Working Party on Criticality (WPC)

Who We Are

The Working Party on Criticality (WPC) is a non-executive UK national committee focussing on criticality safety issues up to, but not including, experimental and in-core power reactor operations. WPC is a formal sub-group of the Safety Directors Forum. The issues considered are relevant to fabrication, transportation, storage and other operations relating to nuclear materials (e.g. new build, enrichment, reprocessing, decommissioning and long-term waste management).

• WPC Scope and Objectives

• WPC Members

  • WPC members comprise Nuclear Site Licensees and other organisations with an interest in criticality safety.

• WPC Sub-groups

  • WPC has a number of sub-groups to cover specific topic areas. Participation in sub-groups is not restricted to WPC members. Contact mail@criticality.org.uk for details. Current groups include:

    • Criticality Assessment of Fissile Wastes

    • Nuclear Codes and Data

    • Fault Analysis techniques

    • Learning from Experience

    • Criticality Emergency Planning

    • Transport Criticality assessment

    • ISO criticality standards development

    • Criticality Handbooks

    • Early Careers

    • UK Criticality Resources

• Continuing Professional Development

  • WPC run an annual workshop to provide opportunities for less experienced practitioners to gain experience on a wide range of technical issues. The workshops also provide an opportunity to improve communication between less experienced members of the criticality community. Participation in workshops is open to all with an interest in criticality safety, not just WPC members.

  • Since March 2021 WPC has been hosting webinars. These are run as hour long sessions, which enables a main speaker to cover a specific topic of interest and allows time for questions and further discussion. To date, we have had presenters from a variety of UK licensed sites and consultancies, the UK regulating body and a number of international presenters. Typically, there are 50-100 attendees for each webinar from both UK and abroad. Topics covered include Learning From Experience (LFE) for criticality inspections, criticality safety of deep geological disposal and application of criticality ‘hand methods’. 

• WPC Papers Since the 1970s over 290 WPC papers have produced. These cover a range of topics from:

  • • Meeting reports

    • Formal WPC position papers

      • WPC/P243 (Issue 2) The WPC Criticality Competence Framework (note: due for review/ revision in 2022)

      • WPC/P267 WPC Position on the Double Contingency Principle  (Issue 2)

    • Sub-group reports

      • WPC/P293 The Use of Criticality Handbooks and Electronic Visualisation Tools

    • Technical papers contributed by members to document their activities for future reference.

      • WPC/P287 Some Observations on the History of Criticality Safety Margins 

    • Good Practice Guides. Contact mail@criticality.org.uk for details.

• • • • WPC/P284 Good Practices in the use of Criticality Codes

      • WPC/P288 Minimum Subcritical Margins

      • WPC/P289 Issue 2 Good Practice Guide to Criticality Detection at UK Nuclear Licenced Sites (2023)

      • WPC P292 Criticality Safety - Organisational Health