SARNET – Severe Accident Research Network

University of Manchester School of Mechanical Engineering, G. Begg Building

CFD Workshop on Test-Cases, Databases & BPGfor nuclear power plants applications

16th July 2008

M. Reeks1 and T. Haste2,1

1University of Newcastle-upon-Tyne2PSI Villigen, Switzerland,

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OVERVIEW

SARNET is a Network of Excellence in the Nuclear Fission area of the EU 6th Framework Programme, with the general aim of integrating in a sustainable manner European research on severe accident phenomenology in light water reactors

The network started in April 2004 and will finish in September 2008; a successor project is being negotiated for a further 4 years in the 7th Framework programme

After a brief summary of project organisation and aims, this presentation indicates how CFD methods are used in the project overall, with focus on the Source Term area, that studies the release and transport of radioactive fission products from the reactor core to the environment

INTRODUCTION

T Albiol et al. ‚ SARNET: Severe Accident Research Network of Excellence, ICONE15, Nagoya, Japan, April 2007

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SevereAccidentResearchNETwork of excellence

Currently:– 18 European Countries and Canada– 51 organizations

19 Research organizations 10 Universities 11 Industry organizations 4 Electricity producers 7 Safety authorities and technical support

organisations– More than 230 researchers– About 20 PhD students

– 800 to 900 person-months per year– About 10M€ effort per year (1.6M€ funded by the EC per year)

www.sar-net.org

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SARNET OBJECTIVES

Resolution of still pending issues important for reactor safety

Optimised use of available resources and competences on severe accidents throughout Europe

Knowledge transfer for safety application

Perpetuate the competence on severe accidents

Encapsulation of the knowledge base on severe accidents through the lumped-parameter ASTEC code

– this program calculates the progress of severe accidents in light water reactors from initiating event through to release of radioactive fission products to the environment

– it enables the results of the scientific research to be used in reactor applications

MAIN OBJECTIVES

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SARNET ACTIVITIES SARNET is organised into a number of work packages

covering– integrating activities (such as research prioritisation, database

management, ASTEC development)– jointly executed scientific research (focussed on corium,

containment and source term matters), and– spreading of excellence (such as organisation of training courses

and mobility of researchers)

CFD is one of a number of analysis methods used in the jointly-executed scientific research (‘topical’) areas

– used in all these areas, but mainly for containment and source term studies

ORGANISATION

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WORK PACKAGES

WP 17 : ETEducation and Training

WP 18 : BOOKBook on severe accident phenomenology WP 19 : MOBMobility programme

Spreading of excellence activities

Integrating activities Jointly executed research activities

WP 1 : ACTDevelopment of an Advanced Communication ToolWP 6 : IEDImplementation of Experimental Database

WP 7 : SARPDefinition of Severe Accident Research Priorities

WP 8 : IAIntegration Assessment

WP 2 : USTIAASTEC Users Support and Training, Integration, and Adaptation WP 3 : PHYMAASTEC PHYsical Model Assessment

WP 4 : RABASTEC Reactor Application Benchmarking

WP 14,15,16 : SOURCE TERMFP Release and TransportAerosol Behaviour impact on Source TermContainment Chemistry impact on Source Term

WP 20 : Management

WP 12,13 : CONTAINMENTHydrogen behaviour Fast Interaction in Containment

WP 9,10,11 : CORIUMEarly phase core degradation Late phase core degradationEx-vessel corium recovery

WP 5 : PSA2Level 2 PSA methodology and advanced tools

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DATABASE

MEDICIS/WEX RUPUICUV

SYSINT

ISODOP

SOPHAEROS

Aerosols and FPIn the reactor circuits

SYSINT

ISODOP

IODE

CPA-AFP

CPA-THY

MEDICIS/WEX

RUPUICUV

SOPHAEROS

CESAR

ELSA

DIVA

t

t

t

t

t

t

t

t

t

t

Safety systemmanagement

IODE

Molten core concreteinteraction

Radioactivity inContainment

ELSAFP relaese

DIVACore degradation

CESARCircuit

Thermalhydraulics

CPA-THYContainment

Thermal hydraulics

CPA-AFPAerosols and FP in

containment

Molten core ejectionAnd direct heating

Of containment

Integral numerical simulation of reactor accident with core melting (Severe Accidents) IRSN-GRS property : ~ 10 m-y/y in charge of software development and user support

Has been distributed to 26 SARNET organizations SARNET scientists support for model improvement and physical assessment:

ASTEC capitalizes, in terms of models, all the knowledge produced in the frame of the Network 40 trained users contribute to joint validation programme (mobilizes around 20 m-y/year) One major version delivered in July 2005 (V1.2)

Size: ~ 350 000 instructions Speed: ~ 3-10 hours to compute 24 h of transients

ASTEC

ASTEC integrates the technical knowledge in SARNET

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USE OF CFD METHODS IN SARNET CFD is used in a number of applications, such as

– design of experiments

– interpretation of experimental results

– plant studies, e.g. to determine the parameter ranges for separate-effect tests

– benchmarking system-level codes, in this case principally ASTEC

– one also notes use in reactor applications outside SARNET to look at detailed aspects where lumped-parameter methods are not sufficient, e.g. where 3-D flows are important, CFD results can be used to guide the use of lumped parameter codes regarding noding, X-flow resistances, other tuneable parameters etc.

