Presentation of SARNET2

1. Presentation of SARNET2 T. Albiol (IRSN), J.P. Van Dorsselaere (IRSN), W. Tromm (FZK), C. Journeau (CEA), I. Kljenak (JSI), T. Haste (PSI), B.R. Sehgal (KTH), D. Beraha (GRS) ERMSAR 2008 Nesseber, Bulgaria, September 23-25, 2008

2. SARNET2 General Objectives: integration, diffusion of knowledge, sustainability • To tackle the fragmentation existing in defining/carrying out research programmes between different countries; • To diffuse the knowledge to the stakeholders, especially in the new EU member states, more efficiently, and associate them to the definition and the conduct of the research programmes more closely; • To bring together top scientists in severe accident research so as to be the world leader in advanced computer tools for severe accident risk assessment; • To perform significant progress towards the closure of the remaining high priority issues in the domain of severe accidents (see next slide); • To establish a self-sustaining organization in the field of severe accident research through activities in networking, integration, knowledge management, exchange of information, dissemination of results and training in order to keep the competence in severe accident management alive in Europe and worldwide.

3. SARNET2 Scientific Objectives • Efforts put on the 6 high priority issues as determined in SARNET / SARP WP: • core coolability during reflood and debris cooling • ex-vessel melt pool configuration during MCCI & ex-vessel corium coolability by top flooding • melt relocation into water & ex-vessel FCI • hydrogen mixing and combustion in containment (flame acceleration) • oxidising impact on source term (Ru oxidising conditions or air ingress for HBU and MOX fuel elements) • iodine chemistry in RCS & in containment • Special focus in the SARNET2 JPA on the corium issues (coolability and MCCI), including major experimental activities • Strong cooperation with international programmes such as Phébus FP, ISTP, ISTC, OECD/CSNI GAMA, ...

4. SARNET2 Partners • 41 partners: • 8 universities • 23 research organisations • 5 industry / utilities • 5 TSOs / safety authorities • 21 countries (18 European countries, USA, Canada, Korea)

5. SARNET2 Organisation scheme Steering Committee (Core Group) General Assembly Information Consultation Submission of Programme Proposals Executive line Proposal line Advisory Committee Management Team EC Control line on SARP programme proposals (attribution of SARNET label) Coordinator WP leaders Executive line WP 1 WP N WP 8

6. SARNET2 Organisation in Work-Packages (as of Sept. 03, 2008)

7. SARNET2 Work-Packages (1 and 2 / 8) • WP1: Management (MANAG) • Coordination, administration and budget. Links with the EC and the Core Group. Creation of a legal entity for the long term self-sustainability • Assessment of progress and results • Periodic updates of the research priorities, including definition of needed research programmes and consensus on closure of issues – in link with PSA2 specialists, industry (advisory committee) and international organizations (OECD, ISTC, ...) • WP2: Spreading of Excellence (SE) • Organization of three courses on severe accidents targeted to students and severe accident “specialists” – in link with the ENEN. Organization of one “Information Day” targeted to NPP Managers. • Organization of periodic ERMSAR Conferences • Mobility Programme

8. SARNET2 Work-Packages (3 and 4 / 8) • WP3: Information Systems (IS) • SARNET2 Web site  large improvements expected compared with the current SARNET Web site • Advanced Communication Tool  same general features as the SARNET ACT. Aim at an even more extensive use within SARNET members • Experimental database  stake: long term data storage in a common standard • WP4: ASTEC (ASTEC) • Continue to integrate in ASTEC the knowledge gained • Code assessment through plant applications (various NPPs types and various scenarios) and sensitivity studies • Continue investigations on coupling ASTEC and PSA2 tools • Continue ASTEC adaptation to other types of water-cooled reactors in Europe: BWR, CANDU • Continue maintenance, users’ support (30 SARNET2 partners will use ASTEC)

9. SARNET2 Work-Packages (5 / 8) • WP5: Corium and Debris Coolability (COOL) • Major motivation: reduce or possibly solve remaining uncertainties on the possibility of cooling structures and materials during severe accidents • Either in the core • Or in the reactor pressure vessel lower head • Or in the reactor cavity • Issues to be covered • Within the scope of accident management for existing reactors • Also within the scope of design and safety evaluation for future ones • 3 key situations and processes considered • Reflooding and coolability of a degraded core • Remelting of debris, melt pool formation and coolability • Ex-vessel debris formation and coolability • Plus bringing research results into reactor applications • Conclude on improved validated models and propose models for ASTEC

10. SARNET2 Work-Packages (6 / 8) • WP6: MCCI (MCCI) • Major motivation: Provide new data and understand corium-concrete interaction by using innovative approaches to address more prototypical phenomena • Project designed to ensure complementarity with ongoing OECD/MCCI project • Project planned to study • Effect of concrete nature on 2-D ablation profiles • Role of metallic layer in MCCI • Efficiency of water cooling to terminate the ablation of concrete • Proposed research regrouping experiments both with simulant and prototypic materials in order • to determine which phenomena cause the observed effect of concrete composition on ablation shape • to assess their influence at reactor scale • Data to be acquired on corium - concrete phase diagrams • Transfer the R&D results to reactor scale and propose models for ASTEC

11. SARNET2 Work-Packages (7 / 8) • WP7: Containment (CONT) • Dedicated to 2 highly energetic phenomena that may threaten containment integrity • Steam explosion • Hydrogen combustion • Main uncertainties for ex-vessel steam explosion • Level of void in the pre-mixing phase • Role of material properties on explosion energy • For hydrogen mixing and combustion, study of • Thermal-hydraulics including hydrogen distribution • Different combustion regimes (including DDT and combustion during DCH) • Their impact on containment structures and measures to prevent combustion processes or at least mitigate consequences • Bringing research results into reactor applications • Elaboration of a generic containment model allowing analyses with lumped-parameter or CFD codes and recommendations for ASTEC

12. SARNET2 Work-Packages (8 / 8) • WP8: Source Term (ST) • Aims at reducing uncertainties in calculating potential radioactive release in the environment especially for iodine and ruthenium • Impact of oxidising conditions • FP release from HBU and MOX fuels, competition between cladding and fuel oxidation, impact on FP release, prototypic air/steam mixtures • Ru transport in RCS, behaviour of Ru oxides including reactions with surfaces and other FPs • Ru behaviour in containment, possible conversion of Ru oxides aerosols to volatile species, potential revolatilisation from liquid phase • Iodine • Transport in RCS including chemical kinetics, re vaporisation, compilation of data on iodine spiking, SGTR • Behaviour in containment, role of painted surfaces, radiolytic destruction of gaseous iodine, binding on materials in sump, effect of PARs • Bringing research results into reactor applications: integral plant scenario calculations, benchmarking, data book maintenance (iodine) and development (ruthenium), critical assessment of SAMGs, proposals of models for ASTEC

13. Conclusions • SARNET2 is now in the final negotiation phase with the EC. • Hopefully, the project should start very early in 2009 for a four year duration. • Besides the scientific objectives, the integration and dissemination aspects, one major objective is the long term self-sustainability of the network through the creation of a legal entity. Thank-you for your attention. AcknowledgmentsThe authors wish to thank the European Commission and its representative, Mr Michel Hugon, for supporting this SARNET2 Project in the 7th FP. They also thank all the persons who took part in the elaboration of the SARNET2 Project, too numerous to be quoted, for their strong and efficient involvement.