ML20006E224
| ML20006E224 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 02/09/1990 |
| From: | Feigenbaum T PUBLIC SERVICE CO. OF NEW MEXICO |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-89-13, NYN-90037, NUDOCS 9002220338 | |
| Download: ML20006E224 (18) | |
Text
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E ' New Ham shire Ted C. E. _-
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Senior Vice President and l Chief Operating Officer l l
NYN-90037 February 9, 1990 United States Nuclest Regulatory Comunission Washington, DC 20555 ;
Attention: Document Control Desk
References:
a) Facility Operating License NPF-67. Docket No. 50 443 b) USNRC Generic Letter No. 89-13, dated July 18, 1989,
' Service Water System Problems Affecting Safety-Related Equipment'
Subject:
Response to Generic Letter 89-13 Gentlemon:
Generic Letter 89-13 requested licensees to implement programs to ensure that their Service Water Systems meet and maintain heat removal requirements. '
To ensure that the Service Water Systems at Seabrook Station Unit 1 are capable of performing their designed function, New Hampshire Yankee [
(NHY) established a multi-disciplined Service Water Task Team. This Team was formed prior to the issuance of Generic Letter 89-13 and has y addressed all significant design, operating, maintenance and testing j issues associated with the Service Water Systems at Seabrook Station '
Unit 1. The Service Water Task Team reviewed Generic Letter 89-13 upon receipt and determined that many of the requested actions had been ]
completed or were in progress, i This letter provides information regarding completed, ongoing and planned actions by NHY associated with the requested actions of Generic Letter 89-13. To assist in your review of this response Enclosure 1 l
provides.a-summary description of the Seabrook Station Service Water Systems and other pertinent information. Enclosure 2 provides the specific NHY responses to the requested actions of Generic Letter 89-13.
l As the detailed information in Enclosure 2 indicates, New Hampshire L Yankee has aggressively pursued actions to ensure that Service Water Systems at Seabrook Station function as designed. Many of the actions l'
l described in Enclosure 2 are periodic in nature and will continue to
, ensure that the heat removal requirements of Service Water Systems at Seabrook Station are met.
9002220338 900209 /
PDR ADDCK 05000443 8p
'p' PNU New Hompshire Yonkee Division of Public Service Company of New Hampshire p P.O. Box 300
- Seobrook, NH 03874
- Telephone (603) 474 9521 I 1
l' United States Nuclear Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 2 If you have any questions on this matter, please contact Mr. Geoffrey Kingston at (603) 474-9521 Extension 3371.
l Very truly yours, ht(& de Ted C. Feigenbaum cc Mr. William T. Russell Regional-Administrator United States Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Mr. Victor Nerses. Project Hansger Project Directorate I-3 United States Nuclear Regulatory Commiscion Division of Reactor Projects Washington, DC 20555 Hr. Noel Dudley NRC Senior Resident Inspector P.O. Lox 1149 Seabrook, NH 03874 STATE OF NEW HAMPSHIRE Reckingham, ss. February 9, 1990 '
Then personally appeared before me, the above-named Ted C.
Feigenbaum, being duly sworn, did state that he is Senior Vice President
& Chief Operating Officer of the New Hampshire Yankee Division of Public Service Company of New Hampshire, that he is duly authorized to execute ;
and file the foregoing information in the name and on the behalf of New Hampshire Yankee Division of the Public Service Compan j and that the statements therein are true to the best of his knowledge and belief. 'l 6M b 3Maam.t !
Beverly E.'dilloway, Notatz) Public My Commission Expires: March 6, 1990 l
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United States Regulatory Commission February 9, 1990 Attention: Document Control Desk ENCLOSURE 1 TO NYN-90037
SUMMARY
DESCRIPTION OF THE SEABROOK STATION ULTIMATE HEAT SINK.
SERVICE WATER SYSTEM AND COOLING TOWER COMPLEX t
United States Regulatory Commission February 9, 1990 Att6ntion: Document Control Desk Page 1
SUMMARY
DESCRIPTION OF THE SEABROOK STATION ULTIHATE HEAT SINK.
