Nuclear Energy Agency Online Bulletin

October 2002

Nuclear science news

Working Party on Nuclear Criticality Safety

The Working Party on Nuclear Criticality Safety and some of the associated expert groups held their annual meeting at NEA headquarters on 9-12 September 2002.

The Expert Group on Burn-Up Credit reviewed the progress of the ongoing benchmarks. Phases IV-A and IV-B on MOX burn-up credit issues are nearing completion. The analysis of Phase II-C, dealing with the sensitivity of criticality prediction to the assymetry of the axial burn-up profile, is ongoing.

SFCOMPO, a database developed by the Japan Atomic Industry Research Institute (JAERI) for the composition of commercial spent fuel composition, has been transfered to the NEA Data Bank for open online access and further development. This database can be accessed at: Participants who wish to submit new data for inclusion in the database are encouraged to contact

The Expert Group on Experimental Needs discussed the procedure for the expression of experimental needs in criticality safety. An online form has been set up to allow criticality analysts, regulators and code benchmarkers to express the needs emerging from the study of present or projected criticality configurations. These needs will be collected and discussed, and appropriate actions (including possible international experimental co-operation) proposed to address commonly identified requirements.

The Expert Group on Criticality Excursion Analysis is currently preparing inter-code comparison benchmarks based on experiments performed at Valduc (CRAC, SILENE) and JAERI (TRACY). Also under development are a web-based information resource on experimental programmes, criticality accidents and available simulation models, as well as pilot evaluations of critical excursion experiments.

The Expert Group on Minimum Critical Values is preparing a report that compiles and compares criticality data for water-moderated and reflected homogeneous UO2, UNH, Pu02 and PuNH systems.

The Expert Group on Source Convergence Analyses will hold its third meeting in Washington DC on 22 November 2002. More information, including the meeting's registration form, is available at:

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