REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS) ACCESSION NBR-'9504190112 DOC.DATE: 95/04/14 NOTARIZED: NO DOCKET FACIL:50-275 Diablo Canyon Nuclear Power Plant, Unit 1, Pacific Ga 05000275 AUTH.NAME AUTHOR AFFILIATION BEHNKE,D.H. Pacific Gas & Electric Co. RUEGER,G.M. Pacific Gas 6 Electric Co. RECIP.NAME RECIPIENT AFFILIATION

SUBJECT: LER 95-003-00:on 950315,fire barriers was outside design basis due to inadequate testing qualification basis. ltr.Implemented fire watches as compensatory measure.W/950414 DISTRIBUTION CODE: IE22T COPIES RECEIVED: LTR ! ENCL i SIZE: TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc. NOTES: RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 PD 1 1 MILLER,M 1 1

INTERNAL: ACRS 1 1 2 2 AEOD/SPD/RRAB 1 1 FIL CENTER 1 1 NRR/DE/ECGB 1 1 RR 1 1 NRR/DE/EMEB 1 1 NRR/DISP/PIPB 1 1 NRR/DOPS/OECB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 RGN4 FILE 01 1 1

EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 ~ 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1

NOTE TO ALL"RIDS" RECIPIENTS: PLEASE HELP US TO REDUCE iVASTE! CONTACI'THE DOCUMENTCONTROL DESK, ROOM Pl-37 (EXT. 504-2083 ) TO ELIMINATEYOUR NAME FROM DISTRIBUTIONLISTS I'OR DOCUMENTS YOU DON'T NLED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 28 ENCL 28 t Pacilic Gas and Electric Company 77 Scale Street. Room 1451 Gregory M. Rueger P.O. Box 770000 Senior Vice President and San Francisco. CA 94177 General Manager 415/973-4684 Nuctear Pov,er Generation Fax 415/973-2313

April 14, 1995

PG&E Letter DCL-95-079

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Licensee Event Re ort 1-95-003-00 Fire Barriers Outside Desi n Basis Due to Inade uate Testin uglification Basis

Gentlemen:

Pursuant to 10 CFR 50.73(a)(2)(ii)(B), PG&E is submitting the enclosed Licensee Event Report regarding certain fire barriers being outside their design basis because the fire barrier testing information that PG&E used as a qualification basis did not meet the requirements of 10 CFR 50, Appendix R. A one-hour, non-emergency report was made to the NRC in accordance with 10 CFR 50.72(b)(1)(ii)(B).

The health and safety of the public were not adversely affected by this condition.

Sincerely,

Gregory M. Rueger

cc: L. J. Callan Melanic A. Miller Kenneth E. Perkins Michael D. Tschiltz Diablo Distribution INPO

Enclosure

N0001887

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9504190112 950414 PDR ADOCK 05000275 S PDR

LICENSEE EVENT REPORT (LER) fACILITTNAME11) Diablo Can on Unit 1 0500027518 Fire Barriers Outside Design Basis Due to Inadequate Testing Qualification Basis

OTHER PACIlmES INVOLVEO O SEOVENTIALIAPA0ER REVISION COCKET NVMSER IS) IAPASER DiabloCan onUnit2 0 5 0 0 0 3 2 3 3 15 95 95 0 0 3 - 0 0 4 14 95 0 5 0 0 0 T)os REPCRT Is svSMATEo PORsvANT To 1HE REovIREMENTs of 10 cfR: 111) MOOEIO>

X 10CFR 50.73 a 2 n B 110) OTHER- 100 (Specify In Abstract below and In text, NRC Form 366A)

Donald H. Behnke, Senior Re ulato Su ort En ineer 805 545-2629 COMPLETE ONE LINEFOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 REPORTASLE REPORTASLE TO NPROS TO NPROS

SUPPLEMENTAL REPORT EXPECTEO II%) EXPECTED SUBMISSION IX] YES (Ifyes, compIete EXPECTED SUBMISSION, DATE) I I No DATE (15) 10 16 95

On March 15, 1995, at 1330 PST, with Unit 1 and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PG&E determined that the fire rating of certain fire barrier material installed in various areas of both units was indeterminate. The fire barrier testing results that PG&E used as a qualification basis did not meet the requirements of 10 CFR 50, Appendix R. PG8 E conservatively declared the barriers inoperable. On March 15, 1995, at 1402 PST, a one-hour, non-emergency report was made to the NRC in accordance with 10 CFR 50.72(b)(1)(ii)(B).

