Tuesday, July 21, 2009

The Keys to Lowering Reactor Costs: Nuclear Waste

I am at present satisfied that this discussion of the potential effects of the LFTR on the cost of handling nuclear waste presents an adequate picture.

The problem of "nuclear waste" is one which is generated by nuclear technologies which fail to efficiently convert U-238 into nuclear fuel. The ultimate source of the problem is found in the uranium-plutonium fuel cycle, and in the use of reactor technology which fails to burn Pu-239 efficiently, and in fuel cycle technology which fails to efficiently, and cleanly reprocess nuclear fuel in a cost effective fashion. As a consequence of the systemic fuel inefficiencies, added facilities for the handling of used nuclear fuel must be added to reactor construction cost. The nuclear industry regards paying the added construction expenses as preferable to paying for fuel reprocessing, However, since we are taking the "full court press" in examining cost lowering measures to reactor construction, the cost of fuel storage facilities is certainly an issue.

In my previous "keys" postings, I found advantageous in both the PBR and the LFTR as far as cost savings are concerned. But the LFTR has a major advantage in terms of a need for post-reactor fuel storage facility costs, and indeed in virtually every aspect of the fuel cycle. About 98% of the Thorium that enters a LFTR is burned up inside the reactor. The other 2% will come out as Neptunium 237, which has a use. In once through uranium cycle civilian reactors, Most of the original fuel charge remains unused when the fuel is withdrawn from the reactor. In addition significant amounts of the fissionable materials remain in the "spent" fuel, and their presence becomes an issue in post-reactor fuel handling. Post reactor fuel handling is a problem for LWRs and for PBRs. And if anything there are more problems in reprocessing post-reactor fuel from Pebble Bed Reactors, than in reprocessing fuel from LWRs. (Kirk Sorensen discussed LFTR fuel reprocessing here, and here.)

There are, however, added fuel handling expenses that come with LFTR technology. The fuel/carrier/coolant salts of the LFTR are in most designs subjected either continuous or periodic processing. The design requires that several sorts of processing should take place. Each process would require a separate processing unit. These fuel reprocessing units would add to the expense, and complexity of the LFTR. In addition they would create safety issues, and there would be significant problems with servicing and maintaining them.

The economics of fuel reprocessing with LFTR is, however, complex. The reprocessing of LFTR involves the extraction of fission products which are valuable minerals and metals. This in tern creates a second revenue stream from the LFTR, the sale of valuable fission byproducts. While it is doubtful that this revenue stream would by itself return all of the capitol costs involved in LFTR fuel reprocessing, it would at least produce a partial return on the capitol investment, beyond revenues produced by the generation of electrical power.

There are hidden advantages that effect reactor construction costs. By solving "the problem of nuclear waste," the LFTR would go a long way toward undercutting public opposition to nuclear power. If nuclear power is more acceptable to the public, investment risk diminishes. Diminished risk means lower capital costs. Hence the superior fuel processing features of the LFTR may in fact indirectly lower reactor construction costs. It would most certainly lower nuclear fuel cycle costs. There is a public relations benefit to constructing what is perceived as being clean or at least cleaner nuclear power. That benefit does have a cash value, even if it is not directly accounted in assessing the cost of reactor construction.

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