ML20006C539

Responds to Generic Ltr 89-13, Svc Water Sys Problems Affecting Safety-Related Equipment. Applicable HX Performance Evaluation Procedures Will Be Revised by 901231 & Ultrasonic Testing Will Be Performed

ML20006C539
Person / Time
Site:	Cooper
Issue date:	01/29/1990
From:	Kuncl L NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CNSS907024, GL-89-13, NUDOCS 9002080197
Download: ML20006C539 (12)

Text

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l GENERAL OFFICE  !

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Nebraska Public Power District

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i CNSS907024. j January 29, 1990

! q Nuclear Regulatory Commission  ;

Document Control Desk i

. Washington, DC 20555J l

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Subject:

Response to Generic Letter 89 13 Cooper Nuclear Station i

Docket 50 298, DPR 46 ,

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' Gentlemen:

On July.18, 1989, the NRC issued Generic Letter 8913 " Service Water System i Problems Affecting Safety Related Equipment". This guidance requested licensees to supply plant-specific information about the service water system to assure 'i the NRC of compliance to listed General Design Criteria and quality assurance requirements, and to confirm that the safety functions of the service water system are being met.

Accordingly, attached is a summary of actions taken and planned by the Nebraska Public Power District (District) to comply with the guidance provided in Generic Letter 8913 and' to provide further assurance that the Cooper Nuclear Station service water system will function as designed.

As requested in Cencric Letter 89 13, the District will provide written notification upon completion of those efforts still, ongoing. The District will also maintain assembled documentation of the attached for a minimum of two years from the date of this submittal to accommodate future NRC audits of the District's submittal.

.. This response is submitted under oath in accordance with the provisions of L 10CFR50.54(f).

L Please contact me at this office if you have any questions.

l-l Since ely, L. C. Kunc1 i

Nuclear-Power Group Manager LCK:sa Attachment l cc:' NRC Regional Office Resident Inspector Office Region IV Cooper Nuclear Station h Arlington, TX l l

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CNSS907024  ;

January 29, 1990 Page 2 of 2 STATE OF NEBRASKA)

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PLATTE COUNTY ) l L, G. Kuncl, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District,'a public corporation and political subdivision of the State of Nebraska; that he is duly authorized to submit this response on behalf of Nebraska Public Power District; and that the statements contained herein are true to the best of his knowledge and belief.

L. G. K'nc1 u

Subscrib d in my presence and sworn to before me this day of  !

rrtun Au , 1990.

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4 Attachment to CNSS907024 January 29, 1990 Page 1 of 10 NEBRASKA PUBLIC POWER DISTRICT RESPONSE TO NRC CENERIC LETTER 89 13

" SERVICE WATER SYSTEM PROBLEMS AFFECTING SAFETY RE!ATED EQUIPMENT"

1.0 INTRODUCTION

By letter dated July 18, 1989, the NRC issued Generic Letter 89 13

" Service Water System Problems Affecting Safety Related Equipment".

Generic Letter 89 13 requested licensees to perform the following or equally effective actions to ensure that their service water systems are in compliance and will be maintained in compliance with 10CFR50 Appendix A. General Design Criteria (GDC) 44, 45, 46, and Appendix B,Section XI.

Generic Letter 89 13 listed the following specific actions for service water systems:

1. 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.

II. Conduct a_ test program to verify the heat transfer capability of all' safety related heat exchangers cooled by service water.

III. Ensure by establishing a routine inspection and maintenance program for open cycle service water system piping and components that corrosion, erosion, protective coating failure, silting, and biofouling cannot degrade the performance of the safety related systems supplied by service water.

IV. Confirm that the service water system will perform its intended function in accordance with the licensing basis for the plant.

1 V. 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.

For clarity,_the specific CNS raw water system will be designated with capital letters as " Service Water", while the all inclusive cooling water systems as defined in the Generic Letter will be designated with lower case letters as " service water" in this response.

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B 2.0 BACKGR3UND Cooper Nuclear Station (CNS) plant design considerations support the intent of'10CER50 Appendix A GDC 44, 45, 46, and Appendix B,Section XI.

Supporting examples are as follows:

- Startup testing provided initial design verification and a baseline for subsequent testing.

• Intake spargers for suspension of partiv.21ste to prevent deposition and blocking.

