is to consider our outer planet probes permanently constrained to our ability to produce RTGs.
« Last Edit: 03/28/2014 01:08 PM by vulture4 »

Offline cartman

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Re: Wired article on Pu-238 production for space missions
« Reply #43 on: 03/28/2014 01:31 PM »
Thanks cartman, but SNAP-10A is a nuclear reactor, not a radioisotope thermolelectric generator (RTG).
oops, yes you're right, my bad :)

Offline clongton

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Re: Wired article on Pu-238 production for space missions
« Reply #44 on: 03/28/2014 01:33 PM »
It's a pity we don't use the Thorium fuel cycle in our commercial reactors. One of the waste byproducts of the reactor is non-weapons grade plutonium that can be used in Pu-238 applications. We'd never run out. Some redesign of the RTG's would be needed of course, but there would never be another problem with the fuel supply.
« Last Edit: 03/28/2014 01:36 PM by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline vulture4

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Re: Wired article on Pu-238 production for space missions
« Reply #45 on: 03/28/2014 02:40 PM »
It's a pity we don't use the Thorium fuel cycle in our commercial reactors. One of the waste byproducts of the reactor is non-weapons grade plutonium that can be used in Pu-238 applications. We'd never run out. Some redesign of the RTG's would be needed of course, but there would never be another problem with the fuel supply.
India is investing rather heavily in the thorium cycle, which is a breeder cycle that requires reprocessing, which would be hard to do in the US as we have (SFAIK) no reprocessing capability. perhaps they would be interested in exporting the plutonium.

Online DLK

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Re: Wired article on Pu-238 production for space missions
« Reply #46 on: 03/30/2014 02:46 AM »
The molten-salt thorium breeder reactor concept eliminates a great deal of the complexity associated with fuel reprocessing, as it can be done while the salt is in a liquid state. Also, there are much less issues with the generation of the long-lived transuranics that plague current light-water U-235 burners. There's a lot to like in the potential of this technology.

Offline Hog

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Re: Wired article on Pu-238 production for space missions
« Reply #47 on: 03/30/2014 04:23 AM »
Questions.

1) The 2020 startup of fresh Pu-238 will produce approx 1kg./year.  Is the entire new Pu-238 production available to NASA, or is DOE actually producing fresh Pu-238 per year at a higher rate for "other" non-NASA uses?

2) Does this future fresh approx. 1kg/year for NASA production limit any possible human/SLS mission to Mars? A more basic wording, will a human/SLS mission to Mars require any sort of Plutonium power sources?

Background
http://en.wikipedia.org/wiki/Pu-238

Thank you.
« Last Edit: 03/30/2014 04:41 AM by Hog »
Paul

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #48 on: 03/30/2014 04:08 PM »
Questions.

1) The 2020 startup of fresh Pu-238 will produce approx 1kg./year.  Is the entire new Pu-238 production available to NASA, or is DOE actually producing fresh Pu-238 per year at a higher rate for "other" non-NASA uses?

2) Does this future fresh approx. 1kg/year for NASA production limit any possible human/SLS mission to Mars? A more basic wording, will a human/SLS mission to Mars require any sort of Plutonium power sources?

1-I thought it was more like 1.5 kg. The material is for NASA use. NASA is paying for it after all. DoE is not producing any other material. In fact, the infrastructure is really crumbling and they need to rebuild it. However, I suspect that NASA's memorandum of understanding with DoE allows DoE to claim that material for other use if necessary (for national security purposes).

2-Human missions to the Moon and Mars will probably require RTGs as backup power supplies. That would increase the need for more material and NASA will have to pay for it. Restarting production of any material at all is an important first step. But it is my understanding that increasing production from the rate that they have decided on will be a significant expense. That will require more material.

Offline Hog

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Re: Wired article on Pu-238 production for space missions
« Reply #49 on: 03/30/2014 06:29 PM »
Questions.

1) The 2020 startup of fresh Pu-238 will produce approx 1kg./year.  Is the entire new Pu-238 production available to NASA, or is DOE actually producing fresh Pu-238 per year at a higher rate for "other" non-NASA uses?

2) Does this future fresh approx. 1kg/year for NASA production limit any possible human/SLS mission to Mars? A more basic wording, will a human/SLS mission to Mars require any sort of Plutonium power sources?

1-I thought it was more like 1.5 kg. The material is for NASA use. NASA is paying for it after all. DoE is not producing any other material. In fact, the infrastructure is really crumbling and they need to rebuild it. However, I suspect that NASA's memorandum of understanding with DoE allows DoE to claim that material for other use if necessary (for national security purposes).