SERVICE WATER SYSTEM AND COOLING TOWER COMPLEX At Seabrook Station, the ultimate heat sink is normally the Atlantic Ocean and alternately the atmosphere. The Atlantic Ocean provides the normal supply of cooling water to the Service Water System.
In the unlikely event that the supply of cooling water from the Atlantic Ocean becomes unavailable to the Service Water System, heat removed by the Service Water System is rejected to the atmosphere by means of a mechanical draft evaporative cooling tower.
Atlantic Ocean water is supplied to and from the Service Wate'.
System through two circulating water tunnels. These tunnels cor.aect the plant site with three submerged offshore intake structures and a multi-port discharge diffuser.
The on-site terminus of each tunnel is a large concrete basin called a ' transition structure.' Extending vertically downward from each transition structure is a 19 foot diameter land shaft. Starting 240 feet below mean sea level at the bottom of the vertical land shafts, two tunnels extend out under the ocean et a slight ascending grade until they reach their respective offchore terminus locations about 160 feet below the ocean's surface. The tunnels, which are machine bored through bedrock to a 22 foot diameter, are concrete-lined to provide a finished 19 foot diameter.
The intake tunnel is approximately 17,000 feet long. The offshore terminus is connected to the ocean by three concrete-lined vertical shafts approximately 10 feet in diameter, spaced approximately 100 feet apart and located approximately 7,000 feet offshore in water approximately 60 feet deep. A submerged concrete intake structure approximately 30 feet in diameter is mounted on top of each vertical shaft above the ocean bottom. The intake structure minimizes fish entrapment by reducing water intake velocity.
The discharge tunnel is approximately 16,500 feet long. The offshore terminus is connected to the ocean by eleven concrete-lined vertical shafts approximately 5 feet in diameter, spaced approximately ,
100 feet apart and located approximately 5,500 feet offshore in water up to 70 feet deep. A double-nozzle discharge fixture is attached to the top of each of these eleven vertical shafts to increase the discharge velocity and diffuse the heated effluent water. The discharge nozzles are painted with a non-blocidal, anti-fouling paint to minimize the attachment of biological fouling organisms.
United Statee Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 2 The Service Water System consists of two independent, redundant trains supplying cooling water to various safety and non-safety-related heat exchangers. Each redundant train is supplied by two service water pumps located in the Service Water Pump House. Each service water rump is capable of providing the full flow capacity required by its redundant train. The four service water pumps draw water from a common bay in the Service Water Pumphouse. The common bay can be supplied from either the intake or discharge transition structure through underground pipes.
The safety-related componente cooled by the Service Water System are the primary component cooling water (PCCW) heat exchangers and the diesel generator water jacket heat exchangers. Six boundary valves are provided to isolate the safety class and non-safety portions of the Service Water System. A basket-type strainer is provided in each train to prevent shells and mussels, which could be carried into these lines, from fouling any of the heat exchangers. A bypass line around the strainers is also provided to allow continued plant operation in the event the strainers must be isolated for maintenance or cleaning. .
Cement-lined carbon steel pipe is used throughout most of the Service Water System in order to prevent long term corrosion. Additional noterials such as molecular-polymer or polyurethane linings are also used for corrosion protection in the service water piping and valves.
Service water pipe which is buried below grade is coated with coal-tar enamel and wrapped with asbestos-felt material. Underground servict water piping is cathodically protected.
The circulating water tunnels and the transition structures are not designed to withstand the safe shutdown earthquake (SSR). In the unlikely event of an earthquake which blocks over 95 percent of tunnel flow area, the mechanical draf t cooling tower would beerve the ultinate heat sink. The cooling tower provides an alternate s9s?ct of cooling ,
water to components cooled by the Service Water Systcn The cooling ,
tower is completely independent of the circulating water tunnels and the ,
Atlantic Ocean. The cooling tower, pumps and associated components are dealgned to withstand the safe shutdown earthquake.
