RBG-26688, Supplemental Special Rept:On 870420,temp in North End of Main Steam Tunnel Rose Above Tech Spec Requirements.Tech Spec Change Request Submitted to Implement Mod Request 86-0342 to Increase Temp Limits in North Tunnel

Supplemental Special Rept:On 870420,temp in North End of Main Steam Tunnel Rose Above Tech Spec Requirements.Tech Spec Change Request Submitted to Implement Mod Request 86-0342 to Increase Temp Limits in North Tunnel

ML20235F595
Person / Time
Site:	River Bend
Issue date:	09/21/1987
From:	Booker J GULF STATES UTILITIES CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RBG-26688, NUDOCS 8709290225
Download: ML20235F595 (3)

Text

,

• 4 GULF STATES UTILITIES COMPANY POST OFF!CE DOX 2961

• DE.AUMONT, TEXAS 77704

1. REA CODE 713 838 6031 September 21, 1987 RBC-26,688 File Nos. G9.5, G9.25.1.4 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1 Docket No. 50-458 Enclosed is Gulf States Utilities Company's Special Report concerning area temperature monitoring -a t River Bend Station. This report supplements GSU's previous submittals dated May 19, 1987, June 18, 1987, July 21, 1987, and August ^18 , 1987 (reference RBG-25976, RBC-26132, RBG-26290, and RBG-264S9, respectively) submitted pursuant to Technical Specifications 3/4.7.8 and 6.9.2.

Sincerely, J. E. Booker Manager-River Bend Oversight River Pend Nuclear Group J P/PDG/DAS/ch Attachment cc: U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 NRC Resident Inspector @

P.O. Box 1051 St. Francisville, LA 70775

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>ow, aM un B709290225 B70921 l\

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e a SPECIAL REPORT REPORTED CONDITION

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At approximately 1630 on 4/20/87, with the unit in full power operation, during the performance of Surveillance Test Procedure STP-000-0001

" Daily Operating Logs", temperatures in the north end of the Main Steam Tunnel rose above the Technical Specification (3/4.7.8) limit of 122 sj degrees F and remained above this limit for greater than eight hours , ,

(reference RBG-25976 dated 5/19/87). Similar Special Reports have been s submitted on 8/28/86, 3/10/86 and 12/11/85 (reference RBG-24271, RBG-23302, and REG-22779, respectively). ,

INVESTIGATION l Main Steam Tunnel temperatures approaching and exceeding the Technical l Specification limit has been a recurring problem during the combination of full power operation and high outside ambient temperatures.

The following table shows the average daily temperature readings taken ',

from the indicator which indicated the highest temperature readings since the temperatures exceeded the Technical Specification limit as raported in the 5/19/87 report and supplemented by Gulf States Utilities Company's letters dated 6/18/87, 7/21/87, and 8/18/87 (reference RBG-26132, RBG-26290, and RBG-26459, respectively). Since River Bend Station was removed from service on 9/14/87 for its first refueling outage, temperatures have been restored below the Technical Specification temperature limit of 122 degrees F. A .

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Date Tavg( F) Date Tavg( F) 8/11/87 130.5 8/21/87 121.5 8/12/87 130.5 8/22/S7 123.5 -

8/13/87 129.5 8/23/87 125.0 8/14/87 129.5 8/24/87 126.0 8/15/87 128.5 8/25/87 125.5 . .~ _

8/16/87 130.0 8/26/87 126.0 8/17/87 129.5 8/27/87 126.0 8/18/87 127.5 8/28/87 126.0 8/19/87* 112.5 8/29/87 126.0 8/20/87* 113.5 8/30/87 126.0

• Note: The unit was shutdown for maintenance on these days. The Technical Specification limit was again exceeded when power ,

operation was resumed.

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g

%,' n. .

s; r

, .Date- .Tavg( F). Date Tavg( F)-

L 8/31/87: .124.5 9/07/87 123.0 9/01/87. 124.5- 9/08/87 124.0

.y 9/02/87 122.5 9/09/87 124.0 9/03/87 123.0 9/10/87 124.0 9/04/87' 123.5 '9/11/87 124.5 9/05/87 123.5. .9/12/87 124.0 l9/06/87 124.0 9/13/87 124.0

', ANALYSIS AND CORRECTIVE ACTION As discussed in the 5/19/87 report, the effects of increasing the temperature limit to 135 degrees F have been evaluated by .the Environmental Qualification Group via Modification Request (MR) 86-0342.

Calculations have been performed to determine the ext nt of reduction in qualified life due to a higher area temperature limit of 135 degrees F.

Calculations have demonstrated _that the safety related equipment under the scope. of 10CFR50.49 with the shortest-qualified life (Namco Limit Switch) will be reduced from 5 years to 4 years if the temperature limit is increased from the preannt 122 degrees F to 135 degrees F.

GSU has submitted a Technical Specification change request to the NRC (reference RBG-26059 dated 6/5/87) to implement MR 86-0342 which' increases area temperature limits in the Main Steam Tunnel-north from the present 122 to 135 degrees F pending NRC approval.

Since River Bend Station was removed from service on 9/14/87 for its first. . refueling outage, temperatures have been restored be'ow the Technical Specification temperature limit cf 122 degrees F. Therefore, this supplement ' completes Gulf States Utilities Company'c response to the original report of this problem identified in RBC-25976 dated 5/19/87.

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