2-Human missions to the Moon and Mars will probably require RTGs as backup power supplies. That would increase the need for more material and NASA will have to pay for it. Restarting production of any material at all is an important first step. But it is my understanding that increasing production from the rate that they have decided on will be a significant expense. That will require more material.

1) Other souces do say approx 1.5 kg, I was going by that nice graphic that shows old, Soviet purchased, "older" then more usable material after upblending, along with the newly produced materials, that graphic stated approx 1kg.

Thanks for your input, and I agree that restarting production is an important 1st step.
Paul

Offline Star One

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Wired article on Pu-238 production for space missions
« Reply #50 on: 03/11/2015 03:21 PM »
Finally something of an update on this issue.

Quote
In 2012, after a few false starts, the Obama administration got Congress to go along with a plutonium-238 restart, under the condition that NASA pay to repair aging DOE infrastructure at the Los Alamos National Laboratory in Los Alamos, New Mexico. When the repairs are complete, the Energy Department will start producing 1.5 kilograms of plutonium-238 a year.

“The question is when that starts,” Caponiti told outer-planets scientists. She said that even if production does not immediately ramp up to 1.5 kilograms a year when the new equipment comes online, “something less than the full production rate” could still support NASA’s needs.

This is because plutonium-238 decays over time (its half-life is just under 90 years), meaning the longer the fuel is stored, the more energy it loses. Of the 35 kilograms reserved in the U.S. stockpile for civil space programs, 17 kilograms meet DOE’s minimum required energy levels. The other 18 kilograms do not, but could be refreshed by an infusion of newly refined plutonium-238.

Even if production gets off to a slow start, any new plutonium-238 helps and “is going to have an immediate effect on missions,” for the better, Caponiti said.

Also at the meeting, Ralph McNutt, a planetary scientist who led a NASA-chartered study of the agency’s future nuclear needs, briefed the group on the results.

The Nuclear Power Assessment Study examined both robotic and crewed mission concepts planned by NASA and the broader space science community over the next 20 years and concluded “nuclear power systems are certainly going to be needed during that time period,” McNutt said.

His presentation marked the first public summary of the study since its November completion. The 185-page report is the product of about six months of work and has not been released because of security concerns, McNutt said.

http://spacenews.com/u-s-plutonium-stockpile-good-for-two-more-nuclear-batteries-after-mars-2020/#sthash.iL4uWZy4.dpuf
« Last Edit: 03/11/2015 03:29 PM by Star One »

Offline Star One

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Re: Wired article on Pu-238 production for space missions
« Reply #51 on: 07/30/2015 05:54 PM »
A further update.

Ohio Senators Call for Plutonium Power Report with New Bill
Quote
Under the Efficient Space Exploration Act, filed July 22 by U.S. Sens. Sherrod Brown (D-Ohio) and Robert Portman (R-Ohio), NASA and the White House Office of Science and Technology Policy would take the lead on a study to determine the space agency’s exact requirements for radioisotope power systems, the plutonium-238 that fuels them, and the risks to planned missions if those needs are not met.

The bill — filed at a time when the U.S. plutonium-238 supply is dwindling and budget cuts forced NASA to cancel development of a more efficient nuclear battery under development at a NASA facility in Ohio — also directs the White House to ensure the Department of Energy, which is responsible for U.S. plutonium production, does not overcharge NASA for plutonium infrastructure upgrades at DOE’s Los Alamos National Laboratory in New Mexico.

- See more at: http://spacenews.com/ohio-senators-call-for-plutonium-power-report-with-new-bill/#sthash.k9YzmC3w.dpuf

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #52 on: 07/30/2015 07:29 PM »
Read the article. It looks like some people in Ohio at the company and probably the NASA field center have been bending the ears of their senators and that's where this comes from. They're not interested in production, they're interested in restarting the ASRG program. I don't see that happening because it requires money that NASA doesn't have.

Recently NASA has talked about restarting Pu-238 production by the end of this decade or even by 2020, which is really puzzling considering that it was originally supposed to start around 15-16. Either it's costing more money of NASA's budget is being short-changed (or both). I also wonder if taking the Europa mission out of the mix reduced the pressure to actually restart production--if true, that's typical, and it has been the problem all along: everybody is always looking for another excuse to kick the can down the road.

I helped run the last big study on this issue and I'm not sure why another one is really needed. The solution is pretty straightforward, just put some money into it and get production restarted.

Offline NovaSilisko

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Re: Wired article on Pu-238 production for space missions
« Reply #53 on: 07/31/2015 04:23 AM »
[...] just put some money into it [...]

