Passive protection systems

Passive protection systems discussed in this section are  

This section discusses general layout and spacing guidelines as they apply to fire protection issues. For complete discussion of facility siting and layout, refer to Guidelines for Facility Siting and Layout (CCPS, 2003b). 

The purpose of layout and spacing is to design a workplace that will minimize personnel injuries, overall property damage, and related business interruption resulting from potential toxic releases, fires, and explosions. Areas to address during layout and spacing include both those that will minimize the incident size and those that will minimize the incident impact. The magnitude of a potential incident may be reduced by  

It is important to note that the distances in the spacingtables are based on potential fire consequences. Explosion and toxic concerns may require greater spacing. The separation distances cited are suggested minimum distances. Increased spacing may be warranted based on site-specific hazards and concerns. Applicable codes, standards, and local regulations should be researched. 

Separation Distances for Equipment Primarily spacing between pieces of equipment in the same unit and spacing between that equipment and the edge of the unit 

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Secondary containment systems are best described as passive protective systems. They do not eliminate or prevent a spill or leak, but they can significantly moderate the impact without the need for any active device. Also, containment systems can be defeated by manual or active design features. For example, a dike may have a drain valve to remove rain water, and the valve could be left open. A door in a containment building could be left open. 

The design basis, especially safety features that are built into the installation, must be documented. Management of change programs must preserve and keep the base record current and protect against degradation or elimination of safety features, including such measures as maximum intended inventories and passive protection systems. 

Topics include inherent safety in a process, considerations lor safer plant siting and layout, Improved equipment and piping design, and active and passive protective systems... 

Passive protection systems such as dikes, drainage systems, blast walls, bunkers, flame arrestors, structural fire protection. 

In nuclear plants, construction cost is strongly dependent on the technology selected, on the seismic characteristics of the site and on the local rules and regulations affecting the type and cost of active safeguard systems and passive protection systems. For these reasons, every attempt at cost evaluation when not aimed at a specific design solution is rather approximate. As a result of this effort, the number of main components (pumps, valves, tanks, etc.) in the MARS plant is reduced to about 50%, with respect to traditional PWRs of the same rated power. 

Passive protection devices are devices that reduce injury while the driver remains passive. It is commonly and mistakenly assumed that this also means that their safety benefits are unrelated to driver behavior. In this section I will briefly review several passive protection systems, and emphasize the driver s role in maximizing their benefits. 

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