ML20246H095

Significant Deficiency Rept L2-88-10 Re Improper Installation of Temporary Support Brackets in safety-related 4 Kv Switchgear.Support Brackets Removed from Switchgear Cubicle Prior to Startup & Procedures Revised

ML20246H095
Person / Time
Site:	Limerick
Issue date:	03/10/1989
From:	Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Russell W NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L2-88-10, NUDOCS 8903200016
Download: ML20246H095 (3)

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PHILADELPHIA ELECTRIC COMPANY l .

2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA A. PA.19101 I ' * " "' "

• March 10, 1989 S. J. KOWALSKI VICE+ PRESIDENT

.m..............

10CFRS0.55(e)

Mr. W. T. Russell, Administrator Docket No. 50-353

'U. S. Nuclear Regulatory Cm mission CPPR-107 Attn: Document Control Clerk Mall Station P1-137 Washington, D.C. 20555

Subject:

Limerick Generating Station - Unit 2 Significant Deficiency Report - SDR No. L2-88-10 Improper Insta11ation of Temporary Support Brackets

Reference:

Telecon of PECO to NRC dated February 9, 1989 File: QUAL 2-10-2 (SDR No. L2-88-10)

Dear Mr. Russell:

As conmitted to in the referenced telecon, we are submitting the attached Significant Deficiency Report SDR No. L2-88-10 concerning improper installation of temporary support brackets in safety-related 4kV switchgear. This condition has been determined to be reportable per 10CFR Part 50.55Ce).

Our corrective action will be to renove all of the support brack-ets from each switchgear cubicle prior to startup of Limerick Generat-Ing Station Unit 2. In the future, the brackets will be installed on a temporary basis only as required to support safety barriers which provide personnel safety dur ing maintenance and testing activities.

Station operating procedures wlII be revised to assure that the support brackets are removed prior to placing a switchgear cubicle back into service.

In conclusion, we consider SDR No. L2-88-10 closed with the issuance of this report. If you have any further questions, please mntact us.

h Sincerely,

. s Atte.chment Copy to: W. T. Russell, USNRC, Region I Administrator R. A. Grarrm, USNRC, LGS 2 Senior Resident Inspector R. J. Clark, USNRC, LGS 2 Project Manager /> [

l l DSM/ds/03068901

i NUCLEAR ENGINEERING ENGINEERING DIVISION ,

N2-1, 2301 Market Street Significant Deficiency Report SDR No. L2-88-10 Improper Installation of Temporary Support Brackets l NRC Construction Permit No. CPPR-107 I

DESCRIPTION OF DEFICIENCY:

While Investigating a problem involving switchgear circuit break-ers becoming caught on the cubicle shutter assenbly when operations personnel renoved breakers, engineering identified the subject condi

• tion described belcw.

Safety barriers for 2.4kV, 4kV and 13.8kV switchgear were designed by PECO for the purpose of providing personnel protection during maintenance and testing activities. The barriers are designed to be Installed over the existing switchgear cubicle shutter assemblies. The installation of the barriers enables the shutter assembly to be blocked f up in the open position and only the necessary connection points be exposed. Different barriers were designed such that a barrier could be installed as required to either block all connections, expose only the j bus terminals, or. to expose only the load terminals. The barriers are constructed of a plext-glass panel which is hung on a support bracket fastened to the rear of the switchgear cubicle above the connection ports. The support brackets can se constructed from netal or polyester material.

The safety barriers and support brackets were intended to be temporary for maintenance and testing purposes only; however, engineer-Ing has di covered that brackets have been left installed in cubicles after the safety barrier was renoved and the breaker returned to nornal operating service.

The 4kV switchgear at Limerick Generating Station Unit 2 are safety-related and the 2.4kV and 13.8kV switchgear are non safety-related.

Correspondence from the switchgear manufacturer Brown Boveri Electric, Inc. Indicates that the installation of metal barrier support brackets significantly reduces the electrical clearances which could result in a flashover. Per the manufacturer, any modification in this area of the switchgear would require a repeat of the Design Impulse Test to verify that the modification did not affect the electrical integrity of the equipment.

In addition, no documentation is available to justify the selsnic acceptability of the safety barrier support bracket installation.

J

• Significant Deficiency Report SDR No. L2-88-10 Page 2 of 2 SAFETY IMPLICATIONS:

Either a flashover caused by the reduced electrical clearances or if the metal support bracket should becone free due to a selsnic event and fall into or in close proximity to live parts resulting in a fault, could render Individual safety-related equipment or the specific

. safety-related 4kV switchgear inoperable.

CORRECTIVE ACTIONS:

All safety barrier support brackets will be renoved from the switchgear cubicles prior to startup of Limerick Generating Station Unit 2. In the future, the support brackets will be installed on tenix>rary basis only, for the purpose of personnel protection during maintenance and testing activities.

ACTIONS TAKEN TO PREVENT RECURRENCE:

Station Operating Procedures are being revised to assure that the safety barriers including the support brackets are renoved prior to returning the switchgear cubicles /cf rcuit breakers to nornal operating service.

DSM/ds/03078901 l

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