PG8 E implemented hourly fire watches as a compensatory measure. PG8E will inspect, evaluate, and modify the fire barriers, as necessary, to ensure that qualified fire barriers are used. PG&E is also reviewing the adequacy of the testing qualification basis of other fire barrier materials.

The root cause and corrective actions for this event have not been determined. A supplemental LER will be issued by 16, 1995, to report the finalized root cause and corrective actions.

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FACtLITYNAME(I) YEAR ':::; SEOVENTIAL 1 x ~ REYISIOI( ERASER "8 MPASER OF Diablo Can on Unit 1 0 5 0 0 0 2 7 5 95 - 0 0 3 '- 0 0 TEXT (111 Plant Conditions

Units 1 and 2 have been in various modes and at various power levels with the conditions described below.

Descri tion of Problem

A. Summary

On March 15, 1995, at 1330 PST, with Unit 1 and Unit 2 in Mode 1 (Power Operation) at 100 percent power, PG&E determined that Pyrocrete fire barrier enclosures did not have an acceptable fire test to support the requirements of 10 CFR 50, Appendix R. The purpose of the Pyrocrete fire barrier. enclosures (KQ) is to protect safe shutdown circuits in various areas of both units. The fire test data PG&E used to credit Pyrocrete fire barrier enclosures are not representative of the installed configurations. On March 15, 1995, at 1402 PST, a one-hour, non-emergency report was made to the NRC in accordance with 10 CFR 50.72(b)(1)(ii)(B).

B. Background

PG&E initiallycommitted to installing 2-hour rated fire barriers within fire zones to protect safe shutdown equipment and electrical cabling. This was done to meet the requirements of. Appendix A to Bechtel Topical Report (BTP) (APCSB) 9.5-1 as part of PG&E's application for an Operating License. The requirements for fire barriers were modified when 10 CFR 50, Appendix R was issued.

10 CFR 50, Appendix R, Section III.G.2, requires that one train of redundant systems necessary to achieve and maintain hot shutdown conditions, located within the same fire area, is free from fire damage by providing one of the following:

1. Separation of redundant circuits by a fire barrier having a 3-hour fire rating, ol

2. Separation of redundant trains by a horizontal distance of more than 20 feet with no intervening combustible or fire hazards, in conjunction with fire detectors and an automatic fire suppression system installed in the fire area, or

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LER MANOR(0)

c"..) MAI8ER:i".".i MPA8KR Diablo Can on Unit 1 0 5 0 0 0 2 7 5 95 - 0 0 3 - 0 0 3 8 1EXT {1)) 3. Enclosure of cable and equipment of one redundant train in a fire barrier having a 1-hour rating, in conjunction with fire detectors and an automatic fire suppression system installed in the fire area.

Information Notice 84-09 states fire barriers installed to meet the requirements of Section III.G.2 of Appendix R must have a basis for their fire rating (such as u/L listing or testing conducted by a nationally recognized testing laboratory for the configuration used in the plant). Generic Letter 86-10 states that, ifan exact replication of a tested configuration cannot be achieved, the application or "end use" of the fire barrier should be unchanged from the tested configuration. As an example, Generic Letter 86-10 states that the use of a cable tray barrier to protect a cable tray that differs in configuration from those that were tested would be acceptable, but the use of structural steel fire proofing to protect a cable tray assembly not be acceptable.

C. Event Description

On , 1977, PG8 E transmitted Amendment 51, including the Fire Protection Review, to its Application for Operating License in accordance with the guidance provided in Appendix A to BTP (APCSB) 9.5-1. On 30, 1978, the NRC requested PG&E to substantiate the fire resistance capability of rated fire barriers by verifying that their construction is in accordance with a particular design that has been fire tested. Also, the NRC requested PG8E to identify the design and the test method used and the acceptance criteria. In addition, the NRC stated that the design as tested was to be representative of field installation.

On July 7, 1978, PG&E committed to installing 2-hour rated fire barriers within fire zones to protect safe shutdown equipment and electrical cabling. On August 3, 1978, PG&E identified where Pyrocrete would be used at DCPP (including its use for barriers to separate safe shutdown circuits) and provided a small-scale fire test report. This report, conducted by an independent laboratory, showed that a wall slab with a 2-inch thickness of Pyrocrete would qualify for more than a 2-hour rating based on the back side of the test assembly not exceeding 250 degrees F above ambient.

