Fukushima Accident and Safety Assurance Measures for TEPCO NPP

Transcription

1 Fukushima Accident and Safety Assurance Measures for TEPCO NPP IEEE NPEC N12-02 San Diego July 25, 2012 Yasushi Nakagawa Tokyo Electric Power Company All Rights Reserved 2012The Tokyo Electric Power Company, Inc.

2 Damage to the Power Supply Facilities by tsunami and earthquake at 1F and 2F site. Fukushma Daiichi(1F) Fukushma Daini(2F) Unit 5 Unit 1 Unit 2 Unit 3 Unit 4 Unit 6 4 Unit 3Unit Unit 2 Unit 1 All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 1

3 Plant Unit Overview of Fukushima Daiichi NPS (1F) and Fukushima Daini NPS (2F) In Operation Since Plant Type Power Output (MWe) Main Contractor Pre earthquake Status BWR GE Operating BWR GE/Toshiba Operating BWR Toshiba Operating 1F BWR Hitachi Planned Outage Full core offloaded to spent fuel pool BWR Toshiba Planned Outage BWR GE/Toshiba Planned Outage BWR Toshiba Operating 2F BWR Hitachi Operating BWR Toshiba Operating BWR Toshiba Operating All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 2

4 Power supply of Unit 1F after Tsunami Okuma Line 1L, 2L: Receiving circuit breaker damaged in earthquake Okuma Line 3L: Renovation work in progress Okuma Line 4L: Circuit breaker shutdown by protection relay activation Shutdown by earthquake Shutdown by Tsunami Ohkuma 4L Ohkuma 3L Ohkuma 2L Ohkuma 1L 3SB 3SA 2SB 2SA 1S 4B 4A 3B 3A 2B 2A 1B 1A 4D 4C 3D 3C 2D 2C 1D 1C 4E 2E 4B 4A 3B 3A 2B 2A 1B 1A The DGs lost the function due to either Switchgear failure, loss of sea water system, or DG main conponent failure. All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 3

5 Power supply of Unit 1F after Tsunami 5C 5A For transmitting power 双双葉葉Futaba 線1L Futaba For 12L transmitting Lpower Yonomori 1L Yonomori 2L 5B 5SA-1 5SA-2 5SB-1 5SB-2 6A-1 6A-2 5D HPCS 6C Shutdown by earthquake Shutdown by Tsunami Survived after tsunami 5B HPCS 6A 線2L5A 6B-1 6B-2 6D 6B

6 Damages of transmission line & Shinfukushima substation by earthquake Collapse of bed soil & sand Transmission tower collapse Tower collapse Collapse (C)GeoEye - About 10 km away from both 1F and 2F site - Important switchgear station from which electricity of 1F & 2F is transmitted to Tokyo area 500kV Disconnector 275kV Circuit Breaker All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 5

7 2F Offsite Power was secured after the Tsunami Tomioka Line 500kV Offsite Power H STr One 500 kv line was available. 66 kv lines were outage because of scheduled Iwaido Line maintenance and substation trouble but recovered. Many power centers and motors were damaged 66kV because of the flooding. P : Cooling Pumps : Diesel Generator Unit #1, 2 STr Unit #3, 4 STr 6.9kV 6.9kV 6.9kV 6.9kV P P P P P P P P 1H 1A 1B 2H 2A 2B 3H 3A 3B 4H 4A 4B Emergency Power for Unit #1 Emergency Power for Unit #2 Emergency Power for Unit #3 Emergency Power for Unit #4 All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 6

