ML18153D298
| ML18153D298 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/12/1993 |
| From: | Virginia Power (Virginia Electric & Power Co) |
| To: | |
| Shared Package | |
| ML18152A044 | List: |
| References | |
| 22, 22-R11, NUDOCS 9304190076 | |
| Download: ML18153D298 (9) | |
Text
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- 22. EVALUATION OF FIRE RATING FOR VENTILATION DUCTS COATED WITH THERMO-LAG SURRY POWER STATION Description of Evaluation This evaluation assesses the adequacy of ventilation ducts coated with Thermo-Lag to be able to maintain the fire rating of the fire barrier in which the duct is installed.
Area Description TURBINE BUILDING The Turbine Building (FA 31) consists of three primary elevations, 9 ft. 6 in. (basement), 35 ft. o in. (mezzanine), and 58 ft. 6 in.
(turbine deck).
To the north of the Turbine Building is the Service Building containing the Control Room (FA 5) and the Unit 1 and 2 Emergency switchgear Rooms (FAs 3 & 4) and other areas not relevant to this evaluation.
The Station Administration Building is to the west, the Condensate Polishing Building is to the east and the south wall is an exterior wall facing the transformers.
The north wall separating the Turbine Building from the Control Room and Emergency Switchgear Rooms is a reinforced concrete wall.
The doors, dampers, and penetration within the wall have a three hour fire rating.
There are four Safety Related ventilation ducts penetrating the north wall of the Turbine Building.
This wall acts as a three hour fire barrier to separate the Turbine Building from adjacent Fire Areas.
The ducts in question penetrate the north wall of the Turbine Building.
Two of the ducts are located on elevation 40 ft.
6 in. near column lines 7C and 9C.
These ducts penetrate the wall separating the Turbine building and the Control Room.
Two CHl0-22 22-1 Revision 11 11/93
e additional ducts are installed at elevation 22 ft. near column lines 6C and lOC.
These ducts penetrate the wall between the Turbine Building and the unit 1 and 2 Emergency switchgear Rooms.
All of the ducts are provided with three hour rated fire dampers; 1-VS-FDMP-9, 19 2-VS-FDMP-10,
- 20.
The dampers however are installed approximately 5 ft. from the barrier surface.
Three of the dampers (9, 19, & 20) are located on the Turbine Building Side of the wall and damper 10 is located on the Unit 2 Emergency Switchgear Room side of the barrier.
The exterior of the duct between the damper and the barrier surface is wrapped with 1 inch thick Thermo-Lag 330 fire barrier material.
BATTERY ROOMS Battery Room lA (FA 9) and Battery Room lB (FA 10) are located within the Unit 1 Emergency Switchgear Room (FA 3), which is located on the 9 ft. 6 in. elevation of the Service Building.
Battery Room 2A (FA 11) is located within the Unit 2 Emergency Switchgear Room (FA 4), which is also located on the 9 ft. 6 in.'
elevation of the Service Building.
Each battery room has a floor area of approximately 120 ft 2, with a ceiling approximately 8 ft.
high.
Each battery room is contained entirely within the ESGR.
Each battery room has reinforced concrete walls on two sides and 8 in. concrete block walls on the other two sides (see Evaluation
- 19).
The ceiling is constructed of poured concrete on steel decking.
Each of the three battery rooms have two ventilation ducts that penetrate the roof.
All of the ducts are provided with three hour fire rated dampers (l-VS-FDMP-1, 2, 11, 12,
& 2-VS-FDMP-3, 13).
The dampers are installed approximately 6 in. above the barrier surface.
The exterior of the duct between the damper and the barrier surface is wrapped with 1 inch thick Thermo-Lag 330 fire barrier material.
CHl0-22 22-2 Revision 11 11/93
e Fire Protection Features TURBINE BUILDING Combustible loading in the Turbine Building is Moderate.
Major contributors to the combustible loading are lube oil and cable insulation.
The Turbine Building has a full area automatic sprinkler system on the 3 5 ft.
o in.
and the 9 ft.
6 in.
elevations.
Upon sprinkler system water flow, an alarm is transmitted to the Control Room.
The major lube oil components are diked and have individual deluge systems actuated by heat detectors over the hazard.
These provide annunciation to the Control Room upon system actuation.
The Turbine Building is also provided with portable fire extinguishers and manual hose stations for manual fire fighting by the fire brigade.
BATTERY ROOMS Both the Emergency Switchgear Rooms and the Battery Rooms have ionization smoke detectors mounted at the ceiling.
The smoke detectors annunciate to the Control Room.
There is no fixed fire suppression system in the Battery Rooms; however, portable fire extinguishers are located nearby.
