ML20149M811

Special Rept:On 871002,sensor (1TE-VPO75) Read 150.3 Degrees F Which Is Greater than Tech Spec 3.7.7 Limit of 150.0 F. No Other Sensor in Vicinity Showed Any Corresponding Rise in Temp

ML20149M811
Person / Time
Site:	LaSalle
Issue date:	02/18/1988
From:	Diederich G COMMONWEALTH EDISON CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 8802290095
Download: ML20149M811 (1)

Text

x Commonwealth Edison Cd

) LaSat County Nuclear Station 4 Rural Route C1, Box 220 PgW .%, 3. -p

/ Marseilles, l'!inois 61341

- Telephone.815/357-6761 February 18, 1980 fi gjgg3

' c ~I Mr. A. Dert Davis fI % ]

Regional Administrator yk 4 Region III * -y U.S. Nuclear Regulatory Consisulon gghh 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Davis,

This special report is being submitted to update cause and corrective actions of previously submitted r.pecial report in accordance with Technical Specifications 3.7.7, ,'ction a, 6.6.C, and the C. W. Schroeder to J. G.

Keppler letter dated December 22, 1983, regarding LaSalle Unit 1 Drywell Teraper a tur e .

On October 2, 1987 at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> with Unit 1 operating at 87.7% power, it was observed that a sensor (lTE-VP075) near the "A" Reactor Recirc"lation Pump was reaol..g 150.3 degrees F which is greater than the Technical Specification 0.7.7 limit of 150.0 degrees F. The temperature remained above 150 degrees F for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> until the operating Department lowered the primary Containment Chilled Water (p;'CW) temperature entering the drywell. Since reducing the PCCW temperatur , 1TE-VP075 has stabilized at approximately 148 degrees F.

Historically, ITB-VP075 has read approximately 125 degrees F. However , sir!ce the recent Unit 1 mid-cycle outage (prior to this event), this sensor has read approximtely 148 degrees F. During a shutdown, where access to the drywell was permitted, the cause for this higher temperature was determined to be loose wires at the RTD head assembly. These wires were tightened. With the unit at power the sensor is now reading, about 121 degrees F which is normal for this condition.

The Sargent and Lundy analysis shows that the temp.rature limit of 150 degrees F affects only one Environmental Qualification (S.Q.) Binder. The components associated with this binder are the four (4) safety related containment monitoring (CM) sensors (ITE-Ct1058, 59, 60 and 61) which are also a part of the drywell temperature monitoring program. Since the CM sensors, which monitor their own temperatures, have not indicated a temperature above 133 degrees F, these values are more applicabic than the readings of sensor ITE-VP075. In addition, no other sensor in the vicinity of ITE-VP075 showed any corresponding rise in temperature Therefore, there is no safety related equiptrent in the drywell that is being affected by the temperature (indicated by 1TE-VP075) exceeding the 150 degrco E Technical Specification limit.

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• M M ,? a2:, N S PDR G, J. Diederich Station Manager L6Salle County Station GJD/KCW/kg xc: Nuclear Licensing Administrator E NRC Resident Inspector '

Ip U.S. NRC Document Control Desk g g INPO - Records Center FE3 N '

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