ML20011E121

Forwards Response to Generic Ltr 89-13, Svc Water Sys Problems Affecting Safety-Related Equipment. Util Currently Performs Visual Insps & Dredgings of Svc Water & Circulating Water Intake Structures Once Each Refueling Cycle

ML20011E121
Person / Time
Site:	Summer
Issue date:	01/31/1990
From:	Bradham O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-13, NUDOCS 9002080030
Download: ML20011E121 (6)

Text

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genkinsvllgSC 29085 SCE&G 4 -~ January 31, 1990 Document Control Desk

'O. S. Nuclear Regulatory Commission Washington, D. C. 20555

Subject:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. HPF Response to Generic Letter 89-13 Gentlemen:

Attached:Is the South Carolina Electric & Gas Company (SCE&G) response to the five Recommended Actions identified in Generic Letter 89-13, " Service Water System Problems Affecting Safety-Related Equipment," provided pursuant to 10CFR50.54 (f). This letter satisfies the initial reporting requirement specified in the Letter. In addition to this response, SCE&G will confirm to the Nuclear Regulatory Commission that all the Recommended Actions-have been implemented within thirty days of such implementation.

I declare that.tL? statements and matters set forth herein are true

-and correct to the best of my knowledge, information and belief.

Should you have any questions, please call at your convenience.

Very truly yours.

O. S. Bradham-EWR/0SB:1bs Attachment c: D.-A. Nauman/0. W. Dixon, Jr./T. C. Nichols, Jr.

R. V. Tanner E. C. Roberts -J. C. Snelson S. D. Ebneter R. L. Prevatte J. J. Hayes, Jr. J. B. Knotts, Jr.

General Managers NSRC C. A. Price NPCF K. E. Nodland- RTS (LTR 890013)

R. B. Clary File (815.14) 0

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E Attachment'.1 to Document Control Desk Letter N

1. Jaouary 31, 1990-Page 1 of 5 South Carolina Electric & Gas Company Response to Generic Letter 89 l Recommended Action (1)

For open-cycle service water systems, implement and maintain an ongoing program of surveillance and control techniques to significantly reduce the.

incidence of flow blockage problems as a result of biofouling.

SCE&G Response To address the recommendations in Action Item 1. V. C. Summer Nuclear Station (VCSNS) is developing procedures and modifications to significantly reduce the incidence of flow blockage problems as a result of biofouling. The VCSNS program wi11 contain the following items:

1. Visual inspection of the Service Water (SW) and Circulating Water

.(CW) intake structures and removal of fouling accumulations.

SCE&G currently performs visual inspections and deedgings (as required) of the SW and CW intake structures once each refueling cycle. These activities will be formalized into station procedures.

2. SW System treatment with a biocide.

VCSNS has installed a chemical injection system to~ treat the SW system via periodic injections of biocide at the SW intake structure. Approval was received from the South Carolina Department of Health and Environmental Control (DHEC) for application of the biocide on October 31, 1989. This approval established discharge limits which will prevent adverse impact to the environment. Application of the biocide is pending final NRC approval of a request submitted by VCSNS on May 19, 1989.

3. Strainer installation on SW supply lines.

VCSNS is investigating the installation of strainers with forward flush and backwash capabilities on the SW supply lines to the Emergency Feedwater System and to the Reactor Building Cooling Units-(RBCU's). If installed, these strainers may help prevent plugging of the small diameter RBCU heat exchanger tubes and clogging of the EFW control valves resulting from e switchover to the SW supply.

4. Regularly scheduled testing of SW components.

Currently, SW components at VCSNS are monitored during normal operations and testing, and corrective action is taken when evidence of flow blockage is found. Additionally, periodic testing 1

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Attachment.1 to Document Control Desk Letter

'E  :. January 31 -1990-

'Page 2 of 5' of SW system pumps and valves is conducted under the VCSNS inservice testing program.

The programs addressed in response to Action Items 2 and 3.in Generic Letter 89-13 (monitoring for heat exchanger degredation and a routine inspection and maintenance program) will provide SCE&G i with additional assurance that SW components are not fouled or clogged.

The activities mentioned in items 1 through 4 above provide the basis for an ongoing program to significantly reduce the incidence of flow blockage problems resulting from biofouling. These activities will be completed before startup following Refuel 6. Refuel 6, which is currently scheduled for the Fall of 1991, is the first refueling outage at VCSNS to begin nine months or more after the date of' Generic Letter 13.

Recommended Action (2) j l

Conduct a test program'to verify the heat transfer capability of all safety- "

related heat exchangers cooled by service water. The total test program should consist of-an initial test program and a periodic retest program.

SCE&G Reponse In response to Recommended Action Item 2 of Generic-Letter 89-13, SCE&G will establish an effective testing program to verify the heat transfer capability of all safety related heat exchangers cooled by service water.. VCSNS is I, developing and implementing test procedures which will determine the actual i heat transfer coefficients of the subject open cycle heat exchangers and will compare these coefficients with their associated design basis required heat transfer coefficients. For some heat exchangers SCE&G is pursuing the alternative of frequent, regular heat exchanger maintenance.in lieu of testing for degraded performance of the heat exchangers.

