Naked Science Forum

Non Life Sciences => Technology => Topic started by: Lawrence on 23/05/2011 15:01:03

Title: Would heat exchange would allow us to re-use spent nuclear fuel?
Post by: Lawrence on 23/05/2011 15:01:03

Lawrence asked the Naked Scientists:
   
Surely even low grade energy from spend fuel radioactivity can be made efficient though perhaps not to produce electricity via a heat exchanger. Domestic hot water heating is just one. Why are more innovative solutions not being explored?

Regards, 

Lawrence

"Imagination is EVERYTHING. Its the preview of life's coming attractions" - Albert Einstein

What do you think?

Title: Would heat exchange would allow us to re-use spent nuclear fuel?
Post by: CliffordK on 23/05/2011 20:06:51

Domestic hot water would be a problem because at least in the USA, each house tends to have an independent hot water system.  And, while one might be able to design a heater module, tracking the waste would be too much of a problem in the modern terrorist society.  And, I believe the waste remains a heavy gamma emitter.

Possibly it could be used in commercial buildings, or universities and government institutions.  Some universities operate a centralized "steam plant" for heating their facilities.

The waste, however, comes in a couple of stages.

Initially after pulling it from the reactor, it is essentially "too hot to handle", and thus the onsite cooling ponds.  After a period of months or years, it then cools down to where it can be safely transported, but then would generate less energy (but, still possibly enough for such a secondary heating effect).

One could still create a low temperature reactor for the cooling ponds that would generate a few KW, or perhaps MW of additional energy that is now being wasted.

Nuclear waste tends to have two components.
Radioactive/fissile material
Reaction Poisons (which cause the fission reaction to be ineffective by absorbing neutrons)

Over 96% of the original uranium remains when the fission reaction is poisoned.

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

The most logical step would be to reprocess the spent fuel to separate out the poisons from the fissile material, and reburn the "MOX" fuel, something that most countries OTHER THAN THE USA do.  Some waste would still be generated, but far less waste, and it would be a better use of our resources.