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GE To Turn World's Biggest Civilian Plutonium Stockpile Into Electricity
First time accepted submitter ambermichelle writes "GE Hitachi Nuclear Energy has proposed to the U.K. government to build an advanced nuclear reactor that would consume the country's stockpile of radioactive plutonium. The technology called PRISM, or Power Reactor Innovative Small Module, would use the plutonium to generate low-carbon electricity. The U.K. has the world's largest civilian stockpile of plutonium. The size of the stockpile is 87 tons and growing. Nuclear reactors unlock energy by splitting atoms of the material stored in fuel rods. This process is called fission. For fission to be effective, neutrons – the nuclear particles that do the splitting and keep the reaction going – must maintain the right speed. Conventional reactors use water to cool and slow down neutrons, keeping fission effective. But water-cooled reactors leave some 95 percent of the fuel's potential energy untapped."
This 'fission' technology sounds interesting, but is it safe?
Yes perfectly safe as long as nothing goes wrong.
I am amazed that conventional water-cooled reactors are only 5% efficient. It sure casts the seemingly low efficiency factors of other alternative fuels(such as the cheapest solar panels) into a different light.
But you are talking about 5% of the energy from a fuel with an energy density which is about 1,000,000 times the energy density of coal
I'm getting tired of all these posts saying "some entity to do something" when the summary says "proposed".
Assuming that "to" means "going to" to everybody else as it does me, I'd appreciate it if the editors could stop doing or allowing that.
You should really read up on the "Integral Fast Reactor" - the S-PRISM this article is about is evolved from the technology developed in the IFR project.
The main potential safety weakness of an IFR is the possibility of sodium leaks leading to a sodium fire (I'm not sure how they manage this risk; it certainly seems like a potentially nasty problem, but I'm sure they've taken some sort of measures to try to prevent that from happening; I hope they are effective).
But, Sodium fires aside, the type of problems you had an Chernobyl, TMI, and Fukushima-Daiichi simply cannot happen in an IFR-style reactor. You can't get supercriticality/runaway fiisson like happened at Chernobyl; you can't get a meltdown; you don't have to worry about steam pressure overwhelming the containment (because water is not used as the coolant, so hence no steam), and you can't get a hydrogen explosion (again, no water in the reactor).
You might get a hydrogen explosion if, somehow, water started mixing with the sodium, as sodium and water will combine to form sodium hydroxide and hydrogen gas, but if they can keep water out of the reactor, then no hydrogen explosions.
So far as I know, there have only been a few sodium fires amongst all the world's sodium cooled reactors over the last 60 years - the most famous one was in Japan back in the late 90's or early 00's, and while that scared the public, it wasn't actually a disaster - just a relatively minor industrial accident in the end. I've never heard of a sodium fire at a nuclear plant becoming a major problem, so I don't think the risk of sodium fires is actually a big, unmanageable 'ticking time bomb', but again, I'm no expert.
Still, I think the technology looks *very* interesting. Let's face it, we have a nuclear waste problem, and either IFR or another type of fast reactor (such as a molten salt fast reactor) are basically the only way to solve that problem. Let's stop fighting the solution to the nuclear waste problem. It truly is the only realistic solution - burn off that 100,000 year "plutonium problem".
It's not that it's not that efficient, it's that it really doesn't need to be. The energy from fission is mostly captured (although you are dumping a lot of heat), but crucially it leaves high energy products behind in the fuel. It's what makes the spent fuel so hazardous to deal with, which is why it's crazy to suggest burying it in the ground!
Why bury something that has so much juicy energy still in it that we can extract with current technology? The answer is political, of course.
The other factor to consider is the sheer magnitude of the energy we're talking about here. E = mc^2 is not just a handy soundbite.
no. but the usual Pu-239 isn't very radioactive, just emits alphas slowly with a very long half life of 24,200 years. That radiation can't even penetrate your skin or go through a piece of paper. Pu-240 is artificial, usually decays by alpha but sometimes spontaneously fissions, it too has long half-life of more than 6500 years. Then there is Pu-238, emits huge amounts of alphas with its short half-life of 88 years, it's used in RTG batteries and also radioisotope heater units. A kilogram of the stuff gives off 500 watts.
Just 'cuz I was curious, and it has some peripheral bearing on the question - assuming 19.816 gm/cm^3 for the density of Pu (more than lead) and also assuming (since it's the UK) we're talking "tons" = metric tonnes = 1000kg = 10^6 gm -
/TSG/
87 x 10^6 gm / 19.816 gm/cm^3 = 4.39 x 10^6 cm^3 = 4.39 m^3.
4.39 cubic meters is a single cube 1.637 meters on a side (or a little more than 5 feet/side, for us backward Yanks). More or less the size of a smallish SUV, yes?
Of course their Pu isn't, one hopes, stored all in one solid cube, which would probably exceed critical mass by some large factor. But still, it's not a massive physical quantity of material you're talking about here.
Area under water behind a dam is uninhabitable and unarable, same goes with solar. Wind is just uninhabitable. If you count the amount of land required by them and compare to land made "uninhabitable" by nuclear, average over power generated, nuclear is a clear winner.
The radiation levels in Chernobyl Zone are lower than natural background radiation in some areas around the globe. Year of living in Ramsar in Iran exceeds nuclear industry limits during emergencies! Calling them "uninhabitable" for 1000 years is a bit of an overstatement... Unarable for food production, maybe, but then you can use those areas for production of automotive fuel.
Oh, and don't forget the amount of land made unarable and uninhabitable by heavy metal poisoning from regular industry, just look at mercury pollution in USA.
You can't get supercriticality/runaway fiisson like happened at Chernobyl
Fast reactors are somewhat notorious for being trickier to control than (well-designed) thermal ones. It's very difficult to avoid a positive void coefficient, and fairly small changes in the fuel geometry can lead to large changes in reactivity. There was a meltdown in an early FBR caused by thermal expansion causing the fuel to bow inwards, increasing the reactivity. Phenix in France also had unexplained loss of reactivity incidents.
Here's a clue - liquid sodium is used for technical and not safety reasons.
Whoever is selling you on some snake-oil "sodium is safe" marketing line is not being honest to you and you are making yourself look naive and poorly informed by repeating it.
Two things, first it only consumes a small portion of nuclear waste and produces a larger volume of a different type of waste - which I'm sure you already know. Second, the established civilian nuclear energy producers have been the ones fighting the solutions to the nuclear waste problem on the basis of cost. I atteneded a seminar on Synrock over twenty years ago and it's only recently that it has been adopted anywhere due to governments pressuring reactor operators to do something with their waste.