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Criticality Resources

The Working Party on Criticality, as a sub-group of the Safety Directors’ Forum, works to produce guidance for practitioners working in criticality safety in the UK, along with engaging international bodies on the development of standards, such as the International Organisation for Standardisation.

This page collates resources produced by the WPC and others for the benefit of criticality safety practitioners. 

WPC Publications

Good Practice Guides (GPGs), Position Papers and Sub-Group Reports

WPC Webinar Series

Webinars by the WPC and invited guests on topics in criticality safety

Neutron Cross Sections for Fission for the Fissile Isotopes U-235, Pu-239 and Pu-241
Plot of neutron cross-sections of fission reactions for Uranium-235, Plutonium-239 and Plutonium-241. Generated using JANIS Web (11/03/2026). Link to JANIS Web embedded in image.

Handbook Curves

Handbook curves can be useful tools for criticality assessors and provide an indication of the criticality of a system and its safety. Compiled handbook curve data exists in the following:

While historic handbook curves can provide an indication of the safety of a fissile system, they should not be relied upon for the demonstration of safety.

1 These handbooks are not in English.

Plot of Plutonium concentration (g/cm3) for a Plutonium-H2O mixture against critical cylinder diameter (in.) for various Plutonium-240 w/o values illustrative of a handbook curve. Credit: ARH-600, Volume II (accessed 12/03/2026). Link available to left.

Learning from Experience Database

The WPC encourages licensees, operators and practitioners to share criticality-related accidents with the wider industry. With this in mind, the WPC have collaborated with the US-DOE to provide an open-source and anonymous database to facilitate knowledge sharing across industry and the criticality safety field.

Credit: EnergyEncyclopedia.com
Credit: EnergyEncyclopedia.com (accessed 11/03/2026). Link embedded in image.

Educational Resources

List of collated educational resources for criticality safety

Standards and Regulations

List of relevant organisations and regulators and their good practice and standards.