BVY-92-092, Responds to NRC Bulletin 92-001 Failure of Thermo-Lag 330 Fire Sys to Maintain Cabling in Wide Cable Trays & Small Conduits Free from Fire Damage. Continuous Fire Watch for 3/4-inch Conduit Established

Responds to NRC Bulletin 92-001 Failure of Thermo-Lag 330 Fire Sys to Maintain Cabling in Wide Cable Trays & Small Conduits Free from Fire Damage. Continuous Fire Watch for 3/4-inch Conduit Established

ML20099B013
Person / Time
Site:	Vermont Yankee
Issue date:	07/24/1992
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-92-092, BVY-92-92, IEB-92-001, IEB-92-1, NUDOCS 9207300099
Download: ML20099B013 (3)

Text

VERMONT YANKEE NUCLEAR POWER CORPORATION i Ferry Road. Brattleboro. VT 0530t+7002 Md).

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k W 8.8MN St ru [ Y y% DO TON RA 01740 OMO 7 79 (711 July 24,1992 BVY 12 092 U.S. Nuclear Regulatory Commission

~ ATTN: Document Control Desk Washington, D.C. 20555

References:

(a) License No. DPR 28 (Docket No. 50-271)  ?

(b) NRC Bulletin 92-01, Fallure of Thermo-Lag 330 Fire Barrier System to Maintain -

Cabling in Wide Lable Trays and Small Conduits Free From Fire Damage, dated 6/24/92 (c) 'Aemo, WH Rasin (NUMARC) to NUMARC Administrative Points of Contact, ,

NRC Meeting with NUMARC on Thermo-Lag Fire Barrier issue, dated 7/8/92

Subject:

NRC Bulletin 92 01 Response T

Dear Sir:

' On_6/25/92, Vermont Yankee was notified by reference b) that the fire protection qualification of Thermo-Lag 330 (TL) fire barrier material was indeterminate, based upon testing performed.

Independently by another utility.' Reference b) further instructed all nuclear fricilities utilizing this

' material to compensate as if the fire barriers were degraded, and to provide, within 30 days of receipt, a written notification describing whether Thermo-Lag barriers were installed and what actions would be taken to ensure or restore fire barrier integrity. This letter is submitted as our response to NRC Bulletin 92-01.

IMMEDIATE CORRECTIVE ACTIONS:

After consideration of the information contained in Bulletin 92-01, five conduits, consisting of two 3/4", one 3" and two 4' were identified as incorporating this type of barrier. Thermo Lag 330 fire wrap is_ installed on these conduits in the 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> configuration. No cable tray applications were identified. As an interim measure, the following compensatory measures were instituted immediately:

1): A continuous fire watch was established for the 3/4" conduit, based on the results of '

the testing that indicated the material may not withstand the required fire endurance rating. 3

2) . An hourly fire watch was established for the 3* and 4" conduit, based on the relatively low combustible loading in the subjuct areas and the testing results that Indicated that larger size conduit (5" was tested) may not be subject to the same concerns raised about the smaller condults.

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. VERMONT YANKEE NUCL E AR POWER CORPOR ATION U.S. Nuclear Regulatory Commission July 24,1992 Page 2 it should be noted that none of the subject conduit applications at Vermont Yankoo are specified in the Vermont Yankee Technical Specifications. Therefore, no Technical Specification requ' red compensatory measures were necessary.

bNALYSIS; A more detailed review of the specific Thermo-Lag 330 applications at Vermont Yankee has subsequently been performed for these conduits, which are considered Appendix *R* fire barriors.

The following are the results of this review:

1) The basis for originally protecting the 3/4" conduits has since been climinated due to sJbsequent design evolution / equipment upgrades, specifically Reg Guide 1.97 suppression chamber water level and temperature upgrades. Therefore, concern for these small diameter conduits are no longer applicable and compensatory measures are not required.

2) Dased upon NUMARC guidance contained in reference c), which states that Bulletin 92-01 should only address conduit pmger than 4 inches, the two 4" conduits wrapped with TL-330 located in the Radwaste Hallway are considered outside the scope of Bulletin 92-01 and thernfore do not require compensatory measures.

3) The one 3' condult that is wrapped with Thermo Lag 330 is the only applicatior' at Vermont Yankee within the scope of Bulletin 92 01. The conduit is wrapped in two Reactor Building locations with TL 330 and houses the de power feed from the Alternate Shutdown Battery to the RCIC system for shutdown outside of the control room. Considered in our evaluation of appropriate compensatory measures were the following:

a) There is no test evidence that properly installed TL 330, 3" conduit fire wrap is unacceptable, b) The Texas Utilities testing was based upon a one-hour fire barrier, Vermont Yankee's configuration is a three hour barrier. Therefore the testing performed to date is inconclusive with regard to our particular configuratior..

c) Fire detection exists in the areas where this fire wrap is present and would immediately alert the Control Room in the unlikely event of P fire in the area.

d) Ignition sources are not present near the location of the condult wraps. Additionally, no junction box is included in the protected cable / conduit routing, e) The conduit is located in a Fire Control Araa, and thus subject to the administrative controls that limit combustibles and impcse strict requirements for " hot-work"

I VERMONT YANKEE NUCLE AR POWER CORPOR ATION U.S. Nuclear Regulatory Commission July 24,1992 Page 3 f) Based upon VY's particular conduit routing / configuration, a review of installation procedures developed from TSIInstallation Instructions, the use of TSI trnined/ certified installers, and considerable quality control oversight, Vermont Yankee is confident that the fire wrap was properly and adequately Installed.

Following careful engineering review in consideration of the above, Vermont Yankee has determined that a once per shift walkdown of the areas that contain the 3' fire wrap is sufficient to ensure that no additional combustibles have boon introduced, and that this conduit is adequately protected.

SUMMARY

The Thermo Lag 330 fire barrier material in question is utilized to a very limited extent at Vermont Yankee. We bellave we have appropriately addressed the issue with the information currently available to the industry. Vermont Yankee is aware of an industry program being coordinated by NUMARC to establish a test database, develop guidance for applicability of tests, develop generic installation guidance and consider / coordinate additional testing as appropriate. We have a high confidence level that the installed 3" conduit fire wrap will provide protection equivalent to a three hour fire barrier. We intend to monitor further developments with this product and will take additional actions if warranted.

We trust that the actions prnposed are responsive to your concerns; however, should you have any further questions, please do not hesitate to contact us.

Very truly yours, Vermont Yankee Nuclear Power Corporation f? q Warren P. Murphy Senior Vice President, Operations cc: USNRC Region I Administrator USNRC Resident inspector VYNPS USNRC Project Manager VYNPS William H. Rasin, NUMARC l

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