8 Integrity of Power Supply System After the Tsunami at 1F and 2F Emergency Emergency use Regular use Regular use 125V DC use Emergency DG DG power 6.9KV M/C M/C 480V P/C PC DC supply Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel Can/can not be used Power panel DG 1A DG 2A DG 3A DG 4A DG 5A(*2) DG 6A (*2) DG 1A DG 2A (*2) DG 3A (*2) DG 4A (*2) DG 1B DG 2B (air-cooled) (*1) DG 3B DG 4B (air-cooled) (*1) DG 5B(*2) DG 6B (air-cooled) Can/can not be used DG 1B DG 2B (*2) DG 3B DG 4B (*2) HPCS DG (*2) DG 1H DG 2H (*2) DG 3H DG 4H M/C 1C M/C 2C M/C 3C M/C 4C M/C 5C M/C 6C M/C 1C M/C 2C M/C 3C M/C 4C M/C 1D M/C 2D M/C 3D M/C 4D M/C 5D M/C 6D M/C 1D M/C 2D M/C 3D M/C 4D - - M/C 2E - - M/C 4E - - M/C 1A M/C 1B 1F:No off-site power available Unit 1 Unit 2 M/C 2A M/C 2B M/C 3A M/C 3B Fukushima Daiichi Unit 3 Unit 4 Unit 5 Unit 6 M/C 4A M/C 5A M/C 4B HPCS DG M/C M/C 1H M/C 2H M/C 3H M/C 4H M/C 6A-1 M/C 1A-1 M/C 2A-1 M/C 3A-1 M/C 4A-1 M/C 6A-2 M/C 1A-2 M/C 2A-2 M/C 3A-2 M/C 4A-2 M/C 6B-1 M/C 1B-1 M/C 2B-1 M/C 3B-1 M/C 4B-1 M/C 6B-2 M/C 1B-2 M/C 2B-2 M/C 3B-2 M/C 4B-2 M/C 1S M/C 5SA-1 M/C 1SA-1 M/C 3SA-1 M/C 2SA M/C 3SA M/C 5SA-2 M/C 1SA-2 M/C 3SA M/C 5SB-1 M/C 1SB-1 M/C 3SB-1 M/C 2SB M/C 3SB M/C 5SB-2 M/C 1SB-2 M/C 3SB-2 - P/C 1C P/C 2C P/C 3C P/C 4C P/C 5C P/C 6C P/C 1C-1 P/C 2C-1 P/C 3C-1 P/C 4C-1 P/C 1D P/C 2D P/C 3D P/C 4D P/C 5D P/C 6D P/C 1C-2 P/C 2C-2 P/C 3C-2 P/C 4C P/C 2E - - P/C 4E - - P/C 6E P/C 1D-1 P/C 2D-1 P/C 3D-1 P/C 4D-1 P/C 1A P/C 2A P/C 3A P/C 4A P/C 5A P/C 6A-1 P/C 1D-2 P/C 2D-2 P/C 3D-2 P/C 4D-2 P/C 2A P/C 5A-1 P/C 6A-2 P/C 1A-1 P/C 2A-1 P/C 3A-1 P/C 4A-1 P/C 1B P/C 2B P/C 3B P/C 4B P/C 5B P/C 6B-1 P/C 1A-2 P/C 2A-2 P/C 3A-2 P/C 4A P/C 5B-1 P/C 6B-2 P/C 1B-1 P/C 2B-1 P/C 3B-1 P/C 4B-1 P/C 1S - - P/C 3SA - - P/C 5SA - - P/C 1B-2 P/C 2B-2 P/C 3B-2 P/C 4B P/C 5SA P/C 1SA P/C 3SA P/C 2SB P/C 3SB - - P/C 5SB - - P/C 1SB P/C 3SB - DC125V main DC125V P/C DC125V main DC125V main DC125V P/C DC125V DIST DC125V main DC125V main DC125V main DC125V main bus panel A 2A bus panel 3A bus panel 4A 5A CENTER 6A bus panel A bus panel A bus panel A bus panel A DC125V main DC125V P/C DC125V main DC125V main DC125V P/C DC125V DIST DC125V main DC125V main DC125V main DC125V main bus panel B 2B bus panel 3B bus panel 4B 5B CENTER 6B bus panel B bus panel B bus panel B bus panel B M/C 5B 2F:Off-site power survived Fukushima Daini Unit 1 Unit 2 Unit 3 Unit 4 Sea water system A RHRS A RHRS A RHRS A RHRS A RHRS A RHRS A RHRS A RHRS A RHRS A SW B RHRS B RHRS B RHRS B RHRS B RHRS B RHRS B RHRS B RHRS B RHRS B Sea Water System O: operable X: damaged *1 functionality lost due to inundation of power panels *2 functionality lost due to the damage of sea water system All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 7

