RBG-27840, Provides Revs to 870607 Request for Approval to Revise Isolation Actuation Instrumentation Setpoints.Cooling Addition Mod Will Continue to Support Original Design Basis. Jc Deddens Affidavit Encl

Provides Revs to 870607 Request for Approval to Revise Isolation Actuation Instrumentation Setpoints.Cooling Addition Mod Will Continue to Support Original Design Basis. Jc Deddens Affidavit Encl

ML20154F114
Person / Time
Site:	River Bend
Issue date:	05/13/1988
From:	Deddens J GULF STATES UTILITIES CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RBG-27840, NUDOCS 8805230100
Download: ML20154F114 (3)

Text

(D GULF STATES UTILITIES COMPANY RrvtR BEND 5i ATION POST OFFKE BOX 220 ST FP.ANOSWLE LOUISAN A 70775 ARE A CODE 504 635 6094 346 8651 May 13, 1988 RBG- 27840 File Code G9.5, G9.8.9.6 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1 Docket No. 50-458 This letter provides revisions to Gulf States Utilities (GSU) submittal of June 7, 1987 (RBC-26059) Attachment 3 as discussed with the staff on April 14, 1988. Attachment 3 of the GSU submittal requests NRC approval to revise the ISOLATION ACTUATION INSTRUMENTATION SETPOINTS for the main steam line tunnel temperature and differential temperature monitors (reference Technical Specification Table 3.3.2-2). Two areas of the steam tunnel vere to have temperature monitor setpoint changes. These are commonly referred to as the north (auxiliary building) and south (turbine building) main steam tunnel (MST). CSU requests the Technical Specification Table 3.3.2-2 items 2.h.1 and 2 changes to the south MST in Attachment 3 of the June 7, 1987 lettar be withdrawn.

GSU has recently determined the additional unit coolers installed in the south MST will now be made a permanent installation. T!.ese unit coolers were originally installed as an interim measure pursuant to 10CFR50.59 as part of modification package MR 86-0003 in the soutn MST to lower the unexpectedly high area temperatures. Additional precautions of periodic visual surveillances in the area indicated any Icakage is well below the present design criteria. This action was also desirable from a personnel access standpoint. The additional cooling capacity reduces area temperatures by approximately 10'F allowing limited maintenance and surveillance activities by plant personnel. Given the desire to enhance access to the MST by the use of the additional cooling, the present setpoints were found sufficient for continued operation; therefore, the south MST setpoint changes are no longer required.

The cooling addition modification will continue to support the original design basis and was evaluated pursuant to 10CFR50.59 and was determined to not represent an unreviewed safety question. The leak detection cetpoint analysis determines the temperature rise resulting from a leak in the l south-MST and uses an initial temperature of 105'F prior to the start of l leakage. The unit coolers were modeled as a heat sink with return air of i 105'F which vill conservatively model the capacity of the cooling. Based on operational data, the additional heat load in the MST is approximately 005

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8805230100 PDR 880513 \

P ADOCK 05000458 res

s NRC Page 2 May 13, 1988 1,000,000 BTU /HR above the original design assumptions. The additional coolers remove approximately 600,000 BTU /HR. Since the cooling only reduces part of the additional heat load, this modification is conservative with respect to the overall increase of additional heat load in the south MST. The normal operating. temperature in the south MST varies from approximately 105'F to 122'F.

With the present configuration and operating conditions, there is an adequate margin to the trip setpoint for normal operation. As a result,  ;

GSU's original design criteria and setpoints for the MST-south leak detection are supported and changes to the present Technical Specification table 3.3.2-2 items 2.h.1 and 2.are not required.

Sincerely, v v

J. C. Deddens Senior Vice President River Bend Nuclear Group JCD/JEB/pENIH/

{ch Enclosure ,

cc: U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 -

Sr. Resident Inspector Post Office Box 1051 St. Francisville, LA 70775 Mr. William H. Spell, Administrator -

Nuclear Energy Division LA Department of Environmental Quality Post Office Box 14690 Baton Rouge, LA 70898

' Walt Paulson .

U.S. Nuclear Regulatory Commission [

Document Control Desk .

Washington, D.C. 20555

i UNITED STATES OF JMERICA NUCLEAR REGULATORY COMMISSION STATE OF LOUISIANA )

PARISH OF WEST FELICIANA )

In the Matter of ) Docket No. 50-458 50-459 GULF STATES UTILITIES COMPANY )

(River Bend Station, Unit 1)

AFFIDAVIT J. C. Deddens, being duly sworn, states that he is a Senior Vice President of Gulf States Utilities Company; that he is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the documents attached hereto; and that all such documents are true and correct to the best of his knowledge, information and belief.

J. C. beddens Subscribed and sworn to before me, a Notary +Public in and for the State and Parish above named, this I5., 4 day of

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