NRC Protective Measures Team Fukushima Challenges; RASCAL 4.2 Update

Transcription

1 NRC Protective Measures Team Fukushima Challenges; RASCAL 4.2 Update National Radiological Emergency Preparedness Conference Lou Brandon April 24, 2012

2 EPA Protective Action Guidelines US Protective Action Decisions occur during Early Phase (0-96 hrs), Intermediate Phase (96 hrs- few months), and Late Phase (beyond few months). Evacuation and sheltering, relocation, and ingestion pathway modeling considerations are explored. Reflecting on the Fukushima incident can provide valuable insight into the challenges we might face in this country. 2

3 NRC Response Teams Executive Team Reactor Safety Team Protective Measures Team Does Independent assessment of Licensee Protective Action Recommendations. Liaison Team Safeguards Team Support Teams 3

4 Quake & Tsunami All times in this presentation are Japan Time 3/11, 14:46 Quake 18:00 Fukushima Unit 1, cooling issues Japan Times 5/16 19:30 Fuel rod damage 3/12 6:50 Unit 1 core significantly damaged (quake +16 hours) Core melt sequence still being analyzed 15:36 Explosion (quake + 25 hours) TEPCO Press release 3/13 19:00 Injecting Seawater Unit 1 NYT June 12 4

5 Initial NRC Assessments Informed water level 50 cm below fuel top Rough starting point - model 10% core melt 3/12, 14:53, Unit 1 Explodes RASCAL: using Generic Fukushima location Total fuel melt, 100%/hr release EPA PAGs exceeded beyond 50 miles Winds and forecast primarily from the SW 21:00 1 st RASCAL run,10% core melt, unfiltered, roughly models ground data 5

6 What is RASCAL? 6

7 Release Pathway 7

8 Example: Thyroid dose to 10 miles for 4 mph - D stability V3.0.5 V4.0 Much Improved Atmospheric and Transport Dispersion Model in V4 8

9 RASCAL model differences in thyroid doses for a core uncovered scenario with differing met conditions Conditions Ratio R4/R305 for thyroid dose at 5 miles 4 mph, D stability 27% 15 mph, B stability 31% 4 mph, G stability 16% 8 mph, D stability, Rain 24%

10 Public Health & Safety 1 st Priority Radiological details of degrading situation were sparse and inconsistent 3/14 Unit 3 Explodes (11:01, winds at times to the SSW toward Tokyo) INPO Report 3/15 Unit 2 loud noise & Unit 4 explode (06:00) Note - (JAEA International Workshop, 2/22-23/2012) estimated release from Unit 2, 1E+17 Bq/h, 13:00-17:00, on March 15, toward NW, or about 10.8E+6 Ci total. 10

11 Protective Action Decisions IAEA June 3/11 20:50 Fukushima Prefecture U1 lost cooling 18:00 Evacuate 2 km radius around Dai-ichi 21:23 NER HQ Prime Minister Nuclear Emergency Response HQ Evacuate 3 km radius, shelter to 10 km 3/12 05:44 Evacuate 10 km radius (Unit 1 Containment pressure increasing) 18:25 Evacuate to 20 km (15:36 explosion) Winds still blowing off shore from the west 3/15 11:00 Shelter 20 to 30 km radius 11

12 Ground Contamination Level? Ministry of Education, Sports, Culture, Science and Technology (MEXT) Difficulty first staging field teams 3/14 30 µsv/h in some areas (1 st data) IAEA Approximately 4-5 µsv/h from deposition in an early release scenario equates to the 20 msv annual relocation dose limit 12

13 Measurements beyond 100 miles Swipes indicate Cs and I present Air samples collected initial estimates Approx 3-17 mrem/hr Thyroid CDE 12 hr TEDE: 20 mrem, Thyroid CDE: 200* How long will the releases last? What protective actions are appropriate? * Calculation confirmed 13

14 Early Insights, Meteorological Data Were Limited From 3/16-3/18 wind forecast was from NW and W Chart can be re-constructed from online MEXT Data 14

15 US Travel Advisory Situation deteriorating quickly Lack of information from Japan US NRC recommends 50 mile evacuation zone 3/16 3/15 20: µsv/h Namie (20 km NW) IAEA 3/22 RASCAL reconstruction w/flyover data Models 290 µsv/h at 22 km, 3/15 20:45 TEDE km (20 miles) Thyroid CDE km (10 miles) Thyroid CDE km (with out rain) 15

16 Coordination DOE\NARAC NRC sent parts of source terms to NARAC Office of Science and Technology Policy Naval Reactors US Embassy in Japan Other Federal Agencies Canada\France\UK & others 3/15 23:00 Japan officially accepts US help DOE AMS deploys 16

