The Integral Fast Reactor is so named because it handles all its fuel reprocessing on-site which does tell us much more about just what it does. Here’s a link to a very good Wikipedia article
Integral Fast Reactor
The external links are worth checking out too. I was put on to the design by a write up in Scientific American…
Smarter Use of Nuclear Waste
…(PDF warning) the title being the obvious selling point. An Integral Fast Reactor uses fast neutrons to make more fuel out of natural uranium mixes. Regular reactors extract fissionable U235 to ‘enrich’ the more reluctant U238. What used to be normally fired from tanks in armour-piercing rounds as ‘depleted uranium’ is U238 after the U235 has been extracted.
A Fast Reactor can also burn ‘nuclear waste’ – because it isn’t really waste. About 97% of the energy potential of uranium is still locked up in such ‘waste’ so in reality all those tens of thousands of tons of ‘waste’ sitting around current reactors waiting for ‘disposal’ are a potential source of uranium for about 300 years worth of power at current usage.
The final advantage – on top of mining less uranium for the same return, producing no long-term waste (which is really potential fuel like plutonium), and burning up all the current ‘waste’ – is that the waste products eventually produced become safe after 300 years storage – not the 10,000 or so that long-term ‘waste’ commits us to. Storage of such fission-products is pretty straight forward and the total mass is 3% of current long-term ‘waste’ for the same energy return.
So why hasn’t the technology been exploited to the full already if it eats up waste? Firstly the specific approach uses metal fuel elements, not oxides, and that’s an area that has been under-explored. Secondly, the design uses liquid metal working fluid, not water or gas, and that’s another under-explored avenue. Sodium – the metal of choice – is also highly reactive, but no more so than lots of other nasty stuff regularly handled in huge quantities day-to-day world-wide without mishap.
Finally, and this is the cynical part, a fast reactor destroys uranium mining on the obscene scale it has grown to. There’s a few mining bucks tied up in using just U235 because it’s so rare (0.72% of uranium is U235.) There’s 1.5 million tons of uranium in proven resources, about double that in estimated, but unprospected resources. Thus there’s only 21,600 tons of usable U235 in all those millions of tons of ores – lots of mining profit and mess-making for not a lot of useful material. A gigawatt reactor uses 100 tons of 3%-enriched uranium per year. That means 720,000 tons of enriched uranium (and 2.3 million tons of depleted) represent some 7,200 GW-years of power. Earth uses 15,000 GW-years and demand grows all the time. A Fast Reactor would burn 1 ton to produce 1 GW-year, thus all estimated economical uranium represents 200 years of World-Energy demand. That’s total demand, currently provided by coal, oil and gas, plus a pittance by nuclear.
Uneconomical uranium becomes ‘economical’ with Fast Reactors because they can burn the uranium straight – it’s feasible to extract it from seawater then and that source is at least enough for several million years at World-Demand levels.
Also U235 makes bombs, but U238 doesn’t – and integral fast reactor fuel-reprocessing doesn’t make bomb-ready material either. A metal alloy of uranium/plutonium might sound like bomb-stuff, but the isotope mix is all wrong and the stuff needs industrial scale handling facilities – easy for a reactor to supply, utterly ludicrous for wannabe bomb-makers in Third-World nations. Fast Reactors are inherently a Non-Proliferating technology when using mixed-alloys. Note that.
On the flip-side enriched uranium reactors commits us all to sustaining the bomb-makers.