9 Overview of the Fukushima Accident The Tohoku-Chihou-Taiheiyou-Oki Earthquake around 14:46, Mar. 11 th Reactor SCRAM due to the Earthquake (Emergency Shutdown) Loss of External Power Start-up *1 Post-SCRAM Operation Post- SCRAM Operation Tsunami struck Fukushima-Daiichi & Fukushima-Daini NPPs around 15:20~, Mar. 11 th Fukushima-Daiichi Unit 4 Units 1~3 Units 5,6 [Power] No AC power, No [Seawater system] Not available [Power] 6B start-up [Seawater system] Not available Fukushima-Daini [Power] AC Power available [Seawater system] Unit 3 available *2 Water injection & heat removal via HP system Water injection via LP system: fire engine (Freshwater & Seawater) Power supply from Unit 6 to Unit 5 Water injection via HP (Steam-driven) & LP systems Water injection via LP system No route ensured for heat removal, response for stabilization Cold Shutdown Condition (Dec. 16) Heat removal ensured by temporary power source & seawater pump Heat removal ensured by temporary power source & motor replacement etc. Cold Shutdown (Mar. 20) Cold Shutdown (Mar. 15)*3 Fukushima-Daiich 1~4 Fukushima-Daiichi 5,6 Fukushima-Daini 1~4 *1 :Emergency Diesel Generator *2 RHR Seawater System *3 Fukushima-Daini Emergency State was Lifted on Dec.26 All Rights Reserved 2012The Tokyo Electric Power Company, Inc. tth 8 8

10 Recovery of Electrical equipment and Power Supply during Fukushima accident All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 9

11 Restoration of lights and I&Cs in Control 1F Temporary lights The Compact type generators were carried from the contractor s warehouse and supply power to temporary lights in the Main Control Room. Temporary power supply Connect temporary batteries to recover I&C. e.g. Reactor water level indicator SRV contrrol circuit All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 10

12 Temporary Power Source (Power Supply car) Recovering Power 1F Unit 5 Unit 5 Unit 6 M/C 6C External Power M/C 6D External Power Operable since 18 th March P/C 6C G 6A P/C 6D M/C 6E G 6B 5U RHR MCC T/B MCC 6C-2 T/B MCC 6C-1 Temporary Underwater Pump (Substitute of RHR )RHR Pump 5C (18 Mar) (18 Mar) DC125V Charger Control Panel 5A DC125V Charger Control Panel 5B Connection Line for accident management Control Room Lighting (12 Mar) (15 Mar) (21 Mar) MUW 5A (13 Mar) SGTS 5A Space Heater SGTS 5A (13 Mar) (13 Mar) Directly connected to the motor Temporary Cables All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 11

13 Recovering of Electrical 2F Pumps of RHR cooling systems (RHRC, RHRS, EECW) were inspected. Motors were replaced for pumps in RHRC and EECW. In order to restore the inundated electrical buses, temporary cable and high voltage mobile power vehicles were prepared. Temporary cable was laid from survived power cubicles in Rad-Waste Building to survived power cubicles in Unit 3 Heat Exchanger Building. Drawing made at TSC for temporary cable laying Motor replacement All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 12

14 Recovering Power 2F Temporary cable of 9 km length was laid by about 200 personnel within a day. Usually this size of cables laying requires 20 personnel and more than 1 month period. After the pumps for RHR cooling systems were restored and temporary cable was laid, RHR (B) of Unit 1 started up at 1:24 on March 14 and other units followed. Finally at 15:42 on March 14 with the start up of Unit 4 RHR, RHR of all four reactors started operation in Fukushima Daini NPS. All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 13

15 Temporary Power Supply and Motor Unit #4 Hx Building Unit #3 Hx Building Unit #2 Hx Building Unit #1 Hx Building Mobile Power Supply Truck (500kVA) Unit #4 Turbine Unit #4 Reactor 6.6kV/480V Transformer Unit #3 Turbine Unit #3 Reactor Mobile Power Supply Truck (500kVA) Unit #2 Turbine Unit #2 Reactor 6.6kV/480V Transformer Unit #1 Turbine Unit #1 Reactor Temporar y Cables Rad-Waste Building TSC Main Office All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 14

16 Safety Assurance Measures for TEPCO NPP All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 15

17 Basic Concept of Safety Assurance Measures for TEPCO NPP Flooding protection measures to cope with tsunami In order to prevent tsunami causing the submergence of safety critical equipment and functional loss, flooding protection measures are taken mainly for reactor buildings. Drainage systems are also provided as a precaution. Fuel damage prevention measures during SBO or loss of heat sink Materials and equipment are stored at high places in plant premises to prevent damage to the fuels in reactors and SFPs even during SBO or LUHS, and flexible procedures provided for an effectively use of these materials and equipment. Effect mitigation measures provided as a precaution for fuel damage A top vent is installed for preventing hydrogen explosions following a bare possibility of fuel damage. For ensuring preparations, a filter vent is also installed to mitigate radiation impact on the environment. Common measures Materials and equipment critical for supporting the restoration of reactor facilities following an accident, and a system of using them are provided. All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 16

