NEA Mandates and Structures

Working Party on Nuclear Criticality Safety (WPNCS)

Mandate (Document reference):

• Summary record of the 7th Meeting of the Nuclear Science Committee held on 29-30 June 1996 [NEA/SEN/NSC(96)3]
• Summary record of the 15th meeting of the Nuclear Science Committee held on 9-11 June 2004 [NEA/SEN/NSC(2004)3]
• Summary record of the 18th meeting of the Nuclear Science Committee held on 13-15 June 2007 [NEA/SEN/NSC(2007)3]
• Summary record of the 21th meeting of the Nuclear Science Committee on 9-11 June 2010 [NEA/SEN/NSC(2010)3]
• Summary record of the 24th meeting of the Nuclear Science Committee held on 12-14 June 2013 [NEA/SEN/NSC(2013)2]
• Summary record of the 27th meeting of the Nuclear Science Committee held on 22-24 June 2016 [NEA/SEN/NSC(2016)2]
• Mandate of the Working Party on Nuclear Criticality Safety (WPNCS) [NEA/SEN/NSC/WPNCS(2020)1]
• Summary record of the 31st meeting of the Nuclear Science Committee held on 23-25 September 2020 [NEA/SEN/NSC(2020)20]
• Summary record of the 29th meeting of the WPNCS on 30 June 2023 [NEA/NSC/WPNCS/M(2024)4 forthcoming]
• Mandate of the Working Party on Nuclear Criticality Safety (WPNCS) [NEA/SEN/NSC/WPNCS(2024)1]

Mandate (Document extract):

Extract from document [NEA/SEN/NSC/WPNCS(2024)1]

Scope

Under the guidance of the Nuclear Science Committee (NSC), the WPNCS will deal with technical and scientific issues relevant to criticality safety. Specific areas of interest include, but are not limited to, investigations concerning static and transient configurations encountered in the nuclear fuel cycle, such as fuel fabrication, transport, separation processing and storage. Areas of activities include:

• evaluation of available experimental data, including critical integral experiments, spent nuclear fuel assay data and decay heat of spent nuclear fuel;
• assessment of experimental needs;
• code and data inter-comparison, co-ordination of international benchmark exercises;
• development of codes and models, assessment of uncertainties;
• development of criticality methodologies and data (including the application of burn-up credit);
• study of uncertainty propagation and quantification analyses for criticality safety assessments;
• study of advanced Monte Carlo techniques (including transfer of best practices to practitioners);
• study of criticality of used nuclear fuel (including investigations on degraded fuel, degraded poisons);
• study of criticality excursions and criticality accident analyses methodologies;
• best estimate simulation and uncertainty quantification of spent nuclear fuel decay heat for reactor accident scenarios (in co-operation with the Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS)) and for repository or disposal safety assessments.

Objectives

The objectives of the WPNCS are to:

• exchange information on national programmes in the area of criticality safety;
• guide, promote and co-ordinate high priority activities of common interest to the international criticality safety community, establish co-operations;
• develop databases and tools, publish handbooks and reports;
• facilitate communications within the international criticality safety community through relevant websites;
• co-ordinate WPNCS activities with activities of other working parties within the NEA and in other international frameworks to avoid duplication;
• provide a technical basis for other international activities, e.g. with the International Organisation for Standardisation (ISO), IAEA, and others;
• co-ordinate the series of International Conferences on Nuclear Criticality Safety (ICNC), held every four years;
• monitor the progress of all activities mentioned above and report to the NSC.

Working methods

The WPNCS will report to the NSC. The WPNCS will meet twice per year (normally one primary, in-person meeting in June-July and one interim, remote meeting in December-January). Additional ad-hoc meetings in support of particular sub-group activities may be organised as needed.

Interactions

The WPNCS will liaise closely with other relevant NSC bodies, in particular with the Working Party on International Nuclear Data Evaluation Co-operation (WPEC) and the Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS. The WPNCS will also co-ordinate as appropriate with the Committee on the Safety of Nuclear Installations (CSNI), in particular with the Working Group of Fuel Cycle Safety (WGFCS) and with the Radioactive Waste Management Committee (RWMC). The objective will be to ensure that the respective programmes are complementary and to provide advice and support where required and undertake common work where appropriate.

The WPNCS will work with its technical review groups to produce the integral experiments’ handbooks, databases and tools, contained in the mandates of its technical review groups.

Deliverables

The deliverables of the WPNCS are technical reports, proceedings of seminars or workshops, state-of-the-art reports, and technical or collective opinion papers, databases, and comparison or benchmark studies. The group will also organise specialist meetings and workshops to further its objectives. The detailed list of deliverables will be tracked in the semi-annual NSC progress reports.