The fuel for a nuclear reactor is both the source of the fission energy that is used to produce electricity and the source of radioactive material during an accident. Ensuring fuel integrity is one of the primary goals of nuclear safety.
Since the inception of nuclear power, there has been substantial experience with the operation of water-cooled reactors – the most prevalent reactor design used for producing energy. This experience has led to the optimisation of the fuel design and reactor operating conditions for energy production while ensuring an adequate margin for safety. Co-operation on research into the criteria for the safe operation of fuel has been conducted under the Committee on the Safety of Nuclear Installations (CSNI) for several decades. First, in conjunction with more general activities on accident analysis, and since the early 2000s, under a separate Working Group on Fuel Safety (WGFS). There are two main types of threat to fuel integrity considered by WGFS. First, there are conditions in which the coolant flow is not sufficient to maintain a safe temperature for the fuel and integrity is lost due to overheating. Second, the control of the nuclear fission reaction may be compromised leading to high rates of energy production in the fuel and loss of integrity.
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