Is spent nuclear fuel recyclable?

I am sitting in a conference in Stockholm about nuclear waste. There are speakers from organisations from all over the world including the International Atomic Energy Agency, the Japan Atomic Energy Agency, delegates from many non-governmental organisation, engineers, and academics studying subjects such as nuclear physics, ethics, and geology.
Conference audience
Gene Rowe of the US Nuclear Waste Technical Review Board gave a highly technical presentation about the prospects of dealing with nuclear spent fuel in the USA via a combination of reprocessing and disposal. I got chatting to him afterwards, and asked him about a claim I have heard repeated many times in South Africa.

95% recyclable?

The claim is that about 95% of spent nuclear fuel can be recycled. This sounds very good! When I asked Mr Rowe how he would respond to such a claim, he replied that this is an often repeated misconception. I found him to be refreshingly forthright and clear.

Some technical background

Uranium ore contains two forms, or isotopes, of uranium, called 235 (which is a nuclear fuel) and 238 (which is not a nuclear fuel). Only 0.7% is 235, and this needs to be enriched to 3 to 5% before the uranium can be used in a power reactor. The waste product from this enrichment is depleted uranium, which has about 0.2% of uranium 235.

Mr Rowe went on to explain some technical issues. Spent fuel is about 94% uranium, of which only 0.8% is the useful uranium 235. It also contains 0.6% of a new isotope, 236. Uranium 236 is a neutron absorber, often called a ‘poison’, that reduces the reactivity, and thus the usefulness, of uranium. In order to reuse the uranium from spent fuel it must be enriched more than uranium ore, to compensate for the 236 ‘poison’.

This starts to encounter regulatory issues, since for e.g. in the USA it is illegal to enrich uranium beyond 5%, due to the risk that highly enriched uranium can be used for making nuclear weapons.

The French connection

Gene Rowe

Gene Rowe discussing the 96% recyclable claim

Later in the day, Christophe Poinssot, head of the Radiochemistry and Process department in the nuclear energy division at CEA Marcoule, a French government-funded research institute, gave a presentation.

He painted a glowing picture of the future of nuclear power, and at times I was a bit confused as to whether I was listening to an academic or an Areva salesman. One of his first slides contained the claim that 96% of spent fuel is recyclable!

Is it, or isn’t it?

During the panel discussion, I asked Poinsott and Rowe to comment on this ‘96% recyclable’ claim. There was a bit of back and forth between the two, and in the end they agreed once the underlying assumptions surfaced. Poinssot admitted he was talking about a hypothetical future where breeder reactors were in wide use, while Rowe was talking about reprocessing for use in existing light water reactors, which are the only type of nuclear power reactor in use in Europe, Africa, and the USA.

In conclusion…

So the facts of the matter are clear. With the current light water reactor technology in use, about 1% or 2% of spent fuel is fissionable, and so about 13% can be reused.  The rest, plus the fuel cladding, must be discarded. To claim that spent fuel “is 96% recyclable” is a lie. The correct statements would be “up to 2% is recyclable with present technology” (light water reactors) or “96% might be recyclable” (if breeder reactors are developed and used). It is unfortunate that academics such as Poinssot fudge this issue in order to promote a nuclear future.

One response to “Is spent nuclear fuel recyclable?

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