ML20236V605

Interim Deficiency Rept 215 Re Fire Safe Shutdown Commitments as Documented in Section 3.2.1,Item 17 of Fire Protection Evaluation Rept.Initially Reported on 871022. Diesel Generator Control Circuits Redesigned

ML20236V605
Person / Time
Site:	Limerick
Issue date:	12/02/1987
From:	Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
215, NUDOCS 8712040400
Download: ML20236V605 (4)

Text

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1F PHILADELPHIA ELECTRIC COMPANY 23O1 MARKET STREET .

P.O. BOX 8699 ,

.J PHILADELPHIA, PA.19101 /

(215)841 45o2 1

s. J. KOWA LSKI VICE.PR E$lDENT -

DEC 0 21987 Mr. W. T. Russell, Administrator I U.S. Nuclear. Regulatory Commission, Region'I Att ention: Document Control Desk washington, DC 20555-

SUBJECT:

Significant Deficiency Evaluation No. 215 Appendix R Safe Shutdown Capability, Fire Area 75 2353-

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Limerick Generating Station, Unit 2-NRC Construction Permit No. CPPR-107 FILE: QUAL 2-10-2 (SDR No. 215)

Dear Mr. Russell:

In compliance with 10CFR Part 50.55 (e) , we are hereby submitting an interim ' report of the subject nonconformance. The Philadelphia Electric Company (PECo)~ discussed this nonconformance with the NRC Region I office during the PECo/NRC Management Enforcement Confe rence on October 22, 1987. The nonconformance concerns fire safe shutdown commitments as documented in-Section 3.2.1, Item 17 of the FPER (Fire Protection Evaluation Report) for Limerick Generating Station, Unit 2. This nonconformance was identified during a. detailed review of the diesel generator (D/G) . trip bypass circuits for Limerick-Unit 1.

Section 3.2.1, Item 17 of the Limerick FPER commits to identifying and analyzing all non-class lE circuits where failure could affect operation of safe shutdown equipment. Contrary to the commitment, cables 20M014 B,C,D,E, 20M015 B,C,D,E, 20M016 B,C,D,E, and 20M017 B,C,D,E, were not properly evaluated during the performance of the Limerick Safe Shutdown Fire Analysis. Because these cables were not properly identified and analyzed as saS . shutdown cables,'- the effect of a fire on these cables was not considered.

These cables are all located in Fire Area 75, . the Service Water Pipe Tunnel. An Appendix R design basis fire in that area _ is assumed to cause the shorting of the internal conductors of'these cables which would cause spurious trip signals to all four.D/G's. These. trip.

signals would' occur via the fire suppression system actuation trip shown l- on Drawing 8031-E-591, Sheet 2.

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8712040400 PDR B71202ADOCK 05000353:y y(g g PDR

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- Had Limerick Unit 2 been in operation, and an Appendix R Fire in Fire Area 75 occurred, Shutdown Methods A,B and R would have still been available. Operator action required to restore the D/G's would have been required to 1) Trip the power source breaker to the fire suppression trip circuit at Panel 20Y202, 2) . Reset the D/G trip signal at the local D/G control panel, and 3) Manually restart the D/G via the control switch either in the control room or at. the D/G local panel.

These actions would not have been required to have been taken for more j than several-hours after the D/G's tripped because the DC systems used to achieve and maintain hot shutdown via shutdown Methods A.B and R would have been unaffected by this scenario.

1 Had these cables been identified properly in the original i i associated circuit analysis, the above steps to restore D/G operation i would need to have been inserted in the appropriate Special Events procedures.

During the identification of safe shutdown cables and the associated circuit analysis, all cables whose failure could have caused the disabling of safe shutdown equipment were to be identified. The basis used to exclude these associated circuits from the safe  ?

shutdown cable data base was that if non-safe shutdown cables were  !

isolated from the safe shutdown cables via a Class lE isolation device, then their failure could not propagate back into the safe shutdown circuitry and no further analysis was required. This basis, however, did not take into consideration the unique functional association of the non-class lE fire protection flow switches with the D/G trip circuitry.

I Although these cables met the required electrical isolation criteria, l they should have been identified as safe shutdown cables because of the functional association resulting from the unique configuration of the i

Class lE isolation relay. Normally when a relay is utilized as the Class lE isolation device, it is configured with the relay coil in the Class lE circuit and the relay contact in the non-class lE circuit.

This configuration provides electrtcal isolation and precludes the non-Class lE circuit from functionally affecting the Class lE circuit.  !

In the unique case of the D/G fire protection flow switch circuitry, the ]

non-Class lE flow switch circuit was wired to the coil of the Class lE isolation relay and the Class lE D/G trip circuit was wired to the l contact. This configuration provides electrical isolation but does not l preclude the non-Class lE circuit from functionally affecting the Class lE circuit.

As a permanent corrective action, we have redesigned the D/G l control circuits by removing the fire suppression flow switch trips.

We have reviewed the consequences of this modification and have determined that these actions will not jeopardize the ability of the D/G's to perform their safety function, nor will any of the other protective features associated with the D/G's be adversely affected.

Defeating the fire protection flow switches will prevent a D/G trip from occurring should the sprinklers in the D/G compartment actuate either spuriously or as a result of a fire.

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In addition, we are re-reviewing the electrical . schematic .  !

drawings and the application of Class lE -isolation relays at Limerick i Units 1 and 2 to ensure that.the functional association which occurred in the D/G fire protection flow switch circuitry is a unique case. The criteria for safe shutdown cable selection is also being reviewed to verify its adequacy. l l

A final report for Limerick Unit 2 will be submitted after .

this review is completed. This report -is expected to be completed and submitted to the NRC by March'31, 1988. j

'I Sincerely, l

/

i S. J. owalski, Vice-President -l '

Engineering and'Research Department AWJ/slc sc1119871835 Attachment Copy tor W. T. Russell, Administrator U. S. Nuclear Regulatory Commission, Region 1 631 Park Avenue King of Prussia, PA 19406 R. A. Gramm, Senior Resident Inspector Limerick Generating Station, Unit 2 U. S. Nuclear Regulatory Commission P.O. Box 46 Sanatoga, PA 19464 l ____ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____ -_ _ . .J

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i OCC: S. J.'Kowalski M. S. Iyer, Bechtel L. B. Pyrih 'D. B. Fatters' ]

R. J. Lees DAC-  !

G. A. Hunger, Jr. W. J. Coyle '

C. J. McDermott J. J. Milito E. J..Bradley W.~W. Bowers l W.'J. Boyer, Jr.. -P. K. Pavlides -j A. R. Diederich. 'J. J.-Gyrath 1 l

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