18 Safety Measures at Kashiwazaki-Kariwa NPS Completed at K-1,7 Enhancement of injection and heat removal - Submerged pump - Heat exchanger truck - Mobile Power Truck - Spare hose Completed at K-1,7 Prevention of accumulating Hydrogen (1)Top vent on Reactor Building In progress Enhancement of injection and heat removal (2)On-site Reservoir To RHR To SFP Off site power line Sea Filtered water tank & Purified water tank Filtered water tank In progress Heat exchange building Enhancement of protection for flooding (1)Embankment (2)Wall (3)Water-tight doors in Reactor Building Turbine building Completed at K-1,7 Reactor building Enhancement of power supply source (1)GT-driven generator truck (2)Emergency high voltage switchgear (3)Cable from emergency high voltage switchgear for RHR (4)Undergroud light oil storage tanks Completed (1) Additional monitoring cars (2) Additional warehouse for emergency materials on the hill All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 17

19 Completed To supply power during SBO - High voltage power trucks - Portable generators - spare cables Safety Measures at Kashiwazaki-Kariwa NPS Submerged pump Sea Spare gas cylinder Motor Control CenterCharger To open SRV -Spare gas cylinders -Spare batteries Fuel pool cooling pump Heat Ex Heat Ex SRV Completed PCV Reactor Clean up pump Reactor Building Spent Fuel Pool Completed To monitor SFP Water Level -Additional instruments Completed To inject water into RPV and SFP -Fire trucks -Spare hoses Completed Status at K-1,7 To Transfer water Filtered or Purified Water Tank to CST - Fire trucks Mobile power trucks Completed To vent PCV - Spare gas cylinders Low voltage Distribution PNL Battery Control Panel To Turbine Spare gas cylinder Containment Vent valve RPV Stand by Liquid Control System Pump RCIC pump Condensate Storage Tank Make-up water pump Diesel driven fire protection pump Purified water Transfer pump Legend Fire protection sys. Make-up water sys. RCIC Fire Truck Filtered water Tank Purified water Tank Fuel pool cooling sys. Reactor Clean up Water sys. Power line Sea All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 18

20 Emergency AC Power Source during SBO or loss of heat sink Status at K-1,7: Completed Assuring AC power supply in case of loss of existing power supply (offsite power/emergency diesel generator) 1)An emergency switchgear (HV switchboard) has been installed on a high ground with an air-cooled gas turbine generator car to supply power to the safety-related switchgear in the plant. 2)A power supply vehicle is prepared to supply power directly to the emergency switchgear or the safety-related switchgear in reactor building. 3)Procedures, tools and equipments are provided for the direct connection of power supply between the power supply vehicle and safety-related pump-motors in case of failure to implement 1) and 2). Seawater equipment building Turbine bldg. Pump ポンプモータ motor P/C 1) Power supply from air-cooled GTG via emergency M/C Reactor bldg. RHR Switchgear 3)Direct power supply to pump motor 500 kva power source vehicle 500kV 電源車 Emergency Switchgear * GTG: Gas turbine generator car 500 kva power source vehicle Air-cooled GTG 2) Power supply from power source car to switchboard in Reactor building All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 19

21 Emergency DC Power Source during SBO or loss of heat sink Status at K-1,7 : In progress RCIC is designed to operate for around 8 hours with DC power during SBO. TEPCO considered measures to extend the life of batteries to operate RCIC for long time. TEPCO evaluated that RCIC can actually continue operating for about 38 hours only with the battery (A) after assessing load of battery (A) in detail. RCIC can continue operating for about 72 hours with following steps 1) to 4). MCC 1H 125VDC Main bus board 1H 125VDC Battery 1H 500Ah MCC 1C VDC charging board 1A [DC power enhancement] 125VDC Battery 1A 4000Ah MCC 1C VDC main bus board 1A MCC 1D-1-1 Link with B system (Proposed - via aux. charging board ) AUX. AUX. AUX. Link with H system (Newly tied with a cable) 125VDC Charging board Aux. Connection of a temporary battery 仮設蓄電池 Temporary battery 125VDC Battery 1B 1600Ah MCC 1D VDC Main bus board 1B 1) To disconnect CVCF(A) from battery (A) 1 hour later, and disconnect DC lighting 8 hours later. 2) To disconnect CVCF(B) from battery (B) 1 hour later. 3) To connect tie-line between battery (A) and battery (B), 8 hours later, and connect tie-line between battery (A) and battery (H) about 36 hours later. 4) To add temporary batteries when the existing batteries are used up. All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 20

