Data requirements for consequence analyses

This section is related to the data that are required to carry out a consequence analysis, which include meteorological data, and population, agricultural and

economic data. The modelling of countermeasures and the data required for this are covered in Section 6.5.

6.4.1. Meteorological data

Meteorological data are required for the whole of the area covered by the con-sequence analysis. This would include data which are specific to the site and national data if the consequence analysis needs to extend beyond this region.

The meteorological data typically include:

— wind direction

— wind speed

— stability category

— rainfall

— mixing layer depth.

Consequence analysis codes typically require this information to be specified at regular intervals (normally hourly) for a prolonged period of time. Ideally, a long enough period, for example ten years, should be covered to ensure that rare weather conditions have been included. However, a shorter time might be acceptable, but would need to be at least one year.

The reviewers need to understand the basis on which the meteorological data have been specified for the consequence analysis and be satisfied that it is represen-tative of the area over which the consequence analysis is to be carried out. For the region close to the site, this would normally be data recorded at the nearest meteoro-logical station. For the region further from the site, this would normally be based on national meteorological data.

Some of the meteorological data may not be complete. In addition, some of these parameters, for example, stability category and mixing layer depth, may not have been routinely measured and may need to be derived from other measure-ments. Where the data available are incomplete or inconsistent, the reviewers need to be satisfied that the way that the data have been processed or added to is satisfactory.

If a probabilistic consequence analysis code is used, the reviewers should be satisfied that the meteorological data are provided in a form that is suitable for the sampling scheme used in the code.

6.4.2. Population, agricultural and economic data

Consequence analysis codes typically require information on the spatial distributions of:

— population data

— land use and agricultural production data

— food distribution data

— economic assets.

These data are needed to determine the radiation doses arising from the external exposure, inhalation and ingestion pathways, and to calculate the impact of imple-menting countermeasures such as relocation and food bans.

These data normally need to be specified in annular segments centred on the site and segmented by radial lines, i.e. an (r, q) grid with a spatial resolution finer near the site than further away from it. This should be consistent with the way that the meteorological data are specified. Since the available data are not specified in this form, a conversion process will usually be necessary to map them to the (r, q) grid.

The reviewers must be satisfied that the land data specified are acceptable. This is usually done by defining the fraction of each spatial element in the (r, q) grid that is land, lakes or sea, and the fraction of the land that is urban or rural. This informa-tion is usually derived from large scale maps.

The reviewers should be satisfied that the population data are acceptable for the purposes of the consequence analysis. Census data, which need to be sufficiently up to date to represent the current population distribution, would normally be used.

These data need to be supplemented where appropriate by local surveys in the imme-diate vicinity of the plant and have to take account of daily and yearly variations in the population distribution.

The land use and agricultural data relate to agricultural production and distribu-tion. They are required to calculate the collective dose due to ingesdistribu-tion. The precise agricultural data required depend on the aims of the Level 3 PSA and the consequence analysis code but typically include the number and type of livestock, the milk produc-tion and the type of crops grown. If food distribuproduc-tion is taken into account, it is neces-sary to specify the regions of food production and consumption. Agricultural data are usually based on government information and need to be mapped onto the (r, q) grid being used by the consequence analysis code. The reviewers should be satisfied that these data have been derived and used in an acceptable way.

The economic data required relate to, for example, the gross domestic product, the value of land and the value of housing for each of the sectors defined in the con-sequence code. These are usually based on government economic data which need to be mapped onto the (r, q) grid being used by the consequence analysis code. This could also include the cost of countermeasures (evacuation, relocation, food restric-tions and decontamination) and the costs of the health effects on the exposed popula-tion. The reviewers should be satisfied that these data have been derived and used in an acceptable way.

6.5. EMERGENCY PLANNING AND COUNTERMEASURES