4.5 Risks from the reprocessing of spent nuclear fuel

be constantly monitored, continually cooled to remove decay heat, and chemically adjusted to ensure correct alkalinity levels. If cooling were to fail for any reason, the pools would fully evaporate within a few days and the fuel assemblies could ignite as their zirconium cladding would react strongly with oxygen in air.118 The same would occur if the pond waters were emptied for any reason, such as a breach of the walls of the pools caused by a terrorist attack. These problems grow worse over time by the fact that the lengths of time spent fuel stays in pools has been increasing and now routinely extend for several decades.

The continued practise of storing spent nuclear fuel for long periods in pools at most nuclear power plants worldwide constitutes a major risk to the public and to the environment. Spent nuclear fuel contains most of the radioactivity in the world’s nuclear waste, and consists of fission and activation products.

In 2014, the US Nuclear Regulatory Commission (NRC) examined whether to require most spent fuel currently held in pools at nuclear power plants to be moved into dry casks and storage vaults. Such a move would reduce the likelihood and consequences of a spent fuel pool fire. It concluded that the projected benefits did not justify the estimated US$4 billion cost of a wholesale transfer.119

However, the NRC report was criticized for seriously underestimating the risk and consequences of a spent fuel fire: models of a potential accident at US nuclear fuel storage sites estimated very serious effects of hypothetical radionuclide releases.120 They contained maps illustrating the radioactive plumes across large areas of northeastern United States. The lead author, Professor Frank von Hippel, Princeton University, warned of drastic economic consequences: “We’re talking about trillion-dollar consequences.” 121 This risk not just affects the US but most countries that operate nuclear power plants, where increasing amounts of spent fuel are being left in cooling pools for increasingly long periods of time.

The absence of robust proven technical solutions and the existence of political opposition to plans for nuclear waste facilities make this difficult situation even more problematic. The present situation poses considerable challenges for current governments and future generations.

In the meantime, it is widely accepted that spent nuclear fuel requires well-designed storage for long periods to minimize the risks of releases of the contained radioactivity to the environment. Safeguards are also required to ensure that neither plutonium nor highly enriched uranium is diverted to weapons use.

4.5 RISKS FROM THE REPROCESSING OF SPENT NUCLEAR FUEL

Two main means exist for managing spent nuclear fuel: long-term storage with the ultimate aim of direct disposal and reprocessing. This section discusses the latter method. In the 1950s and 1960s, during the Cold War, countries constructed reprocessing plants in order to create weapons with plutonium separated from spent fuel.

118 von Hippel, F.N. and Schoeppner, M. 2016, Reducing the danger from fires in spent fuel pools, Science & Global Security, 24(3), pp. 141-173. 119 Barto, A. 2014, Consequence study of a beyond-design-basis earthquake affecting the spent fuel pool for a US Mark I boiling water reactor, United States Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. 120 von Hippel, F.N. and Schoeppner, M. 2017, Economic Losses from a Fire in a Dense-Packed US Spent Fuel Pool, Science & Global Security, 25(2), pp.80-92. 121 Stone, R. 2016, “Spent fuel fire on US soil could dwarf impact of Fukushima”, Science, May 24, viewed 25 May 2019, https://www.sciencemag.org/news/2016/05/spent-fuel-fire-us-soil-could-dwarf-impact-fukushima

Reprocessing involves the dissolution of spent fuel in boiling concentrated nitric acid followed by the physico-chemical separation of plutonium and uranium from the dissolved fuel. This difficult, complex, expensive and dangerous process results in numerous nuclear waste streams, very large releases of nuclide waste to air and sea, and large radiation exposures to workers and to the public.

Only about 15 percent of the world’s spent nuclear fuel is reprocessed. Most countries have abandoned the reprocessing option and currently only France and Russia practice plutonium separation on a commercial scale. These countries that have historically carried out the work for a range of other countries now mainly process their own fuel. Reprocessing creates large quantities of highly active liquid (HAL) waste, which are heat-producing and extremely radioactive. As described below, liquid waste presents severe problems for current waste management. Originally, liquid waste was to be glassified and stored in a more manageable solid form called vitrified waste. However, such processes, though implemented rather successfully in France, have proved difficult in the UK and the US, and much of this waste may remain in liquid form for the immediate future. In addition to HAL waste, reprocessing also results in the following waste streams:

• Emissions of radionuclides in the air

• Discharge of radionuclides into the sea

• Large stockpiles of separated plutonium

• Tens of thousands of drums with separated reprocessed uranium

• Thousands of steel canisters containing vitrified waste

• Radioactive graphite from AGR fuel sleeves and decommissioned reactors

• Concrete silos filled with fuel claddings stripped from spent fuel, and

• Many other radioactive waste, including sludges, resins, and filters.

The collective doses to the world’s population from the long-lived gaseous nuclides C-14, and I-129, and from medium-lived Kr-85 and H-3 (tritium) emitted at Sellafield and La Hague are very large, much higher than for nuclear power plants. While any discharge of alpha emitters is prohibited at reactor sites, it is authorized at La Hague within the limits of 0.01 GBq in gaseous and 140 GBq in liquid effluents.122

The global collective dose, truncated at 100,000 years, resulting from the discharges of the La Hague reprocessing facility alone has been calculated to be 3,600 person sieverts per year.123 Continuing discharges at similar levels for the years of La Hague’s operational life until 2025 would cause over 3,000 additional cancer deaths globally, if the linear no-threshold theory of radiation is applied.

122 Schneider, M., and Marignac, Y. 2008, “Reprocessing of Spent Nuclear Fuel in France”,

International Panel on Fissile Materials, Research Report #4, viewed 24 May 2018, http://fissilematerials.org/publications/2008/05/spent_nuclear_fuel_reprocessin.html 123 Smith, R., Bexon, A., Sihra, K., Simmonds, J.2007, “The calculation, presentation and use of collective doses for routine discharges,” In Proceedings of IRPA12: 12. Congress of the International Radiation Protection

Association: Strengthening Radiation Protection Worldwide-Highlights, Global Perspective and Future Trends.