ML18093A455

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LER 87-011-00:on 870917,determined That Breaker Coordination Could Not Be Shown to Be Documented for Several Voltage Levels.Cause Unknown.Investigations Continuing to Identify Historical Breaker Coordination basis.W/871016 Ltr
ML18093A455
Person / Time
Site: Salem PSEG icon.png
Issue date: 10/16/1987
From: Mel Gray, Zupko J
Public Service Enterprise Group
To:
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-87-011-02, LER-87-11-2, NUDOCS 8710220188
Download: ML18093A455 (6)
v • d • e


Text

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  • EXl'llll!I: 1/31/le LICENSEE EVENT REPORT (LER)

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hn ty-'mn 1111..i 1111 NO SUIMISllON DATE 11111 I I I On September 17, 1987 at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, it was determined that breaker coordination could not be shown to be documented for several voltage levels in either Salem Unit 1 or Unit 2. This conclusion is based on a draft report of an evaluation of protective relaying of vital busses with respect to the requirements of 10CFR 50 Appendix R.

There is a possibility that circuits associated with non-shutdown loads damaged by a postulated fire could cause the loss of power to shutdown equipment fed from separate vital busses. The root cause has not been determined. Investigations are continuing to identify the historical breaker coordination basis and to establish the adequacy of the current configuration. Root cause will be identified based upon the results of these investigations. Results are expected by the end of December 1987. Actions taken until completion of the breaker coordination study includes establishment of .fire watches where postulated fires could potentially damage redundant vital cabling.

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I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE

. Unit 1 5000272 87-011-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as {xx)

IDENTIFICATION OF OCCURRENCE:

Inadequate Breaker Coordination*

Event Date: 09/17/87 Report Date: 10/16/87 This report was initiated by Incident Report No.87-348.

CONDITIONS PRIOR TO OCCURRENCE:

N/A DESCRIPTION OF OCCURRENCE:

On September 17, 1987 at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, it was determined that breaker coordination could not be shown to be documented for several voltage levels in either Salem Unit 1 or Unit 2. This conclusion is based on a draft report of an evaluation of protective relaying of vital.

busses with respect to the requirements of 10CFR 50 Appendix R.

There is a possibility that circuits associated with non-shutdown loads damaged by a postulated fire could cause the lo~s of power to shutdown equipment fed from the same vital bus. Pursuant to the requirements of 10CFR 50.72(b) (2) (iii) (A), a "four hour report" to the NRC was made on September 17, 1987 at approximately 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br />.

APPARENT CAUSE OF OCCURRENCE:

Investigations are continuing to identify the historical breaker coordination basis and to establish the adequacy of the current configuration. Root cause will be identified based upon the results of ~hese investigations.

Appendix R Subsections III(G) and III(L) require protection of redundant safe shutdown cabling, including associated circuits. Fire damage to circµits includes the consideration of h6t ~ho~ts, op~n circuits, and shorts to ground. Appendix R requires protection to the extent that fire damage to the cabling of non-shutdown equipment will not result in the loss of power to redundant shutdown equipment. This protection could be provided by either breaker coordination or physical separation and fire protection measures.

Since breaker coordination cannot be shown to be documented and fire protection measures are not provided for the subject non-shutdown equipment cabling, ~ssociated circuits damaged in a postulated fire could result in the loss of redundant equipment. required for hot shutdown.

L*ICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 s1-01i-oo 3 of 5 ANALYSIS OF OCCURRENCE:

Appendix R fire.protection requirements are only applicable to cabling and equipment necessary for safe shutdown of the plant.

However, associated cabling for non-safe shutdown equipment that is fed from a common bus must also be considered because fire damage to this cabling could result in the loss of power to safe shutdown equipment. Breaker coordination precludes this possibility by ensuring the overcurrent protection device immediately upstream from a fault, caused by a postulated fire, opens before any breaker further upstream.. Thus the electrical loads that are isolated due to the fault are only thos~ loads fed from the lower tier breaker.

Without breaker coordination, the possibility exists that a* line fault in cabling that does not ~eed safe shutdown equipment could result in a breakeL opening upstream, thus inadvertently isolating the power supply for equipment.fed from busses located between the breakers. These electrical loads could include equipment necessary for the safe shutdown of the plant.

  • The draft breaker coordination evaluation indicated that breaker coordinatio~ may not exist for all devices 6f the following voltage levels: 460V-230V Load Centers; 23.0V Motor Control Centers; 120VA.C Systems; 125VDC Systems; and 28VDC Systems. Therefore, a postulated fire damaging non-snutdown related cabling at these voltage levels could result in the loss of power to safe shutdown equ.ipment. The draft breaker coordi.nation evaluation indicates that breaker coordination exists at the 4160V voltage level with respect to the Diesel Generators. Subsequent analysis has shown that breaker coordination also exists between the 4160V voltage level and offsite power sources.

