Lessons learned from the Fukushima Accident

Transcription

1 FORGING A NEW NUCLEAR SAFETY CONSTRUCT WORKSHOP December 3-5, 2012, USA Session 4 Public Protection Lessons learned from the Fukushima Accident Shigeo NOMURA President 1

2 [1] Emergency response training and exercises based on more realistic accident scenarios Factors to be considered for Operator s ER Training & Exercises based on TEPCO 1F Severe Accident (SA) 1. External events - Catastrophic natural disasters; Multiple & Sequential 2. Internal events - single failure for multiple NPPS 1) Station Black Out, 2) Loss of Ultimate Heat Sink, 3) Uncontrollable operation 3.1 Early stage procedures - Detection & prevention of SA by plant diagnosis - Flexible accident management & damage control for multiple failures - On-site & off-site warning & restriction 3.2 In the progress of SA - Mitigation for core meltdown and hydrogen explosion - Adjust local resident emergency plan with environmental release of rad. materials by leakage, bending, and hydrogen explosions 3.3 Post SA - Stabilization of SA, Radiation monitoring & control, Minimization of environmental impact,. 2 2

3 [2] Developing an updated technical basis for emergency planning zone size Trend of Ambient Dose Rate within 80 km from 1F NPPs June, 2011 to March, 2012 KURAMA Automatic automobile radiation monitoring system with GPS 0.02 [μsv/h] Km High dose area exists in the semi-circular shape, not a concentric circle. This result is reflected to determine the emergency planning zone; PAZ, UPZ. (changed from past 8-10 km to 30 km after nuclear accident) - Zone size depends strongly on source term, geography, & weather condition. 4

4 [2] Developing an updated technical basis for emergency planning zone size Nuclear Regulation Authority (NRA) released the updated Preparedness & Response for Nuclear Emergency Oct 31, Divide stages for emergency - Initial stage: EAL (Emergency Action Level) - Post radioactive release: OIL (Operational Intervention Level) 2. Area to be determined - PAZ (precautionary Action Zone) 3~5 km - UPZ (Urgent Protective Planning Action Zone) 5~30km, > 100 msv for 7 days - PPA (Plume Protection Planning Zone) > 30km, local spot Local emergency plan will be fixed on the simulation data by using NRC-MACCS2 3. Preparedness for plant operator - Strengthen Level 4 & 5 defense-in-depth - Robustness for on-site information gathering and transfer - Drills & Training 4. Establish multiple information transfer lines for local public 5. Establish robust emergency radiation monitoring, medical control, etc. 6. Mid, long-term procedure for reentry, clean-up, monitoring, health check, etc

5 Annual Dose Rate (msv/y) [3] Resolving the linear no threshold (LNT) problem in radiation protection - science vs. economic and social dimensions Japan s Basic Policy for Emergency Response on Land Decontamination Work based on ICRP decided by Nuclear Emergency Response HQ, Aug.26, 2011 Refer: 1) K. Moriya: Fukushima Office for Environmental Restoration, Ministry of the Environment 2) MEXT monitoring of air dose rate data Emergency Exposure State - Deliberated evacuation areas - Restricted areas Existing Situations Reduce < 20mSv/y - Large wide area decontamination30km - Intensive decontamination for hot spots (roadside drains, gutters, etc.) by government initiatives for re-entry of residents 20km NW from 1F 40km 60km & Others by Municipal government plan with nation s budget & expert supports Reduce 1 msv/y Long term goal (μsv/h)

6 [3] Resolving the linear no threshold (LNT) problem in radiation protection - science vs. economic and social dimensions Resident Self Efforts to improve the Existing Situations - Solve concerns for long term low dose consequences - Off-Site Clean-up Efforts Handy type rad. monitor Risk Communication with Residents Weather integral radiation monitor Whole Body Inspection All Foodstuff Inspection Current radiation protection is based on resident daily life and self-check mechanism. To judge scientifically for low dose health effect, probability approach is difficult to understand for public. It is necessary to recover the confidence for specialist and science itself in Japan after Fukushima. 7

7 Appendix

8 [1] Emergency response training and exercises based on more realistic accident scenarios Off-rmal Procedures for Nuclear Severe Accident in Fukushima s case - Plant operators and agency people focused to obtain onsite plant information, prevent the worst case and mitigate the sequential severe accidents. - On-site emergency was controlled in the independent seismic, radiation proof command facility. - Public protection was forced to judge by the limited information under the inadequate diagnosis for 1F NPP conditions. - Several steps of evacuation (2, 3, 10, 20km) and sheltering (20-30km) were implemented for each events of loss of cooling, pressure increase, risk of multiple AS. 8

9 [1] Emergency response training and exercises based on more realistic accident scenarios Factors to be considered for Off Site Local s ER Training & Exercises based on TEPCO 1F Severe Accident (SA) - Information vacancy districts due to 1) blackout for several days, supported by Emergency Generator 2) difficult connection by over accessed mobile phone 3) collapse of city hall, off-site center for data gathering 4) Car radio,tv,etc. were the only available media sources. - Self protection and collaboration in the unit of each communities for 1) loss of accommodations 2) shortage of water, food, oil & gas 3) severe damages of supply chain & transportation system 4) evacuation from NPP severe accidents Wide range flexible rescue was key action to mitigate them.

10 The Effect of the Nuclear Disaster at Fukushima Dai-ichi NPP on Local Governments M.Nakamura & K.Dake; J.AESJ, 647, Vol.54,2012 Local Goverment Futaba -cho Okumacho Naraha -cho Tomioka -cho Minami soma-city Namie -cho Electricity supply after 3.11 EG EG EG, move? EG Available TEL,FAX 1, 1 1, 1 OK 1Satellite OK NPP Inform. from TEPCO hing A few hing hing hing hing Emergency Declaration 3/11 19PM Evacuation 2km by prefecture 3/11 20PM Evacuation 3km Sheltering 3-10km 3/11 21PM Evacuation 10km 3/12 5AM Evacuation 20km 3/12 18PM Evacuation 20km Sheltering 20-30km 3/15 11AM FAX From TV TEL from Gov. FAX indication of the direction, place, method of evacuations from Government & Prefecture.

11 Wide Spread of Cs Air borne Monitoring of Radiation Dose Rate (v. 2011) 80km 9-17 msv/y msv/y 30km 20km >170 msv/y 1F NPPs 1m above ground level (μsv/h,v.5, 2011)

12 How effect the health more than 100 msv? Probability of Death by Cancer (%) % 1% 1.5% Distinct results can t be observed below 100mSv. Increase by radiation Cancer by daily life habits (Smoking, Drinking, Virus, Germ,,,,) Accumulated Dose (msv) When 1,000 persons receive 100 msv, death by cancer increases possibly 300 to 305 persons for their lifes. Refer NIRS HP

13 Weather Integrated Radiation Measurement Device - New device can measure the weather conditions and the air dose rate together in the same point. - It works long time in any place; urban area, mountainous district. by independent solar energy. Fukushima prefecture : Demo-type ( 3units ) : Proto-type ( 4units ) Fukushima Daiichi NPPs Weather observation item Radiation measurement Solar battery Transfer of observed data Transfer of still picture Position information Device size Specifications Temperature, Humidity, Atmospheric pressure, Amount of rainfall, Wind, direction & velocity Detection element:silicon semiconductor Type of radioactive ray:γ-ray Measurement range:0.01~ 99.99μSu/h Energy range:60kev~1.25mev DC12V-85W 10 minutes interval 10 minutes interval GPS system Height 2.8m, Weight 50kg NTT FOMA Internet System server Developed by Yamada Giken co,ltd & JAEA collaborative research.