Put money into it? Unthinkable... :P
« Last Edit: 07/31/2015 05:39 PM by NovaSilisko »

Offline Star One

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Re: Wired article on Pu-238 production for space missions
« Reply #54 on: 07/31/2015 05:56 PM »

Read the article. It looks like some people in Ohio at the company and probably the NASA field center have been bending the ears of their senators and that's where this comes from. They're not interested in production, they're interested in restarting the ASRG program. I don't see that happening because it requires money that NASA doesn't have.

Recently NASA has talked about restarting Pu-238 production by the end of this decade or even by 2020, which is really puzzling considering that it was originally supposed to start around 15-16. Either it's costing more money of NASA's budget is being short-changed (or both). I also wonder if taking the Europa mission out of the mix reduced the pressure to actually restart production--if true, that's typical, and it has been the problem all along: everybody is always looking for another excuse to kick the can down the road.

I helped run the last big study on this issue and I'm not sure why another one is really needed. The solution is pretty straightforward, just put some money into it and get production restarted.

Yes that was my reading too, it seemed more about ASRG than PU-238 production. Pretty disappointing as can I feel like saying can we not move on from ASRG and just concentrate on getting production going again.

Offline vulture4

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Re: Wired article on Pu-238 production for space missions
« Reply #55 on: 08/02/2015 10:02 PM »
I agree. Even human BEO exploration will depend on nuclear energy. If we cannot even produce Pu-238 these more ambitious projects look infeasible.

Offline DarkenedOne

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Re: Wired article on Pu-238 production for space missions
« Reply #56 on: 08/04/2015 01:53 AM »
A further update.

Ohio Senators Call for Plutonium Power Report with New Bill
Quote
Under the Efficient Space Exploration Act, filed July 22 by U.S. Sens. Sherrod Brown (D-Ohio) and Robert Portman (R-Ohio), NASA and the White House Office of Science and Technology Policy would take the lead on a study to determine the space agency’s exact requirements for radioisotope power systems, the plutonium-238 that fuels them, and the risks to planned missions if those needs are not met.

The bill — filed at a time when the U.S. plutonium-238 supply is dwindling and budget cuts forced NASA to cancel development of a more efficient nuclear battery under development at a NASA facility in Ohio — also directs the White House to ensure the Department of Energy, which is responsible for U.S. plutonium production, does not overcharge NASA for plutonium infrastructure upgrades at DOE’s Los Alamos National Laboratory in New Mexico.

- See more at: http://spacenews.com/ohio-senators-call-for-plutonium-power-report-with-new-bill/#sthash.k9YzmC3w.dpuf

The problem I have with that article is the exact requirements phrase.  The simple fact of the matter is that scientists are not going to propose missions or approve missions that rely on resources that are unavailable.  On top of that we have not even begun to really consider the requirements for manned missions, which are generally substantially greater.  The fact of the matter is that the best course of action for space exploration is to overestimate and overproduce.  I would much rather us produce more than we need and end up wasting some of it then to restrict out solar system exploration because of it.  Besides my guess is that we will have no trouble selling it for substantially more than our cost to produce if we find that we have a surplus. 

Offline Dante80

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Re: Wired article on Pu-238 production for space missions
« Reply #57 on: 08/09/2015 07:15 AM »
How about Americium-241? It can be a decent candidate, and its a lot more easily available (due to it being part of commercial reactor nuclear waste).

Also, in the first page there was a post about small nuclear reactors, and the fact that the power outputs they give would be unneeded in space exploration in the following decades. The truth is that this is not really the case. I mean, a small reactor is not easy to do but there is definitely science it enables. And that is ice/ground penetrating SAR arrays that would put MARSIS and SHARAD to shame, and reveal us a lot of things in a lot of different targets.

Also, a small reactor could enable features like a high bandwidth data transmitter, or nuclear electric propulsion..

Anyone remember JIMO?
« Last Edit: 08/09/2015 07:24 AM by Dante80 »

Offline WindnWar

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Re: Wired article on Pu-238 production for space missions
« Reply #58 on: 08/09/2015 04:39 PM »
Has there ever been an RTG built with AM-241? From what I can find it only has about 1/4 the power generating ability of Pu-238, though I was unable to find an exact watt to gram percentage. RTG efficiency goes down the lower the temp differential of the junctions are. That would tend to mean a much larger and heavier RTG, though it does have the advantage of being readily available material with almost 5 times the half life and only needs slightly more shielding.

Offline WindnWar

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Re: Wired article on Pu-238 production for space missions
« Reply #59 on: 08/09/2015 05:08 PM »
I found this study on use of it in the sterling generators for possible lunar missions. Not much on use in RTG's though ESA has been looking into it. Looks like about double the mass required for it by doubling the number GPHS modules to get the same heat output as PU-238, though the advantage is over a 10 year span there is basically no power drop due to the long half-life.

If only we had a sterling generator.

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