Nuclear Energy Agency Online Bulletin

July 2000

Radioactive Waste Management Information

The NEA/EC "Gas Generation Workshop" (1) was hosted in Reims, France, by ANDRA and the University of Reims on 26-28 June. Close to 50 specialists from research centres, universities and national waste management organisations attended.

In underground repositories for radioactive waste, significant quantities of gases may be generated as a result of several processes, notably the interaction of groundwaters and brines with waste and engineered materials present in the disposal system. In some cases, the gases may migrate through the engineered barrier system and the natural geological barrier. The potential impact of gas generation, accumulation, and migration on the performances of the various barriers and, ultimately, on the long-term safety of a repository should therefore be addressed and assessed in the development of safety cases for radioactive waste underground repositories.

A review of the current status of the basic understanding of the topics concerned was published by the EC in 1999. This status report (2), prepared under the joint auspices of the European Commission (EC) and the OECD Nuclear Energy Agency (NEA), provides a review of:

On the above basis, the Gas Generation Workshop focused on the complementary question: "What is still needed for an adequate consideration of the gas issue in safety cases?" Participants heard presentations of planned national strategies for dealing with gas-related issues, and devoted a large amount of time to in-depth discussions by working groups with the objective of providing concrete recommendations on how to address the following gas-related, safety-relevant issues in the future:

The proceedings, to be published by the OECD/NEA, will consist of a synthesis of the workshop outcomes, the series of reports from the working groups and a compilation of extended abstracts. The synthesis will not be aimed at providing a summary of the gas topic, which is the subject of the above-referenced EC/NEA status report.

An ancillary technical visit to the Bure site was organised by ANDRA following the workshop.


1. "Gas Generation, Accumulation and Migration in Underground Repository Systems for Radioactive Waste: Safety-relevant Issues", Reims, France, 26-28 June 2000; a workshop organised by the OECD Nuclear Energy Agency and the European Commission and hosted by the French National Radioactive Waste Management Agency (ANDRA) with the support of the University of Reims Champagne-Ardenne.

2. W.R. Rodwell, A.W. Harris, S.T. Horseman, P. Lalieux, W. Müller, L. Ortiz Amaya and K. Pruess (1999), Gas Migration and Two-phase Flow through Engineered and Geological Barriers for a Deep Repository for Radioactive Waste; a joint EC/NEA status report published by the EC as European Commission Report EUR 19122 EN.