Long Term Sustainability of Nuclear Fuel Resources

Abstract

The basic issue in considering the contribution of nuclear power to solving the world’s energy problem in the future is the availability of uranium resources and its adequacy in meeting the future needs of nuclear capacity. Increased interest in nuclear energy is evident, and a new look into nuclear fuel resources is relevant. In this chapter we address the issue of nuclear fuel resources long term sustainability in relation to the expected growth of the world nuclear power. Three main aspects have to be analyzed in order to estimate how long the world’s nuclear fuel supplies will last: nuclear fuel resources (uranium and thorium), technologies for nuclear fuel utilization, and energy requirements growth scenarios including different scenarios for nuclear share growth. Uranium nuclear fuel resources are analyzed based on joint OECD Nuclear Energy Agency (NEA) and the International Atomic Energy Agency categorization which classifies resources into conventional resources and unconventional resources. Conventional resources are further divided into identified resources (reasonably assured and inferred) with four cost ranges and undiscovered resources (prognosticated and speculative) with three cost ranges. Analyzed unconventional resources include phosphate deposits and seawater. Total resources are estimated to about 6.3 million tons of uranium in identified resources and 10.4 million tons of uranium in undiscovered resources. The amount of uranium contained in phosphate deposits and seawater is estimated to 22 million tons and 4 billion tons, respectively. Thorium nuclear fuel resources are analyzed based on slightly different categorization than uranium one. Four categories are used: reasonably assured resources, estimated additional resources of type I and II, and prognosticated resources. Total thorium resources according to the latest OECD-NEA report are estimated to about 6 million tons. Detailed analysis of potential technologies for improved nuclear fuel utilization is required in order to assess long term sustainability of nuclear fuel resources. Nowadays, thermal converter reactor technology with once-through nuclear fuel cycle is used. The effectiveness of the technology can be improved in the area of enrichment process as well as by introducing reprocessing of the spent fuel on larger scale. Other technologies are also on the development stage that allows their implementation in short or medium period of time. These include: thermal and fast breeder reactors of different kind, thorium based fuel cycle, and conversion of uranium or thorium by particle accelerators or fusion devices. Very important aspect of long term sustainability of nuclear fuel resources are scenarios for energy requirements growth, and scenarios for growth of nuclear share in electricity production resulting in overall nuclear capacity growth. On one hand, low growth scenario has a moderate continuous growth strategy of 1.3% per year. On the other hand, high growth scenarios are required if nuclear energy is to give an essential contribution to carbon emission control. Finally, there is a scenario based on a compromise between low and high growth assumptions. These scenarios have been used to estimate exhaustion time periods of nuclear fuel resources for different fuel utilization technologies. The obtained exhaustion time periods range from 50 years for the once-through thermal converter fuel cycle with high increase in world nuclear capacity to many thousands of years for breeder reactor technology or for other methods of releasing the energy of U238. A development of these methods would require several decades, in return for practically unlimited amount of nuclear energy. Our analysis shows that nuclear fuel resources are not a limiting factor for a long term large scale nuclear power development. Our study is based on the most recent data on nuclear fuel resources, energy growth predictions, and technologies for the nuclear fuel utilization improvement, as well as our own developed code for calculation of nuclear fuel demand for different nuclear energy growth scenarios.