ML20059M669

Intervenor Exhibit I-MFP-F1A,consisting of Re Ler 1-91-020-00 Re Failure to Perform TS 3.7.9.4,Action a on Time Due to Llack of Available Design Info

ML20059M669
Person / Time
Site:	Diablo Canyon
Issue date:	08/20/1993
From:	Rueger G PACIFIC GAS & ELECTRIC CO.
To:
References
CON-#493-14435 I-MFP-F1A, OLA-2-I-MFP-F1A, NUDOCS 9311190227
Download: ML20059M669 (7)

Text

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March 31, 1992 '93 GCT 28 P 6 :27 %q< $t)(

PG&E Letter No. DCL-92-074 -

U.S. Nuclear Regulatory Commission. g/2gh3 DOW 48Ek i

ATTN: Document Control Desk

. Washington, D.C. 20555 J =

5 Re: Docket No. 50-275, OL-DPR-80 l

l Diablo Canyon Unit 1 l

Licensee Event Report 1-91-020-00 l

Technical Specification 3.7.9.4, Action a. Not Performed on Time l

Due to Lack of Available Design Information

! Gentlemen:

Pursuant to'10 CFR 50.73(a)(2)(1)(B), PG&E is submitting the enclosed Licensee Event Report (LER) concerning a Technical Specification 3.7.9.4 violation resulting from failure to establish a compensatory. continuous fire watch with backup fire suppression equipment within one hour of

< discovering a condition.that rendered the solid state protection system room Halon system inoperable.

l This event has in no way affected the health and safety of the public.

Sincerely, ,

As/ l Y'f/llf1i (

Gregory M. Rueger cc: Ann P. Hodgdon lecton arcuinony convissicN ip J o rill W h 9 0'I)' OLS 0**" *7pp - F/4 Harry Rood '" the "'at'" cf AMOAAb# 86"#IO E Howard J. Wong w em m /

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DIABLO CANYON UNIT 1 mu TECHNICAL SPECIFICATION 3.7.9.4, ACTION A. NOT PERFORMED ON TIME DUE TO LACK 0F AVAILABLE DESIGN INFORMATION

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su=traostat maroas txpect D o EXPECTED SUSMISSION DATE W YES (if yes, complete EXPECTED SUBu!5510N DATE) X WO ag5'ss; 16 On November 30, 1991, with Unit 1 in Mode 1 (Power Operation) at 100 percent power, Technical Specification (TS) 3.7.9.4 was not met when a continuous fire I watch with backup fire suppression equipment was not established in the Unit I solid state protection system (SSPS) room within one hour of discovering a damaged ceiling tile in that room.  ;

1 The damaged tile was temporarily reinstalled on November 30, 1991, and on '

December 13, 1991, thedamagedtilewasreplacedwithanewtile,whichmadetheceilingf functional. j l

On March 3, 1992, the results of PG&E engineering evaluations concluded that the Unit I l SSPS room Halon system was inoperable from November 30 to December 13, 1991 because the l damaged ceiling tile had not been replaced and the ceiling was not functional.

The root cause of this event was lack of available design information. The TS-required action was not implemented because available documents did not specify the gas barrier function that the SSPS room ceiling performs in maintaining Halon concentration for fire suppression. Since the 1978 design change that specified the design of the SSPS room ceiling, the PG&E design process has undergone significant changes to ensure design documents and procedures supporting design changes are also changed to include required revised design information. To prevent recurrence, an Operations Night Order has been issued to describe SSPS room ceiling integrity and its effect on SSPS room Halon system operability. j 1

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1. Plant Conditions Unit I was in Mode 1 (Power Operation) at 100 percent power.

II. Description of Event A. Summary:

On November 30, 1991, Technical Specification (TS) 3.7.9.4 was not met when a continuous fire watch with backup fire suppression equipment was not established for the Unit I solid state protection system (SSPS) (JC) room within one hour of discovering a damaged ceiling tile in that room. The damaged tile was later determined to have caused the SSPS room Halon fire suppression system to be inoperable.

B. Backgrouna TS 3.7.9.4 requires the Halon system to be operable any time the equipment protected by the Halon system is operable (Mode 1 through Mode 4 (Hot Shutdown)]. With the Halon system inoperable, the TS action requires that, within one hour, a continuous firewatch be established with backup fire suppression equipment.

Surveillance Test Procedure (STP) M-19B, "Halon Fire Suppression System Functional Test," verifies on an 18-month frequency that fusible links function as intended for damper deployment to maintain required Halon concentration in the SSPS room for the required duration. STP M-19B assumes that SSPS room in-leakage and out-leakage are the same as when the acceptance test was initially performed. STP M-19B includes no criteria for room ceiling integrity.

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An investigation was conducted to determine if there have been previous occurrences of damaged SSPS room ceiling tiles that could have adversely affected SSPS room Halon system operability. The investigation determined that there have been instances when the integrity of an SSPS room ceiling has been challenged or considered as part of other events which could have affected operability of the SSPS room Halon systems. There is insufficient information in the documentation to determine if TS 3.7.9.4 violations resulted from these past events.

C. Event

Description:

On November 30, 1991, during a walkdown of the Unit 1 SSPS room, a damaged ceiling tile was observed on top of a cabinet in the room. An Action Request (AR) was written to document this condition.

The damaged tile was temporarily reinstalled on November 30, 1991; however, the tile was not reinstalled in a manner which restored the 5702S/85K

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us- un functionality of the ceiling. It was not determined at that time that SSPS room ceiling integrity could affect Halon system operability, thus Action a. of TS 3.7.9.4 was not performed and no compensatory actions were taken.

