Above: The availability of disposal routes for low level waste (LLW) and very low level waste (VLLW) will become more and more important as nuclear plants are decommissioned


after decontamination, in an overall optimisation approach. This is reinforced by the fact that disposal facilities for radioactive waste or spent fuel are rare assets, and of high cost, and have to be used as efficiently as possible.


Assessing waste levels The report finds that there is an estimated 301,000 tonnes of heavy metal (tHM) of spent fuel in storage worldwide, while about 7000 tHM is discharged annually. About 70% of spent fuel is currently stored in pools, but most new facilities are dry storage. The current total global inventory of solid radioactive waste is approximately 32 million m3 26.6 million m3


, of which (83% of the total) has been disposed of permanently and a further 5.6 million m3 (17%) is in storage


awaiting final disposal. More than 92% of the volume of solid waste is classified as being LLW or VLLW. Around 95% of the radioactivity is associated with intermediate and high level waste. The report says significant progress has been made in


formulating national policies and in legal and regulatory systems to manage Intermediate Level Waste (ILW) and LLW. The most important remaining challenge is development, public acceptance and funding of facilities for high level waste and spent fuel. For countries with small inventories, the development of


disposal facilities can be a challenge and there has been discussion about sharing efforts. But most nuclear states expect to dispose of their waste in facilities located on their territories. Where there is co-operation it involves technology development, rather than sharing of facilities, and significant progress has been made in the last two decades in treating, conditioning and storing waste. Three deep geological repositories should start operation in the next 10 years in Europe but spent fuel, high level waste (HLW) and most ILW remain in safe storage, rather than final disposal. Disposal routes are also needed for waste generated by nuclear accidents.


Segregate or not? The report explores whether it is more efficient to segregate classes of waste and send them to different repositories than allow for mixed or co-disposal. If the former route is taken, more work goes into segregating the waste. Sometimes, such as in France, the economic trade-off


between direct disposal of the waste and waste treatment to reduce disposal volumes or to enable recycling can be difficult. In contrast, countries such as the UK have reduced costs by using routes such as licensed industrial landfill, where appropriate, using such concepts such as ‘below regulatory concern’ for waste that arises within a nuclear industry context but that has no radiological implications for the public. This is important, in particular, for managing


decommissioning waste, where large volumes of low or very low level waste will be generated. There is a broad consensus that the preferred method of ensuring long-term safety for spent fuel and HLW is isolation in a deep geological repository. A small number of countries are considering co-location


of different waste classifications in geological facilities. This co-disposal can be simpler with fewer facilities required. But it can also introduce design complexity to avoid interferences between the waste types, as well as significant increases in the volume of material requiring handling at geological depths. The report says that a set of evaluation tools will be


required to support an integrated supply chain covering all aspects of waste production and management. Nuclear fuel cycle strategies need to be fully integrated with the overall spent fuel and radioactive waste management policy and infrastructure to ensure an optimal use of resources. Introducing efficiencies into individual steps in isolation can create additional challenges in subsequent steps.


Decommissioning issues and other trends The amount of spent fuel in long-term storage is increasing. The report says that the number of nuclear states that send their spent fuel for reprocessing overseas is falling, as reprocessing plants are closed or are nearing the end of their lifetime. In any case, after several decades in operation, the


existing pool of nuclear reactors has generated a significant inventory of spent fuel, which increases yearly; accordingly, temporary storage is a need that goes beyond the choice of whether or not to reprocess fuel. Over recent years, many countries have had to extend their temporary storage capacity to accommodate these inventories by means of the extension of existing facilities or the construction of supplementary facilities.


www.neimagazine.com | November 2024 | 17


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