Lessons of Fukushima-Daiichi NPP's Accidents for Achievement of the 1st Class Safety in the World. SBO in Fukushima Daiichi NPPs

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1 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Fukushima Severe Accident Dose Management & Global Lessons Learned in Occupational Dose Reduction Lessons of Fukushima-Daiichi NPP's Accidents for Achievement of the 1st Class Safety in the World January 9, 2012 (Hyatt Regency Pier) Dr. Tadashi NARABAYASHI Nuclear and Environmental Systems Hokkaido University Optimization of Nuclear Safety Regulation JSME Power and Energy System Division 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 1 Tsunami Flooding Area in each NPP Fukushima Daiichi Fukushima Daini Onagawa Flood Flood Rushed Flood Rushed Tohkai Daini Flood Rushed 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 2 Tsunami Flooding Area in each NPP Fukushima Daiichi Dike Tsunami Height #1~#4 #5, #6 Grand Level #1~#6 Sea Water Pump Flooding through hatches and air intake for EDG EDG M/C, P/C Large Door T/B Basement Hatch SBO in Fukushima Daiichi NPPs DG #1 #2 #3 #4 #5 #6 A: B: A: (B1) B:OK (FP/B 1F) A: B: A: B:OK (FP/B 1F) A:OK-> B:OK-> Water Cooling A:OK-> ( B1) Water Cooling B:OK (DG/B 1F) Fukushima Daini #5,#6 Grand Level #2~#4 No Flooding #1 Flooding through hatches and air intake for EDG Metal- Crad Swich Power Center Barely Barely (T/B 1F) Barely (T/B 2F) Barely ( B2F) Barely ( B2F) Dike Door M/C,P/C Hatch Tsunami Height O.P.+7m Air intake for EDG Hatch M/C,P/C EDG DC Buttery ECCS RCIC (C/B B1) HPCI: IC:OK(FC) (C/B B1) RCIC:OK OK (T/B BM1) HPCI:OK RCIC:OK (C/B B1) (No Fuels in RPV) OK (T/B BM1) OK (T/B BM1) HPCS:OK ( B1) 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 4

2 SBO in Fukushima Daiichi NPPs Tsunami DC P/C AC P/C EDG RHRS AC Power Lost EDG Trip ICs in unit #1 were tripped by FC Loss of battery power for main control room caused the fail-close action to MO isolation valves to stop the IC. It was a fail-dangerous system. If the IC continue to operate, the accident would be terminated soon. Isolation Condenser Steam Blowout Battery Lost Loss of UHS DC Power Lost Process Measurement IC,RCIC,HPCI Control MS-SRV Actuator Solenoid Valve Lost Air Lost HVAC, SGTS AO Valve MO Valve PCV VENT Faliure Motor Water Makeup Pump Heat Removal, ECCS 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 5 Flood Engine Pump Water Tank Fire Pool RCIC steam turbine also stopped by loss of battery power in Unit #2 and #3. S/P temperature and pressure were so high that AM water injection took a lot of times. RPV IC Control Valve S/P 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 6 CV Pressure Trend in unit #1 After loss of ECCS and IC core cooling, CV pressure increased. Water level drifted by vaporizing water in reference leg. Radiation level increased at T/B. Hydrogen explosion occurred after S/C wet venting. Water level drifted Pressure and Water Level in #1 RPV Analysis results show the RPV depressurization started before RPV bottom failure. It might be caused through melted TIP tubes in the core. Water level measurement was drifted by the loss of water in a reference leg by high-temperature superheated core. RPV Bottom TAF Level (3hr) RPV Pressure (MPa) IC cooling RPV Water Level (m) BAF Level (3hr) Water Injectionl (15hr) Water Level data drifted more than 4m 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 8

