NRC-94-0011, Responds to NRC 931222 RAI Re GL 92-08, Thermo-Lag 330-1 Fire Barriers

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Responds to NRC 931222 RAI Re GL 92-08, Thermo-Lag 330-1 Fire Barriers
ML20067A435
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 02/11/1994
From: Gipson D
DETROIT EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-94-0011, CON-NRC-94-11 GL-92-08, GL-92-8, NUDOCS 9402170337
Download: ML20067A435 (7)


Text

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E U .. Douglas it Gipson r a Sonsor Vge President 4 clear Gewraton Detroit r.-

6400 Nortn Un H ghway EcF8ison - {313) $36-f249 l

February 11,-1994 NRC-94-001.1  :

t U. S. Nuclear Regulatory Commission =l Attn: Document Control Desk Washington, D. C. 20555 i

References:

1) Fermi 2  :

NRC Docket No. 50-341 NRC License No. NPF-43

2) NRC Generi: Letter 92-08, Thermo-Lag 330-1 Fire Barriers", dated December 17, 1992 ,
3) Detroit Edison Letter to NRC,."Setroit Edison- '

Response to NRC Generic Letter 92-08, NRC-93-0043, dated April 8,1993

4) NRC Letter to Detroit' Edison, " Request fhr
  • Additional Information Regarding Generic Letter l 92-08, Thermo-Lag 330-1 Fire Barriers," dated December 22, 1993

Subject:

Detroit Edison Response.to NRC Request for Additional ,

Information Regarding Generic Letter 92-08 >

The purpose of this letter.is to provide Detroit Edison's response to NRC Request for Additional Information (RAI) regarding Generic Letter 92-08 (Reference 4) which was issued to obtain additional information-regarding resolution of the Thermo-Lag issues. . As requested, a copy-is also being submitted to the Regional Administrator, U.S. Nuclear Regulatory Commission,' Region III.

Detroit Edison provided a response to Generic Letter.92-08 via Reference 3 which stated, in part,.that Detroit Edison is monitoring industry activities to restore fire barrier integrity: through programs -

coordinated by NUMARC. . The response further stated that Detroit'- ,

Edison would apply 'the results of these programs, if applicable, to ,

the' Thermo-Lag installation at Fermi 2.

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Subsequent' to the submittal of the response to Generic Letter 92-08, Detroit Edison opted not to wait for the results of. the ' industry

-programs coordinated by NUMARC and decided to resolve Thermo-Lag issues by either removal or reclassification of Thermo-Lag fire  ;

barriers at Fermi 2.

As stated in the response to Ceneric Let6er 92-08, eleven areas were identified where Thermo-Lag fire barriers having a 3-hour rating are  ;

installed at Fermi 2. In the following eight of these. eleven areas, Thermo-Lag fire barriers are being removed and replaced by concrete blocks and qualified 3-hour rated fire barriers such as 3M barriers, UL designs U435 and x717, promat boards, silicone foam and elastomer seals:

1. Cable Tray Enclosure for Cable Trays 1C-037 and 1P-070, CCHVAC Area, El. 677'-6" Two (2) cable trays10-037, and 1P-070 are routed between the Division 1 CCHVAC Equipment Area and the. Ventilation Equipment Area both on El. 677'-6", and have been enclosed by an envelope of Thermo-Lag material. The purpose of this structure was'to provide a three hour-rated barrier to' enclose and protect these trays as they traverse the Division II CCHVAC area. This-enclosure is being replaced with an approved three hour fire rated assembly.
2. Separation Barrier Between the Redundant CCHVAC Air Handling Units in the CCHVAC Area on El. 6778-6" ,

Due to the close proximity of the divisionalized CCHVAC equipment-in the CCHVAC area on El. 677'-6", a three hour rated fire barrier was constructed of Thermo-Lag material to separate this equipment. This barrier is being-replaced with an approved three hnur fire rated assembly.

3 Electrical Blockout Closure in the Cable Tray Area on El. 631'-0" .;

Thermo-Lag material was used to seal the electrical blockout opening between this area and the cable tunnel on elevation '.

613'-6". The purpose of this barrier was to provide a three hour fire rated seal in a floor opening. This penetration seal is being replaced with an. approved three hour fire rated barrier.

4. Electrical Blockout Closure in the Cable Spreading Room on i El. 630'-6' Thermo-Lag material was used to seal the electrical blockout opening.between this area and the Cable Tunnel on elevation '

613'-6" and into the barrier separating the two (2) halves of the Cable Tunnel. The purpose of this barrier was to provide a three'  ;

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-hour fire rated seal in a floor opening. This penetration seal c is being replaced with an approved three hour fire rated barrier.