On 15, 1978, the NRC issued SER Supplement No. 8 that identified the need for PG&E to perform a full-scale fire test on Pyrocrete according to ASTM E-119 because the small-scale fire test of Pyrocrete submitted on August 3, 1978, was not representative of actual field installations. On 19, 1978, PG8 E responded that it planned to perform full-scale fire tests.

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TEAR g'EOVENTIAL;, ', REVISION IEAISER ': 1AAI8ER Diablo Can on Unit1 0 5 0 0 0 2 7 5 95 - 0 0 3 - 0 0 4 8 TEXT{11)

On February 2, 1979, PG&E submitted a letter that revised its position and stated that full-scale testing in accordance with ASTM E-119 was not necessary. PG&E indicated that it had developed a fireproofing configuration based on comparative test results that met the 2-hour fireproofing requirements. Tests performed by PG&E's cable suppliers on cable identical to cable installed at DCPP showed the cable could withstand 540 degrees F for over 2 hours. Testing by PG&E's Department of Engineering Research veriTied the cable could withstand in excess of 540 degrees F. To provide conservatism, PG8 E chose the acceptance criteria for a fire wall that would not exceed 250 degrees above ambient on the unexposed wall surface. PG&E again cited the small-scale test results it submitted in August 3, 1978, but acknowledged the test was not a full-scale test and did not have Factory Mutual approval or a U/L listing. PG&E's letter noted that, by comparing U/L listed tests using Pyrocrete to other fireproofing materials in a wall configuration, the Pyrocrete design configuration for conduit protection is conservative. The tests PG&E cited for this comparison were for fire proofing of columns and beams showing varying thickness of Pyrocrete, gypsum, and wallboard needed for 2-hour protection. The comparison showed Pyrocrete required the least thickness of the three materials. Similar results were cited in comparing U/L non-load bearing wall tests

On 13, 1980, The NRC issued SER Supplement No. 9 that accepted the Pyrocrete fire barriers based on PG&E's February 2, 1979 letter.

On February 17, 1981, 10 CFR 50.48 became effective which required plants licensed prior to January 1, 1979, to meet the requirements of Sections III.G, III.J, and III.O of Appendix R. PG&E re-evaluated the Fire Protection Program for Unit 1. Because the 2-hour Pyrocrete enclosures were previously approved by the NRC, credit was taken for the 2-hour rated fire barriers to meet Appendix R requirements. On , 1983, PG&E submitted a request for exemptions from Appendix R for Unit 1. The exemptions committed to install 1-hour and 3-hour fire barriers in some areas, and took credit for the 2-hour Pyrocrete enclosures where applicable. Thermo-Lag was the fire barrier material used to meet the 1-hour and 3-hour fire barrier commitment. The NRC approved these exemptions in SER Supplement No. 23 on , 1984.

PG&E conducted a similar Appendix R review for Unit 2 and submitted a request for exemptions on December 6, 1984. The NRC approved these exemptions in SER Supplement No. 31 on , 1985.

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LERMRAEER 8) YEAR,;,',). SEOVENllAL:;:;;l REYl8lON 'c'JM8ER ':::. MPA8ER " Diablo Can on Unit 1 0 5 0 0 0 2 7 5 95 - 0 0 3 - 0 0 5 8

On October 30, 1992, PG8E initiated a nonconformance report (NCR) for Thermo-Lag fire barriers that had been installed to meet Appendix R requirements. The Thermo-Lag qualification was suspect due to concerns with the manufacturer's test and acceptance criteria. At various times, PG8 E replaced the Thermo-Lag with other materials. For several installations, PG8E used Pyrocrete as the replacement material. These included the fire barrier enclosures for the emergency diesel emergency stop switches and C02 manual actuation switches (1-hour fire barriers), and auxiliary saltwater pump and exhaust fan circuits (3-hour fire barriers). To meet Appendix R requirements for these installations, PG8 E used the same fire rating requirements for the new installation as was credited for the replaced installation.