17 RASCAL Modeling Limitations Limited to assess 1 unit at a time Limited: ad hoc approach to % fuel melt Limited: 48 hour calculation (release) time Can t view deposition/gr values beyond 48 h Limited: 48 hour holdup time before release Containment Source term held up 24 h -> ~ 3% Limited: only 1 fresh batch in SFP No original saved case preservation Saved cases did not identify creator 17

18 First Flyover on 5/17 between Dai-ichi and Tokyo area 18

19 U2 33% Core Damage/Melt based on Flyover Data Wind forecast was mph toward NW for about 12 hrs during 3/15 PM RASCAL reconstruction Light rain over 12 hours reduced long range impacts 19

20 Plume Phase Dose Projections 1.6E+07 Ci 20

21 US Travel Advisory 3/16 DOS authorizes voluntary departure from US Embassy, Yokohama, other areas 4/14 lifted voluntary departure allowing US dependants to return We continue to recommend that U.S. citizens avoid travel within the 50-mile radius of the Fukushima Daiichi Nuclear Plant. U.S. citizens who are still within this radius should evacuate or shelter in place. 3/16/2011 NRC press release 21

22 Deliberate Evacuation Area 4/22 30 days to move out Evacuation Prepared Areas By 3/22 Hospital and Nursing Homes relocated voluntary evacuation requested of others (lifted September 30) Evacuation Area 4/22 Restricted with Penalties 22

23 2nd Year Relocation Guidance (500 mrem) also corresponds to yellow zone. Japanese acted to relocate 20 msv/yr (Red) zone. 23

24 In USA, is 2 nd Yr PAG limiting? Ideally, 2 nd year relocation zone may shrink due to decay and weathering to become no larger than 1 st year zone at the beginning of the 2 nd year. RASCAL predicts (with weathering) 2000 mrem 1 st year would become about 1300 mrem 2 nd year (might not get to 500 mrem). Could decrease in Fukushima dose rates suggest that ideal may occur? 24

25 Soil Sample (5/1, released 5/31) Sample Data Sample ID: Sample desc: Sample type: Oaza 7 km W Soil Ground concentrations Nuclide Ground Conc ( Bq/m²) I E+06 Cs-137* 1.20E+06 Cs E+06 Cs E+04 Sr E+03 Sr E+02 Te-129m 1.75E+06 Soil samples were taken by MEXT, 5 cm diameter, 15 cm deep. Lab results were converted to surface deposition and modeled with RASCAL Intermediate Phase Doses ( rem) 1st Yr Exposure 1st Year 2nd Year 50 Years with Delay Groundshine 5.35E E E E+00 Inhalation 5.88E E E E-05 Total 5.35E E E E+00 Notes Reentry delay was 90 days 1st year PAG = 2 rem, 2nd year objective = 0.5 rem, 50 year objective = 5 rem 25

26 RASCAL Models Ground Deposition Soils Collected 6/6-7/8 RASCAL reconstruction (slide 19) predicts a Cs-137 concentration of about 3600 KBq/m 2 at 30 km, center line NW. (within factor of 2) 26

27 MEXT Monitoring Points 6/17/11(~25%) MEXT Data Pt 32 Pt 33 Pt 79 (~30 km NW) (µsv/h) (µsv/h) (µsv/h) 3/25/ /17/ /16/ /31/ Is the large decrease in rates from December 16 due to weathering? This is apparently from snow cover in January. 27

28 May 6, 2011 (measured 4/6-29) Dose rate at the beginning of the 2 nd year that will yield 500 mrem/yr from Cesiums is about 1.0 usv/h based on RASCAL projections 28

29 September 12, 2011 (measured 8/16-28) Now it is the dark green area that corresponds to the 2 nd Year Relocation Zone (shrinking). 29

30 Not much change in the dark green area that corresponds to the 2 nd Year Relocation Zone (still shrinking?). 11/1/2011 Legend Air dose rate at 1 m above ground level (Sv/h) [Converted into the value as of November 1] 30

31 Factoring in weathering and a 40% sheltering credit for time indoors, additional 2nd year relocation concerns are minor. Figure 6: Areas corresponding guidance for relocation in the first year and any year after the first year where it has been assumed that there is some reduction in dose because of time spent indoors. It is assumed that the dose integration time for the first year would span from 15 November 2011 through 14 November

32 Relocation Decision Practice Relocate 1 st year zone based on 2 rem/yr Can predict where 2 nd year may be exceeded But may underestimate all reduction effects May be premature to relocate 2 nd year zone at the beginning of the 1 st year. Helpful government and public remediation efforts may occur. Higher dose levels may be acceptable for the circumstances 32