On December 3, 1991, the Work Planning Center (WPC) noted on.the AR that the SSPS room volume for Halon concentration retention could be adversely affected by a damaged ceiling.

On December 13, 1991, a new tile was permanently. installed to replace the damaged tile and the functionality of the ceiling was res~tored.

The fire protection system engineer questioned the impact'of a damaged ceiling tile on the operability of the SSPS room Halon' system and

! contacted the fire protection design engineer for his evaluation of l

the d' sign information readily available at the plant.

l l On December 18, 1991, the fire protection design engineer reviewed the available design information for the SSPS room ceiling and determined i

that there was insufficient readily available design information l available. However, the lack of information in.the FSAR did not constitute a nonconformance since a design document existed specifying tile installation requirements.

l On January 3,1992, Quality Control questioned the fire protection i design engineer's determination and requested additional evaluation from the design engineering group.

On February 11, 1992, based on further evaluation by the design engineering group, the operability of the SSPS room Halon system was established as indeterminate betw;.. November 30, 1991 and December j 13,~1991. A nonconformance report was issued.

! On March 3,1992, a Technical Review Group (TRG) determined, based on j design engineering evaluations, that the SSPS room Halon system became l inoperable on November 30, 1991 and that Action a. of TS 3.7.9.4 l should have been entered.

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

None.

E. Dates and Approximate Times for Major Occurrences:

1. November 30, 1991: Event date. A damaged ceiling tile was discovered on top of a cabinet in the Unit 1 SSPS room. The damaged ceiling tile was immediately reinstalled.

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2. December 13, 1991: The damaged ceiling tile was replaced, ,

restoring the functionality of the ceiling.

3. March 3, 1992: Discovery date. Engineering evaluations concluded that the SSPS room Halon system was not operable with the damaged ceiling tile in place.

F. Other Systems or Secondary Functions Affected:

None.

G. Method of Discovery:

Personnel in the TRG reviewing design engineering evaluations of the Unit 1 SSPS room Halon system performance with a degraded ceiling determined that the system was inoperable between November 30, 1991 and December 13, 1991, due to a damaged ceiling tile.

H. Operator Actions:

None required.

I. Safety System Responses:

None required.

111. Cause of the Event A. Immediate Cause:

I Personnel did not realize that the integrity of the SSPS room ceiling affected the operability of the Halon system.

B. Root Cause: l The root cause of this event was lack of available design information.

No readily available document specified that the integrity of the SSPS room ceiling must be maintained for SSPS room Halon system operability. The TS-required action was not implemented due to design documents not specifying the gas barrier function that the SSPS room ceiling performs in maintaining Halon concentration for fire suppression.

The reportability of this event was also not immediately determined due to the lack of available design information.

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C. Contributory Cause(s):

1. There is no description of the design or function of the SSPS room ceiling in the FSAR.

2. There is no mention of inspection of the condition of the SSPS room ceiling in STP M-198.

3. There is no specific direction provided in any procedure for the repair of SSPS room ceiling tiles.

IV. Analysis of the Event The nominal volume of an SSPS room is approximately 2240 cubic feet (ft')

(14'x16'x10'). The cominal volume above the suspended ceiling is also approximately 2240 ft'. A conservative engineering evaluation has been performed assuming the suspended ceiling does not restrict Halon diffusion, i.e., damaged or missing tiles. This evaluation determined the maximum Halon concentration achieved in the SSPS room would be less than that required to suppress a fire. The actual amount of diffusion and the resultant Halon concentration in the SSPS room would be a function of the size of the opening in the ceiling.

Although the Halon system was conservatively considered to be inoperable when the damaged tile was temporarily reinstalled, smoke detectors in the SSPS room were operational that provide annunciation in the mtrol room.

Manual fire suppression equipment was available in close proximity to the SSPS room for fire brigade use. The SSPS room is immediately adjacent to the control room and operators are qualified fire brigade members, thus, I operators would have expeditiously responded to an SSPS room fire. In the event of an SSPS room fire that could impact control room habitability, an orderly and safe reactor shutdown could have been performed from the remote shutdown panel, if required.

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

V. Corrective Actions l A. Immediate Corrective Actions:

1. The damaged tile was temporarily reinstalled on November 30, 1991.

2. A new tile was installed to replace the damaged tile on

! December 13, 1991 and the functionality of the ceiling was l restored.

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3. Engineering inspected the Units 1 and 2 SSPS room ceilings on ,

March 2, 1992, and determined they were acceptable.

B. Corrective Actions to Prevent Recurrence:

1. An Operations Night Order has been issued to describe SSPS room ceiling integrity and its effect on SSPS room Halon system operability.

2. A Plant Staff Review Committee (PSRC) interpretation of TS 3.7.9.4 will be issued, which will include a description of the SSPS room ceiling functioning as a barrier to contain Halon within the SSPS room in the event of a Halon system actuation.

With any condition that degrades this ceiling function beyond criteria described in revised design documents, an entry into Actio . a. of TS 3.7.9.4 will be required.

3. Design documents will be revised to specify the significance of ,

the functionality of the SSPS room suspended ceiling affecting  ;

the operability of the SSPS room Halon fire suppression system.

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4. SSPS room ceiling installation and repair instructions will also ,

be revised appropriately to address design requirements.

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5. STP M-19B will be revised to include visual inspection of' the SSPS room ceiling integrity. j

6. A cautionary sign wil) be installed at the hatch in the SSPS room suspended ceiling that provides access to the overhead space.

7. STP M-70, " Inspection of Fire Barrier Penetrations," will be revised to include visual inspection criteria for the SSPS room l ceiling integrity following inspection of the space above that ceiling.

VI. Additional Information A. Failed Components:

None.

B. Previous Similar LERs:

None, i

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