The cooling tower complex consists of a three cell tower, a basin 1 with five interconnected compartments, two pump rooms and associated '
piping, valves and equipment. Of tho three cells, one outboe.rd cell is independent and dedicated to Unit 1, and the center cell is common to ;
both Unit 1 and Unit 2. The Unit 1 independent cell contains one fan and the common cell contains two fans. The cooling tower complex can be connected manually to supply all or only safety-related Service Water l
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t United States Regulatory Commission February 9, 1990 Attention: Document Control Resk Page 3 System loads. Automatic conLection of the cooling tower to the safety-related service water loads occurs upon specific conditions indicating lose of normal service water cooling capability. When the cooling tower is supplying service water loads, the cooling tower pumps with their associated valves, piping and equipment circulate water from the cooling tower basin through the selected heat exchangers. The flow is returned to the cooling tower basin through either the cooling tower sprays or through the spray bypass header.
Control of biological fouling in the Service Water and circulat-ing Water Systems is achieved by continuous low-level chlorination.
This process is described in more detail in Enclosure 2 to this letter.
- Although the preferred method of biological fouling control of the Circulating and Service Water Systems is continuous low-level chlorina-tion. Seabrook Station is designed with the ability to control biological fouling in the Circulating Water System by means of thermal backflushing. In the thermal backflushing mode of operation, the ,
direction of circulating water flow in the tunnels is temporarily reversed: that is, the warm water from the condenser is returned to the ocean through the intake tunnel, while the discharge tunnel is used to ,
supply ocean water to the plant. In the thermal backflushing mode of Circulating Water System operation, previously discharged water re-enters the main condenser as a result of the reversed tunnel flow.
This previously-discharged water is at an elevated temperature and is further heated as it passes a second time through the main condenser.
The temperature attained by the circulating water as it exits the main condenser for the second time is sufficiently high to kill biofouling organisms attached to the intake tunnel surfaces. During tunnel heat treatment operations, service water is cooled by the mechanical draf t cooling tower.
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United States Regulatory Coaunission February 9, 1990 Attention Document Control' Desk c:
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ENCLOSURE 2 TO NYN-90037 DED ACTIONS OF GENERIC LETTER 89-13 r
United States Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 1 RESPONSE TO THE NRC-REC 0144 ENDED ACTIONS OF GENERIC LETTER 89-13 NRC-RECOMENDED ACTION I 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. A program acceptable to the NRC is described in
' Recommended Program to Resolve Generic Issue 51' (Enclosure 1 to -
Generic. Letter 89-13). It should be noted that Enclosure 1 (to Generic Letter 89-13) is provided as guidance for an acceptable program. An equally effective program to preclude biofouling would also be acceptable. Initial activities should be completed before plant startup following the first refueling outage beginning 9 months or more after -
the date of this letter. All activities should be documented and all relevant documentation should be retained in appropriate plant records.
NHY RESPONSE:
The program acceptable to the NRC described in Enclosure 1 to Generic Letter 89-13 consists of the following baeic elements:
A. Intake structure visual inspection for macroscopic biological fouling.
B. Continuous chlorination of the Service Water System for macroscopic biological fouling control.
i C. Periodic flushing and flow testing of redundant and infrequently used loops.
D. Annual collection of water and substrate samples to determine if Asiatic clams have populated the water source.
The NHY response to NRC-Recommended Action I will address items (A) through (D) above.
A. Intake Structure Visual Inspection for Macroscopic Biological Foulina.
The intake and discharge tunnels at Seabrook Station were initially l circulated with Atlantic Ocean water during the summer of 1985. Since l= then, the Circulating and Service Water Systems have been frequently I
operated for varying lengths of timo in support of operations and i testing. To date, three inspections of the offshore intake and/or j discharge structures have been performed. These inspections were '
performed in November, 1986, April, 1988 and November, 1989 by divers p assisted by a remotely-operated vehicle carrying a video camera. I
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United States Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 2 In November, 1986, the three intake structures, the three vertical shafts connecting each intake structure to the intake tunnel and the !
first 100 feet (approximately) of the intake tunnel were inspected. l Pictures of the intake structures obtained as part of the pre-planning for this inspection indicated the presence of attached biological fouling organisme. Therefore, during this inspection, the three intake structures and fouled portions of the vertical shafts were cleaned. The inspections revealed that the vertical shafts and tunnel surfaces i downstream of the sodium hypochlorite solution injection points ;
(located approximately four feet below the intake structure) were free t of attached biological fouling organisms. Also during this inspection, the eleven (11) double-noatie discharge fixtures were inspected and cleaned. The discharge fixtures were found to have only a saml1 ,
quantity of attached biologicel fouling organisms.