The heat exchangers for which VCSNS will be testing and trending overall heat transfer coefficients are the following:

Component Cooling Heat Exchangers HVAC Chillers Diesel Generator Intercoolers Diesel Generator Jacket Water Coolers Diesel Generator Lube-011 Coolers l Diesel Generator Air Start-Aftercoolers For these heat exchar,gers, SCE&G will also monitor and record cooling water flow and inlet and outlet temperatures during modes of operation in which cooling water is flowing through the heat exchangers. SCE&G will verify that the cooling water temperatures and flows are sufficient to support the design basis function of the heat exchanger.

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.ax. , Attachment 1-to-Document Control Desk letter January. 31.-1990-Page 3 of 5; 7'

4 SCE8,G will perform preventative maintenance on the following heat exchangers.

in lieu of testing and trending heat transfer coefficients:

(1) Service Water Pump Motor Bearing Lube-011 Cooler The-water side of this cooler will be inspected on a routine basis and cleaned as required. There is no instrumentation to measure lube-oil flow or temperatures. Due to piping configurations, portable flow measuring equipment cannot be used to obtain accurate water flow rates.

(2) Reactor Building Cooling Units Temperature and flow data representative of actual accident (full load)'conditionscannotbecollected. The adequacy of the RBCU heat transfer capabilities will be confirmed as follows:

(a) Pressure drops and SW flow rates on the water side of the RBCU's will be trended. Based upon this trending, heat exchanger inspection and cleaning, as required, will be performed.

(b) Each RBCU will be visually inspected on the air side and any observed fouling will be removed.

In addition, the chemistry control program of the associated closed cycle cooling systems will be reviewed-for adequacy and effectiveness over the total operating history of these systems. For the systems where this adequacy cannot be confirmed, the heat transfer capability will be established through testing, inspection, or maintenance depending upon the heat exchangers. involved.

The-above actions will be utilized to establish baseline data for future monitoring and trending of heat exchanger performance and will be completed prior _to startup following Refuel 6. The initial frequency of either testing or maintenance will be established at intervals'no greater than one refueling cycle. The optimum frequency for periodic retests or maintenance will.be established after three tests or maintenance actions have been performed. The frequency determined will assure adequate heat transfer capability during the intervals between test or maintenance actions.

Recommended Action (3)

Ensure by establishing a routine inspection and maintenance program for open-cycle service water system piping and components that biofouling, corrosion.

-erosion, protective coating failure and silting cannot degrade the performance of the safety-related systems supplied by service water. The maintenance program should have at least the following purposes:

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' Attachment 1 to Document Control Desk Letter

. January.31, 1990

Page 4 of 5 A. To remove excessive accumulations of biofouling agents, corrosion products, and silt; B. To repair defective protective coatings and corroded service water -

system piping and components that could adversely affect performance of their intended safety functions, f SCE&G Repsonse To address the items in Recommended Action 3. Virgil ~r. Summer Nuclear Station has initiated the following activities:

Visual inspection and photographic documentation of SW System piping and components.

Cleaning of SW System piping and components as required after visual inspections.

Wall thickness measurements by UT inspection at various SW piping locations.

These activities provide the basis for a routine inspection and maintenance program for.SW piping and components to ensure that corrosion, erosion, protective coating failure, silting, and biofouling will not degrade the performance of safety-related systems supplied by Service Water. The formalized procedures for these activities will be completed before startup lfollowing Refuel 6.

s Recommended Action-(4)

I_ Confirm that the service water system will perform its intended function in l accordance with the licensing basis for the plant. This confimation should l: , include a review of the ability to perform required safety functions in the 1- event of failure of a single active component. To ensure that the as-built i

system is in accordance with the appropriate licensing basis documentation.

l this confirmation should' include recent (within the past 2 years) system

j. walkdown inspections.

SCE&G Repsonse l SCE&G will perform a detailed walkdown inspection of the Service Water System-to ensure that the as-built system is in accordance with the appropriate licensing basis documentation.

Additionally, SCE&G will conduct a review of the SW System's ability to L perform.its required safety functions in the event of a single active failure. This review will cover the: 1

- FSAR i

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Attachment 1

to Document Control Desk Letter-

.. danuary 31, 1990 Page-5:of:5-

-: Design Basis: Document'

- Flow Diagrams

-> Electrical Diagrams

- Technical Specifications-System and Emergency Operating Procedures Results of the system'walkdown will be factored into this study as appropriate. The review and system'walkdown inspection will be completed before startup following Refuel 6.

Ree: -r.ded Action (5)

Confirm that maintenance practices, operating and emergency procedures. and training that involves the service water system are adequate to ensure that safety-related equipment cooled by the service water system will function ~as

' intended and that operators of this equipment will perform effectively. This

. confirmation should include recent-(within the past 2 years) reviews of

. practices, procedures, and training modules.

SCE&G-Response

-SCE&G has evaluated the maintenance practices, normal operating and emergency procedures, and training modules that involve the Service Water. System. -The results of-this evaluation confirm that VCSNS places sufficient emphasis on

, the system such that safety related equipment cooled ter the SW System will function as intended and that operators of this equipment will-perform effectively.- Additionally, SCE&G will update the-practices, procedures and training modules to incorporate the information gained from implementing Generic Letter 89-13.

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