Nuclear risks from atmospheric dispersion in Northern Europe

Transcription

1 NKS NordRisk: Nuclear risks from atmospheric dispersion in Northern Europe Bent Lauritzen Risø DTU Presented at the NKS meeting March, Stockholm

2 NKS NordRisk NordRisk NordRisk II Objective: To provide practical methods for assessing and comparing nuclear risks due to long-range atmospheric transport and deposition = Simplified Probabilistic Risk Assessment

3 NordRisk project Probabilistic Risk Assessment (PRA) Risks from prolonged emissions: Total impact Risks from short term accidental releases: Risk ranking Emergency preparedness planning

4 NordRisk: Practical risk assessment for longrange atmospheric transport of radionuclides Participants: Risø DTU Danish Meteorological Institute Norwegian Radiation Protection Authority Danish Emergency Management Agency Swedish Radiation Safety Authority Geislavarnir Rikisins

5 Probabilistic Risk Assessment: Model independent PRA Model-independent PRA Based on historical data, e.g. Chernobyl Kuwait Oil Fires Volcano eruptions Statistical description regression analysis against simplified model mean value, fluctuations

6 Chernobyl 137 Cs fallout

7 Chernobyl 137 Cs fallout 0 c [kbq/m 2 ] 1 K-model: R = 00 km v = r [km]

8 Probabilistic Risk Assessment: Numerical PRA Source term r 0,q(t) NWP model data Meteorology v(r,t) Atmospheric dispersion model Radionuclide concentration field c(r) Probability density function p r (c)dc

9 Probabilistic Risk Assessment: Numerical PRA Source term r 0,q(t) Meteorology v(r,t) Atmospheric transport Concentration field r 0 r c(r) Probability density function p r (c)dc

10 Numerical PRA for atmospheric dispersion Shortcommings for long-range atmospheric transport Large numerical weather prediction model ensemble Complicated, time-demanding calculations Difficult to interpret Non-generic (specific to release characteristics, weather ensemble)

11 Probabilistic Risk Assessment combined approach Model-independent PRA Based on historical data, e.g. Chernobyl Kuwait Oil Fires Volcano eruptions Dispersion model calculations Statistical description regression analysis against simplified model mean value, fluctuations

12 NordRisk Objectives: 1. To provide a practical method for assessing and comparing nuclear risks due to atmospheric transport and deposition 2. to build an atlas of long-range atmospheric dispersion and deposition following a number of release scenarios in Northern Europe 3. to supplement this atlas with practical tools for rapid risk assessment for other (user defined) release scenarios

13 NordRisk Relevance: Build up competence in PRA; atmospheric dispersion Modelling and presenting variability/uncertainties Enhance collaboration: MetNet, NKS, End-users

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18 NordRisk Atlas Chernobyl release, Cs-137 deposition Cs-137 aerosol

19 Cs-137 aerosol I-131 aerosol I-131 gas

20 K-model regression Chernobyl release, dry deposition DERMA calcs. 20 Nic

21 K-model regression Chernobyl release, dry deposition K-model R = 4 km, v = Nic

22 K-model regression Chernobyl release, dry deposition Relative difference 22 Nic

23 gd(α) fd(r) Cs-137 Dry deposition CNP Regression analysis NZS scaled deposition density (m-2) SEL Five release sites: Novaya Zemlya Chernobyl Sellafield Savannah River Sinpo SIN -3-6 R 400 km v SVR distance (km) angle (rad) Nic

24 NordRisk Atlas. Fluctuations Leningrad, 137 Cs deposition (1985) 1.0E E E E+01 p(c/<c>) 1.0E E E-02 frequency gamma fct. 1.0E E E E E E E E E E E E+02 c/<c>

25 Short term releases: 24 hrs Leningrad, 137 Cs deposition (1985) 1.0E E E E E+01 p(c/<c>) 1.0E E E E-03 frequency gamma fct. 1.0E E E E E E E E E E E E E E E E+04 c/<c>

26 Short term releases: 24 hrs Leningrad, 137 Cs deposition (1985) 1.0E E E E E+01 p(c/<c>) 1.0E E E E-03 frequency gamma fct. 1.0E E E E E E E E E E E E E E E E+04 c/<c> pc ( > 0 c) 3

27 Fluctuations depend on Modelling assumptions source term release duration Risk indicator Spatial scale of averaging Add uncertainty

28 Chernobyl I-131e, air

29 Chernobyl Cs-137, air

30 Novaya Zemlya Cs-137, dep.

31 Novaya Zemlya Cs-137, air

32 Novaya Zemlya I-131e, air

33 Chernobyl Cs-137, dep.

34 NordRisk Some conclusions Atlas over long-range atmospheric dispersion Selected NPP s, radionuclides, meteorological data Mean values, variability Statistical analysis K-model gamma model Software tool K-model with user-defined parameters

35 NordRisk II - project plan Extended atlas: More release sites, NPPs in Northern Europe Detailed topography, climatology, specific to Nordic countries Other risk indicators Total deposition, air concentration Dry, wet deposition travel time, fast transport patterns. Statistical analysis Mean value and fluctuations Assessment of global dispersion parameters Default parameters for simplified PRA Preparation of data in a format suitable for ARGOS DSS Emergency planning, education

36 NordRisk II New super computer at DMI, Cray XT5 AMD Opteron Quad- Core Microprocessors Two identical systems Each system contains 256 computer nodes (8 cores), in total 4096 cores Peak: 38 Tflops Memory: 8.2 TBytes Disk: 1 TBytes

37 NordRisk II The performance of the new super computer at DMI is effectively -20 times faster than the previous one, which was employed during the NordRisk project. This will allow producing an extended risk atlas covering more release sites in the course of the current NordRisk II project. These risk sites will be selected according to their relevance for risk assessment in the Nordic countries. The calculated concentration and deposition fields will be made available in a format enabling import in the ARGOS nuclear decision support system.

38 Thank you for your attention