33 50 Mile Zone Relaxation 5/16 US Updates Travel Advisory Highway and Train, Tokyo to Sendai, Open 6/6, Coast Guard announced vessels should avoid transiting waters within 20 km (relaxed 50 mile - water) 7/19 Sendai airport cleared for US citizen use US DOS, Oct 7, 2011: Based on current data from Japan, we recommend that U.S. citizens avoid all unnecessary travel to areas within 20 kilometers of the Fukushima Daiichi Nuclear Plant. In addition, U.S. citizens should avoid all unnecessary travel to the area northwest of the plant that the Government of Japan has designated as the Deliberate Evacuation Area. 33

34 Food Protective Actions Guidelines Nuclear Safety Commission of Japan Provisional values updated 2007 Indices relating to limits on food and drink ingestion Nuclide Radioactive iodine Index values relating to ingestion limits in guidelines for coping with disasters at nuclear facilities etc. (Bq/kg) Drinking water 300 Milk, dairy products* Vegetables (Except root vegetables and tubers) 2000 Drinking water Radioactive cesium Milk, dairy products 200 (Sum of Cs-134 and Vegetables Cs-137) Grains Meat, eggs, fish, etc. 500 * Provide guidance so that materials exceeding 100 Bq/kg are not used in milk supplied for use in powdered baby formula or for direct drinking to baby. US FDA Derived Intervention Levels (Bq/kg) Radionuclide Group DIL Sr I Cs group 1200

35 Samples Water 3/23 Press Release Water supply exceeding the level of the Index values for infants (radioactive iodine) (Reference 3): Kawamata-machi (town) Water Supply Utility: 1 point, 174 Bq/kg (on March km NW), Minamisoma-shi (city) Water Supply Utility: 1 point, 137 Bq/kg (March km N), and Iwaki-shi (city) Water Supply Utility: 1 point, 103 Bq/kg (March km S) Water supply exceeding the Index values for infants (radioactive iodine) (Reference 3): Kanamachi Treatment Plant (1 point, 210 Bq/kg (March km SW)) After receiving the survey results, the Ministry of Health, Labour, and Welfare (MHLW) requested that Iwaki-shi (city) and Tokyo Metropolitan Government inform their residents using water supply in the relevant areas in Iwaki-shi (city) and Tokyo to refrain from having infants intake tap water (including giving infants formula milk dissolved by tap water, etc.) today. City Distance Water (km) (Bq/kg) Kawanata-machi 59 NW 174 Minamisoma-shi 29 N 137 Iwaki-shi 52 S 103 Kanamachi 238 SW 210?

36 Samples - Food I-131, Cs-134, Cs June-11 Fukushima Iwaki-shi 13-June-11 lefteye flounder ND June-11 Fukushima Iwaki-shi 13-June-11 slime flounder ND June-11 Fukushima Iwaki-shi 13-June-11 righteye flounder ND June-11 Fukushima Iwaki-shi 13-June-11 stone flounder ND June-11 Fukushima Iwaki-shi 13-June-11 spotted halibut ND June-11 Fukushima Iwaki-shi 13-June-11 hippoglossoides dubius ND June-11 Fukushima Iwaki-shi 13-June-11 horse mackerel ND June-11 Fukushima Iwaki-shi 13-June-11 greenling ND June-11 Fukushima Iwaki-shi 13-June-11 brown hakeling ND June-11 Fukushima Iwaki-shi 13-June-11 greeneyes ND June-11 Fukushima Iwaki-shi 13-June-11 japanese common flying squid ND ND June-11 Fukushima Iwaki-shi 13-June-11 swimming crab June-11 Fukushima Iwaki-shi 13-June-11 hen-clam ND June-11 Fukushima Iwaki-shi 13-June-11 abolone June-11 Fukushima Iwaki-shi 13-June-11 northern sea urchin ND Cs limit 200 Bq/kg (includes 10% allowance for Sr) Ocean bottom feeders exceeding limits? Make sense?

37 Food Controls MLHW Press Release 4/4/2011 In General: Prefectures guide local/district sampling Sample food types once per week Adjust frequency as needed Multiple samples, multiple areas, averages Nat l, Prefecture, and private laboratories Foods embargoed by type Food must pass three successive tests

38 Fukushima City Asian Leaders Japan Times 5/22

39 Progress of the Roadmap for Immediate Actions for the Assistance of Residents Affected by the Nuclear Incident NER HQ, November 17, 2011, P 11 5) Implementation of monitoring for radioactive materials in food and tap water - Regarding radioactive materials in food and tap water, the relevant local 12 governments are conducting ongoing examinations, and the results are being disclosed daily by the Government. (*) Of the 49,474 cases of examination for food, 865 cases exceeded the provisional regulation limit (as of November 5), and of 56,833 cases of examination for tap water, 69 cases exceeded the indicator values (as of November 4). There have been no instances of tap water level exceeding the limit since March 30.

