Given the current state of the energy market combined with the environmental worries we are facing, plus the average age of the reactors in the US it is time for nuclear power to make a come back. We have had nearly 30 years since the last major accident with a nuke plant in the US. Massive improvements have been made in design and safety. If the NRC can create a program to pre-certify a set of stock gen 2 designs so they can be built as "cheap" prefab units, and reduce the hassles with site selection we can reduce our need to buy hydrocarbon fuel from outside the US and reduce the need to burn dirty but home sourced coal.
I do not agree that we have figured out what to do with spent fuel. Burying it is likely not the right answer, but reprocessing might not be right either. So while we figure out what to do with the spent fuel, we shouldn't waste the heat it produces.
As for the matter of proliferation most of the fuel "burned" in US reactors has so much Pu240 that you would get nothing but a fizzle. Interestingly this very property could reduce the spent fuel problem and create a way to “peak” with nuclear power.
After removal, the fuel rods are placed in pools to cool off, since the residual radioactivity they contain produces a vast amount of heat. With a low boiling point working fluid as a secondary coolant significant energy could be recovered from the waste heat in the pool and used to spin "steam" turbines during periods when peaking power is needed. By moving the rods closer in the pool the increased amount of subcritical fission could keep the rods hot for a long time and reduce the amount of fissile material in the rod.
The optimal solution would be an element that could be made into sheathing for the rods that went struck with a neutron would produce a high energy alpha or beta with a very short half life, with a nonradioactive decay product. The issue is the best material for this job is Gold, but Gold is too expensive so Cadmium 114 could be used since Cadmium 115 has a short half life (3 days) and after a beta decay produces Indium and lots of heat. Cadmium 114 isn’t hard to get since the control rods of nuclear reactors are rich in it after a few years of neutron bombardment. Interesting while after decay the Gold turns to Lead, the Cadmium ($10/Kg) decays into Indium ($1,000/Kg), sounds like alchemy doesn’t it? With a Cadmium sheath the rods could be very close, and creating lots of heat but never reach critical mass. However, given the high neutron cross section of Indium the sheath material would have to be changed out frequently to ensure high recovery of Indium.
The “peaking pond” would be built to allow the rods to be moved horizontally so that as the time that power would be needed approached the rods could be moved closer together so they could start really heating up again. Then just before the predicted “peak” demand was reached the rods would be separated again, since they will continue to heat up after being moved apart. During off peak times the power generated could drive the cooling pumps and accessory equipment, allowing the “peaking pond” to be self sufficient.
In case anyone from Westinghouse reads this I hope your lobbyists are working 24/7 to get something like what I suggested hidden in a bullet proof bill that can be passed and signed before next year.
No comments:
Post a Comment