1-Is this driven by decadal survey expectations? 2-Or just because it is wise in general? 3-Are there specific missions in mind for this?
They are now in the process of refining those targets to extract minute amounts of Pu-238, ...
There were a couple of possible Discovery class missions that lost out in the last Discovery round: a Titan lake boat and a comet hopping mission.
The staff at the RTG booth at DPS last week sounded very upbeat. Also, Jim Green confirmed at NASA night that they will go ahead and build the two stirling generators that would have been used if Insight had not been selected and then put them in storage. The next Discovery round will be allow to propose to use them, but that won't be until 2016 with the current budget cuts to the planetary program.
Any idea where this refining will take place? They're tearing down buildings in Paducah where Oak Ridge's gaseous diffusion took place during the later years of the Cold War. A bit of a mess there, as in many similar places like Hanford or Rocky Flats, with nasty clean up and former worker cancers, etc.
Quote from: edkyle99 on 10/27/2012 02:46 amAny idea where this refining will take place? They're tearing down buildings in Paducah where Oak Ridge's gaseous diffusion took place during the later years of the Cold War. A bit of a mess there, as in many similar places like Hanford or Rocky Flats, with nasty clean up and former worker cancers, etc.I don't. But I presume that it will be at Oak Ridge. I cannot remember exactly how this all was explained to me, but what has happened so far has essentially been to gain experience required to start production. The person who told me put it sorta like this: nobody has handled this stuff in two decades; they have handled processed Pu-238, but they have not actually processed it themselves. And they have not handled all the other materials that are generated with it. And what they are doing is "exposing" humans to a dangerous material for the first time in decades and they need to make sure that their safety procedures are correct. There are other things involved. For instance, they have models that predict how much Pu-238 they expect to get when they put the targets into the reactor. But they actually have to do it and see if what they get out is what their models say they are supposed to. That's what they're doing with this test batch. They'll use the experience they gain from doing this to figure out exactly how to restart production.When I worked the RPS study (and I've forgotten most of that stuff) I think we were given a rough timeline for production. It was something like 1 year of study (which included things like designing some of the equipment), 1 year of testing and planning, and 5 years of irradiating targets to start producing materials, leading to about 7 years from a go-decision to finally getting useful material at the end. I think we're about two years into that overall schedule.As it has also been explained to me, producing nuclear materials involves a lot of arcane chemistry. They have these little metal targets made of aluminum and neptunium, and they insert them into the reactor where they get bombarded with radiation (note that there are spots in the reactor that are very close to the core and other spots that are a little farther out, so not every target will necessarily get irradiated the same amount). When they remove the targets they have to dissolve them, separate out the materials, then do all kinds of other refining. This involves multiple steps, nasty chemicals, probably generates toxic fumes and maybe even radioactive gases, and you have to control all of that to make sure that nobody gets exposed to anything that can harm them, nothing leaks down the drain, etc. It's very elaborate and complex, and sometimes more of an art than a science. They're relearning all of that.
I really hope they can make this all work out again and have a domestic source of supply (in useful quantities as well).
I presume--I don't know--that they are also doing full life tests on their ASRG designs.
Quote from: Blackstar on 10/27/2012 11:08 amI presume--I don't know--that they are also doing full life tests on their ASRG designs. 1-I didn't think to ask. They had some videos of tests and a nice detailed model, but I don't know how old those were.SNIP2-On a semi-related note, the current JPL reference design for the Europa Clipper had a separate power module which could be either a few ASRGs (3 or 4? can't remember) or solar arrays. Solar is slightly heavier, but could still do the science baseline.3-And the guys in the Boeing booth were saying that their FAST concentrator solar arrays should work right out to Saturn...
...stop changing the design, pick a single design...