The April, 1988 inspection was a follow-up to the November, 1986 inspection to determine the extent of intake structure biological fouling built up since the November, 1986 cleaning. During this inspection, the three intake structures, vertical shafts and the first 100 feet (approximately) of the intake tunnel were again inspected.
Attached biological fouling organisms were observed, as expected, on the intake structures and vertical shafts upstream of the sodium hypochlorite injection points. The vertical shafts and tunnel surfaces downstream of the sodium hypochlorite injection points were found to be free of attached biological fouling organisms. No cleaning was planned or performed during this inspection. Also in April, 1988, surfaces of the on-site intake and discharge transition structures and the first 100 feet (appr.oximately) of the on-site terminus of the intake and discharge tunnels were inspected using a remotoly-operated vehicle carrying a video camera. This portion of the inspection revealed a small amount of solid debris, a few starfish and crabs: but essentially no attached biological fouling organisms were observed.
In November, 1989, pre-planned activities consisted of inspecting and cle.aning one intake structure, and inspecting two discharge fixtures. The intake structure vertical shaft and the top twenty (20) feet of each discharge fixtures' vertical shaft were included within the scope of the inspection. As expected. biological fouling organisms were attached to the intake structure and vertical shafts upstream of the sodium hypochlorite injection points. Minimal biological fouling of the discharge fixtures and vertical shafts was observed. ;
New Emmpshire Yankee plans to conduct an offshore structure inspection during or prior to the first refueling outage of Seabrook ;
Station Un:lt 1. The extent of this upcoming inspection will be based upon our eveTuation of the results of the above-described inspections.
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United States Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 3 f
Beyond the first refueling outage NHY expects to develop a program of periodic offshore structure inspections in order to ensure that biological fouling is monitored and controlled.
Since the intake and discharge tunnels were initially filled in 1984, only the 100 foot sections of tunnel described above have been inspected. The amount of biological fouling present throughout the entire tunnel length is indicated by the Manning number. Increased tunnel biological fouling will increase the resistance to circulating water flow in a fouled tunnel and result in an increased level difference between the Atlantic Ocean and water in the respective transition structure. The Manning number is calculated based on the level difference between the transition structure and the Atlantic Ocean. Hanning numbers are calculated annually and trended to provide an indication of changes in the amount of tunnel biological fouling.
B. Continuous Chlorination of the Service Water System for Macroscopic Biolonical Foulina Control.
The method of macroscopic biological fouling control selected for the Circulating and Service Water Systems at Seabrook Station is continuous, low level chlorination. This method injects sodium hypochlorite solution into the intake ocean water at each of the three 1 offshore intake structures and, if necessary, at additional injection points at the intake and discharge transition structures and the- ,
Circulating Water and Service Water Pumphouses. Sodium hypochlorite l solution is injected at a rate such that a concentration of 0.2 mg/l total residual oxidant and measured as equivalent C12 is not exceeded in the discharge transition structure. 1 1
The term ' continuous low level chlorination' denotes a continuous rather than a batch process. However, for each chlorinated system, the process may not be ongoing throughout the year. The Circulating Water System is continuously chlorinated during the biologically-active periods of the year as determined by observation of the attachment activity on biopanels which are described below. The Service Water System is continuously chlorinated throughout the entire year. The cooling tower basin is chlorinated by batch process during the l biologically-active periods of the year. l Conformance with the requirements of the National Pollution Discharge Elimination System (NPDES) Permit issued by the U. S. ,
Environmental Protection Agency (EPA) and the State of New Hampshire is I achieved through implementation of a Chlorine Minimization Program. The I sodium hypochlorite solution dose, duration and frequency are adjusted as specified in the Program to reduce the discharge of total residual oxidant to a level as low as practicable while maintaining the Circulating and Service Water Systems free of biological fouling.
