Plant Unit Groups

Although plant layouts, safety reports, on-line public information sources and high-resolution satellite imagery can be used to collect data on plant units, sometimes it may not be possible to find detailed information for each plant unit individually. Especially for historical natechs, available data sources describe plant units not individually but as group of plant units having similar characteristics (e.g. similar dimensions, roof type, stored substance). Also, if the location of the plant units is not exactly known, there is no additional benefit in entering the plant units having similar characteristics as sepa-rate records since the same on-site hazard parameters will be calculated during the damage estimation for all similar plant units. Taking this into consideration and with the aim of making data entry more convenient, RAPID-N supports plant unit groups, which include lumped information about plant units without location data. Plant unit group records are used to store information on plant unit groups, including related properties and substances.

The data fields of the plant unit group records are listed in Table 1.

Table 1. Plant unit group data fields

For each plant unit group, the plant where the plant units are located should be selected from the available plants in the database. A name describing the group should be provided and the type of the plant units should be specified. If the number of units within the group is known, it can be indicated explicitly. The substance stored in the plant units can be specified by selecting the substance from the list of substances available in the database. The characteristics of the plant units, including amount and concentration of the substance stored, can be indicated by using the property definition framework of the system (Figure 1). The system assumes that the entered properties are representative of a single plant unit within the group. Hence, individual but not total numbers should be entered for quantitative properties. Properties should be unique. Uncertain values of numerical properties can be specified by using fuzzy numbers. The system only lists properties valid for the selected plant unit type ac-cording to plant unit type settings. See "Plant Unit Types" section for more details.