Validation of CFD methods and development of best practice per se are not main aims within SARNET

– the codes are applied rather than developed and validated, and the users are assumed to know how to use their codes effectively

– note also the CFD activities within OECD/NEA/GAMA, http://www.nea.fr/html/nsd/csni/cfd.htm, with best practice guidelines, http://www.nea.fr/html/nsd/docs/2007/csni-r2007-5.pdf, these are not within SARNET but many of the same organisations are involved

USE OF CFD - GENERAL

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CONTAINMENT STUDIES Examples are:

– Interpretation of results from the TOSQAN and MISTRA tests on influence of containment sprays on the atmosphere behaviour (depressurisation, gas mixing), comparison of LP and CFD methods, see also OECD International Standard Problem 47 report http://www.nea.fr/html/nsd/docs/2007/csni-r2007-10.pdf

– Investigation of processes inside passive autocatalytic recombiners (PARs) using data from the REKO-3 facility, influence on the containment atmosphere and of steam condensation, hydrogen recombination, effects of steam and oxygen depletion

– Investigation of hydrogen combustion using data from the ENACCEF facility, effect of concentration gradients on flame acceleration/deceleration

USE OF CFD – CONTAINMENT STUDIES

H Wilkening et al. ‚ European Research on Issues concerning Hydrogen Behaviour in Containment within the SARNET Network of Excellence , ICAPP’08, Anaheim, USA, June 2008

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USE OF CFD – CONTAINMENT STUDIES

H Wilkening et al. ‚ op cit.

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SOURCE TERM STUDIES Examples are:

– Reactor calculations in combination with other codes such as the LP programs ICARE/CATHARE and ASTEC to determine gas flows and compositions that may result from air ingress into the vessel following hot leg and lower head breach (EdF, IRSN), determining conditions for separate-effect tests on air oxidation of fuel and cladding

– Design calculations for facilities investigating the dynamic chemical interactions of iodine-containing and ruthenium-containing species in the primary circuit under severe accident conditions (IRSN, VTT)

– Interpretation of circuit chemistry aspects of the Phebus-FPT2 integral in-reactor experiment on core degradation, and fission product release and transport, and behaviour in-containment (IRSN)

– Interpretation of an integral ThAI experiment (Becker Technologies) on iodine behaviour in-containment coupled with thermal hydraulic and aerosol aspects, in the frame of a SARNET benchmark led by GRS with contributions from GRS, IRSN and AECL

– Investigation of results of the RECI experiments (IRSN) on the effects of PARs on airborne iodine in the containment (IRSN, Demokritos, et al.)

USE OF CFD – SOURCE TERM STUDIES

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USE OF CFD – SOURCE TERM STUDIES

A Auvinen et al. ‚ Progress on Ruthenium Release and Transport under Air Ingress Conditions, ERMSAR2007, FZ Karlsruhe, June 2007

SATURNE calculation of flows in the lower head and cavity under air ingress conditions (EdF)

Reactor meshing for CFD calculation (Saturne)

Refined meshing in the annulus zone

Coarse meshing in the dome

40.000 to 60.000 cells

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USE OF CFD – SOURCE TERM STUDIES

http://www.becker-technologies.com/web-e/html/Reaktorsicherheit/thai-anlagen.html

Illustrations of the ThAI facility

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CONCLUDING REMARKS CFD methods have an important role within SARNET for support of

experiments, in plant studies and for benchmarking more detailed models, for example in the major European severe accident analysis code ASTEC, that is a main product of the network

The focus is on application rather than on development and validation The applications are mainly in the areas of containment studies, and in

source term research It is expected that CFD methods will continue to be used in the follow-

on SARNET2 project in the 7th Framework programme, subject to the satisfactory outcome of negotiations with the EC that are currently in progress

CONCLUSIONS

The authors thank the European Commission for funding SARNET, in the 6 th Framework Programme area “Nuclear Fission: Safety of Existing Nuclear Installations”, under contract number FI6O-CT-2004-509065.