3 CV Pressure Trend in unit #2 After loss of RCIC water injection, DW pressure increased. Water level was decreased after RCIC tripped. RPV pressure was too high to water injection by Fire pump. Explosion sound occurred near S/C. RPV Pressure was too high to water injection of prompt water injection in #2 of prompt water injection after RCIC stopped in unit #2 caused the core damage and H2 generation started. High-pressure discharge pump driven by diesel engine should be used. Unit #2 RPV Pressure Trend Water level in RPV RCIC Started RCIC Stopped SRV ed RPV (MPa)? DW Pressure RPV Pressure (MPa) Lost of Battery Melt Core relocation to Low plenum RPV Bottom H2 production (kg) Core Damaged 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 10 Radiation level increased after CV rapture H2 detonation were occurred after vent operation (#1, #3, #4) Radiation level increased soon after #2 CV rapture 1F Monitoring Trend Radiation Level (Sv/h)10000 #1 Vent started #1 Detonation #3 2 nd Vent #3 1 st Vent #3 Detonation #4 Detonation #1 Vent #3 1 st Vent #3 2 nd Vent #2 2 nd Vent Fukushima Daiichi Sevier Accidents Unit #1 Unit #2 Unit #3 Unit #4 IC Trip Core Melt Vent RCIC (Steam turbine driven) HPCI, RCIC (Steam turbine driven) Core Melt Vent Core Melt H2 Leak Vent 3/11 3/12 3/13 3/14 3/15 3/16 3/17 3/18 Nikkei Science, July INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 11 3/11 3/12 3/13 3/14 3/ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 12

4 H2 Leak Path from CV CV top flange and hatches might be leak pass Cause of H2H Detonation in #4 #4 was in outage. No fuels in the core Hydrogen from #3 flowed into #4 via SGTS 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 14 #4's SGTS Filters were contaminated Fukushima Daiichi Unit #4 SGTS valves and contamination check results Aug. 25, 2011 TEPCO Stuck #3's SGTS Filters were contaminated Fukushima Daiichi Unit #3 SGTS valves and contamination check results Dec. 26, 2011 TEPCO Fan S/P SGTS Filters Fan Fan Vent Line S/P Stuck SGTS Filters Gravity Dumper Fan c Stuck Vent Line Filters in SGTS showed that H2 and FP supplied from #3 flowed into # INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 15 Vent Line 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 16

5 Vent was a cause of suicide bombing? Fail- valve in SGTS supplied H2 and FP into Hydrogen Detonation and CV Rapture Top Flange Leak #4 #3 #2 #1 PCV SGTS Filter Detonation Detonation CV Rapture Detonation SGTS Filter 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 17 Air Photo Service Co INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 18 Water Recycle System for Core Cooling We proposed water recycle system for core cooling on March 28 H 2 Venting Spent Fuel Pooleolight (2)Contaminated Water Shield along Seashore Large Egg and Elephant's Leg TMI-2:Large Egg in core Chernobyl: Elephant's Leg Condenser Sea DecayHeatMW Onthedecrease Salt Salt Plant Boiling volume reduction FPrecoveryTank Zeolite Cleanup Feed Water Tank Cooling Tower Water Recovery Tank 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 19 5MW Radiation Shield Concrete Steel Panel (1) Water Recycle for Core Cooling, Shield, Remove debris Egg 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 20

6 Comparison between Chernobyl and Fukushima Minsk Belarus Russia Released FP Cs,I Fukushima Chernobyl 1 1/13 Lessons of Chernobyl NPP Accidents promoted the installation of Filtered Vent System to protect radioactive materials exhaust. French, German, Switzerland, Finland, Norway DF 1/100-1/1000 I2 CsI etc. Spent Fuel Pool Total 1 1/50 Mist Separator Reactor 30km Zone Size Kiev Fukushima Ukraine TMI-2 1 Core thermal output Fukushima Chernobyl 100 ~0.01 Pool 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 22 Objectives of Filtered Vent System Objectives of Filtered Vent System (1)Preventing C/V rapture (2)Preventing Radioactive material exhaust Fukushima Daiichi NPP #1 C/V 7bar + Vent + H 2 Explosion ~1day #2 C/V 7bar + No Vent + C/V rapture ~3.5days #3 C/V 6bar + Vent + H 2 Explosion ~3days Prevent over-pressure C/V rapture + Exhaust of RI and H 2 Filtered Containment Venting System (FCVS) Feed and Bleed under Long SBO & LUHS Backfitted on 1992 for (mitigation of Sever Accident) Visit Chooz NPP, EDF France Filtered Vent Prevent over-temperature C/V rapture + H 2 leakage Special Emergency Heat Removal System (SEHR) JSME visit Leibstadt NPP, Swiss, on Nov.11, INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 24