22 Emergency DC Power Source during SBO or loss of heat sink Status at K-1,7 : Complete The safety relief value (SRV) is opened to depressurize the reactor. Spare nitrogen cylinders are prepared in addition to the existing cylinders to supply compressed air for opening the valve. The portable battery is prepared as an alternative means in case that the power to open the SRV is lost. SRV Main Control Room or Reactor bldg. Temporary operation switch (SW) Temporary power supply Accumulato r SW + cable (Length: 30 m) 12VDC battery (Capacity: 56 Ah) Opening SRV using a battery All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 21

23 Further enhancement of power supply functions Status: Planning In addition to safety measures, TEPCO is planning to further enhance power supply function to extend SBO coping time without portable devices. Power source vehicle Install additional 125V batteries Emergency Switchgear Install additional generator, charger and batteries on the higher floor Reactor Bldg Prepared Control Bldg Additional special generator Special Charger 125V battery Control Room charger Additional 125V batteries (A) 125V battery (A) P/C(C) B1 MB2 B2 Seal type 125V batteries 250V Battery Main bus panel DC MCC M/C(C) Replace existing vent type 250V batteries with seal type 250V batteries for ensuring the room for additional 125V batteries All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 22

24 Further enhancement of power supply function (Plan) Status: Planning Load ~1h ~8h ~24h 24h~ ~72h RCIC auxiliary equipment Vital AC Power CVCF Power Non Safety I&C Safety I&C disconnect disconnect AC lighting Power Supply Battery (A) increased capacity Additional battery on the higher place Additional generator charger Supply Power disconnect Supply Power Supply Power All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 23

25 Summary The Fukushima accident was caused by the simultaneous loss of multiple safety functions due to far beyond design basis of tsunami. The main factors of the accident are the simultaneous loss of total AC power and DC power for a extended period of time and the loss of the heat removal function of the emergency seawater system for a extended period of time. Various countermeasures such as installation of Reactor Building Top vent, and preparation of mobile power vehicle and heat exchanger vehicle start to be implemented at Units 1 and 7 in Kashiwazaki Kariwa NPS. In those countermeasures, TEPCO enhanced or will enhance the power supply function to extend SBO coping time at Kashiwazaki Kariwa NPS. TEPCO is prepared to contribute to developing or revise IEEE standards in order to further enhance world-wide nuclear safety. All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 24

26 Thank you for your attention. All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 25

27 Website Information TEPCO English website TEPCO Internal Investigation Committee Final Report (June 20 th, 2012) English version will be on the following website soon. TEPCO Internal Investigation Committee Interim Report (Dec. 2 nd, 2011) Mid- to Long-Term Road Map Towards Decommissioning of 1F Units 1-4 (Dec. 21 st, 2011) INPO Special Report on Fukushima Daiichi Nuclear Power Station EPRI Fukushima Daini Independent Review and Walkdown NEI Article on Fukushima Daini All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 26

28 References All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 27

29 Inundated Areas at 1F Inundation throughout almost all areas where main buildings sited Units 1~4: Inundation height in areas where principal buildings sited: OP approx. 11.5m~15.5m (Localized inundation height in southwest area: OP approx. 16m~17m) Unit 5 & 6: Inundation height in areas where principal buildings sited: OP approx. 13m~14.5m Almost whole area was flooded Fukushima Daiichi Unit 6 Unit 5 Unit 1 Unit 2 Unit 3 Unit 4 Elevation of major Unit-5,6 buildings: O.P.13m Elevation of major Unit-1-4 buildings: O.P.10m Radwaste Processing building (C)GeoEye All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 28

