VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD

Implications of FukushimaDaiichi accident on NuclearSafety ResearchSAFIR2018 Interim Seminar 23.3.2017Ilona Lindholmhttp://photo.tepco.co.jp/en/index-e.html

202/05/2017 2

OutlineIAEA/IEM lessons learned for strengthening R&D in light of Fukushimaaccident

Research Needs & Projects related to Issues from FukushimaAccident –EPRI, ETSON, OECD/NEAIAEA/IEM R&D Strategies after Fukushima Accident

OECD/Safety Research Opportunities post-Fukushima (SAREF)Common interest to safety research knowledge gaps andFukushima Daiichi decommissioningInterest to safety research but no Fukushima Daiichi post-accidentexaminationsDecommissioning needs information

SAFIR2018 ”wish-list” of Fukushima research topicsFukushima aspects in current SAFIR2018 projects

3302/05/2017

Research Needs & Projects related to Issues fromFukushima Accident –EPRI, ETSON, OECD/NEA

EPRI:MAAP simulations of Fukushima accidentExternal hazardsAccident tolerant fuelsLong term storage of spent fuelTechnologies for decommissioning

ETSON:Quatification of source terms,Prevention of large releasesDispersion of released radiactive materialMitigation of hydrogen hazardsCooling of degraded coresFuel behavior in accidents at storage facilities

OECD/NEA:BSAF (Benchmark study of Fukushima Accident)HYMERES (Hydrogen mitigation)PKL3 (Primary Coolant Loop Tests)ATLAS Advanced Thermal-Hydraulic Test Loop

Fuel removal work at the common pool inFukushima Daiichi NPS Unit 4(http://photo.tepco.co.jp/en/index-e.html)

4402/05/2017

IAEA/IEM lessons learned for strengtheningR&D in light of Fukushima accident

R&D strategies after Fukushima:Measures to protect NPPsagainst extreme external andinternal eventsPrevent and mitigate severeaccidentsSevere accident analysisEmergency preparednessand responsePost-accident recoveryIAEA Report on Strengthening Research and Development Effectiveness in the Light of theAccident at the Fukushima Daiichi Nuclear Power Plant, International Experts Meeting 16-20February, Vienna, Austria

Pre-investigation results of the area inside thepedestal for the Unit 2 Primary ContainmentVessel (http://photo.tepco.co.jp/en/index-e.html)

5502/05/2017

IAEA/IEM R&D Strategies after Fukushima AccidentIntegrated approach needed

International partnershipsIntegrated experimental & theoreticalinvestigations

Improved computer codesPrediction of accident progression andconsequences

Effectiveness of accident managementExternal hazardsMulti-unit sitesSpent fuel poolsSafety margin evaluationsCooling of core; managing molten coreConfinement of radioactive material(venting, H2 risk)

Freezing condition visually confirmed forthe Landside Impermeable Wall (ice wall)(http://photo.tepco.co.jp/en/index-e.html)

6602/05/2017

OECD/Safety Research Opportunities post-Fukushima (SAREF)

Common interest for research knowledge gapsand Fukushima Daiichi decommissioningacticvitiesAreas of common interest:

Severe accident progressionSSC performance and conditionsRecovery phase

Other areas of interest, no post-accidentexaminations identified:

External effects, multi-unit risk and loss ofultimate heat sinkRobustness of electrical systemsHuman performanceSeismic response (building andcomponents)

Safety Research Oppertunities Post-Fukushima, Initial Report of the SeniorExpert Group, NEA/CSNI(2016)19

7702/05/2017

Common interest to safety research knowledgegaps and Fukushima Daiichi decommissioning 1(2)

Severe accident phenomenaIn-vessel phenomenaPrimary system and RPVfailureEx-vessel phenomenaContainment failure andventingFission product behaviourand source termPool scrubbing

Unit 1 Unit 2 Unit 3

8802/05/2017

Common interest to safety research knowledgegaps and Fukushima Daiichi decommissioning 2(2)

SSC performance and conditionSalt water and concrete debriseffectsMission time and systemsurvivability (cables, sealing,instrumentation, RCIC system,relief valves and piping,environmental degradation ofmetallic components)

Recovery phase:Long-term accident managementDebris waste management

Survey on Torus room wall in Unit 1 ofFukushima Daiichi Nuclear Power Station(http://photo.tepco.co.jp/en/index-e.html)

9902/05/2017

Interest to safety research knowledge gaps but noFukushima Daiichi post-accident examinations

External effects, multi-unit riskand loss of ultimate heat sinkRobustness of electrical systemsSpent fuel poolsHuman performanceSeismic response (of building andcomponents)

Apperance of Unit 3 ReactorBuilding after explosion(http://photo.tepco.co.jp/en/index-e.html)

Investigation Results inside Unit 3Spent Fuel Pool using aWaterproof Camera(http://photo.tepco.co.jp/en/index-e.html)

101002/05/2017

Decommissioning needs information

Evalution of the distribution andrisk assessment of fuel debrisand fission products remainingin PCVSafety and risk assessment inplanning and implementing fueldebris retrieval

Structural integrityRe-criticalityRadiative materialdispersionDose exposureDesign and development oftechnologies for debrisretrieval and storage Start of decontamination by remote-controlled

decontamination device Unit 3 R/B(http://photo.tepco.co.jp/en/index-e.html)

111102/05/2017

SAFIR2018 ”wish-list” of Fukushima researchtopics

Special working group established in February2015 (4 members)Severe accidents, extreme weather conditions,source term, safety margins, spent fuel poolaccidents, safety culture, performance oforganisations, flexibility in SAMAcceptance criteria for passive safety systemsSevere accident managementLong-term effects of radiation on containmentpenetrations and bio-corrosionAgeing of concrete structures and acceptancecriteria for DECPRAOverall safety and DiD

Unit 3 PCV Equipment Hatch InvestigationUsing A Small Investigation Device (Robot)(http://photo.tepco.co.jp/en/index-e.html)

121202/05/2017

Fukushima aspects in current SAFIR2018 projectsSAUNA

Defence-in-depth issues: resilienceengineering

CORESuccess in accident managementReflective orientation in the beyond-design-basis accidentsMangement of extreme physiologicalstressEmergency exercise paractisesSafety management practises

MAPSSignaled and silenced aspects of safetyInstitutional isomorphismsInward-looking and self-refrential tendencyin the content and design of stress tests

CASASeveral severe accident topics

CATFISHChemistry of iodine

EXWEClimate research topic

NESTEarthquakes

PRAMEAPRA level 3, multi-unit issues

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