Cable Tray Enclosure for Cable Tray 1K-034 in the Relay. Room 5

Stairwell Enclosure Between El. 613'-6" and 643'-6" A three hour rated fire barrier of Thermo-Lag material was constructed around cable tray 1K-034 to provide the required-separation from cable tray 2K-030 both of which are located in the relay room stairwell. This barrier is being replaced with an i approved three hour rated fire barrier.

6. Ventilation Equipment Area Wall, Elevation 659'-6" The west wall of the ventilation equipment area on elevation  !

659'-6" contains a large Thermo-Lag material wall section/ seal between columns 9 and 10. This seal was installed above and around four (4) HVAC ducts and some a port steel where the ducts travel through this wall and into a arge pipe /HVAC chase to maintain the three hour fire rating of the wall. This Thermo-Lag seal is being replaced with an approved three hour fire rated assembly. -

7 CCHVAC Equipment Area Wall Sections Elevation 677'-6" The concrete block wall enclosing the small HVAC room in the CCHVAC area on the fifth floor contains three (3) openings and some adjacent support steel which were sealed with Thermo-Lag to maintain the fire rating of the wall. These Thermo-Lag seals-~are being replaced with approved fire rated assemblies.

8. Cable Tray Enclosure for Trays 1C-078 and 1P-073 Elevation ,

667'-6" i Two (2) cable trays (1C-078 and 1P-073) are routed between the. i Division I CCHVAC equipment area and-the SBGTS rooms have been enclosed by a envelope. of Thermo-Lag. The purpose of this. ,

structure was to provide a three hour rated fire barrier to enclose these trays as they traverse the Division-II CCHVAC, area. The two trays were originally considered to_be required ,

-for safe shutdown but subsequent reanalysis determined that-the cables in trays10-078 and 1P-073 are not_ required for safe shutdown. Hence, the cable enclosure is no: longer required and j

is being removed.

The openings' exposed by the removal of Thermo-Lag cable vault;in the Division I CCHVAC' enclosure wall'and in the wall into the..  ;

SBGTS area are being filled with UL listed'three hour rated and  !

air tight seals using approved material.s to restore those. .l barriers to their original design configuration. [

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USNRC

. February 11, 1994 NRC-94-0011

, Page 4 In the remaining three areas it was determined that the requirements of Appendix R to 10CFR50 could be met withoui. these Thermo-Lag installations. Hence, the following three barriers are being reclassified as smoke and gas barriers and, thus, are not being removed or replaced:

9 HVAC Chase Floor Closure, Elevation 613'-6"

-t The HVAC chase at column H-10 extends from elevation 613'-6" to elevation 677'-6" and is completely _ devoid of combustible material for its 64 foot vertical length. The walls of this chase are constructed and sealed as 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated barriers. The floor of this chase was constructed of Thermo-Lag material and- i was intended to be a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated barrier. .

Automatic fire detection is provided at both the_613'-6" and 677'-6" floor openings of this chase. 'The mezzanine area on elevation 603'-6" is also provided with an automatic wet pipe sprinkler system plus additional sprinkler coverage for selected cable _ trays on the mezzanine. Manual' fire suppression capability is provided at each end of this chase.

UFSAR Section 9A.4.2 3 states that the combustible loading below ,

the chase translates to a fire duration of less than one hour, however, the presence of the wet pipe sprinklers and automatic detectors will ensure any fire occurring in the vicinity of the-chase opening will be quickly detected and extinguished.

Therefore, any postulated fire on elevation 603'-6" will not be; of sufficient intensity or duration to propagate up a 64 foot high HVAC chase. As documented in'UFSAR Section 9A.4.2.16 the-combustible loading at elevation 677'-6" translates to a fire >

duration of less than two minutes. Also, there are no combustible materials in the HVAC chase.

Therefore, based on the above discussion, flame propagation between elevations 603'-6" and 677'-6" via the 64 foot high HVAC chase at column F-10 is not a credible event regardless of the-presence of.the Thermo-Lag barrier. Hence, this barrier is being reclassified as a continuous non-fire rated smoke and gas barrier as defined in NFPA 101.