30 Location of Openings from which Sea Water could Flow into Main Buildings (Fukushima Daiichi Nuclear Power Station) O.P.+4m O.P.+4m 6 号機 5 号機 Unit 6 6 号機 DG 建屋 Unit 5 O.P.+13m Unit 6 building Turbine building タービン建屋 原子炉建屋 Reactor building 1 号機 2 号機 3 号機 4 号機 Unit 1 Unit 2 Unit 3 Unit 4 O.P.+10m 運用補助共用建屋 : Openings at the ground level from which sea water could flow into buildings :Openings connected to underground trenches/ducts where sea water could flow into buildings 3u Emergency air inlet louver All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 29

31 Inundated Areas at 2F Inundation occurred throughout all areas along the sea, but it was not observed to have inundated over the slope and into areas where major buildings are sited. Run up of tsunami centered on the south side of Unit 1 Inundation height in sea side area: OP approx. +7.0~7.5m Inundation height in areas where principal buildings sited: OP approx. 12~14.5m Inundation height in area south of Unit 1: OP approx. + 15~16m Limited area was flooded Inflowed intensively Unit 4 Unit 3 Unit 2 Unit 1 Elevation of major Unit-1-4 buildings: O.P.12m (C)GeoEye All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 30

32 Location of Openings from which Sea Water could flow into Main Buildings (Fukushima Daini Nuclear Power Station) Inside Unit 1 heat exchanger building Units 3 & 4 Sea side of turbine building Heat exchanger building Turbine building Unit 4 Unit 3 Unit 2 Unit 1 Reactor building :Openings at the ground level from which sea water could flow into buildings :Openings connected to underground trenches/ducts where sea water could flow into buildings All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 3131

33 Intensity of the earthquake at the power stations In Fukushima Daiichi the observed data partially exceeded the maximum response acceleration with respect to the design-basis earthquake, however most data was below the baseline Observation Point (The lowest basement of reactor buildings) Horizontal (N-S) Observed Data Maximum Response Acceleration (gal) Horizontal (E-W) Vertical Maximum Response Acceleration against Basic Earthquake Ground Motion (Gal) Horizontal (N-S) Horizontal (E-W) Vertical Unit * 447 * 258 * Unit * 550 * 302 * Fukushima Daiichi Unit * 507 * 231 * Unit * 319 * 200 * Unit * 548 * 256 * Unit * 444 * Unit * Fukushima Daini Unit * 232 * Unit * 216 * 208 * Unit * 205 * 288 * *: The records were stopped approximately seconds after recording started. Note) Standard ground motion Ss: Seismic motion that was newly established to evaluate seismic safety, taking into account the earthquakes, etc., that could occur around the power station, based on the revised seismic design review guidelines. All Rights Reserved 2012The Tokyo Electric Power Company, Inc

34 Tsunami and 2F The new design basis Tsunami height for 1F & 2F were evaluated based on the JSCE Tsunami assessment methodology. (1F: O.P.+5.7m, 2 F: O.P.+5.2m) The countermeasures were implemented at both NPSs, such as pump motor elevation and openings that were all equivalent from the viewpoint of resistance against Tsunami hazard. The 15m class Tsunami caused by M9.0 class earthquake that accidentally attacked 1F was far beyond design basis and whatever evaluation and whatever countermeasures did not matter at this time. 1F 4 月 9 日記者発表 Design basis tsunami Assumed height highest tsunami O.P.+5.7m water level O.P. +5.7m - Base level O.P. 0m - 2F Design basis tsunami height O.P.+5.2m Ocean-side area Inundation height apx. O.P m Safety measures has taken against 5.2m Tsunami height Site level O.P. +4m Hx building Main building area Turbine building Reactor building Base level O.P.0m breakwater Water intake Site level O.P. +12m O.P.:Onahama Point All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 33

35 Permitted Design Basis Tsunami assessment Historical tsunamis of Iwate and Miyagi coast were larger than that of Fukushima Approved design basis at Fukushima NPS was m Historical tsunami heights (m) tsunami heights (m) Inundation Run-up Fukushima NPSs Fukushima NPSs Preliminary results by The 2011 Tohoku Earthquake Tsunami Joint Survey Group( 07 May 2011 Tsunami assessment in construction permit Unit Ground Level Tsunami Height m R/B,Tb/B m Pumps m Design Basis Modified in 2002 (2009) 11 march F (6.1) F F All Rights Reserved 2012The Tokyo Electric Power Company, Inc. 34