ML18024A073

Letter Regarding an Interim Report of Reportable Deficiency Regarding Potential Transformers on 4.16KV Switchgear and Advising the Commission That the Definitive Report Will Be Submitted by July 31, 1978

ML18024A073
Person / Time
Site:	Susquehanna
Issue date:	04/17/1978
From:	Curtis N Pennsylvania Power & Light Co
To:	Grier B NRC Region 1
References
Download: ML18024A073 (5)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RID DISTRIBUTION FQR INCOMING MATERIAL 50-3 eS REC: GRIER B H ORG: CURTIS N W DOCDATE: 04j'17/78

'RC PA PNR 8. LIGHT DATE RCVD: 05J04f78 DOCTYPE: LETTER NOTARIZED: NO COPIES RECEIVED

SUBJECT:

LTR 1 ENCL 0 FURNISHING INFQ RE CONSTRUCTION DEFICIENCY REPT CONCERNING WESTINGHOUSE SUPPLIED MEDIUM VOLTAGES METAL CLAD SWITCHGEAR WHICH MAY NOT BE FULLY CAPABLE OF WITHSTANDING THE POSTULATED SEISMIC EVENT FOR SUB JECT FACILITY... ADVISING REQUIRED DEFINITIVE REPT WI PLANT NAME:SUSQUEHANNA UNIT REVIEWER INITIAL: X JM SUSQUEHANNA' UNIT 2 DISTRIBUTER INITIAL:~~

DISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS ++++<%%%+<+<<<+<<+

CONSTRUCTION DEFICIENCY REPORT < 10CFR50. 55(E).

(DISTRIBUTION CODE 3004>

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GOSSICK 5 STAFF+4LTR ONLY<i) MIPC4+LTR ONLY< 1)

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r' \ LIP TWO NORTH NINTH STREET, ALLENTOWN, PA. 'I 8101 PHONE: (215) 821-5151 NORMAN W. CURTIS Vice President Engineering 8 Construction c<< C~

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@err M Mr. Boyce H. Grier Director, Region I ff$ X U.S. Nuclear Regulatory Comhtission CA 631 Park Avenue King of Prussia, Pennsylvania 19406 SUSQUEHANNA STEAM ELECTRIC STATION INTERIM REPORT OF REPORTABLE DEFICIENCY

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REGARDING POTENTIAL TRANSFORMERS ON 4.16KV SWITCHGEAR DOCKET NOS 50 387 g'0 388

~i g'/gg LICENSE NOSI CPPR-101, CPPR-102 ERs 100450/100508 FILE 840-4 PLA-246 Dear M . Griers This relates to a reportable deficiency, under the provision of 10CFR 50.55(e),

which was. identified to Mx' A Toth NRCg Region I by Mr. A. R. Sabol, PPGL during a'elephone conversation on 3/31/78. The deficiency involves Westing-house supplied medium voltage, metal clad switchgear which may not be fully capable of withstanding the postulated seismic event for the Susquehanna plant.

Z Specifically, Westinghouse C

has advised that, the potential transformer secondary disconnecting contact assemblies on equipment similar to that supplied for Susquehanna have failed to withstand recent seismic tests. Westinghouse further stated that, under seismic conditions, it is possible that the secondary contacts could be dislodged from their normal positions causing open circuiting or shorting of the secondary circuits.

It has been established that eight of the sixteen units, purchased for use in safety related applications, have been shipped to the SSES plant site. To preclude installation of this equipment, Bechtel has identified (3/16/78) these eight units in a QA Stop Work Report (No. 78-06) as being nonconforming. As a result, Bechtel QC has written a Nonconformance Report (NCR No. 2514) and each switchgear unit has had a "Hold Tag" attached.

Bechtel Engineering has reviewed the system design and they have concluded that the worst condition exists with the loss, on each switchgear bus, of the potential transformers on both incoming feeders coupled with the loss of one, or both, of the bus voltage monitoring transformers.

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PENNSYLVANIA POWER 8 LIGHT COMPANY

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Mr. Boyce pi. Grier 2 April 17'978 Under this condition, the incoming bus feeders from the safeguard transformers would be automatically disconnected and the diesel generator power source connected restoring power to the bus.

The feeder breakers supplying power to the shutdown loads are normally open.

A LOCA occurring during or after the postulated seismic event would initiate a closing signal to the motor feeder breakers of the shutdown loads, i.e. RHR and Core Spray Pumps.

These feeder breakers would close and immediately trip due to the false undervoltage indication as sensed by the undervoltage relay. The circuit breakers would be unable to close again because of 'the permanent undervoltage trip signal imposed on them.

The above analysis assumes that the failures concurrently occur on all'redundant switchgear buses.

Bechtel Engineering has further concluded that this loss of capability to supply power to shutdown equipment under a LOCA constitutes a safety hazard to the operation of the plant and represents a deficiency in final design.

As proposed remedial action, Westinghouse has advised that modification kits are available which, when installed, would eliminate the faulty secondary dis-connecting assemblies from the circuit. This is accomplished by hard wiring

'the secondary to the load circuits. Bechtel Engineering is considering the use of these modification kits pending assurance from Westinghouse that this modi-fication will meet all the requirements of the technical specification.

We anticipate submittal of the required definitive report of the deficiency by 7/31/78.

Very truly yours, N. W. Curtis Vice President-Engineering 6 Construction

$ 6iG/ARS: mcb cc: Ms. M. C. Bar to N4 Mr. H. F. Lilligh Bechtel SSES Mr. N. W. Curtis N4 Mr. E. M. Mead N5 Mr. R. L. Emery N4 Mr. M. R. Muir Bechtel SFHO Mr. J. W. Geiling N5 Mr. J. R. Schmiedel Bechtel SFHO Mr. J. D. Green SSES Mr. R. J. Shovlin N4 Mr. H. L. Harris SSES SpsE Correspondence File N3 Mr. Jo To Kauffman TW16 Susquehanna Letter File N3