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• Weir wall was' added to the river bottom in front of the intake j

- structure as a result of a silt deposition study to reduce silt f loading. This design facilitates the intake of cicanor water near channel surface.

• Traveling screens remove particulate in excess of 3/8" in diameter.

Service Water system strainers provide for removal of particulate

' in excess of 1/8" in diameter.

• Closed loop Reactor Building Closed Cooling Water system (for i brevity, this system is annotated REC, for Reactor Equipment

' Cooling, at Cooper Nuclear Station).

• Closed loop Diesel Generator Jacket Water (DGJW) system.

Thc ! 'mtrict has addressed the NRC's concerns regarding service water syc 1 .perability at nuclear plants. In April, 1981, the NRC issued l IE nul_etin No, 81-03. This bulletin required licensees to assess macroscopic biological fouling at their respective facilities.

-The District responded to Bulletin 81-03 on May 29, 1981. The following steps were taken:

Additional preventive maintenance tasks written.

Upgraded condenser / heat exchanger inspection procedures.

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> 1 In response to NRC Inspection Report 87-10 (SSFI) findings, the District completed actions to verify that the service water system'is capable of- ,

removing safety design basis heat loads. These actions are as follows:

• Periodic Service Water system post LOCA flow testing to-verify that post LDCA flows are being maintained.

• Quantitative performance testing of REC and Residual Heat Removal (RHR) heat exchangers each refueling outage.

• Service Water system initial design basis review.  !

• Service Water system casualty procedure revisions for post lDCA equipment configuration.

t 3.0 ACTIONS TAKEN IN RESPONSE TO GENERIC LETTER 89-13 ,

This section describes the actions taken or planned by the District to comply with Generic Letter 89 13. The Generic' Letter Recommended Actions are considered to be applicable to the Service Water, RHR Service Water Booster, Reactor Equipment Cooling, and Diesel Generator-Jackot Water systems. The Service Water and RHR Service Water Booster systems are open cycle systems, The REC and DGJW systems are closed-cycle systems.

The REC system has a program in place which controls and maintains the syctem chemistry within the limits of the Institute of Nuclear Power Operations-(INPO) recommendations. Notwithstanding those controls, the District had previously identified the need for further enhancements to preclude any potential for fouling of safety related heat exchangers. ,

These enhancements include the planned addition of a slip-stream filter domineralizer unit followed by a system flush and selected component inspection. Implementation of these enhancements will be completed ,

prior to startup from the 1991 refueling outage.

The DGJW system also has a program in place which controls and maintains system chemistry within prescribed limits. At this time there aro no upgrades planned for this system.

Attachment to CN5S907024

January 29 c1990 Page 4 of 10 The following itsar are provided in response to specific actions contained in the Ceaeric Letter

1. Implement and maintain an ongoing program of surveillance and control' techniques to significantly reduce the incidence of flow K

blockage problems as a result of biofouling.

The present ir , structure inspection includes examination e

of the basin is, silt, debris, and deterioration (including corrosion) and frequent monitoring of silt invels. The deterioration inspection is performed by using divers or dowatering the bay.

During the dcaign of CNS, a determination was made that_the inherent scouring action of the sandy river water precluded any need for chlorination. Inspections made on condensers-and heat exchangers.since the station became operational serves as ongoing confirmation of the CNS design.

-Furthermore, the Corbicula species has not be detected-at CNS.

The REC heat exchangers are provided with demineralized water connections for flushing and layup with domineralized water during periods.when a heat exchanger is.out of service. The CNS' operating procedures already include requirements to layup the_ heat exchanger with demineralized water when it is expected to be out of service for extended periods, The use of demineralized water for layup precludes i the need for chlorination because fouling from micro /macrobiological organisms is-minimized._ RHR heat-exchangers are typically not taken out of service. During those periods when the heat exchangers are taken cat of 5

service, dry layup is employed; thus neither_ chlorination nor domineralized water is required. Service Water system cooling loops are regularly used and tested, making layup impractical during operation. 1 i

The present CNS surveillance program provides for flow testa j once per operating cycle to ensure the service water system j and the associated required safety related components meet i r or exceed the post-LDCA design flow requirements. In .

addition, pump performance is monitored and trended "

quarterly to detect trends adverse to system performance, g l

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' Attachment to CNSS907024-b cJanuary.29,c1990 Page 5 of 10 Presently, heat exchangers, when opened, are inspected for indications of Corbicula and other macroscopic biological fouling organisms.

