Guidance and EU experience on Site Permit issuance of NPPs

1. Guidance and EU experience on Site Permit issuance of NPPs Regulatory review of siting requirements for meteorology and radioactive releases - Finnish experience VN/RA/01 Task 1&2 Workshop Hanoi, October 2012 Confidential Ilari Aro STUK

2. Siting – list of topics to bereviewed • Site effects in plant design • site characterization: meteorology • Radiation safety • dispersion • Emergency planning • protection / evacuation • Interaction with land use planning – population issues

3. Nuclear power plants in Finland • Olkiluoto NPP (TVO) • 2 operating units - ABB BWRs • New EPR under construction • EIA completed for a new unit • Loviisa NPP (Fortum) • 2 operating units - VVERs • EIA completed for a new unit • Fennovoima Ltd • EIA completed for a new unit

4. Calculating and measuringradiationreleases • Guide YVL 7.1sets out in moredetail the Council of State'sregulations for radiationexposure and release limits. Itsetsforth the general requirements for analysismethods, for exposurepathways to beexaminedbydosecalculation and for the evaluation of individual and collectivedoses to the population. • Guide YVL 7.3presentsdetailedrequirementsapplicable to the conducting of analyses on the dispersion of radioactivereleases and Guide YVL 7.2setsforthdetailedrequirements for the calculation of individual and collectivedoses to the population. • YVL 7.5presentsrequirements for meteorologicalmeasurements. • YVL 7.6 and YVL 7.7concernsradioactive release measurements and radiationcontrol in the environment. • Whenradiationdoses to the surroundingpopulationarecalculated, the region'sspecialcharacteristics--hydrological, geological and meteorological--aswell as the livingconditions and habits of the populationshallbeconsidered.

5. Objective of meteorologicalmeasurements • Meteorological measurements in the vicinity of a nuclear power plant are needed to assess the dispersion of the releases of radioactive materials in the atmosphere in the following cases: the releases of radioactive materials to be considered in the safety analyses of a nuclear power plant; the releases caused by the normal operation and transients of a nuclear power plant; the releases caused by accidents of a nuclear power plant. • Safety and accident analyses, which are carried out as early as in the design and construction phases of a nuclear power plant, utilize meteorological data that represent the site concerned. These data are complemented by meteorological measurements conducted in the vicinity of the plant. • The data on meteorological conditions and radiation dose analyses are needed to plan and conduct rescue operations in the emergency planning zone and to assess the timing of a potential controlled release of radioactive materials. In addition, the authorities make national dispersion and dose predictions concerning a more extensive area and, possibly, similar predictions affecting other countries.

6. System requirements • The meteorological measurement system of a nuclear power plant shall have a sufficient and representative number of observation stations, considering the local environmental factors. Observations of other meteorological stations located in the near-field of the nuclear power plant and of FMI can also be used to assess the dispersion of radioactive materials in the environment. • The meteorological measurement system shall function reliably under all anticipated environmental conditions. The power supply of the measuring and data transmission systems shall be secured by an independent system for a sufficiently long time. In addition, the measuring and data transmission systems shall be doubled where necessary. For this purpose, the functions that must tolerate a single failure shall be specified. Ref. to YVL Guides 2.0 and 5.5. • The structures of the weather mast shall withstand a maximum load caused by the extremely exceptional wind and freezing conditions (there is a 95% probability that the frequency of occurrence is as high as or higher than the statistically calculated load once in a hundred years).

7. Measurementsrequiredby STUK • Wind velocity: • ±0.2 m/s at wind velocities of less than 2 m/s (lowest detection limit of the measurement 0.4 m/s) • ±5% at wind velocities higher than 2 m/s • Wind direction: ±5° • Temperature: ±0.15 °C • Temperature difference: ±0.2 °C/100 m • Precipitation: ±0.2 mm • Time of precipitation: ±5 min • Air pressure: ±0.3 hPa (mb) • Relative humidity: ±5%

8. Meteorologicalconditionsdescribed in SAR • The PSAR shall contain a description of the meteorological conditions in the area and the mesoclimate. The description shall include the wind distributions, stability classifications and mixing height values at different times of year, which indicate the dispersion conditions in the area. • Furthermore, the report shall include a plan for the meteorological measurements to be conducted at the plant site and in its vicinity. • In addition, the FSAR shall contain an account of the meteorological conditions in the area, which is drawn up on the basis of measurements conducted during a period of at least one year and other available data, as well as an updated climate report. • The data contained in the FSAR shall be complemented at regular intervals on the basis of measurements carried out in the nuclear power plant area during operation.

