ML20153B428
| ML20153B428 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 03/03/1988 |
| From: | Johnston W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| NUDOCS 8803220136 | |
| Download: ML20153B428 (1) | |
See also: IR 05000352/1987027
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ATTN:,, Mr. h W. Gallagher
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Phila3,lphia, Pannsylvania 19101,
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Gentlemen:
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Subject:
Inspection No. 50-352/87-27 and 50-353/87-11
This refers to your letter da+dd February 5,1988, in response to our letter
dated December 30, 1987.
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Thank you for informing us of the corrective and preventive actions documented
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in your ,le der. These actions will be examined during a future inspection of
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your licensed program.
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8803220136 080303
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PHILADELPHI A ELECTRIC COM PANY
2301 M ARKET STREET
P.O. BOX 8699
PHILADELPHIA, PA.19101
(215) e 41 4 500
SENIOR V C
RESIDE T N U C L.E A R
February 5, 1988
Docket No.
50-352
Mr. William T. Russell
Regional Administrator
U. S. Nuclear Regulatory Ccomission,
Region !
Attn:
Doctment Control Desk
20555
SUBJECT:
Limerick Generating Station, Unit 1
Reply to Notice of Vlotation
(Inspection Report Nos. 50-353/87-11 and
50-352/87-27)
Dear Mr. Russell:
Your letter dated December 30, 1987 transmitted the "Notice of
Violation" concerning the Inspection Reports 50-353/87-11 and
50-352/87-27. These Inspection Reports were previously transmitted to
the Philadelphia Electric Conpany In letters dated Septenber 28, 1987
and Novmber 23, 1987, respectively.
The Nntice of Violation" described the failure to provide
adequate fire protection features for control cables associated with
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the Emergency Diesel Generators (EDGs) to assure that one redundant
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train remained free of fire damage. Attached is our reply to the
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A one week extension to allow for submittal of this response
within thirty days frcm recelpt of the notice was discussed in a
telephone conversation between Mr. W. C. Birely of Philadelphia
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Electric Ccnpany and Mr. J. Linville of Region I on February 1,1988.
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If you have any questions or require additional Information,
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please do not hesitate to contact us.
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Very truly yours,
Attachnent
HTJ/kem/01258804
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cc: Addressee
E. M. Kelly, Senior Resident Inspector
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Attschment A
Page 1 of 3
Docket No. 50-352
Philadelphia Electric Company's
Reply to the Notice of Violation
Restatement of the Violation
License Condition 7.c.3, requires, in part, that the licensee maintain
in effect all provisions of the Fire Protection Evaluation Report
(FPER) through Revision 6.
Section 3.2.1 of the FPER through Revision 6 specifies that fire
protection features shall be provided for structures, systens and
ccmponents important tn safe shutdown, and shall be capable of Ilmiting
fire danage so that one train of systens necessary to achieve and
maintain hot shutdown conditions from either the control room or
anergency control station (s) is free of fire damage.
Contrary to the above, as of October 2, 1987, fire protection features
were not provided for control cables associated with the Energency
Diesel Generators (EDGs), a system important in maintaining safe
shutdown, to assure that one redundant train receIned free of fire
danage. These control cables were associated with the autonatic fire
suppression system flow switches that shut down the EDGs In the event
of a fire in the EDG roan. These cables were routed in the service
water pipe tunnel area and were not provided with a means to maintain
one of the trains free of fire dansge.
If a fire occurred In the
tunnel area, it could create multiple Internal shorts in the
connections between the flow switches and associated time delay relays
resulting in trip signals for all four EDGs, with two EDGs required by
the FPER to achieve and meintain hot shutdown.
Adnission or Denial of the Vlotation
Philadelphia Electric Conpany acknowledges the violation as stated.
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Reason for the Violation
The reason for the violation was a deficiency in a procedure used
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during the concrehensive Appendix R Safe Shutdown Fire Analysis
conducted for LGS Unit 1 in 1982. During the identification of safe
shutdown cables and the associated circuit analysis, all cables whose
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failure could cause the disabling of safe shutdown equipment were to be
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Identified. One criterlon In the procedure for exclusion of these
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associated circults fran the safe shutdown cable data base (Drawing
8031-E-1550) was that if they were Isolated fran the safe shutdown
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cables via a Class 1E isolation device, then their failure could not
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propogate back into the safe shutdown circuitry and no further analysis
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was required. This exclusion criterlon was deficient in that It did
not address the need to evaluate the functional association between
non-class 1E circuits and class 1E circuits.
In this event, the
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Attachment A
Page 2 of 3
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Docket No. 50-352
functional association was between the non-class 1E fire protection
flow switches and the EDG trip circuitry. Although these cables net
the required electrical isolation criterlon, they should have been
identified as safe shutdown cables because of the functional trip of
diesel generator by the fire protection systen. Because these cables
were not properly identified and analyzed as safe shutdown cables, the
effect of a fire on these cables was not considered.
Extent or Stonificance of the Violation
These cables supply poner to EDG fire suppression flow swltches which
function to trip a EDG frexn service vhen fire suppression water ficw to
the EDG cell is sensed under non-LOCA condition. This action was
designed to minimize the potential dansge which could result from the
sprinkler systen spraying water en an operating diesel . The subject
cables are all located in Fire Area 75, the Service Water Pipe Tunnel .
An Appendix R design basis fire In that area, postulated to cause the
shorting of the Internal conductors of these cables, could cause a trip
signal to all four EDG's under non-LOCA conditions.
Corrective Actions and Results Achieved
The supply breaker (Panel 10Y202-Circuit 17) for the flow switch poner
cables was pronotly de-energized under a Tenporary Circuit Alteration
(TCA). The four flow switch relays (74-51528-13, 74-51628-13,
74-51728-13, 74-51828-13) were renoved on October 21, 1987 under
Modification 87-5457. An evaluation of the consequences of
de-energizing the power cables and renoving the flow switch circuit
relays has detennined that these actions will not adversely affect the
ability of the EDGs to perform their safety function, nor will any of
the other protective features associated with the EDGs be adversely
affected.
Defeating the fire protection floa switch logic circuitry will prevent
an automatic EDG trip from occurring should the fire suppression system
actuate or an Appendix R fire occur.
Actions to Prevent Recurrence
The Fire Protection - EDG trip is believed to be the only case at LGS
where non-Class 1E circuitry generates a functional trip in Class 1E
circuitry.
Fbwever, as conmitted to at the October 22, 1987
Enforcenent Conference, the 1982 Appendix R review for LGS is being
evaluated to provide assurance that this violation is an Isolated case.
As part of this review, relay arrangements between and anong Class
IE/non-1E circuits are being reviewed and docunented. There are four
arrangenents possible between Class IE or non-1E relay coils and their
Class 1E and/or non-1E contacts.
The relay arrangenent review includes
relays in both safety and non-safety systems and docunents which of the
four arrangenents exists for each relay.
In addition, the Bechtel
drawing revision approval process has been expanded to include
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Attachment A
Page 3 of 3
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Docket No. 50-352
verification that undesirable coll and contact arrangements are not
created by modification work.
Also, to help us to avoid situations such as occurred In this
case, we have reviewed the sections of our Quality Assurance Plans
that address the evaluation of potentially reportable defect" and
nonectrpliances and have initiated changes.
These changes will be
incorporated within 60 days.
Date for Full Ccrnpliance
The relay arrangement review will be ccrrpleted by March 31, 1988.
DMS/aud/01208802
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