Reprocessed uranium
Reprocessed uranium (RepU) is the uranium recovered from nuclear reprocessing, as done commercially in France, the UK and Japan and by nuclear weapons states' military plutonium production programs. This uranium actually makes up the bulk of the material separated during reprocessing. Commercial LWR spent nuclear fuel contains on average (excluding cladding) only four percent plutonium, minor actinides and fission products by weight. Reuse of reprocessed uranium has not been common because of low prices in the uranium market of recent decades, and because it contains undesirable isotopes of uranium.
| Isotope | Proportion | Characteristics |
|---|---|---|
| uranium-238 | 99% | Fertile material |
| uranium-237 | 0% | Around 0.001% at discharge, but half-life only 1 week. Produces soluble, long-lived neptunium-237 which is hard to contain in a geological repository. |
| uranium-236 | 0.4%-0.6%[1] | Neither fissile nor fertile. Affects reactivity. |
| uranium-235 | 0.4%-0.6% | Fissile material |
| uranium-234 | >0.02% | Fertile material but can affect reactivity differently [2] |
| uranium-233 | trace | Fissile material |
| uranium-232 | trace | Decay product thallium-208 emits strong gamma radiation making handling difficult |
As of April 2007, uranium prices had begun to rise again, and if the price becomes high enough, it is possible that reprocessed uranium will be re-enriched and reused. A higher enrichment level will be required to compensate for the 236U which is lighter than 238U and therefore will concentrate in the enriched product.[3] Also, if fast breeder reactors ever come into commercial use, reprocessed uranium, like depleted uranium, will be usable in their breeding blankets.
There have been some studies involving the use of reprocessed uranium in CANDU reactors. CANDU is designed to use natural uranium as fuel; the U-235 content remaining in spent PWR/BWR fuel is typically greater than that found in natural uranium, which is about 0.72% U-235, allowing the re-enrichment step to be skipped. Also, the previous sentence directly contradicts the above table. Fuel cycle tests also have included the DUPIC (Direct Use of spent PWR fuel In CANDU) fuel cycle, where used fuel from a Pressurized Water Reactor (PWR) is packaged into a CANDU fuel bundle with only physical reprocessing (cut into pieces) but no chemical reprocessing.[4]
References
- 1 2 "Processing of Used Nuclear Fuel". World Nuclear Association. 2013. Retrieved 2014-02-16.
- ↑ "Uranium from reprocessing".
- ↑ "Advanced Fuel Cycle Cost Basis" (PDF). Idaho National Laboratory.
- ↑ "The Evolution of CANDU Fuel Cycles and Their Potential Contribution to World Peace". DUPIC.
Advanced Fuel Cycle Cost Basis - Idaho National Laboratory
- Module K2 Aqueously Reprocessed Uranium Conversion and Disposition
- Module K3 Pyrochemically/Pyrometallurgically Reprocessed Uranium Conversion and Disposition
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