![]() ![]() This paper describes both small and full more » scale tests to assess the adequacy of fire retardant coatings and full scale tests on fire shields to determine their effectiveness. ![]() However, tests confirmed that these guidelines and standards are not sufficient, in themselves, to protect against exposure fires. Characterization of electrically initiated fires revealed a margin of safety in the separation criteria of Regulatory Guide 1.75 for such fires in IEEE-383 qualified cable. This paper summarizes the activities of this ongoing program through October 1980. Sandia National Laboratories is executing a program for the Nuclear Regulatory Commission to provide data needed for confirmation of the suitability of current design standards and regulatory guides for fire protection and control in water reactor power plants. The EPRI fire PRA method and data will show that there are excessive conservatisms in studies that were made for many plants and can benefit them accordingly. Test data and fire event experience also removed excessive conservatisms in the Peach Bottom control and cable spreading rooms, and the Seabrook primary component cooling pump, turbine building relay and cable spreading rooms. The rates are supported by the experience in the EPRI Fire Events Database for U.S. EPRI`s electrical cabinet heat release rates are based on tests that were conducted for Sandia`s fire research program. Past studies often overestimated the heat release from electrical cabinet fires. The principal reason for a hundredfold reduction in the Peach Bottom core- damage frequency is the more » determination that no electrical cabinet fire in a switchgear room would damage both offsite power feeds. The results from the requantification show that there were excessive conservatisms in the original studies. Except for the fire methods and data, the original assumptions were used. The two existing studies are the Seabrook Station Probabilistic Safety Assessment that was made in 1983 and the 1989 NUREG-1150 analysis of the Peach Bottom Plant. This report describes the requantification of two existing fire probabilistic risk assessments (PRAs) using a fire PRA method and data that are being developed by the Electric Power Research Institute (EPRI). Halon 1301 is the preferred fire extinguishing agent for this application because it does not leave harmful residues that could damage costly electrical and mechanical equipment. After the concentration reaches 7 percent, additional Halon 1301 is continuously released inside the machinery house at a rate which replaces the Halon that is lost through the house's many small, permanent openings such as rope openings, louvers, vents, and pipe and cable runs. This concentration is sufficient to extinguish a fire, but isn't toxic to personnel. After a delay to allow time for the ventilation fan to stop, Halon 1301, a gaseous fire extinguishing agent, is released inside the machinery house until it reaches a concentration of about 7 percent. If the fire is detected in the machinery house, more » all power is shut down to the motor-generator sets, ventilation fan, and all electrical controls. The system can also be triggered by a manual control. An alarm is sounded, and extinguishing agents are released either in the machinery house or in the ring gear area. ![]() These sensors are located inside the machinery house and under the house and shovel frame where it rotates around the crawler chassis ring gear. ![]() Temperature sensors detect heat from a fire, and trigger the system. It is more rugged than similar industrial-type fire protection systems. = ,Īn automatic fire sensing and suppression system using both dry chemical and Halon 1301 was developed. ![]()
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