Criticality is the state of a nuclear reactor when there is a self-sustaining chain reaction of fissionable material. Criticality experiments are controlled tests using fissile materials, like plutonium or enriched uranium, brought to the critical point for analysis and benchmarking. These experiments allow criticality safety analysts to use the data to validate calculation tools and cross-section libraries.
The primary purpose of the International Criticality Safety Benchmark Evaluation Project (ICSBEP) is to compile critical and subcritical benchmark experiment data into a standardised format that allows criticality safety analysts to easily use the data to validate calculation tools and cross-section libraries.
The Working Party on Nuclear Criticality Safety (WPNCS) deals with technical and scientific issues relevant to criticality safety. Specific areas of interest include (but are not limited to) investigations of static and transient configurations encountered in the nuclear fuel cycle. These include fuel fabrication, transport and storage.