ML20086H246

AO 50-271/72-09:on 721026,two Barton Steam Line Differential Pressure Switches (DPIS 13-83 & 13-84) Failed to Actuate at Required Pressure of 180 Inches.Locking Devices May Be Causing Change.Switches Immediately Reset

ML20086H246
Person / Time
Site:	Vermont Yankee, 05000000
Issue date:	11/01/1972
From:	Rosalyn Jones VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086H243	List: ML20086H246 ML20086H250 ML20086H255
References
AO-50-271-72-09, AO-50-271-72-9, VYV-2310, NUDOCS 8401160141
Download: ML20086H246 (2)

Text

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9 VERMONT YANKEE NUCLEAR POWER CORPORATION SEVENTY SEVEN OROVE STRCCT RUTLAND, VERMONT 03701 VYV-2310

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, s VERNON. VERMONT 05354 November 1, 1972

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Director / Y> >gy Directorate of Licensing

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REFERENCE:

Operating License DPR-28

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Docket No. 50-271 d;/

Abnormal Occurrence No. A0-72-09 $$p- -6YW

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Dear Sir:

An defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.B d, we are reporting the following abnormal occurrence as A0-72-09.

On October 26 during conduct of RCIC surveillance testing, two Barton steam line differential pressure switches (DPIS 13-83 and -84) failed to actuate at a pressure of 180 115" H 2O as required by a specification in Table 3.2.2.3 of Technical Specifications. At this ll k time the reactor was operating at approximately 60% power.

• l '3 t o The switches were imnediately reset and were functionally tested f)!1 and verified to actuate at',a pressure of 180 115" H 20. This remedial g: f acticn was completed in a time span that precluded the necessity of pl

'f further immediate action. An investigation of "Hi-Shock" lockirg devices installed on the switches indicated that tightening the devices may have i b, caused the cam roller to slide so that it was no longer in the center of III the can thereby imposing a change of setting. Investigat: ion of the other Bartons in the plant (approximately 26 instruments) revealed that to date this is the'only instrument that has been affected in this manner.

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7 The Plant Operations Review Committee concluded that the locking '

devices may be causing a change in setpoint. If the switches are found 8401160141 721122 PDR ADOCK 05000271 S PDR g10G

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COPY SENT REGION ' __.

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(x i VERMONT YA~dEE NUCLEAR POWER CORPORATI U.S. Atomic Energy Commission November 1, 1972 -

Page 2 out of tolerance af ter the next surveillance (by 26 November), the vendor representative will be contacted to provide further information regarding installation and use of the locking devices.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION

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,. e R.F. / Jones Plant Superintendent DWE/rpb 9