ML20138J248
| ML20138J248 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/18/1985 |
| From: | Diederich G COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 8512170469 | |
| Download: ML20138J248 (2) | |
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Commonwealth Edison LES li3 County Nucirr Statsa o a HarzlRouc 01 Box 220 Marseilles, Illinois 61341 Telephone 815/357-6761 t
5 November 18, 1985 pgign, n pe,nna ma mmg b
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Mr. Jc. mea G. Keppler Q-
.Begional Administrator
-;p t1 Pegiry: III f1LE N#
'd.3. Nuclettr_ Hegulatory Commission s.
,f(99 Roosevelt Pond.
Glen Ellyn, Il.U noi3 60137
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Dear Mr# Keppler:
This special repart is being submitted, in accordance with Technical Specifi-cation 3.7.7.'1 and the C. W. Fchroeder to J. G. Keppler letter dated February 9,1904, 'regarding the LaSalle Unit 2 dryvell temperature.
On July 26, 1985, at about 0P04 hours, one of 'the thermocouples near the top of the Unf_t 2 drywell started indicating a temperature well above the normally experienced temperature. Additional data shoved that several sensors around tne safety relief valvea were between 150 degrees F and 156 degrees F.
Other temperature sensors indicated that some snubbers may have exceeded the maximum allowable operating temperature of 300 degrees F.
This condition existed until August 1,1985, when a unit shutdown caused the temperatures to drop to a point where entry was permitted to investigate the heat source.
During the short outage, changes were made to the ventilation system to insure that;.the temperatures vould remain below the Technical Specification limit for the safety relief valVea. A piece qr insulation around a feedwater line, found to be not securely strapped, was Teinstalled properly.
During a subae-
. ylent outage on Unit 2, an inspection of the drywell vaa performed to deter-
' mine the cause of the continuing high temperature problem. Additional sections of insulation vere found to have been improperly installed.
It was also dis-covered that one of the dampers at the exharat of one of the main fans was failed cloard. These changes are believed to be sufficient cause for the high temperatures nperienced in Unit 2.
The failed closed damper has been repaired and the insulation repiirs are scheduled.
In addition, a second inapection of dryvell insulation vill be performed prior to unit re-start to further reduce the likelihood of continuing high temperature problema.
An analysis by Sargent and Lundy for the SRV solet'oid qualified life, indi-cated that the solenoids hoe a NUREG 0588 Catagory II rem 11ning life of about 32 years r.t the temper # urn that the solenoids vill experience with the unit operating at fall power if no additional ventilation changes occur.
NOV 2 5 BB5 8515'.170469 851118 PDR ADOCK 05000371 S
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<p; Several snubbers in the vicinity of the one sensor which indicated a temper-
' ature above-300. degrees F vere satisfactorily functionally tested.
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G. J. Diederich Station Manager IaSalle County Station
- GJD/KCW/DRR/kg Enclosure xc: 'NRC Resident Inspector-INPO - Records Center US NRC Document Control Desk a
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