ML20054D882

Final Deficiency Rept Re Lack of Redundant Sensing Current Transformers for Overcurrent Protection in 4.16-kV Switchgear,Originally Reported on 820216.Second Current Transformer,Associated Relays & Control Circuitry on Order

ML20054D882
Person / Time
Site:	River Bend
Issue date:	04/15/1982
From:	Booker J GULF STATES UTILITIES CO.
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, RBG-12-430, NUDOCS 8204230470
Download: ML20054D882 (2)

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'J GULF STATES UTILITIES COMPANY POST O F FIC E DOx 2951 . H E A U 8A O N T , TEXAS 77704 AREA CODE 713 830 6631 April 15, 1982 RBG- 12,430 File Nos. G9.5, G9.25.1.1 Mr. John T. Collins, Regional Administrator

%' r U. S. Nuclear Regulatory Commission Region IV, Office of Inspection and ~ )rcement h%

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Dear Mr. Collins:

River Bend Statin-Unit 1 Docket No. 50-458 On March 16, 1982, Gulf States Utilities (GSU) informed Region IV that a deficiency reported on February 16, 1982, had been determined to meet the reporting requirements of 10CFR50.55(e). The deficiency was a lack of redundant sensing current transformers for overcurrent protection in certain 4.16KV switchgear.

The attachment to this letter provides information required by 10CFR50.55(e) paragraph (3). This concludes GSU's reporting of this deficiency.

Sincerely, f

J. E. Booker Manager-Engineering & Licensing River Bend Nuclear Group JEB/LAE/kt Attachment

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F April 15, 1982 RBG- 12,430 ATTACHMENT Background and Description of Problem A review of FSAR Section 8.3.1.1.4.3 (Containment Electrical Penetration Protection) was conducted against the requirements of Regulatory Guide 1.63, Revision 2. This review identified an area of concern with regard to the final design of Class 1E electrical penetration protective system. The lack of channel independence and a single failure situation in the 4.16-KV metal-clad switchgear serving the reactor recirculation pump motor through a Class 1E penetration, is a deficiency. Specifically, two redundant Class IE circuit breakers were provided with only one set of sensing current iransformers and associated relays used to trip both redundant breakers. A persisting overcurrent condition could cause damage to the electrical penetration.

J Safety Implications The 4.16-KV metal-clad switchgear deficiency is a significant deficiency in final design such that the design does not conform to the criteria in the FSAR; had it remained uncorrected, it could have adversely affected the safety of operations.

Corrective Action Procurement of a second current transformer, associated relays, and redundant control circuitry is underway. A second set of current transformers and associated relays will be added to ensure that the 4.16-KV switchgear design conforms to the FSAR and Regulatory Guide 1.63, Revision 2. The 4.16-KV switchgear will be corrected prior to delivery to the jobsite.

Pursuant to standard engineering practices, Stone & Webster Engineering Corporation's River Bend Station Project Electrical Engineering Department is reviewing electrical one-line diagrams to ensure proper protection of electrical penetrations. It was this review that identified the above-stated problem. Specific corrective action for this problem, includes revising one-line Diagram No. 12210-EE-IN-3 and Purchase Order No. RBS-242.521 to provide for the addition of redundant overcurrent protection equipment for the 4.16-KV switchgear. One-line Diagram No. 12210-EE-1N-3 will be reissued with corrections by April 30, 1982. The one-line diagram review, initiated in December 1981 and still underway, will be completed by June 1, 1982.