engineering question #8656



Ryan, a 16 year old male from Qualicum Beach asks on December 17, 2011,

Q:

Why don't some countries like Canada reprocess spent uranium into plutonium?

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the answer

Jeremy Whitlock answered on December 19, 2011, A:

The simple answer is that reprocessing of used uranium fuel is expensive compared to mining new uranium, so an economic decision is made in Canada (and many countries) to store used fuel for future consideration.  Uranium is plentiful at the moment, but eventually it won’t be, and the used fuel stored today could very easily form one of tomorrow’s treasured energy resources.  For the moment however, Canada is fortunate to sit on some of the richest reserves of uranium in the world.

On a related note, we should also remember that Canadian-designed CANDU reactors utilize plutonium today to a degree that exceeds that of any other commercial power reactor.  The physics of CANDU not only make it uniquely capable of operating on natural uranium (obviating the need for expensive uranium enrichment technology), but also result in it generating about half of its energy from plutonium created “in situ” as the uranium-238 atoms (the bulk of natural uranium, and the ones not typically involved in the fission process) absorb excess neutrons and decay into plutonium-239. 

The subsequent energy extracted from the combination of uranium and plutonium in the CANDU fuel is substantial enough that there is relatively little left over to reprocess for further use – compared to the used fuel of other reactor designs (some of which is reprocessed in other countries for this reason).  So another way of answering the question is to say “Canadian reactors make efficient use of uranium fuel the first time through” – but of course this doesn’t rule out future reprocessing when it makes sense economically.

 

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