Education and Training in SARNET Network on Severe Accidents

In April 2004, many world-wide organizations involved in R&D on severe accidents decided to network together in SARNET, in the framework of the 6th Framework Programme of the European Commission, linking their capacities of research in the SA area in a consolidated manner in a Network of Excellence. A second phase of the network (SARNET2) has started in April 2009, again supported by EC in FP7, for 4 years and again under the coordination of the French IRSN. The partners contribute to a Joint Programme of Activities including, for “Education and Training”, the following main actions: development of educational courses for students and researchers, and training courses for specialists; promotion of personnel mobility among various European organizations; - organization of large international conferences on SA research

ASTEC and ICARE/CATHARE modelling improvement for VVERs

ASTEC and ICARE/CATHARE computer codes, developed by IRSN (France) (the former with GRS, Germany), are used in RRC KI (Russia) for the analyses of accident transients on VVER-type NPPs. The latest versions of the codes were continuously improved and validated to provide a better understanding of the main processes during hypothetical severe accidents on VVERs. This paper describes modelling improvements for VVERs carried out recently in the ICARE common part of the above codes. These actions concern the important models of fuel rod cladding mechanical behaviour and oxidation in steam at high and very high temperatures. The existing models were improved basing on the experience in the field and latest literature data sources for Zr + 1%Nb material used for manufacture of VVERs fuel rod claddings. Best-fitted correlations for the Zr alloy oxidation through a broad temperature range were established, along with recommendations on model application in clad geometry and starvation conditions. A model for the creep velocity was chosen for the clad mechanical model and some cladding burst criteria were established as a function of temperature. After verification of modelling improvements on Separate Effect Tests, validation was carried out on integral bundle tests such as QUENCH, CODEX-CT, PARAMETER-SF (the application to the CORA-VVER experiments is not described in the present paper) and on the Paks-2 cleaning tank incident. The comparison of updated code results with experimental data demonstrated very good numerical predictions, which increases the level of code applicability to VVER-type materials. © 2010 Elsevier B.V

L’organisation de la recherche sur les accidents graves

Les programmes français de R&D sur les accidents graves sont souvent menés en collaboration entre l’IRSN, le CEA, EDF et AREVA. Mais ce domaine impliquant des ressources humaines et financières très importantes, les collaborations entre les acteurs du nucléaire, industriels, centres de recherche et organismes de sûreté sont également nombreuses à l’échelle internationale, en particulier dans un cadre EURATOM (par exemple avec le réseau d’excellence européen SARNET) ou OCDE. L’efficacité de ces collaborations et la mutualisation des efforts devraient permettre de pallier la réduction des budgets sur les accidents graves sur les réacteurs de Génération II ou III, tout en préparant la sûreté des futurs réacteurs de Génération IV

Les objectifs de la recherche sur les accidents graves

Les accidents graves de réacteurs ou accidents de fusion du coeur sont caractérisés par l’importance des rejets radioactifs qu’ils peuvent générer. En conséquence, un ensemble de mesures de prévention comme de limitation des conséquences ont été prises en France comme à l’étranger d’abord historiquement à l’issue de l’accident de Three Mile Island, puis selon une démarche d’identification des risques associés aux différents phénomènes, plus récemment, enfin, en s’appuyant sur des considérations probabilistes. La recherche et le développement sous-tendent largement cette évolution en fournissant les connaissances, méthodes et outils. Différentes contraintes s’appliquent à la recherche notamment les coûts élevés associés qui justifient une internationalisation et une hiérarchisation

The Severe Accident Phenomenology Short Course (SAP): 12 years of excellence for dissemination of Severe Accident knowledge at international level

The last course Severe Accident Phenomenology (SAP) has been held at Stockholm (KTH) in 2015 (July 6th-10th) in the frame of the NUGENIA Technical Area N°2/SARNET on “Severe accidents”. This 1-week course was jointly organized by KTH, CEA, IRSN and University of Pisa and has been hosted by KTH at Stockholm. This is the 6th course since the start of SARNET in 2004. This course was a success showing that the European Network of Excellence SARNET was really the leader for the dissemination of Severe Accident knowledge at international level: 74 participants from Europe, Asia and South-America have been present. The objective of this course is to train Master-PhD students, young engineers and researchers recently involved in severe accidents in nuclear power plants (NPP). The SAP has evolved from the first course in 2006 till 2015: different important topics for SA phenomenology, progression and mitigation in current water-cooled Gen.II and III NPP, but also the different design solutions in Gen.III have been taught. For the two last sessions (2013 and 2015) new lectures have been given on Fukushima-Daiichi severe accidents and current situation. The next course will be held in 2018 in Madrid with the support of CIEMAT and Madrid University. A special focus will be developed on recent knowledge gained on Fukushima-aiichi severe accidents