9. Meteorology for emergencypreparednessRef to Markku Seppänen, FinnishMeteorological Institute • STUK usesFinnishMeteorological Institute (FMI) for meteorologicalsupportduringemergencies. • There is a directlinkfrom FMI supercomputer to STUK to getreal-timeweatherinformation and dispersion estimates for allNorthernNPP’sfourtimes per day to have a realistic, immediate release estimate in case there is an accidentgoing on in NPP. • Thishelps a lot for planning the immediateresponse to such an eventoraccident. Accurateweatherinformationincludingrain is crucial in doseestimationduringemergencies. • STUK hasdevelopeditsown release models / programs and utilizesEuropean RODOS model as well in radiationexposurecalculations. FMI /VTT hasalsodevelopeditsown dispersion model SILAM that is publiclyavailablethrough FMI web-pages. FMI is alsowilling to consult on installationif/whenassistance is needed. • Weathermast is needed at NPP site for measuringmeteorologicalconditionssuch as windspeed and direction, temperature, stabilityclass definition, precipitationetc

10. Principlepicture WeatherMast at NPP

11. Measuringmethods for stratification in the surfacelayer of atmosphere and for rain • Stability (class) is an importantparameter in a emergencysituationthat describe turbulentconditions at the site. Itcanbecalculated of temperature and windobservations. Differentcalculationmethodsgivedifferentresults. Finnishsolution: on line-calculations on the maststation and at FMI. • In a emergency situation it is also important to know rain conditions over the whole potential risk area. Rain wash out radioactive particles of the atmosphere. • There are in situ measurements on the weather stations. Station observation don't know anything what is happening between stations. Weather radars are available for areal observing of rain. Extrapolation is possible.

12. Example of weather radar networkpicture (FMI) Light Moder. Heavy

13. Dispersion modelling: SILAM – system in Finland (FMI) • Forecasts for potential risk area, dose rate, doses etc. Simulate turbulent transport and dispersion of nuclear gases and particles in atmosphere. Canbecalculatedwith long timeweathermodel data. As good as the numericalweather data used in dispersion model. SILAM-model home page: silam.fmif.i • FMI makesautomaticmodelruns for Finnish and nearbyNPP’s 4 times/day – results to STUK • Everydutymeteorologistcanmakecalculations. Nuclearsituation center officerscanmakemorecalculations. STUK’sexpertscanuse SILAM to test and calculatewithdifferentsourceterms. • Easy to supplymodelproducts to RescueOfficers and otherrelevantauthorities. FMI Consulting Services hasusedSILAM-systemwithsuccesswithsomesiteevaluationproject in Europe.

15. Acceptance criteria for radioactive releases / max doses to general public– needed meteorological data • Normal operation: radiation dose limit 0,1 mSv / year • Reliable statistical meteorological data over the year • Anticipated events: radiation dose limit 0,1 mSv • Design basis accidents: radiation dose limit 5 mSv • Design extentionconditions: radiation dose limit 20 mSv • Conservative stability class for radiation dose calculation • Severe accidents: no acute health effects, tolerable long term contamination: Cs-137 release < 100 TBq • Growing season and non-growing season • PSA Level 3 • Reliable statistical meteorological data over the year • Emergengy response • Real time weather data

16. Dose assessment models developed by VTT • ARANO (PRA3-code): was developed and used for NPP site evaluation studies in 1975-76 in co-operation with the Finnish Meteorological Institute (FMI). The model can be applied within distances up to 100 km). • ROSA: emergency preparedness support tool for real time dose assessments in the vicinity of the plant (up to 20 km distance). Model is based on ARANO code and utilizes real time weather data with 10 minutes intervals. Model is still operational at Olkiluoto • TRADOS: 1983; long-range dispersion and dose assessment tool • SILAM: long-range dispersion and dose assessment tool; first applications in 1996. Atmospheric dispersion model is based on a Monte Carlo type random walk method • VALMA. A simplified and more flexible user interface to apply the dispersion estimates calculated by SILAM or by a simple model based on weather data derived from a single measurement tower. • DETRA: Radionuclide transport in biosphere & food chains (terrestrial & aquatic) and estimation of radiation doses.

