Abstract. This paper discusses concepts for three-component fuel bundles containing plutonium, uranium and thorium for use in pressurised heavy water reactors, and cases for and against implementation of such a nuclear energy system in the United Kingdom. Heavy water reactors are used extensively in Canada, and are deploying within India and China, whilst the UK is considering the use of heavy water reactors to manage its plutonium inventory of 140 tonnes. The UK heavy water reactor proposal uses a mixed oxide (MOX) fuel of plutonium in depleted uranium, within the enhanced CANDU-6 (EC-6) reactor. This work proposes an alternative heterogeneous fuel concept based on the same reactor and CANFLEX fuel bundle, with eight large-diameter fuel elements loaded with natural thorium oxide and 35 small-diameter fuel elements loaded with a MOX of plutonium and reprocessed uranium stocks from UK MAGNOX and AGR reactors. Indicative neutronic calculations suggest that such a fuel would be neutronically feasible. A similar MOX may alternatively be fabricated from reprocessed <5% enriched light water reactor fuel, such as the fuel of the AREVA EPR reactor, to consume newly produced plutonium from reprocessing, similar to the DUPIC (direct use of PWR fuel in CANDU) process.

Today’s operating nuclear power plant fleet is primarily composed of ageing Generation II reactors, these predominantly being in Organisation for Economic Co-operation and Development (OECD) countries. However, significant new build activity over the past two decades, primarily in Asia and in non-OECD countries more widely, is adding new Generation III and III+ reactors to a more globally distributed fleet. Previous construction, maintenance, and operational experience is now informing the development of the next generation of reactors, which are expected to be smaller and make use of novel technologies. To be operable in a free-market energy system, these novel nuclear power plants must be economically competitive with both large established nuclear power technologies and low-carbon energy generating options. Security accounts for a significant proportion of today’s nuclear power operating costs, including capital expenditures for expensive retrofits into existing plants. Consequently, to remain competitive, new approaches are needed to build security into the fabric of the plant during the design phase. The chapter introduces the evolutionary and innovative reactor designs (EID) under development. Detailed consideration of the many individual technologies is not feasible here; instead the chapter discusses some of the common elements relevant to many technologies, which can provide insights for the majority of EIDs, and considers the key areas that lead to changes in the security features of EIDs. It focuses on security-by-design approaches in the development of the next generation of nuclear reactors and addresses some safeguards-by-design elements where these link to security. It also covers the underlying frameworks of nuclear security and its suitability for EIDs.

This documentassessesand comparesthe environmentalimpactsof variousal-Ib ternativesfor remedial action at the Gunnisonura_i,;m mill tailingssite located O.S miles south of Gunnison, Colorado. The site covers 56 acres and contains 35 acres of tailings, 2 of the original mill buildings[tj and a water tower.

The Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), Public Law 95-604, authorized the U.S. Department of Energy (DOE) to clean up the Belfield and Bowman, North Dakota, uraniferous lignite processing sites to l reduce the potential health impacts associated with the residual radioactive materials remaining at these sites. Remedial action at these sites must be performed in accordance with the U.S. Environmental Protection Agency's (EPA) standards promulgated for the remedial action (40 CFR 192) and with the I concurrence of the U.S. Nuclear Regulatory Commission (NRC) and the state of North Dakota. l The inactive Belfield uraniferous lignite processing site is one mile southeast of Belfield, North Dakota. The inactive Bowman uraniferous lignite processing site at the former town of Griffin, is seven miles northwest of l Bowman, North Dakota and 65 road miles south of Belfield. Lignite ash from the processing operations has contaminated the soils over the entire ]O.7-acre designated Belfield site and the entire ]2.]-acre designated Bowman site. Dispersionof the ash has contaminatedan additional20.6 acres surroundingthe Idrl I " rl 'I_ " "' 'lP li TM

Nuclear fuel is not a renewable resource, and reserves of uranium and other fuel materials must be carefully stewarded to ensure the long‐term operability of nuclear energy systems. This article discusses the geological and geographical distribution of uranium resources globally, including unconventional sources such as uranium dissolved in seawater and surplus military nuclear materials. The growth of production capacity, supply, and demand relationships are presented under different scenarios. Secondary sources of uranium fuel, as well as nuclear fuel cycle options that can increase the quantity of nuclear fuel producible from a given starting quantity of natural uranium, such as the use of mixed‐oxide fuels and underfeeding of enrichment plants, are introduced. The article also includes a discussion of breeder reactors, which can be fueled with a much broader range of nuclear fuel types than currently used reactor technologies, greatly increasing the proportion of natural uranium which can be used within nuclear power reactors. Finally, thorium is introduced as an alternative nuclear fuel to uranium, which is more abundant than uranium but brings unique technical challenges. At the start of 2017, globally there were estimated to be approximately 6,142,000 tonnes of identified uranium resources recoverable at a cost of less than $130 per kg of uranium. This should be sufficient to meet the needs of a projected nuclear reactor fleet for several decades, even under high growth scenarios for nuclear energy. As such, there is currently little commercial drive toward the use of alternative nuclear fuel types.