When the plant in La Hague was commissioned in 1976, its annual output amounted to a few tonnes of processed spent fuel. Production rose to a peak in 1997, and totalled 1,100 tonnes in 2004, giving an indicator of the progress accomplished. Fuel production for overseas customers declined in subsequent years. Germany finished reprocessing its waste in 2010. Japan also stopped sending its spent fuel to La Hague, having built its own plant in Rokashomura.
PUREX is a proven process that has benefitted from numerous technical improvements over the years. The uranium and plutonium recovery rate approaches 99.9%, due to the selectivity of the solvent used for the extraction process (tributyl phosphate). Uranium and plutonium recovery performance is excellent.
Processing spent MOX fuels, reputed to be difficult due to their higher radioactivity, became a reality in 2004. It is in principle possible to recycle plutonium a second time in MOX fuel, then in the reactor. This possibility is not envisaged for current PWR reactors, but may be for EPR reactors.
Reduced waste volumes and environmental releases
A major benefit is the reduction in waste volumes, despite an increase in the volume of spent fuel processed. Compacting solid waste (in particular, fuel-containing cladding fragments) considerably reduces the volume of intermediate-level (ILW-LL) waste. As this category of waste releases little heat, the reduction in volume will facilitate disposal.
Reprocessing plants release small quantities of gaseous or liquid radioactive waste (in particular tritium) into seawater around La Hague. No solid releases are permitted. Gaseous and liquid releases must comply with statutory limits. Releases are monitored by independent European agencies. Despite increasing plant output, the quantities of such environmental releases (other than tritium) have fallen spectacularly as a result of the measures adopted. In 2004, releases were at around 1% of the authorised amounts.
In application of laws passed in 1991 and 2006, research is conducted with the aim of decreasing the remaining residual releases:
- Technetium: This long-lived fission product limits performance of the uranium and plutonium extraction and separation process, as technetium tends to take the same route as uranium. The research conducted holds out the prospect of industrial solutions that would enable 99% of technetium to be recovered, compared with the current level of 90%.
- Iode-129: This very long-lived fission product (which has a radioactive half-life of 15 million years) is released during the shearing and dissolution operation. Not all of it is trapped, allowing a fraction to enter the environment. Iodine-129 is only slightly radioactive. Specific gas stripping and trapping would enable 99% of iodine to be recovered, compared with the current level of 90%.
- Tritium: The radiotoxicity of tritium is particularly low (2,600 times less than iodine-129) but no practical solutions for trapping it have been identified. Note that tritium is also produced naturally by cosmic radiation.
A proven, smooth-running industrial process like PUREX is difficult to change. The production of high-level waste in the form of glass package cannot be called into question. There are no short-term plans to implement the results of current research into more comprehensive separation of the radioelements present in this waste, such as minor actinides.
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