17. Results of dispersion calculation (concentration in air and in deposition) either in central memory or in separate data base Radioactive decay and production of daughter nuclides Activity in air Activity indeposition Activity in air C(x,y,z=1 m) C(x,y,z) CA(x,y,0) Externaldose fromplume Internal dose via inhalation Externaldose from de-position Internal dose via food-chains Calculation of radiation doses in the SILAM model In the development of the SILAM model by FMI and VTT the radiation dose assessment models are using similar methods as in TRADOS & ARANO. The real time prediction of dispersion of releases employs a completely different approach. The dispersion and dose calculation models are coupled to each other, but the model includes the possibility to employ the once calculated dispersion analysis results data base to sensitivity analyses regarding dose estimates. The versatile modelling system allows the production of estimates of dispersion and dose forecasts with gradually increasing accuracy.

18. Radiological impact modelling for emergency response analyses • Emergency preparedness exercises and advance & real-time simulations for preparing the situation description for exercises • Deterministic and probabilistic safety analyses. • Research use (for example model validation against experimental measurement data; for this purpose the 137Cs-release from Algeciras iron foundry and specific tracer experiment in ETEX project has been modelled by SILAM) • Different kinds of source terms: Besides the main purpose (= releases from nuclear facilities as a results of transients and accidents and normal operation) other source terms can also be modelled, such as transportation accidents, dirty bombs etc. Provided that the radionuclide composition, time behaviour of release, release height and so on are known • What are the important key output (default) quantities ? • Nuclide-specific concentrations in air [Bq/m3] and deposited amounts [Bq/m2] • External dose rates [e.g. μSv/h, mSv/yr] • Integrated external doses within 24 h, week, month etc • Committed internal doses (within 50 yrs) [Sv] or short-term internal doses within 24 h, 1 week etc

19. User interface (www-based) for the SILAM model VTT has developed a www-based graphical user interface (GUI) for SILAM. The GUI is operated over internet and does not require programme installations by users (to client work stations) The central server has 8 processors and is managed by the Finnish Meteorological Institute (FMI). Several users and multiple calculation processes for each user can be handled simultaneously (in parallel) Main methods applied for GUI are PHP-language and MySQL-data base management system. Main objective is to have reliable access by all relevant emergency preparedness organisations (such as STUK, FMI, meteorologist on duty etc) to the same system. Several user classes have been defined

20. Simplified interface (VALMA) for employing the SILAM model for dose assessments and example applications • The interface provides easier access to the dispersion calculation results by SILAM and gives possibility to flexible adjustment of input parameters and assumptions for dose assessment • The example results obtained for total external dose rate (from the plume and deposition) visualized by the VALMA model interface • The picture corresponds to an assumed release from the Kola NPP and shows dose rate in mSv/h. • The situation is 48 h after the release start • The yellow colour for example corresponds to 0.4 µSv/h • Corresponding calculations have been performed for the Finnish NPP sites and other location close to Finland.

21. Application areas of radiological impact assessments for nuclear facilities • Dose assessments as a necessary final stage in deterministic and probabilistic nuclear safety analyses • In most cases the safety requirements are expressed in the form of annual doses or committed doses • Emergency preparedness exercises – also in case of real time weather conditions • The leader of the exercise can flexibly change the assumed dispersion conditions and assumptions for the temporal behaviour of the release • With modelling one can also simulate “surveillance measurement” results for the automatic measurement stations and air sample locations (for the Loviisa drill in November 2003 this option was employed) • Advance planning of emergency preparedness • The effectiveness of alternative countermeasures can be evaluated

22. Somefindings on VARANS regulation on dispersion of radioactivematerial • On the basis of headings VARANS regulationfollows IAEA No. NS-G-3.2 on dispersion of radioactivematerial • Whencomparingtext, copying is extensive. Itwouldbewiser to refer to the IAEA No. NS-G-3.2 in VARANS regulation for sitingthancopyingitdirectlybecause IAEA is notregulatoryorganizationwithregulatorywritingstyle. Itproducesguidance for allinterestedparties and often IAEA style is moretrainingstylewithexplanatoryexpressions to enhanceunderstandingthansuitableregulatorystyle. • Regulatorybodycanselectsuitableregulatoryrequirementsfrom the IAEA requirementdocumentswith ”shall” formulation for itspurposesbutdirectcopying of safetyguideswith ”should” formulation is not a good idea. • Chapter 3 referencepublications: IAEA nro 110 and nro 50-C/SG-Q on qualityassuranceareoutdatedreferences

23. Comments • Regulatorycontrolby VARANS ? • Shouldyoupresentsomethinghow VARANS control and whatdocuments/analysis VARANS needsfromapplicante.g. for licensing. • Weathermast ? • Shouldyoupresentsomerequirements on it?