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United States Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 4 The chlorine Minimization Program utilizes biological settlement panels (biopanels) strategically placed to indicate the settlement and growth rate of biological fouling organisms within the systems. These biopanels are immersed in the incoming ocean water at the intake transition structure and in the Circulating and Service Water Pump Houses. The biopanels are periodically monitored for indications of biological fouling settlement and growth. Sodium hypochlorite solution dosage is regulated in response to indication of settlement of biological fouling organisms on the biopanels consistent with discharge permit requirements.
As described in Enclosure 1 to this letter, Seabrook Station is designed with the ability to control biological fouling of the Circulating Water System by means of thermal backflushing. Thermal backflushing is not the preferred method, however, because plant power level must be reduced during the backflushing operation.
C. Periodic Flushina and Flow Testinn of Redundant and Infrecuentiv-yped Loons.
Redundant and infrequently used loops of the Service Water and Cooling Tower Systems are periodically tested and inspected as described below in order to ensure that they are not fouled or clogged. The cooling tower supply and return lines are recirculated and tested quarterly during the Cooling Tower Pump Quarterly Operability Test.
During this test, each cooling tower pump is operated, one train at a time, at rated capacity for at least one hour. During the recirculation period, the residual oxidant concentration of the water in the cooling tower basin is adjusted by addition of sodium hypochlorite solution as necessary. The concentration of residual oxidant is limited to 0.2 mg/l in order to ensure compliance with discharge permit requirements. During the test, water is circulated between the c9oling tower basin cnd components cooled by the Service Water System through the normally-static cooling tower supply and return lines. As a result, any foreign material present in the cooling tower supply lines will be flushed to the in-line, basket-type strainers located upstream of the cooled components.
In addition to the above actions, the internal piping inspections described in the response to NRC-Recommended Action III are performed on the infrequently-used Service Water Cooling Tower supply lines.
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D. Annual Collection of Water and Substrate Samples to Determine if Asiatic Clams Hava Populated the Water Source.
Samples of water and substrate from the Browns River within the Hampton-Seabrook estuary and the Atlantic Ocean have been collected annually foi more than a decade by an environmental consultant to .
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United States Regulatory Commission February 9, 1900 Attention Document Control Desk Page 5 Seabrook Station. These include samples of the pisnktonic life stages ;
of indigenous species (bivalve larvae), as well as juveniles and adults collected within the substrate and on biofouling test panels positioned offshore. Collections have been utilised to identify and enumerate benthic (bottom-dwelling) organisms within the vicinity of Seabrook Station.
To date, there has been no evidence of the Asiatic Clam (Corbicula sp.) occurring within the environment adjacent to Seabrook Station. The blue mussel (Mytilus edulis) has been identified as a dominant benthic organism within the narine environment adjacent to Seabrook-Station.
NRC-RECOMMENDED ACTION IIi Conduct a tsst program to verify the heat transfer capability of l all safety-related heat exchangers cooled by service water. The totsl test progr.2m should consist of an initial test program and a periodic retest program. Both the initial test program and the periodic retest program should include heat exchangers connected to or cooled by one or more open-cycle systems as defined above.
In implementing the continuing program for periodic retesting of safety-related heat exchangers cooled by service water in open-cycle systems, the initial frequency of testing should be at least once each fuel cycle, but after three tests, licensees and applicants should determine the best frequency for testing to provide assurance that the equiparat will perform the intended safety functions during the intervals between tests and meet the requirements of GDC 44, 45, and 46.
The minimum final testing frequency should be once every 5 years. A ;
summary of the program should be documented, including the schedule for tests, and all relevant documentation should be retained in appropriate plant records.