40 New Radiation Safety Levels The Japanese government has announced new radiation exposure and ingestion limits targeted to become law in April. The current level for food cesium contamination in food, currently set at 500 Bq/Kg, will be lowered to 100. The limit for milk will be brought down from 200 Bq/l to 50, and for drinking water the new limit will be just 10 Bq/l, down from

41 RASCAL 4.2 Released 3/26/2012 User Interface Very Similar Release Notes Include Details of many fixes, updates and improvements 41

42 Intermediate Phase Doses (rem) Pathway 1st Year 2nd Year 50 Years Groundshine (FGR-12) 1.58E E E+01 Submersion (FGR-12) 4.41E E E-05 Effective Inhalation (FGR-11) 2.48E E E-03 Total 1.59E E E+01 Delay TEDE Remainder (rem) Before 168 h/wk in area with 0% in bldg Return 1st Year 2nd Year 50 Year 0 d 1.59E E E+01 1 d 1.58E E E+01 2 d 1.58E E E+01 4 d 1.56E E E+01 7 d 1.55E E E d 1.53E E E d 1.51E E E d 1.43E E E d 1.28E E E d 1.13E E E d 7.21E E E d 3.52E E E y 0.00E E E y 7.76E E y 4.96E E y 2.36E E y 0.00E E y 7.30E y 6.70E y 6.21E y 4.62E y 2.73E y 1.47E y 6.00E-01 FM Dose screen Example 10 µci/m 2 Cs-137* and 10 µci/m 2 Cs-134 Return after 10 years would yield less than 5 rem in next 40 years. 42

43 RASCAL TurboFRMAC Consistency 43

44 Different Iodine DCFs The iodine DCFs are different because the RASCAL Iodine DCFs are a weighted average of the 1 micron particle DCFs (25%) and the vapor DCFs (75%) whereas the TF 2011 DCFs are the 1 micron particle DCFs. The weighting of the vapor and particle DCFs in RASCAL is based on the RASCAL assumption related to the forms of iodine in the environment [25% particle, 35% reactive gas (e.g. I 2 ), 40% non-reactive gas (CH 3 I)].

45 V4.2 Source Term Re-construction Table 1.14 RASCAL 4.2 Estimates of Fukushima I-131 and Cs-137 Releases Unit 1 Unit 2 Unit 3 Total I-131 Inventory (Bq) 1.36E E E E+18 I-131 Release (Bq) 4.85E E E E+17 I-131 Release Fraction 3.6% 4.0% 2.4% 3.3% Cs-137 Inventory (Bq) 1.02E E E E+17 Cs-137 Release (Bq) 4.10E E E E+16 Cs -137 Release Fraction 4.0% 5.1% 3.0% 4.1% The important point is that this analysis demonstrates that RASCAL has sufficient flexibility to make reasonable estimates of the Fukushima release rates even with the complexity of the accident scenario. Van Ramsdell, RASCAL Tech Doc 45

46 Importance Version 1.0 March 28, radionuclides Relative Importance of Pathways Days gs 1.000E E E E E E E E+00 cs 3.957E E E E E E E E-08 inh 1.159E E E E E E E E-05 Importance to dose at t = 0. days Ground shine Inhalation Submersion 1 I I I I Sr I Rb Pu I I Sr Kr Cs I Xe Te Cm I Te-131m Te Rb La Cs Xe Cs Ce-144* Cs I Cs-137* Te Sr Ru-106* Te-131m Ba Ba La Sb I Cs Importance to dose at t = days Ground shine Inhalation Submersion 1 Cs-137* Sr Cs-137* Cs Pu Cs Y Am Y Sr Cs-137* Sr Ru-106* Cs Ru-106* Am Y Am Ce-144* Pu Ce-144* Pu Ru-106* Pu Pr Pu Pm Pm Ce-144* Pr Pu Pm Pu Pu Cm Pu Cm Te-127m Cm Prototype: Bad Actors Ranked by Dose over Eight Time Intervals and Three Pathways 46

47 On the Horizon Standard Interface for importing or exporting of source terms. Prototype for processing multiple units Restructure RASCAL to run for longer time frames Include State of the Art Reactor Consequence Analysis (SOARCA) source terms Improved alliance with NARAC and others 47

48 Questions Lou Brandon Athey Consulting (304)