A manually actuated, total
- flooding, Halon 1301 fire suppression is installed in each Emergency Switchgear Room.
The system is primarily for the ESGR, but the system is sized large enough to extinguish a fire in the Battery Rooms.
The combustible loading within the Battery Rooms is moderate.
The only combustibles are the battery casings and the insulation on the power cables to the batteries. The chance of significant transient combustibles or of an ignition source within the battery room is unlikely due to the administrative controls (i.e.; no storage, no smoking, no welding/cutting) and due to the physical configuration of the area (these are single use rooms).
CHl0-22 22-3 It is not considered Revision 11 11/93
. i
e likely for a battery short circuit to cause an ignition of the combustibles due to the low voltage of the batteries.
There is no other equipment in the room which could cause an ignition.
The combustible loading within the Emergency switchgear Rooms is high.
The combustible loading for the Unit 1 and 2 Emergency Switchgear Rooms consist of large amounts of electrical cable insulation.
There is also a potential for a small amount of transient lubricating oil to be transported via the unit 2 switchgear Room to Mechanical Equipment Room# 3.
Safe Shutdown Equipment TURBINE BUILDING The Turbine Building contains several circulating and service water MOVs that are required for cold shutdown.
The Turbine Building also contains the auxiliary steam system to the air ejectors, which are required for alternative safe shutdown if the PORVs are inoperable, and several main steam valves which are required for alternative safe shutdown if the MSIVs are inoperable.
The Turbine Building also contains manual isolation valves for the Charging Pump Service Water (CPSW)
System.
These valves are located in valve pits below elevation 9 ft. 6 in. in each unit's Turbine Building.
The flow path for the CPSW system is such that either the Unit 1 or Unit 2 CPSW piping can supply water to the CPSW pumps for each unit.
BATTERY ROOMS The only equipment located in the Battery Rooms are the station batteries.
The station batteries are part of the safety-related 125V DC power system; however, they are not required for safe shutdown under Appendix R.
CHl0-22 22-4 Revision 11 11/93
There are numerous pieces of safe shutdown equipment located in the ESGRs (i.e., instrumentation, bypass switches, vital buses, 4kv switchgear, load and motor control centers, etc.)
Alternate safe shutdown capability is provided in accordance with Appendix R for the case of a fire in either Unit's ESGR.
Evaluation The pass/fail criteria for fire dampers based on Underwriters Laboratories Standard UL 555 is the passage of flame through the damper.
The passage of smoke or heat is not a factor in the evaluation of fire dampers.
The duct configuration will have similar characteristics as a fire damper, i.e. no flame passage even though smoke and heat will be allowed to pass to the opposite room.
For the purpose of this evaluation, no flame passage means that no flame leaves the duct on the non-fire side of the barrier. It is noted that the inside of the duct on the non-fire side of the barrier may be impinged by flame, but this is of no consequence since the duct is assumed to no longer be able to fulfill its purpose of providing ventilation.
For fire to enter the duct this assumes that the equipment feeding the duct is damaged.
Southwest Research Institute (SwRI) Final Report No. 01-2427-001, dated October 1988, conducted fire endurance tests on unprotected steel duct systems (see Attachment 1).
The objective of the test program was to demonstrate whether an unprotected steel duct that does not contain a fire damper at the barrier opening, will remain in place throughout a 120 minute fire exposure and effectively maintain the integrity of* the fire barrier at that opening, consistent with the criteria for fire dampers.
The test exposes the ducts to a standard fire exposure as defined by ASTM E-1*19.
Three ducts were tested by SwRI.
Two ducts were constructed of 22-CHl0-22 22-5 Revision 11 11/93
gauge galvanized steel sheet and the third duct was constructed of 20-gauge stainless steel sheet.
There were no significant observations recorded throughout the 120 minute fire exposure.
None of the duct sections collapsed or fell into the furnace and the integrity of each system, where it extended through the fire wall, remained intact. No through opening developed between a fire stop and a duct at any wall penetration.
On July 15, 1992 the National Institute of Standards and Technology (NIST) conducted 1 and 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire endurance tests to determine the fire resistance properties of 1/2 and 1 inch thick Thermo-Lag pre formed panels.
The results of those tests were discussed in NRC Information Notice 92-55 (see Attachment 2).
The three hour test using 1 inch thick Thermo-Lag panels resulted in the average thermocouple reading exceeding 325 °Fin 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 20 minutes.
At the conclusion of the test, the material was soft and exhibited plastic deformation, and the fire exposed stress skin crumbled upon contact.
Neverless, visible signs of damage on the unexposed side were limited to off-gassing, slight browning, and crystallization at the surface.
