For the facility model, VISAC utilizes the standard geometry package BRL-CAD. This package was chosen for its compatibility with many other codes [e.g., EVA-3D, MEVA, PATRAN, ADINA, EPIC-2, PSARC, and NASTRAN (U.S. Army, 1991)]. A full description of the many uses of BRL-CAD can be found on ARL's BRL-CAD web site http://ftp.arl.army.mil/brlcad/. However, unlike many CAD packages, BRL-CAD uses solid geometry; therefore, it is almost impossible to convert models from typical geometry packages that use surface orientation to BRL-CAD. All BRL-CAD model generation typically must be performed using the primitive graphical user interface MGED provided with the BRL-CAD package (U.S. Army, 1991). MGED is a GUI intended to provide a means of viewing the model and adding or modifying geometric bodies within it; nonetheless, its editing capabilities are less than desirable.

Because of the editing limitations found within MGED, a high-level geometry editing package has been developed within VISAC. The purpose of this editor is to provide a means of constructing a nuclear facility from basic building blocks within a few minutes instead of the days or weeks that it would normally take by using MGED.

This timesaving can be accomplished by assuming that most nuclear facilities are constructed of the same basic building types. For the construction of a simple Pressurized Water Reactor (PWR), several buildings would be chosen from a menu. Typically, the buildings that would be chosen are -- a containment building (that houses the reactor), an auxiliary building (that houses the support equipment), a turbine building (that houses the power production equipment), a diesel generator building (to provide backup power, sometimes located within the turbine building), a transformer building (can also be located within the turbine building), and an intake structure (to provide cooling water for the turbines). An example of this selection process is provided in Figure 1. Not shown in the figure is the ability to rotate the entire building and to show the internal structures (x-ray view). These features will be revealed in Figure 2.

Figure 1. Building a simple nuclear facility from menu boxes.

Figure 2. Components on the third floor of auxiliary building.

It is interesting to note that all of the containment buildings shown look similar; however, each represents a significantly different design (e.g., one represents a small ice condenser unit while another represents a large dry containment). Also, separate containment buildings are provided for the three major U.S. vendors: Westinghouse, Babcock & Wilcox, and Combustion Engineering.

Once a facility is constructed, several modifications can be performed to make the facility match the specific site of interest. These adaptations include moving, adding, and rotating components within the buildings. Components can also be exchanged amongst the various buildings. Figure 2 shows a containment and auxiliary building. The components on the third floor of the auxiliary building are shown in red. As can be seen, the auxiliary building has been rotated 90 degrees from what is visible in Figure 1. Each red component is intended to represent a piece of equipment that will be used in the fault trees. The red circles at the top of the auxiliary building, which correspond to emergency water storage tanks, are required if the intake structure becomes unavailable.

Figure 3 illustrates movement of these tanks along with several pumps (the boxes shifted from the bottom of the building to the top). The figure also demonstrates the addition of several components that represent control consoles, indicated by the black arrow. Lastly, Figure 3 illustrates the addition of a grid that can be used to aid the user in the proper placement of buildings.

Figure 3. Movement of water storage tank and creation of new components.

BRL-CAD geometry editor.

Figure 4. Screen shot showing a highlighted critical component.

Figure 5. Component window with selected critical component highlighted. Note that this component is a multi-region and multi-floor component. The elevation bar to the right indicates that this component goes through the ceiling and continues on to the next floor above this one.

Contact Information

Return to the VISAC home page