. Program enhancements, as outlined below, are planned as a result of Generic Letter recommendations and guidelines.-

1. A sampling-and analyzing inspection of biological l fouling organisms will be added to the intake structure basin inspection effective with the 1990 ,

Refueling Outage.  !

2. Those safety related heat exchangers in the service a water system that require and do not currently have. i layup instructions will have those steps added to y existing operating procedures. This will be completed by June 1,1991.

II. Conduct a test program to' verify the heat transfer capability of-all safety related heat exchangers cooled by service water.

i The District currently verifies the heat transfer capability of RHR,-REC,'DGJW, and Diesel Generator Lube Oil-(DCLO)-

safety related heat exchangers cooled by the Service Water system. Heat exchangers are. tested at least once each operating cycle, except for the:RHR'A and B' heat exchangers, ,

which are-alternately tested _each operating' cycle in order l to meet design basis flow testing requirements. Where i possible, testing is donc at-design heat' removal rates. -If j I

design heat removal rates are not attainable, then-temperature and flow compensation is made in calculations to adjust the results to design conditions. Both permanently  ;

installed and temporary instrumentation are utilized in the  !-

CNS heat exchanger performance monitoring program. .

In addition to verification of heat transfer capability, the r District verifies design service water flow rates to all safety related components in the Service Water and RHR  !

Service Water Booster systems. Flow mitication is l performed once per fuel cycle for each of these systems.

This program demonstrates that components are not ] j significantly degraded by fouling or obstructions. j l

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Attachment to CNSS907024 January 29, 1990 Page 6 of 10 CNS programs for heat exchanger monitoring have been reviewed in detail with regard to the Generic Letter requirements. Program enhancements, as outlined below, are planned as a result of Generic Letter recommendations and guidelines.

These enhancements will be completed by the end of the 1991 Refueling Outage.

1. Those Service Water and RHR Service Water Booster system safety related heat exchangers whose heat transfer capability is not currently monitored will be added to existing performance programs or, alternatively, will be subject to maintenance inspections, as required in the Generic Letter. This will be partially completed during the 1990 Refueling Outage, with the remaining items completed during the 1991 Refueling Outage.

2. Applicable heat exchanger performance evaluation procedures will be revised by December 31, 1990, to require trending to ensure flow blockage or excessive fouling ac.umulation does not prevent the performance of safety related functions.

3. Instruction will be provided in applicable heat exchanger performance evaluation procedures by December 31, 1990, to ensure that tests are performed before and after any corrective actions are taken.

4. The current engineering practice of adjusting heat exchanger test results to design heat removal rates with calculations shall be formalized by revision of appropriate CNS performance procedures by December 31, 1990.

III. Ensure by establishing a routine inspection and maintenance program for open-cycle service water system piping and components that corrosion, erosion, protective coating failure, silting, and biofouling cannot degrade the performance of the safety related system supplied by service water.

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Heat exchanger inspection and cleaning are routine preventive maintenance activities at Cooper Nuclear. Station.

Plant maintenance procedures identify. service water syste:n heat exchangers to be inspected and provide opening, cleaning, and closing instructions. If found, accumulations-of foulants are removed. It is required that appropriate personnel be present for cleanliness and corrosion inspection. Where possible, corrosion mechanisms are identified. Heat exchangers are also inspected for the presence of pitting and to . verify the integrity of waterbox

., coatings. I certain heat exchangers have been inspected and sampled to determine'the presence of Corbicula and any other macroscopic biological fouling. None have been identified to date. .

1 Present frequencies of heat exchanger inspections vary from once per-cycle-to once every three cycles. These frequencies have been established through_ operating i experience and have proven to be adequate. -l q

Only the Service Water. system underground supply headers are- -l coated with bitumastic primer and top coat. . Review of the i heat exchanger inspections has' revealed no evidence _of j severe coating deterioration; therefore,-no additional j inspections are required. Monitoring of heat exchanger j foulants is considered to be sufficient inspection to meet d the Generic Letter requirements.