PSE&G is further evaluating the conclusions of this draft breaker coo~dination report. In the interim, compensatory measures have been taken to ensure that a fire does not occur that could damage associated non-safe shutdown cabling and possibly cause the loss of power to redundant safe shutdown equipment.. This helps ensure the continued protection of the health and safety of the general public.

CORRECTIVE ACTION:

In response to the draft breaker coordination report, each plant area (both Units) was reviewed to establish the potential for fire induced circuit problems. Safe shutdown can be achieved utilizing two of the three plant's vital power* divisions. If a fire area contains cabling.

associated with only one vital division of power, safe shutdown is not impacted by a postuiated fire in that area. For those plant areas where a fire could potentially damage redundant vital cabling, fire watches have been established. *If the area is protected by an installed fire detection system, an hourly roving fire watch has been established. If no detection is present, a continuous fire watch has been established. A fire watch is provided in related fire areas with the exception of 14 High Radiation/High Contamination Areas due to ALARA concerns. The following compensatory measures have been

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 . 5000.272 97.:..011-00 4 of 5 CORRECTIVE ACTION: (cont'd) taken to ensure a fire will not develop in these areas which c_ould

~mpact safe shutdown equipment:

Volume Control Tank Room {CBI (both Units) - The fire watch will not enter the room, however, the area around the room is covered by an hourly fire watch. The room does not contain any vital cabling. Therefore, a fire in the room would need to propagate beyond the room before the potential exists to adversely impact safe shutdown capability. ~he room boundaries, although not rated fire boundaries, do provid~ a degree of ~eparation between the redundant and separated power cabling. Similarly the Spent Resin Storage Tank Rooms, the Chemical Volume and Control System (CVCS) f CBJ Holdup Tank Rooms 13 and 23 and the pipe alleys of both Units will not have a fire watch pat~ol. These rooms also do not contain vital cabling.

11, 12, 21, & 22CVCS Holdup Tank Rooms (both Units) - Cameras have been installed to monitor these rooms. The fire watch will observe the camera monitor as*part of the patrol for the area. A smoke detector has been installed in the Unit 2 CVCS Holdup Tank Rooms common exhaust ductwork. A smoke detector will be installed in the Unit 1 eves Holdup Tank Rooms common exhaust duct by October 20, 1987.

Letdown Heat Exchanger Room {CBl (both Units) - The fire watch will be limited to areas surrounding the room. The room is provided with fire detection and is closed with water tight doors for high-energy line break considerations. These doors do act as fire barriers to some degree, although, they are not "rated".

Containment (both Units) -. The building temperature will be monitored on an hourly basis in lieu o*f a fire watch. The operators have been instrueted to take sp~cific actions if the temperature rises.

A safety evaluation has been issued (S-C-M200-NSE-0709). It. addresses the concern for the continued safe operation of Salem Units No. 1 and No. 2 in light of the breaker coordination concern and the other Appendix R concerns addressed by Unit 2 LER 311/87-009-05. It concludes that continued operatl.on of Salem Units .No. 1 and No. 2 is justified based on the use of compensatory measures (e.g., fire watches).

The fire watch patrols throughout both Units provide reasonable assurance that the fire damage will be limited to oniy one train ofredundant vital cabling/equipment. Therefore, the safe shutdown capability of the Units is maintained. Also, the fire watch patrols provide surveillance for hazardous conditions not normally detected by installed fire protection systems. Such conditions include: obvious activities by plant personnel that could increase the fire hazard in the area; conditions likely to cause a fire such as spills of flammable liquids or major malfunctioning of equipment; conditions

LICENSEE EVENT REPORT (LER) TEXT-CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 87-011-00 5 of 5 CORRECTIVE ACTION: (cont'd) likely to adversely affect fire protection such as blocked fire brigade access routes; and major accumulation of transient combustible materials.

The long term corrective action is to establish and verify the existence of breaker coordination at all voltage levels. Any hardware modifications and/or setpoint changes will be made after the conclusions of the draft breaker coordination study have been verified.

~~9*

General Manager -

Salem Operations MKG:pc SORC Mtg. *a1~oss

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PS~G Public Service Electric and Gas Company P.O. Box E Hancocks Bridge, New Jersey 08038 Salem Generating Station October 16, 1987 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555.

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Dear Sir:

SALEM GENERATING STATION N

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f LICENSE NO. DPR-70 )> 0 DOCKET NO. 50-272 en

§ UNIT NO. 1 LICENSEE EVENT REPORT 87-011-00 ,...,

0 This Licensee Event Report is being submitted pursuant to the requirements of 10CFR 50.73{a) (2) {v) {D). This report is required within thirty (30) days of discovery.

Sincerely yours, J<k~~

General Manager-Salem Operations MJP:pc Distribution

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