1 NHY RESPONSE:
1 At Seabrook Station Unit 1, four safety,related heat exchangers are l cooled by the Service Water System. These heat exchangers are listed I below: )
Identification Description i
CC-E-17A Train A Primary Component Cooling Water Heat Exchanger i CC-E-17B Train B Primary Component Cooling Water Heat Exchanger )
DG-E-42A Train A Diesel Generator Jacket Water Heat Exchanger "
I DG-E-42B Train B Diesel Generator Jacket Water Heat Exchanger
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United States Regulatory Commission February 9, 1990 l Attention: Document Control Desk Page 6 '
l New Hampshire Yankee will conduct an initial thermal performance test on each of these heat exchangers. Periodic retests will be ]
performed on a continuing basis. i The initial thermal performance test of the primary component ;
cooling wate. -PCCW) heat exchangers will be performed during the Power j Ascension Test Program. Since any thermal performance testing of the l PCCW heat exchangers requires the presence of a reasonable heat load, l plant operation at power will be required in order to complete the initial test. It is anticipated that the initial test and baseline :
measurements for_the PCCW heat exchangers will be performed at the 100 )
percent power test plateau.
The initial thermal performance test of the diesel generator jacket i water (DGJW) heat exchangers can be performed during routine diesel surveillance testing since the diesels are synchronixed with the grid I and operated at rated load during this testing. The initial thermal l performance test will be completed for each DGJW heat exchanger prior to l June 30, 1990. ]
l Periodic retents to monitor the thermal performance of these heat exchangers will be performed on at least an annual basis until a minimum l of three (3) tests are completed. If, after evaluating the results of the annual retests, it is determined that the retest interval can be extended, a new test interval will be established not to exceed five (5) years. Whenever feasible or possible, retests will be performed prior to performing corrective work that will affect the thetmal performance of the heat exchangers. If the corrective work is of an' emergency nature such that a formal retest can not be performed prior to the repairs, and previous test data can not be used to satisfactorily evaluate trends, then the retest interval will be returned to an annual basis until a minimum of three (3) tests are completed as before. New baseline measurements will be taken following corrective work that could affect thermal performance.
The NHY service water heat exchanger thermal performance monitoring program will include both the initial test, (baseline measurement), and retest programs. The program methodology will involve standard heat exchanger thernal analysis techniques. Measurements of inlet and outlet fluid temperatures for both the cold and hot fluids, and mass flow rate for at least one flow stream will allow calculation of the heat rate, log mean temperature difference, overall heat transfer coefficient, and heat exchanger efficiency. Changes in fouling resistance, heat transfer area, and internal flow geometry can be detected by analyzing trends in the above parameters. Due to the complicated thermal-hydraulic
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United States E4gulatory Commission February 9, 1990 Attention Document Control Desk Page 7'
_ relationships present in any heat exchanger, retest measurements will typically be performed at or near baseline con 31tions to allow meaningful comparisons.- Appropriate alternative analysis will be performed if retest conditions differ significantly from baseline
_ conditions.
s When baseline information is obtained as a part of an initial test or any babsequent retest following corrective maintenance, the results r will be compared to the design requirements for the heat exchanger.
t Acceptance will be based on an evaluation that demonstrates measured
_ performance is better than or equal to the specified design performance.
r NRC-RECOMMENDED ACTION III_t_
Ensure by establishing a routine inspection and maintenance program for open-cycle service water system piping and components that 1 corrosion, erosion, protective contir.g failure, silting, and biofouling a cannot degrade the performance of thz safety-related systems supplied by
- - service water. The maintenance program should have at least the gg following purposes
E A. To remove excessive accumulations of biofouling agents.
., corrosion products, and silti g, B.- To repair defective protective coatings and corroded service water system piping and components that could adversely affect performance of their intended safety functions.
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!E This program should be established before plant startup folicy'ng
[ tho first refueling outage beginning 9 months after the date of ti.lu letter. A description of the program and the resulta of these maintenance inspections should be documented. All relevant
-_. documentation should be retained in appropriate plant records.
