Active protection systems types

The project plan should encompass all aspects of a fire protection system, such as the underground fire water distribution system, fire pumps, aboveground water header, valving and standpipes, structural support, and detection and alarm systems. All work on the fire protection system must be coordinated with other work activities at the site or in the operating unit. The recommended installation practices for the different types of fire protection systems are covered in consensus standards, such as NFPA. The installation process is illustrated in Figure 9-1. 

The fire protection system consists not only of a deluge system activated by the ultraviolet sensors, but also of fusible link type fire systems. The deluge system has a trip mechanism from mercury checks activated by heat-activated-devices, a manual release on the deluge valve, a pneumatic remote trip station, and an electrical push button along with the electrical trip mechanism from the U/V detectors. The remote trip stations are located by escape routes so it is possible for the operator to trip the systems as he exits the building without exposing himself to further danger. 

Type-3 technologies require active control to mitigate a disturbance and consequently are protective systems associated with the process flowsheet. Notice that certain control actions cannot be modeled easily without overspecifying the system such as the manual override of the quench valve by the operator. For this reason, the constraint list, as described earlier, is associated with each piece of process equipment. This allows us to associate in an a posteriori manner additional control structures that are available to the process. 

In planning to deploy building protection from chemical and biological airborne threats, the missions executed in a specific building need to be considered to ascertain the requirements of building protection and the importance of the mission relative to the life-cycle costs of a protection system. Addressing the full complexity of DOD missions is beyond the scope of this report, but broad types of activities can be defined to aid planning. 

Sacrificial-anode-type cathodic protection systems provide cathodic current by galvanic corrosion. The current is generated by metallically connecting the structure to be protected to a metal/alloy that is electrochemically more active than the material to be protected. Both the structure and the anode must be in contact with the electrolyte. Current discharges from the expendable anode through the electrolyte and onto the structure to be protected. The anode corrodes in the process... 

Some safety-related systems (e.g nuclear reactors) are categorised as such simply because they pose an unacceptable safety risk to their environment and they require additional protection systems to contain that risk within an acceptable level. In contrast, systems such as Air Traffic Control or Railway Network Control are designed specifically to provide risk reduction and can be likened to one big protection system. This paper presents a generic approach for the specification and realisation of safety requirements for the technical and human elements of both types of safety-related systems. The term realisation is used here to cover all activities associated with requirements implementation, validation and verification. 

Some safeguarding devices are used to detect the presence of people and to trip the machines they safeguard. The main two to be described here are photoelectric safety systems and laser scanners, which are both types of active optoelectronic electrosensitive protective systems. Pressure sensitive devices such as pressure mats and trip bars are other types of trip device. 

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. 

---