ML16130A159
Text
FHAR6A.TMIRev27.doc6-16.0PROTECTION AGAINST WATER SPRAY TO CONFORM WITH 10CFR50APPENDIX RThe Appendix R evaluation provides a reasonable assurance that at least onesafe shutdown division is free of fire damage after a postulated fire in any firearea/zone. A safe shutdown component is free of fire damage if it can performits intended functions before, during, and after the postulated fire without repair.Since the fire has to be extinguished by a fire fighting suppressant, theequipment located in the fire area/zone must be protected against not only thefire but also the fire suppressant if that equipment is required for the shutdown.The fire suppressant damage should not prevent the operation of the equipmentfor shutdown. The required equipment, located in the adjacent fire zones that donot have physical boundaries with the fire area/zones in question, must also bechecked for possible fire suppressant damage.A review of potential water damage was made to assure that the water damageto the shutdown system wouldnot jeopardize the safe shutdown.Mechanical components such as pipes and valves are not subject to firesuppressant damage. Electrical and electronic components are susceptible towater damage. Some electric cables, which are only suitable for usein drylocations, are prone to insulation failure under wet conditions. To guard againstthe water damage, all electrical and electronic equipment used outdoors areenclosed in some type of water (rain) proof enclosure (NEMA 3, 4, and 6enclosure). Indoor electrical equipment in nonhazardous areas are normallyprovided with a NEMA 12 enclosure which protects the enclosed equipmentagainst dust and light-splashing seepage or dripping liquid. The types ofindustrial enclosures provided for the electrical equipment at TMI-1 werereviewed and the extent of water damage was established for the redundantequipment located in the same fire area/zone. The building discussion providesa description of drainage capability and a listing of equipment reviewed for waterdamage. Vulnerability of shutdown equipment to water damage and thedisposition to limit the water damage is discussed in detail. The following generaldiscussion is for other electrical components and cables, which are not listed inthe building discussion.a.PumpsWater damage to the makeup pumps, decay heat removal pumps,nuclear service river water pumps, and decay heat river water pumps,would not prevent safe shutdown because redundant pumps are locatedin the different fire zones. The physical boundaries existing between theadjacent fire zones provide reasonable assurance that the limit of firedamage will be contained to one train only. A discussion of other pumpsis contained in Table 6-1.b.Motor Operated Valves and Solenoid ValvesWater damage to electrical operation of the valves is no concern becausevalves will be manually operated. Moreover, the motor is totally enclosedand is unaffected by water spray.
FHAR6A.TMIRev27.doc6-16.0PROTECTION AGAINST WATER SPRAY TO CONFORM WITH 10CFR50APPENDIX RThe Appendix R evaluation provides a reasonable assurance that at least onesafe shutdown division is free of fire damage after a postulated fire in any firearea/zone. A safe shutdown component is free of fire damage if it can performits intended functions before, during, and after the postulated fire without repair.Since the fire has to be extinguished by a fire fighting suppressant, theequipment located in the fire area/zone must be protected against not only thefire but also the fire suppressant if that equipment is required for the shutdown.The fire suppressant damage should not prevent the operation of the equipmentfor shutdown. The required equipment, located in the adjacent fire zones that donot have physical boundaries with the fire area/zones in question, must also bechecked for possible fire suppressant damage.A review of potential water damage was made to assure that the water damageto the shutdown system wouldnot jeopardize the safe shutdown.Mechanical components such as pipes and valves are not subject to firesuppressant damage. Electrical and electronic components are susceptible towater damage. Some electric cables, which are only suitable for usein drylocations, are prone to insulation failure under wet conditions. To guard againstthe water damage, all electrical and electronic equipment used outdoors areenclosed in some type of water (rain) proof enclosure (NEMA 3, 4, and 6enclosure). Indoor electrical equipment in nonhazardous areas are normallyprovided with a NEMA 12 enclosure which protects the enclosed equipmentagainst dust and light-splashing seepage or dripping liquid. The types ofindustrial enclosures provided for the electrical equipment at TMI-1 werereviewed and the extent of water damage was established for the redundantequipment located in the same fire area/zone. The building discussion providesa description of drainage capability and a listing of equipment reviewed for waterdamage. Vulnerability of shutdown equipment to water damage and thedisposition to limit the water damage is discussed in detail. The following generaldiscussion is for other electrical components and cables, which are not listed inthe building discussion.a.PumpsWater damage to the makeup pumps, decay heat removal pumps,nuclear service river water pumps, and decay heat river water pumps,would not prevent safe shutdown because redundant pumps are locatedin the different fire zones. The physical boundaries existing between theadjacent fire zones provide reasonable assurance that the limit of firedamage will be contained to one train only. A discussion of other pumpsis contained in Table 6-1.b.Motor Operated Valves and Solenoid ValvesWater damage to electrical operation of the valves is no concern becausevalves will be manually operated. Moreover, the motor is totally enclosedand is unaffected by water spray.