ML20209J077

Safety Evaluation Concluding That Licensee Provided Adequate Information to Resolve ampacity-related Points of Concern Raised in GL 92-08 for BFN & That No Outstanding Issues Re GL 92-08 Ampacity Issues for Browns Ferry NPP Exist

ML20209J077
Person / Time
Site:	Browns Ferry
Issue date:	07/16/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20209J029	List: ML20209J025 ML20209J077
References
GL-92-08, GL-92-8, NUDOCS 9907210123
Download: ML20209J077 (4)

Text

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rerug q^, UNITED STATES 8 ,

' NUCLEAR REGULATORY COMMISSION

$ l WASHINGTON, D. C. 20586

?,.....j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION GENERIC LETTER 92-08 AMPACITY DERATING ISSUES j TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT. UNITS 1. 2 AND 3 )

DOCKET NOS. 50-259.60-260 AND 50-296

1.0 BACKGROUND

By letter dated November 7,1995, Tennessee Valley Authority (TVA or the licensee) made modifications to the existing Thermo-Lag fire barrier of one division of the Residual Heat 4 Removal Service Water System cables which are located at the Browns Ferry Nuclear Plant ,

(BFN) Intake Pumping Station.

The staff evaluation for BFN, which constitutes the review and approval of TVA's ampacity <

dorating test or analyses for installed Thermo-Lag fire barrier configurations, follows.

2.0 EVALUATION The licensee utilized Watts Bar Nuclear Plant (WBN) test data to derive the ampacity derating factors for the Thermo-Lag configuration installed at BFN. The licensee ampacity dorating test methodology followed the guidance in draft institute of Electrical and Electronics Engineers (IEEE) Standard P848, " Procedure for the Determination of the Ampacity Derating of Fire Protected Cables," Revisions 11,12, and 14, dated April 6,1992, February 24,1993, and April 15,1994, respectively, except for changes identified in Individual test plans.

The licensee conducted extensive ampacity dorating testing of various Thermo-Lag fire barrier configurations at the licensee's Central Laboratories Services Department (denoted " Phase I tests") in Chattanooga, Tennessee, from March 9 to April 6,1993; April 30 to May 10,1993; and June 1 to June 22,1993; and at Omega Point Laboratories (denoted " Phase ll tests") in San Antonio, Texas, from August 16 to 26,1994; September 14 to October 6,1994; November 15 to December 3,1994; and January 4 to 23,1995. Phase 3 and 4 ampacity tests, which involve the Thermo-Lag material 770-1, were also completed as part of the corporate test program.

The licensee provided adequate disposition of the following concems, which were associated

' with the review of the WBN test program: (1) Effect of reduced Cure Time for the Thermo-Lag s material; (2) Use of simultaneous testing of more than one test article at one time; (3) ,

Presence of negative ampacity dorating factor test results and (4) Extension of IEEE P848 l methodology for non-standard configurations.

The table below lists the WBN ampacity derating factors:

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OD So PDR 59 Enclosure l

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Watts Bar Nuclear Plant Ampacity Derating Values l AMPACITY DERATING RACEWAY REPORT NO. FACTOR (%)

24" cable tray with %" TSI TUE 12340-95169 31.5 configuration Large air drop with 5/8" + 3/8" TSI TUE 12340-95168 31.7 configuration 1" conduit with 5/8" TSI configuration TVA 93-0501 7.0 1" conduit with 5/8" + 3/8" TSI TVA 93-0501 8.0 configuration 4" conduit with 3/8" + 3/8" TSI TVA 93-0501 7.0 configuration 24" cable tray with solid steel cover, TVA 11960-97332 40 with 5/8" TSI configuration 3 24" trays in a common 5/8" TSI TVA 11960-97334 36 configuration 3-1" conduits in a single row in a TVA 11960-97335 8 common 5/8" TSI configuration 2 rows of 3-1" conduits in a common TVA 11960-97336 26 5/8" TSI configuration 1" conduit in a 5/8" TSI configuration TVA 11960-97768 12 mounted on a small Unistrut frame 1" conduit in a 5/8" TSI configuration TVA 11960-97769 6 mounted on a large Unistrut frame 2 rows of 3-1" conduits in a common TVA 11960-97770 9 5/8" TSI configuration mounted on a large Unistrut frame Note: TSI- Thermal Sciences incorporated Apolication of Amoscity Deratino Methodolooy l

Question 4 from the NRC staff request for additionalinformation dated August 29,1996 for WBN posed the following query:

Given the completion of trie ampacity derating tests (Phases I,11, Ill) for the Thermo-Lag fire barriers that are installed at WBN Unit 1, the licensee should confirm that the existing ampacity design margins are adequate and sufficient j 1

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p I.. .

for each installed fire barrier configuration. The licensee should delineate the minimum excess ampacity dorating margins for the various electrical distributiori circuits (e.g.,4 kV, 480 V) enclosed by the Thermo-Lag fire barrier material at the Watts Bar Nuclear Plant.

In its submittal of October 24,1996 for WBN, the licensee stated that upon completion of the ampacity test program, its Corporate Engineering organization evaluated the results and established conservative ampacity correction factors for the various Thermo-Lag fire barrier ,

enclosed electrical raceway configurations. In its submittal of March 22,1995 for BFN, the '

licensee made the following assertions: (1) the licensee will rely on its own quality assurance l

and Thermo-Lag qualification test programs to qualify future Thermo-Lag installations; and (2) the licensee will remove the existing Thermo-Lag material in the BFN Intake Pumping Station and replace this material with new qualified material. The licensee confirmed the subject material replacement by letter dated November 7,1995. Although the licensee's response did not provide the minimum excess ampady mrgins data, this information is ,

l avallatsle for onsite review. The confirmation that the innpacity derating margins are adequate I and sufficient for each fire barrier adequately resolves the objectives of the subject evaluation.

3.0 CONCLUSION

S I

Given that the staff has reviewed and approved of the ampacity derating test program results for WBN as specified in References 1 and 2 and the BFN Thermo-Lag fire barrier configuration is representative of the applicable WBN tested configuration, the staff finds that the licensee has provided adequate information to resolve the ampacity-related points of concem raised in Generic Letter 92-08 for BFN. Therefore, the staff finds that there are no outstanding safety concems with respect to Generic Letter 92-08 ampacity issues for Browns Ferry Nuclear Plant, Units 1,2, and 3.

Principal Contributor: Ronaldo Jenkins Date: July 16, 1999 l

T 4.0 REFERE M

1. NRC Letter from R. E. Martin to O. J. Zeringue dated January 6,1998, " Supplementary Safety Evaluation Report on Ampacity issues Related to Thermo Lag Fire Barriers at Watts Bar Nuclear Plant (TAC NO. 85622)."

2. U.S. Nuclear Regulatory Commission NUREG-0847, " Safety Evaluation Report Related to the Operation of Watts Bar Nuclear Plant, Units 1 and 2," Supplement 18, issued October 1995.

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