NHY RESPONSE 1 Ik ;
The routine inspection and maintenance program applicable to the
' Service Water System at Seabrook Station includes the following actions:
E 'A. A centralized Service Water System data base has been
_ established on the Station's infonnation resources computer. 6 This data base organizes the inspection information pertaining 19 to Service Water System components. The data base facilitates efficient and productive recording. updating, retrieving, f analyzing, trending and reporting of this data. Inspection and
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maintenance resulte end comments pertaining to welds, spool Em
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I United States Regulatory Come.ission February 9, 1990 Attentions Document Control Desk Page 8 :
pieces, valves and specific pipe locations are typical examples '
of data maintained in the data base. As a further example, the
-data base.contains a catalog of the status of each underground ,
pipe field-welded joint. The cataloged data includes welded joint identification, grouting compound identification, weld date, inspection date, results and rework actions.
B. Internal surfaces of service water piping, including l infrequently-used loops, were visually inspected in April,1988.
Representative portions of above-ground piping were visually inspected by direct observation while crawling through the pipe.
-Representative portions of underground piping were visually inspected by use of a remotely-operated vehicle with an attached ;
video camera. The purpose of these visual inspections was to
- note the presence or e.bsence of foreign material or biological fouling organisms, and observe the material condition of the cement, molecular-polymer and polyurethane linings, protective coatings and butterfly valve conditions. The inspections indicated that the pipe interior linings were in excellent-condition and that no biological fouling organisms were present.
Internal piping inspections will again be performed at-the first refueling outage of Seabrook Station Unit 1. The extent and frequency of additional inspections will be~ determined based upon the results.of the-inspections performed at the first refueling outage.
C. Inspections of the circulating water tunnel structures are performed as described in the response to NRC-Recommended Action I, Item A.
D. Safety-related heat exchangers in the Service Water System are ,
visually inspected and examined by eddy-current techniques en a periodic basis with a frequency determined by operating experience.
E. A Seabrook Station procedure has been developed to provide )
instructions for repair of protective coatings to piping. The procedure provides instructions for repair of cement and molecular-polymer linings.
1 -F. A Service Water System Materials Test Program has been developed and implemented. In December,1988 a test stand was erected in I the Cipculating Water Pump House as a facility to perform in-situ testing of materials used in or under consideration for use ,
in the Service Water System. Four short sections of cement-- l lined pip 6 representative of that currently in use in the l l
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t United States Regulatory Commission February 9, 1990
- Attention: Document Control Desk Page 9 Service Water System are installed in the test stand.
, Represented on the four pipe test specimens are various service water piping design features and flaws that could potentially exist in service water piping. Examples lof d6 sign features and ,
potential flaws include field welds with and without backing rings, different joint compounds and cement lining with cracks.
On the test stand, inlet water is pumped through the piping test specimens at approximately the same velocity as would be present in the actual system. Stagnant flow conditions have also been established on the test stand. Approximately every six months, the piping test specimens are removed from the test stand and inspected for evidence of erosion, corrosion, '
microbiological 1y-induced corrosion and biological fouling.
Two objectives of the Program are to determine the effects of microbirlogically-induced corrosion on carbon steel and to determine the' service water piping corrosion rate.
NRC-RECO9 ENDED ACTION IV:
Confirm that the service water will perform its intended function in accordance with the licensing basis for the plant. Reconstitution of the design basislof the system is not intended. This confirmation should include a review of the ability to perform required safety-functions in the event of failure of a single active component. To ensure that the as-built system is in accordance with the appropriate licensing basis documentation, this confirmation should include recent L
(within the past two years) system walk down inspections. This ,
confirmation should be completed before plant'startup following the first refueling outage beginning nine months or more after the date of this letter. Results should be documented and retained in appropriate plant records.
NRY RESPONSE:
The licensing basis of the Service Water and Cooling Tower Systems is established in the Seabrook Station FSAR. The Service Water System is described in FSAR Section 9.2.1 and the Cooling Tower System is
! described in FSAR Section 9.2.5.
New'Hampshi.e Yankee has confirmed that the Service Water and Cooling Tower Systems will perform their intended function in accordance with the licensing basis for the plant. This confirmation is based upon the results of preoperational testing, a comparative analysis of cooling tower performance, a failure analysis and an engineering review.
