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Comment by dm2 | Hacker News Reader

Why wouldn't they want to use it for fuel in nuclear reactors?

My understanding is that weapons-grade plutonium is not easily usable in a conventional reactor; the vast majority of reactors in operation today run on uranium, which is enriched to a much lower percentage than weapons-grade fissile material.

TL;DR different elements, different concentrations of isotopes.

A standard commercial reactor is ~5% enriched. That means that 5% of the Uranium is U235, and the rest U238. U238 absorbs neutrons, however, eventually becoming plutonium. This plutonium is where a majority of the energy comes from. It's just too damn hard to separate it out into something that would be weapons grade, unless the reactor was specifically built that way from the start.

They already have the facilities to recycle plutonium for MOX fuel.

https://en.wikipedia.org/wiki/MOX_fuel#Fast_reactors

http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Fuel-Re...

http://www.huffingtonpost.com/renee-parsons/mox-fuel_b_27078...

http://www.nirs.org/factsheets/basicmoxinfo.htm

well in a light water reactor some of thr fuel can be Pu, but you really can't go beyond 30%. With that said, if you build a reactor that doesn't need to moderate the neutrons and slow them down you could use nothing but plutonium as a fuel. But why bother, LEU is just fine and you cant make a bomb with it. Whereas plutonium is a proliferation hazard and much more expensive.

That would be like throwing gasoline into a natural gas turbine. The one is simply not suitable for consumption by the other.

Apart from the other excellent answers, there just isn't that much fissile material there. The amount required to fuel a bomb is significantly less than the amount required to fuel a power reactor - it simply wouldn't be economical to recover the fissile material, purify and downblend it.

Note that there is a separate program that takes excess weapons HEU from Russian stockpiles and downblends it for sale as nuclear fuel. This is the "Megatons to Megawatts" program, and it has downblended almost 500 tons of HEU since 1995.

They do. Decommissioned HEU is downblended to LEU levels for use in power reactors. You dont need that level of enrichment for a power reactor. About 5% enrichment is all commericals reactors use. The program has been in place since the 1990s and is running to this day. It's called Megatons to Megawatts.

http://en.wikipedia.org/wiki/Megatons_to_Megawatts_Program

In this particular case, the limiting issue was probably international relations. Securing it on-site solves the problem of keeping it away from terrorists, without raising all sorts of questions about access, transport, secrecy, payments, etc. between three nations (U.S., Russia, Kazakhstan).

It is. There's been a big program to do just that called "Megatons to Megawatts": http://en.wikipedia.org/wiki/Megatons_to_Megawatts_Program

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