ML20084S229

Supplementary Ao:Four Temp Switches Were Found to Trip at Values Exceeding Tech Specs Limits.Caused by Sensors Placed Too Closely to HPCI Turbine & Steam Piping.Different Temp Sensor Will Be Installed

ML20084S229
Person / Time
Site:	Quad Cities
Issue date:	12/19/1975
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20084S228	List: ML20084S226 ML20084S229 ML20084S232
References
50-265-75-29, NJK-75-614, NUDOCS 8306160282
Download: ML20084S229 (2)

Text

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l o ^Com 1we'Ith Edison  ;

Ou:d- :s Nuclear Poacr Stat.on ,f Post Offica Box 216 7 Cordova, Illinois 61242  %

(,j Tclephone 309/654 2241 i CD) w. s, Q : 6R!N %pl-n, o ueia

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O December 19, 1975 ' ' l -f_if. b Director of Of fice of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission ,

Washington, D. C. 20555 Re fe rences : 1) quad-Cities Nuclear Power Station Docket No. 50-265, -

DPR-30, Unit 2 Appendix A, Sections 1.0.A.2, 3 2.A, .

6.6.B.I.a

2) Abnormal Occurrence Report No. 50-265/75-29_, dated August 8, 1975 The purpose of this letter is to provide you with supplementary information

- regarding Quad-Cities Abnormai Occurrence Report No. 50-265/75-29, High Pressure Coolant injection (HPCI) System Turbine Area High Temperature Sensor Setpoint Dri f t. The four temperature swi tches which were found to trip at values exceeding Technical Specification limitations were discovered while investigating a HPCI system automatic isolation.

The Unit 2 HPCI system was placed in operation for testing purposes at 12:03 a.m. on July 31, 1975 following repairs to the HPCI turbine speed control linkage. These repai rs were made necessary as a result of an occurrence on July 29, 1975 whereby the system could not pump the required 5000 gallons per minute. This event had been reported in Abnormal Occur-rence Report No. 50-265/75-27 At 12:15 a.m. the HPCI syst.em received an isolation signal.

The isolation was determined to be initiated by the high temperature switches receiving input from sensors located approximately five Inches above the exhaust end of the turbine. In addit'on, the room cooler for the HPCI room had been removed from service at 10:00 p.m. on July 30 in order to replace a broken fan belt, it is felt that these sensors and the other three groups of sensors which initiate a HPCI system isolation are located too close to the HPCI turbine and steam piping. Also, the sensors are too sensitive to the normally warm atmosphere within the HPCI room. Because of these conditions, minor packing leakage will cause an isolation.

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O O The purpose of the high temperature isolation is to detect a steam supply line leak and to isolate the system to prevent loss of reactor inventory.

It is felt that the present temperature sensor type and location provides a greater than necessary sensitivity to accomplish this purpose.

Quad-Cities Station Action item 4-75-48 has been issued to the Instrument Department to.obtain and install an alternate type of temperature sensor on a test basis. Relocation to a less sensitive position will be con-sidered during this test. A purchase request has been made, and to date approximately one-half of the parts have been received. Installation

. will conmence upon receipt of the remainder of the order.

Very truly yours, _ .

COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION

/ '. ' lN N. J. Kallvianakis j -.

Station Superintendent NJK/L FG/l k cc: Office of Inspection and Enforcement G. A. Abrell G. L. Redman s

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