TURBINE BUILDING The ducts in the Turbine Building are arranged such that they come directly out of a piece of equipment and pass horizontally through the fire barrier and connect into ducts and equipment on the opposite side of the barrier.
The ducts, minimum 22-gauge sheet metal construction, are for ventilation purposes only and contain no combustible material within the duct.
The fire tests conducted by SwRI indicate the 22 gauge metal duct will provide at least a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> fire rating on one side of the barrier. Therefore a duct which is continuous on both sides of the barrier would be expected to provide a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> fire rating.
The addition of the Thermo-Lag material around the duct on one side of CHl0-22 22-6 Revision 11 11/93
e the barrier is expected to enhance the fire resistance rating of the duct.
The fire scenario in question is a fire on one side of the barrier, and the duct needs to keep the fire from going to the opposite side of the barrier. This scenario assumes that there is only a fire on one side of the barrier. Therefore the outside of the duct and the hangers on the non-fire side of the barrier is not being impinged by flame.
This will greatly decrease the chance of failure of the duct and hangers.
Activation of the sprinkler system in the Turbine Building would alarm the fire to the constantly manned Control Room.
This would alert the fire brigade.
Fire hose stations and portable extinguishers are readily available for manual fire fighting by the fire brigade.
The location where ducts pass through the poured concrete wall is substantial enough to withstand a fire.
The duct is an integral part of the barrier.
Since the duct is mounted to the wall in a sturdy manner there is little chance that the duct will fail at the barrier.
The concrete barrier is rated for three hours.
BATTERY ROOMS The ducts for the Battery Rooms begin at the ceiling of each battery room and extend upward before turning horizontally and connecting to equipment.
There is no duct within the battery rooms.
The ducts, minimum 22-gauge sheet metal construction, are for ventilation purposes only and contain no combustible material within the duct.
The fire tests conducted by SwRI indicate the 22 gauge metal duct will provide at least a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> fire rating on one side of the barrier.
The addition of the Thermo-Lag material around the duct CHl0-22 22-7 Revision 11 11/93
on one side of the barrier is expected to enhance the fire resistance rating of the duct.
The fire scenario in question is a fire on one side of the barrier, and the duct needs to keep the fire from going to the opposite side of the barrier. This scenario assumes that there is only a fire on one side of the barrier.
Therefore the worst case is expected to be a fire outside of the rooms since the outside of the duct and the hangers could be impinged by flame.
Any failure of the duct and hangers would be above the fire damper installed within the duct and Thermo-Lag.
Therefore that portion of the duct between the barrier surface and damper is expected to remain intact.
In addition, the heat and flame from a fire outside of the battery room would be directed upward and away from the duct connection at roof of the battery room.
Activation of the smoke detection system in the Battery Rooms would alarm the fire to the constantly manned Control Room.
This would alert the fire brigade.
Fire hose stations and portable extinguishers are readily available.
The fire brigade would also have the option of manually tripping the total flooding Halon 1301 system for the ESGR which would extinguish a fire in the Battery Rooms.
The location where ducts pass through the poured concrete roof is substantial enough to withstand a fire.
Since the duct is mounted to the roof in a sturdy manner there is little chance that the duct will fail at the barrier.
The concrete roof is rated for three hours.
Conclusion The four ventilation ducts which penetrate the north wall of the Turbine Building and the six ventilation ducts that penetrate the roof of the Battery Rooms are considered equivalent to three-hour CHl0-22 22-8 Revision 11 11/93
fire dampers.
This determination is made in accordance with Generic Letter 86-10.
The technical bases that justify this conclusion are summarized as follows:
- 1.
Based on fire tests conducted by SwRI, the ducts in the Turbine Building are expected to provide at least a 4 hr. fire resistance rating without the Thermo-Lag.
The addition of the Thermo-Lag only enhances the fire resistance rating of the duct.
- 2.
The ducts for the battery rooms are expected to provide at least a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire resistance rating based on the combination of 22 gauge metal duct and a 1 inch thick panel of Thermo-Lag attached to the outer surface of the duct.
- 3.
There are no combustibles inside the duct.
- 4.
Sprinklers in the Turbine Building will provide detection and early fire control.
Smoke detectors in the Battery Rooms and Emergency Switchgear Rooms will provide detection of a fire and annunciate it to the Control Room.
Extinguishers and hose stations are available for manual fire fighting in all areas.
In addition, the total flooding Halon system in the ESGR is available for manual operation and is expected to extinguish a fire in the Battery Rooms.
- 5.
Failure of the duct at the barrier penetration is unlikely.
This is due to the sturdy construction of the barrier where the duct passes through the barrier and the duct being an integral part of the barrier.
CHl0-22 22-9 Revision 11 11/93