Nuclear fission

2DATA FOR HAZARD CHARACTERISATION

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  Data related to hazard sources;
  
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  Data related to plant design.
  

1. Data related to hazard sources

The stationary sources represent mainly industrial and storage facilities, in which combustible or explosive substances are produced or stored. The mobile sources represent mainly transport of such substances. Within the hazards resulting from the mobile sources air transport is considered separately due to its specifics and possible direct physical contact of the aircraft with the plant or its part(s).

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  structure of industry in vicinity of NPP site,
  
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  distance of stationary industrial facilities from NPP site with emphasis on those, in which chemical, flammable or combustible materials are stored or transported via pipelines,
  
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  types and amount of hazardous substances produced and stored in the facilities or transported via pipelines,
  
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  information on storage, manipulations and internal safety measures adopted in these facilities in relation to the hazards resulting from their operation,
  
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  meteorological and Hydrological data.
  

The data on mobile sources should include information on:

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  structure of transport lines (roads, railways, water roads, product lines¹⁾, piping) in vicinity of NPP site,
  
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  distances of the transport lines from NPP site,
  
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  type and amount of transported hazardous substances,
  
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  data on technical means used for transport of hazardous substances,
  
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  frequency of the transports.
  

The above mentioned data are intended to be used mainly for appraisal of hazards related to external fires and explosions. Among the fires there is also a special category of “forest fires“ for which also data on surrounding vegetation and landscape are required.

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  nearby airfields or airports (civil, military) and their distances from NPP site; data related to the type (unpaved or hard surfaced) and orientation of runaways,
  
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  number of airport operations (take-offs, landings) related to the airports,
  
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  airways around and across the NPP site; data on transit civil transport flights within airways (statistics on number of flights in these corridors, types of aircraft operated within area of interest, etc.),
  
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  other aviation activities within region of interest (military bases or training areas, agriculture, sport and special purpose flights).
  

2. Data related to plant design

The main sources of plant specific data are:

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  plant design technical documentation,
  
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  plant specific analyses (elaborated for SAR, PSA studies, etc.),
  
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  plant historical data from operational experience.
  

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  generic data from or for plants of the same or similar design,
  
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  internationally accepted databases (IAEA, OECD, NRC) especially as a source of frequencies and screening values,
  
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  knowledge and results from analyses of real external events similar to those under consideration for specific plant,
  
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  data from available calculation/simulation studies.
  

As far as numerical simulation data are considered, the following can be useful (mostly for fires and toxic releases):

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  meteorological data from the numerical weather forecasts made in the past. This can be particularly useful if re-analysis data and/or the results from weather forecast systems are available, as they can improve statistics.
  
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  meteorological data from the simulations of climatic models, as they provide projection of the development of weather conditions in the period of the future operation of NPP.
  
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  optionally data from the simulations of fires and explosions in the vicinity of NPP ;this may be relevant if advanced calculations are used to produce such data (for example using models of the class of computational fluid dynamics), as otherwise simple models can be applied,
  
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  optionally data on simulations for similar facilities as the ones located in the vicinity of NPP.
  

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  identification of the methods for assessing key input parameters: this can be done mostly by detailed analysis of the consequences of the external events related to man-made hazards and the response of NPP to such events; in principle, a full risk analysis (like QRA – Quantitative Risk Assessment) for the external event could provide good initial data for the response analysis; however this can be hardly done, therefore, the analysis of the major or enveloping accidents outside the NPP, should be performed at least,
  
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  assessing data completeness via statistical methods and/or expert judgement: in a number of cases there are mathematical rules when and how to apply statistical methods. However, in the considered case, typical situation is the lack of data, then missing or censoring techniques can be applied, but in any case this should be supported by expert judgement,
  
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  accuracy or uncertainty of the measurement and numerical simulation data: in most cases observations or simulated numerical data should include information on their accuracy; if not, they should be treated carefully and additional analysis of their uncertainty could be performed.