3F0795-05, Responds to Two Specific Issues Raised by NRC Staff Re Thermo-lag Fire Barrier Test Program

Responds to Two Specific Issues Raised by NRC Staff Re Thermo-lag Fire Barrier Test Program

ML20086S693
Person / Time
Site:	Crystal River
Issue date:	07/27/1995
From:	Beard P FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0795-05, 3F795-5, NUDOCS 9508020082
Download: ML20086S693 (4)

Text

!

},

Florida Power CORPORATION i

thcesa namn 1

1 I

July 27, 1995 3F0795-05 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555

Subject:

Response to NRC Staff Comments on Thermo-Lag Related Ampacity Derating Tests for Crystal River Unit 3

Reference:

NRC to FPC letter, 3N0695-10, dated June 22, 1995

Dear Sir:

The purpose of this letter is to respond to the two specific issues raised by the NRC Staff in the reference letter regarding our Thermo-Lag fire barrier test program.  ;

NRC Concern 1 i

The staff believes that ampacity derating tests for safety-related electrical raceways should be treated as Appendix B activities. You intend to use the Appendix B QA program for fire protection (as described in the Standard Review Plan Section 9.5) for your ampacity derating tests.

This would not address all the areas of Appendix B. Please discuss your rational,e.

FPC Response Ampacity derating tests for safety-related electrical raceways performed by Underwriters Laboratory, Inc. (UL) for FPC will be classified as safety related, and performed under the FPC Appendix B Quality Program as described below.

020018 9508020082 DR 950727 ADOCK 05000302 PDR k CRYSTAL RNER ENERGY COMPLEX: 15760 W Power Line St . Crystal FWyer, Florida 344284708 e (904) 7956486 A Horida Progress Company ,

0(C \

i \0

__ ___________________________________________ ___________ ___ J

7.

U. S. Nuclear Regulator 3F0795-05 Page 2 of 4 FPC's Procurement Quality Section performed a pre-award survey of UL to establish their capability for performing fire endurance and ampacity derating testing. The Survey Team used the NUPIC Commercial Grade Item Survey Checklist, Revision 2, which addresses programmatic controls in the areas of Design Control, Procurement Control, Material Controls, Manufacturing Processes, Inspection and Test Controls, Measuring & Test Equipment Control, and Quality Program Control. In addition, the Survey Team focused on the following critical characteristics important to ampacitiy derating testing:

. Custody of customer-supplied material to be tested

. Construction of test assemblies

. Ambient condition control of the test environment (pressures, temperatures, air flow)

. Control of thermocouples (type, location)

. Control of tolerances

. Independent observation of tests

. Consistency of UL procedures with ASTM /IEEE Standards The survey determined that UL does not possess a 10 CFR 50, Appendix B program, and that the services provided are classified as Commercial Grade. Therefore, FPC will dedicate the ampacity test services using a combination of dedication methods described in EPRI Document NP-5662,

' Guideline for Utilization of Commercial Grade Items in Nuclear Safety Related Applications.' FPC will accept responsibility for the reporting requirements of 10 CFR 21. This process will assure that the ampacity test services will be treated as Appendix B activities.

Regarding quality assurance and fire protection activities, FPC is specifically committed to NRC Guideline, " Nuclear Plant Fire Protection Functional Responsibilities, Administrative Controls, and Quality Assurance," 1977. Fire endurance tests will be performed under the quality requirements established in the Crystal River Unit 3 Fire Protection Plan, which are based on this NRC Guideline.

NRC Concern 2 Please demonstrate the applicability of ampacity test results using the steel test specimens to actual Thermo-Lag protected aluminum constructed electrical raceways at your facility.

FPC Response FPC has committed to conduct ampacity tests in accordance with the latest I available draft of IEEE P848 (Draft 16). Section 4.2 of P848 specifies  !

the raceway material to be steel. Recognizing that CR-3 uses aluminum l raceways, with the exception of steel raceways located in the Reactor  !

Building, it was necessary to determine if steel raceway ampacity tests i would bound the CR-3 specific installation. l To this end, several telephone conversations were held with various members serving on the P848 committee including the chair and vice-chair.

Based on these discussions, the reasoning behind the decision for requiring steel raceway for P848 ampacity testing was found to be:

. Steel raceway is predominantly used by the industry.

/

3.

U. S. Nuclear Regulatory l 3F0795-05 l Page 3 of 4

. The desire to eliminate the introduction of additional variables other than fire barrier material.

. The ampacity correction factors derived from using steel raceway would be conservative when applied to' the same barrier using aluminum raceway.

The-third point may be verified by considering the Neher-McGrath method of calculating ampacity (J. H. Neher and M. H. McGrath, "The Calculation of ,

the Temperature Rise and Load Capability of Cable Systems," AIEE Transactions, October 1957, pp. 752-773.). Equation 42 calculates the thermal resistance between the raceway and the surrounding environment and is given by:

(= 15.6n#

D,# I + 1. 6 E (1 + 0. 0167T,)

D, where e is the emissivity of the raceway. It can be seen from the equation that thermal resistance increases as e decreases. Completing the Neher-McGrath ampacity calculation results in lower ampacity for smaller values of e and higher ampacity for larger values of c.

The emissivity for aluminum is typically less than steel. For raceway installed in a power plant for a number of years, Table A-10 of J. P.

Holman, " Heat Transfer," Third Edition, gives a range for oxidized aluminum from 0.20 to 0.31. Preliminary data from baseline ampacity tests at Underwriters Lab indicates that emissivity for galvanized steel raceway ranges from 0.64 to 0.68. Due to the difference in emissivity, this results in a lower ampacity for aluminum raceways when compared with steel raceways, all other parameters held constant.

When a fire barrier is applied to the raceway, the protected ampacity will usually be less than the baseline ampacity. If a tight fitting fire barrier is used, the effects of the raceway emissisity v:ill be reduced or masked due to elimination of the air gap between the raceway and fire barrier. The result is that the difference between the protected ampacity for aluminum and steel raceways is smaller than the difference for the unprotected cases.

These two effects combine to give the following results when calculating ampacity correction factors and ampacity derating factors.

From Section 5.2 of P848, the ampacity correction factor (ACF) is given by:

ACF = PROTECTED AMPACITY BASELINE AMPACITY

.- . ...- _-. _ - - - - - . . - - . _ - . . -.- ~_ _

.y

.f t.'- .U.'S. Nuclear Regulatory I 3F0795-05 Page 4 ofl4.

versus ACF it is

By. making .a comparison case willofbethe calculated more conservaACF,,,,kive, i.e. sm,iaTk,er,,since seenthattheACF,,Nyforsteelisgreaterthanforaluminumraceway.

the-baseline.ampac The ampacity derating factor (ADF)Lis given by:

BASELINE AMPACITY - PROTECTED AMPACITY  !

- BASELINE AMPACITY versui, ADF results in a greater derating r Calculating factor for steel the than ADF,,,,for aluminum,.tgiYerefore, FPC believes that using steel raceways .in accordance with IEEE P848/D16 results in conservative i values for ampacity derating when applied to CR-3 aluminum raceways.

Please contact W.'L. Rossfeld at (904) 563-4374 if you have'any questions concerning this letter. .

Sincerely,.

i

. . Beard, Jr. i' Senior-Vice President Nuclear Operations PMB/SCP:ff ,

xc: Regional Administrator, Region II NRR Project Manager Senior Resident Inspector i

i t