Ultrasonic testing (UT) to detect the degradation of piping  ;

and components has been performed on selected high wear;  !

areas of Service Water and RHR Service Water Booster system 1 piping and components. Additional inspections are planned in the future. These measures are intended to identify and 1 monitor areas of deterioration to ensure that the safety i function of components is not adversely effected. l CNS inspection and maintenance program enhancements are i planned as a result of Generic Letter 89-13 recommendations i and guidelines. These enhancements as outlined below will' be completed by June 1,1991. j l

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p2 Attachment to CNSS907024 January 29, 1990 Page:8 of.10

1. Those Service Water and RHR Service Water Booster-system heat exchangers not currently inspected for fouling and corrosion will be added to existing programs or, alternatively, will be subject to performance evaluations.

2 '. Selected wall thickness testing-(UT) of Service Water and RHR Service Water Booster system piping, fittings, and valves will be continued with periodic rotesting of high wear areas. This program shall be formalized in accordance with Generic Letter recommendations with regard to documentation.

3. Certain heat exchanger and pump maintenance procedures shall be revised to provide.better documentation with regard to the extent and results of the inspections.

IV. Confirm that the service water system will perform its intended l function in accordance with the licensing basis for the plant.

The District will verify, prior to startup from the 1991

-- i refueling outage, the following aspects of the licensin6 basis as defined in the CNS Updated Safety Analysis Report (USAR):

1. Flows as established to meet the CNS Accident and Transient Analysis.

2. That the system designs meet the applicable Single j b Failure Criteria.

3. That the heat exchangers are capable-of removing the ,

specified heat loads. l The District considers this verification applicable only to the germane portions of the Service Water system, RHR SW

l. system, REC system, and DCJW system.

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-V. Confirm that maintenance practices, operating and emergency procedures, and training that involves the service water system

0. are adequate to ensure that safety related equipment cooled by the i

service water system will function as intended and that operators

of this equipment will perform effectively.

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Attachment to CNSS907024 January 29,'1990 ..

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CNS-Operations Manual procedures are reviewed for current applicability no less frequently than every two years, six months. Administrative 1y, the procedures'are maintained i current and correct with this process.

Maintenance practices on the service water system are -

E controlled by established procedures. The confirmation  ;

review of maintenance practices and procedures for the.

Service-Water, RHR Service Water Booster, safety related REC-loops, and the DGJW systems has included review of instructions for clarity to help reduce human error in the  !

repair and maintenance of components within these systems. -

Additionally, it was determined that these procedures 'i provide sufficient technical guidance for pump and heat exchanger maintenance. However, revisions to-existing proceduresJand development of new proceduros to address the  ;

concerns of this Generic Letter will be undertaken, as  !

previously identified in this response.

The operating and emergency procedures are reviewed as I outlined above. These procedures, however, vill again be reviewed to ensure that, as a minimum, the list of references are current, listed'setpoints are correct, applicable design changes have been incorporated, and j applicable Technical Specification changes have been -

incorporated.

The confirmation review of operating and emergency i j.. procedures for the Service Water and RHR Service Water.

Booster, safety related REC loops, and the DGJW system includes review of instructions.for clarity to assist in  !

reducing. human error in the operation of these systems. 4 Reviews are conducted for design changes, NCRs, SOERs, SERs, j LERs, and many other industry and plant documents to ensure that training materials are maintained current. This review is performed through the Documents and Events Review b Committee (DERC) on a weekly basis. For changes of significance, Training Work Requests (TWRs) are generated which track revisions and/or updates to training m.terials.

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-. Attachment to CNSS907024 ,

fJanuary 29 1990

Page,10 of 10-

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g h The above confirmation process was followed in reviewing r' . operations and~ maintenance training material for the Service Water, RHR Service Water Booster, safety related REC loops, p, and DGJW systems as applied to this generic letter. A review of existing training material was conducted and a determination was made that the material was.in satisfactory ,

condition and that the appropriate persons are being trained. Training actions for this generic letter are, completed.

Program enhancements as outlined below are planned as a '

s result of generic letter recommended actions end guidelines. -

1. The confirmation review of maintenance practices and procedures will be completed when the previously ,

identified new procedures are developed. - This

confirmation will be completed by September 1, 1991. >

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2. The confirmation review of operation and emergency -i procedures will be completed when revisions are .

completed on operating procedures previously-identified in this response. This confirmation will t p be completed by June 1, 1991.

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