10. HVAC Chase Floor Closure, Elevation 630'-6" A second HVAC chase at column F-13 extends from elevation 630'-6", directly above the southwest corner of the Relay Room, ,

to the Control. Room ceiling at elevation 654'-0"; and is l completely devolu of combustibles for its approximate 23 foot- i length. The HVAC ducts entering this chase at and'on elevation  :)

630'-6" are provided with fire dampers. The walls and the 'j l

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ceiling around the HVAC ducts exiting the chase on elevation ,

654'-6" are 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated barriers. However, the metal HVAC ducts ,

exiting the chase at elevation 654'-0" are not provided with fire ,

dampers. Two pieces of Thermo-Lag material were~ used to seal the '

floor of this chase as a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated barrier.

Automatic fire detection is provided at both the 630'-6" and 654'-0" elevation of this chase. The Relay Room is also provided with an automatic halon suppression system. Manual fire suppression capability is provided in 'both the Relay and Control rooms. Additionally, the Control Room is continually staffed by ,

personnel trained in fire suppression.

UFSAR Section 9A.4.2.4 states that the combustible loading in the Relay Room translates to a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> fire duration, however, the-presence of the-automatic detection and halon suppression system-will ensure that any postulated fire in this room will be quickly  ;

detected and extinguished. The area above the Control Room ceiling is practically devoid of combustibles in the' vicinity of this chase. Therefore, any postulated-fire in the Relay Room will not be. of sufficient intensity or duration to breach the two T small Thermo-Lag floor panels and then travel up a approximate 23 foot high chase which itself is devoid of combustibles, breach the metal ductwork above this chase, and spread into the Control .:

Room suspended ceiling area. The fire would have to breach the metal ductwork twice, ance_just to get'into the ductwork itself, and again to break out into the 654'-0" elevation.~ Also, NFPA 90A gives HVAC ductwork in walls equal to a one hour fire a resistance rating.

Therefore, based on the above discussion, flame propagation betweea the Relay Room and the Control Room-via the HVAC chase  !

and two breaches of the metal ductwork at column F-10 is' not-a credible event. Hence, the Thermo-Lag barrier is being_  ;

reclassified as a non-fire rated continuous smoke and gas barrier. ,

as defined in NFPA 101 used to maintain the halon' concentration in the Relay Room by preventing it from spreading into the chase.

11. Relay Room Stairwell Enclosure in the-Northeast Corner of the Relay Room on El. 613'-6" A three. hour rated fire barrier was constructed'of Thermo-Lag- '

material to separate the Relay Room from the Control Center ,

northwest stairwell at elevation 613'-6". This barrier is being .  ;

reclassified as a continuous smoke and gas barrier as defined by NFPA 101, and;is no longer considered as a' fire' barrier. The  !

remaining stairwell walls become the three hour rated fire _

barrier separating the Relay -Room from the Cable Spreading and

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Control Rooms. To support this change the following upgrades are ,

USNBC

, February 11, 1994 NRC-94-0011 Page 6 being performed to the existing stairwell walls and ceiling, converting them to three hour rated fire barriers.

o lhe doors leading into the Cable Spreading Room (RM2-4) on elevation 630'-6" and the Control Room (R3-20) on elevation 643'-6" from the stairwell are being replaced with three hour rated doors, o The underside ceiling of the stairwell will be coated with a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire rated cementitious mixture fire barrier.

The justification for these reclassifications is being included in the Fermi 2 Fire Hazards Analysis (UFSAR Appendix 9A). All efforts to replace or reclassify Thermo-Lag fire barriers at Fermi 2 are being planned for the current outage and are expected to be completed by Fall, 1994. Documentation attesting qualifications of replacements and reclassifications are available at Fermi 2 for review and inspection, k

V If you have any questions, please contact Mr. Girija S. Shukla at-(313) 586-4270.

Sincerely, cc: T. G. Colburn J. B. Martin M. P. Phillips W. J. Kropp t-

.USNRC

~- February 11, 1994  :

NRC- 94-0011

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I, DOUGLAS R. GIPSON, do hereby affirm that the foregoing statements are based on facts and circumstances which are true and accurate to ,

the best of my knowledge and belief. .

t t

m s 'lYJ e DOUGLAS R/. GIPSON' Senior Vice President .T t r ,

On this I!

day of I N *ol , 1994, before me personally.

appeared Dougiae R. Gipson, being first duly sworn and says, that he-executed the foregoing as his free act and deed.

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Notary Public

' KAREN M. GEED -

NOTARY PUDuc-5/0NRCE COUNTY,M!CH.

MY CcW.tSON DyiRES 4-2744

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