On January 19, 1995, as a follow-up to the Thermo-Lag NCR, PG8E investigated the adequacy of Pyrocrete as a fire barrier material. Preliminary reviews within PG8E indicated that, given the existing combustible loading, the use of Pyrocrete was acceptable, but that a more complete evaluation of the use and qualification of Pyrocrete was needed. During this evaluation a quality problem report was initiated on February 17, 1995, to track the Pyrocrete qualification issue. Investigation of this quality problem included an extensive review of engineering and licensing files and discussions with cognizant engineers to determine the qualiTication basis for the Pyrocrete fire barrier enclosures.

On March 15, 1995, based on the results of the Pyrocrete evaluation at that time, PG8 E determined that the fire tests credited to qualify the Pyrocrete fire barrier enclosures were not representative of the installed configurations. Therefore, the fire rating of the Pyrocrete enclosures was indeterminate. PG8E conservatively declared the Pyrocrete fire barrier enclosures inoperable, instituted the applicable compensatory measures, and made a one-hour, non-emergency report to the NRC in accordance with 10 CFR 50.72(b)(1)(ii)(B).

D. Inoperable Structures, Components, or Systems that Contributed to the Event

None.

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FACILITYNA)AE(1) LER IAAASER (8> YEAR (LI",'EOIENTTIAL „, . REVISION )RAISER .'i+ )48)8ER Diablo Can on Unit1 0 5 0 0 0 2 7 5 95 - 0 0 3 - 0 0 6 8 TEXT(1)) E. Dates and Approximate Times for Major Occurrences

1. February 2, 1979: PG8 E reported to the NRC that Pyrocrete enclosures conservatively met their 2-hour fire rating commitment.

2. March 15, 1995, 1330 PST: Event/Discovery Date: PG8 E determined that fire tests credited to qualify Pyrocrete enclosures were not representative, and the fire rating of Pyrocrete enclosures could not be determined as required by the requirements of 10 CFR 50, Appendix R.

3. March 15, 1995, 1402 PST: A one-hour, non-emergency report was made to the NRC in accordance with 10 CFR 50.72(b)(1)(ii)(B).

F. Other Systems or Secondary Functions Affected

None.

G. Method of Discovery

A This event was discovered in an evaluation conducted as one of the corrective actions for a NCR on Thermo-Lag.

H. Operator Actions

None required.

I. Safety System Responses

None.

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FACI(ITYWAIE(I) OOOKET MPA8ER (T) EER )XAI8ER(8) YFPlt: yj SEOVEMTIAL

A. Immediate Cause

The Pyrocrete fire barrier enclosures installed in both units have not been tested as required by 10 CFR 50, Appendix R.

B. Root Cause

PG8E is investigating the root cause and will report the results of this investigation in a supplement to this report.

IV. Anal sis of the Event

PGRE performed an evaluation of the fire areas affected and preliminarily determined that the Pyrocrete fire barriers would protect the circuits based on the combustible loading and fire hazards within the areas. Each of the areas affected has previously been reviewed under a Fire Hazards Appendix R Evaluation (FHARE). The FHAREs credit the low combustible loading and the available fire protection systems. The Pyrocrete would be expected to protect the circuits and not impact the ability to safely shut down the plant in the event of a fire. Consequently, this event did not adversely affect the health and safety of the public.

Changes to this preliminary analysis, if applicable, will be reported in a supplement to this report.

Corrective Actions

A. Immediate Corrective Actions

PGRE implemented fire watches as a compensatory measure in accordance with its equipment control guideline for fire rated assemblies.

B. Corrective Actions to Prevent Recurrence

PG&E is investigating corrective actions to prevent recurrence and will report the results of this investigation in a supplement to this report.

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FACtUIVt4ME (I) VEILER,( SEOVfNIAL;.,', REVISION MSASER '<: .I MS)8ER Diablo Can on Unit 1 0 5 0 0 0 2 7 5 95 - 0 0 3 - 0 0 8 ~ 8 TEXT(17) VI. Additional Information

A. Failed Components

None.

B. Previous LERs on Similar Problems

LER 1-94-001-01 on fire barrier penetration seals had as its root cause a programmatic deficiency: The review of documents during development of the penetration seal specifications and design drawings apparently did not include ~ a detailed review of vendor installation procedures and associated fire tests. As the primary corrective action to prevent recurrence, PG8 E stated it would establish a program to develop a basis for the qualification of fire barrier penetration seals with respect to qualified fire tests or commensurate with the hazards. The penetration seal program is still under development and is intended to focus on seals. It likelywould not have prevented the recent untested installations of Pyrocrete even ifthe program had been available.

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