7 Visit Leibstadt NPP, KKL, Switzerland FCVS:Filtered ( Filtered Containment Venting System Filtered Vent Vent valve will be open by manual shaft when SBO DF > 1000 Aerosol > 100 I 2 Rapture Disk (~3bar) Stuck Steam Fuel rod MOV Normal MOV Normal NaOH 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 25 Backfitted on 1992 for (mitigation of Sever Accident) Solubility ph10 Solubility ph7 ~ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 26 SEHR:Special () Emergency Heat Removal System After the TMI-2 accidents, KKL back-fitted the DiD3 (additional C/V cooling) and DiD4 (mitigation of Sever Accident). DiD: Defense in Depth Special Power Generator on Height 4000kVA mobile gas-turbine generator at 31m parkinghepco TP+85m Steam Fuel rod Heat Exchanger Gas-turbine generator will be installed at 25mChubu Electric) Suppression Pool TP+25m D/G D/G Two D/G for SEHR Underground Dwells 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 27 Gas-Turbine Generetor 4000kVA, 3.2MW 3.3kV-6.6KV Start within 40sec 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 28

8 Countermeasure 2. Heat Removal System Cooling Tower Decayheat:% 1000MWe:30MW PCV Main Transformer Power Transmission Steam Water Sea Heat Sink by Sea Water Network Chubu Electric Hamaoka NPP RPV RCIC Turbine Generator PLR Pump Main Condenser S/P Sea Water Pump Feed Water Pump 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 30 Sustainable Energy in German: Only 1.9% Solar Coal Oil Others Capacity Factor Wind Nuclear: 20.3 TW Solar: 17.0 TW Biomass Killer Heat Wave in Europe The death toll in France, Killer heat Total 50,000 died in 2003 and 2006 Elbe River, Dresden, German, July 2006 Nuclear Sustainable Energy Solar Hydraulic Wastes Broun Coal Breakdown of Sustainable Energy Power Source in German 2010(Total 6.2x10 11 kwh, Tentative) Sustainable Energy Statics 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ Global Warming brings heat waves CO 2 may be much danger than radio activities 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 32

9 Fossil Energy Estimation in Future King Abdulaziz University asked to Hokkaido University for Nuclear Education Human being will exhaust all fossile fuels 㻞㻜㻜 Oil in Saudi Arabia would be empty within 60 years if they wouldn't use nuclear Demand Equivalent Oil Energy (108 t) Ἔ 䜶䝛䝹䜼䞊䠄൨䡐䠅 Nuclear Education for Saudi Arabia ᅾ Present 㻝㻡㻜 Y 133ᖺ 133ᖺ Ⅳ Coal 㻝㻜㻜 ኳ 䜺䝇 Natural Gas President Saeki, Hokkaido Univ. 㧗 ቑṪ⅔䛷 Utilization of 䝥䝹䝖䝙䜴䝮䜢 Plutonium in FBR 䛩䜜䜀 ศ 2570Y 2570ᖺ Y 100ᖺ 100ᖺ Y 60ᖺ 60ᖺ Y 42ᖺ 42ᖺ 㻡㻜 Ἔ Oil Oil Natural Gas Coal 㻞㻞㻜㻜 㻞㻟㻜㻜 Uranium 㻜 㻝㻥㻜㻜 㻞㻜㻜㻜 㻞㻝㻜㻜 㻞㻠㻜㻜 㻞㻡㻜㻜 す ᖺ Year 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 34 Nuclear Education in Malaysia Progress in Kuala Lumpur, Malaysia Tsunami-Proof NPP 2012 INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 36

10 Conclusion Fukushima Daiichi NPP accident would be terminated, if sufficient examination lead to install countermeasures for tsunami, such as water proof door, mobile power, etc. In Europe, it had already installed the Heat Removal System and Filtered Venting System from the lessons of TMI and Chernobyl Accidents. Vent line should be independent from SGTS/HVAC line. From the Lessons of Fukushima-Daiichi Accidents, we should achieve the 1st class Nuclear safety in the world NPPs. Solar and sustainable enegy will not sufficient to replace the nuclear energy. Both the energy should be used in future. Nuclear education is very important to maintain the Nuclear safety technology and safety culture in the world INTERNATIONAL ISOE ALARA SYMPOSIUM Prof. Narabayashi, Hokkaido Univ. 37