Dr Barry Brook’s nuclear blog “Brave New Climate” really has been influencing my thinking lately. In total layman’s terms, this is why I think IFR’s should at least be considered.
- IFR’s EAT today’s nuclear waste.
- In other words, today’s nuclear waste becomes FUEL that could run the world’s energy needs for the next 500 years, by which time we’d probably have fusion or some super-cheap solar alternatives.
- 500 years of cheap baseload power is attractive in a world of peak oil, gas, and coal.
- It burns 90% of today’s waste and the 10% that remains is so ‘super-hot’ that it burns itself back to safe levels in only 300 years and then is safe. Know any 300 year old buildings? If we started today, by the time we ran out of ‘normal waste’ to use, the first batches of ‘super-hot’ reprocessed waste could be decommissioned from high security storage and be safe.
This is one pathway to a Co2 free, radioactive waste free world for the next 500 years at least.
What about nuclear bombs?
Should we be spreading this dangerous technology that allows bombs? Well, first, IFR’s don’t produce the right material for bombs.
Second, sure, if a country gets significantly advanced in their nuclear processing they could divert some material into making bombs. Which countries produce the most Co2? That would be America, China, Japan, India, Europe, etc. Now, which countries already have either nuclear power or nuclear bombs? That would be the same list. The nuclear genie is already out of the bottle, so there is no use protesting against nuclear power on the basis of nuclear bombs as it is already too late. All you would be protesting against is the intensity of nuclear power in those countries that already have bombs, and are already the biggest Co2 polluters. You would not be preventing the spread of the technology into most of the big global players, as they already have it!
Divorce the 2 arguments, as they are not necessarily related anyway! Bombs have to be dealt with politically, where nuclear power can be dealt with both politically AND technically. (By only allowing reactors that can’t produce bomb material).
Now to Barry’s post which graphically portrays the difference between Light Water Reactors and Integral Fast Reactors.
Just compare the fuel cycle of the old LWR with the IFR Barry promotes.
To run a 1 GWe reactor for 1 year, about 170 tons of uranium ore is required. After enrichment of U-235 to 3.5 – 5%, this yields about 20 tonnes of material suitable for manufacture into uranium oxide fuel pellets (at ~50,000 MWd/t burnup). The rest is discarded as ‘depleted uranium’, which still contains about 0.25% U-235. After a year of operation, the following ‘waste’ results: 18.73 t of uranium (mostly U-238), 1 t of fission products (the atomic shards left over after heavy fissile isotopes are split), 0.25 t of plutonium (i.e., 250 kg, which has been bred in the reactor as a result of U-238 absorbing a neutron and then undergoing a couple of beta decays) and 0.02 t of minor actinides (mostly americium and curium).
This ’spent fuel’ can be either secured for eventual storage in a deep geological respository (hint: bad idea), or reprocessed to recover the Pu for further fissioning. The result of this type of reprocessing, adopted by the French, is that instead of getting six-tenths of 1 per cent of the energy out of mined uranium, we get eight-tenths, with no significant reduction in waste life. Only one or two passes are possible. Wow… excuse me if I’m not particularly impressed (it’s also an expensive process and rings proliferation alarm bells for some folks).
Now, let’s consider the alternative IFR fuel cycle:
First, note that no mining is required — this will be true for many centuries, until all of the existing used fuel (left over from LWRs) and depleted uranium that we have stockpiled is consumed, to make a lot of electricity.
First, 700 tons of LWR spent fuel must be reprocessed to extract ~10 tonnes of fissile actinides (mostly Pu, Am and Cm of various isotopes, and laced with some trace lanthanoids which keeps it ‘hot’). More detail on this ‘fissile load’ will be given in future posts. This one-time reprocessing also results in 80 t of makeup uranium (40 t for the core, such that the resultant metal fuel rods are ~20 % fissile, and 40 t for the breeder blanket), with the remaining uranium being available for future inputs as this plant, and others, generates electricity, year in, year out. About 1.5 t per GW year will be needed if the IFR is running at a high fissile-fuel-breeding rate. Note: The blanket uranium loading will be zero for a burner configuration, and much larger amounts for maximum breeding. The amount used in the diagram is something in between.
Each year, an average of 13.5 t of nuclear fuel will be removed from the reactor and run through the on-site pyroprocessing unit (details in later posts). This procedure allows separation of the fission products from the heavy metals (which are recycled back into the IFR). The F.P. are encased in a highly durable, inert glass (or perhaps a synroc), and must be isolated for 300 to 500 years to allow for 10+ half-lives of Sr-90 and Cs-137. No long-term (multi-millennial) geological disposal is required.
As a high priority, Tom Blees, Yoon Chang and others are now working towards getting the first LWR spent fuel recycling plant built in the US. Tom discussed this initiative during his recent seminar at ANSTO. The prospects are looking bright.
And what of the ‘excess actinides for startup of new IFR‘? This is a very important point, and will be the topic of the next IFR FaD post. This, in turn, will lead naturally into an exploration of the feasible fuel breeding and roll out rates for IFR power plant deployment over the coming decades.