Preoperational testing has denonstrated the ability of the Service Water and Cooling Tower Systems to supply flow rates exceeding those s
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United States Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 10
. required to fulfill their respective safety functions. Preoperational testing of water and air flow combined with a proprietary comparative analysis demonstrated the ability of the cooling tower to remove heat at a rate. exceeding that required to fulfill its safety function. The proprietary comparative analysis performed by the cooling tower manufacturer compared the expected heat removal performance of the '
Seabrook cooling tower to the performance during a formal test of a cooling tower built by the same manufacturer with cells nearly identical in size to those of the Seabrook. cooling tower.
The comparative analysis substantiates the Seabrook cooling tower's ability to fulfill its safety function.
A failure analysis of the Service Water System and its components was performed and is presented in FSAR Section 9.2.1.1 (Table 9.2-3).
This analysis included cooling tower components and demonstrates that single failure design criteria have been met.
An engineering review of the Service Water and Cooling Tower Systems was performed in 1989. The engineering review compared the as-built system configurations as shown in the Seabrook Station Piping and Instrumentation Dravings (P& ids) to the configurations as described in the FSAR. The as-built system configurations were also verified by a system walkdown inspection. Outstanding design modifications pertaining to the Service Water and Cooling Tower Systems were evaluated to determine if any of these modifications were required to enable the systems to fulfill their safety function. The engineering review verified that the as-built configurations of the Service Water and Cooling Tower Systems as shown on P& ids were as described in the FSAR and as observed during the systems walkdown inspection. Outstanding design modifications pertaining to these systems were evaluated to be performance enhancements and thus not required to enable the systems to perform their safety function.
NRC-RECOMMENDED ACTION V:
Confirm that maintenance practices, operating and emergency ;
procedures,'and training that involves the service water system are l adequate to ensure that safety-related equipment cooled by the service I water system will function as intended and that operators of this I equipment will perform effectively. This confirmation should include recent (within the past 2 years) reviews of practices, procedures, and training modules. The intent of this action is to reduce human errors j
}- in the operation, repair, and maintenance of the service water system.
f This confirmation should be completed before plant startup following the j first rofueling outage beginning 9 monthe or more after the date of this l letter. Results should be documented and retained in appropriate plant l I
records.
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United States Regulatory Commission February 9, 1990 Attention: Document Control Desk Page 11 EHY RESPONSE New Hampshire Yankee performed a review to confirm that Seabrook Station maintenance practices, operating procedures, emergency procedures, and training impacting 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. The review established two general objectives. The first objective was to determine what actual practices l were in place to minimize and correct system fouling. Actual practices which occurred within the last two years regarding Service Water System erosion, corrosion, biofouling, foreign material intrusion, debris intrusion, depositions, and pipe coating failures were reviewed. The second objective was to determine the effectiveness of procedures and practices in minimizing human errors during the operation, maintenance or repair of the Service Water System. The types of human errors that are being experienced in the industry were determined by review of NUREG-1275, Volume 3, ' Operating Experience Feedback Report - Service Water System Failures and Degradations." This document revealed that human errors in the industry have primarily involved mispositioning valves, de-energizing the wrong equipment, inadvertently isolating components, udspositioning breakers and switches, and mislabeling valves. There have also been errors in the industry involving inadequate installation of parts during or following maintenance activities.
Seabrook Station documents which were reviewed in connection with the first objective included preventive maintenance records, system inspection reports, related procedures and training records.
Discussions with appropriate personnel were conducted regarding system status and current concerns. In connection with the second objective, surveillance requirements and procedures, operating procedurec, administrative procedures and policies were reviewed. Also Station ,
Information Reports (SIRS) involving the Service Water System for the past two years were reviewed.
The review determined that there has been a high level of management attention to Service Water System fouling problems at Seabrook Station. Concerns with the lining of pipes and valves have been effectively corrected and are being monitored to ensure that system and component integrity is maintained. Biological fouling is also being effectively monitored and controlled. Short-term and long-term corrective actions for corrosion and erosion of heat exchanger tubes are being actively pursued. Human errors in operation at.d repair ,
of the Service Water System at Seabrook Station nave been minimal. )
A detailed report of the review summarized above is maintained in Seabrook Station records.