The World of Mineral Deposits

Abstract

Nuclear fuel relates to materials that are capable of releasing energy by the fission process, which is at the heart of a nuclear reactor. It is arguably the most important element in nuclear power. The safe and economic behavior of the fuel is a key factor in the continuing long-term development of nuclear power. Modern nuclear fuel is the result of large-scale investment in research, experimental testing, and operational experience. Natural uranium and thorium are the basic raw materials for nuclear fuels. Natural uranium contains two main isotopes: ∼99.3%238U, which is a fertile isotope, and ∼0.7%235U, which is the only "fissile" isotope in nature. Nuclear fuels can be broadly classified as the following: metals, alloys, and intermetallics; ceramics; carbides and oxycarbides, nitrides, cermets, TRIGA fuel; U-Zr hydrides and TRISO particles. Fuel is the consumable part of a reactor and therefore, from the economic point of view, it is important to decrease fuel consumption. The strategy, hence, should be to renew the fuel as little as possible by allowing it to remain longer in the reactor. New and advanced fuels for Generation IV reactors, exposed to extreme conditions, need to be designed with a high burn-up capacity, high density, high melting temperature, high thermal conductivity and modest linear expansion coefficients. They should not interact with cladding in a detrimental manner, should be safe, have proliferation-resistant manufacturing, and minimal radioactive waste burden. The fuels that have been developed for power reactors include metals, alloys and intermetallics, oxides, carbides, nitrides, and hydrides. © 2012 Elsevier Inc. All rights reserved.