ML20236V975
| ML20236V975 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 07/28/1998 |
| From: | Dacimo F COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-89-13, NUDOCS 9808040327 | |
| Download: ML20236V975 (9) | |
Text
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Commonwealth FAle.oo Compan) e l.asalle Generating Station 2601 North 21st Itoad Marseilles, IL 61.4119757 Tel HI 5.%7#'61 July 28,1998 United Stat:a Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555
Subject:
Generic Letter 89-13 Revised Response LaSalle County Nuclear Power Station, Units 1 and 2 Facility Operating License NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374
References:
1.
Generic Letter 89-13, " Service Water System Problems Affecting Safety-Related Equipment,"
dated July 18,1989.
2.
Generic Letter (GL) 89-13 Supplement 1,
" Service Water System Problems Affecting Safety-Related Equipment," dated April 4,1990.
3.
W. T. Subalusky to U.S. NRC letter dated December 20,1996, transmitting LaSalle County's response to NRC Inspection Report 50-373/374-96011.
Reference 3 responded to a number of deficiencies related to the Safety Related Service Water System at LaSalle Station. Subsequent reviews
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revealed that LaSalle's original Generic Letter 89-13 program was weak in i
I several areas.
LaSalle Station has performed a re-baseline of the Generic Letter 89-13 program. This letter is transmits our revised response to References 1 and l
- 2. This submittal supersedes all previous docketed responses regarding l
Generic Letter 89-13 implementation at LaSalle Station.
LaSalle Station's revised response is included as Attachment A and l
provides an overview of the LaSalle's Generic Letter 89-13 program.
g 9808040327 980728 l-hDR ADOCK 05000373
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A linicom Compan)
l if there are any questions or comments concerning this letter, please refer them to Harold D. Pontious, Jr., Regulatory Assurance Manager,
. (815) 357-6761, extension 2383.
Respectfully,
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l Fred R. Dacimo Site Vice President LaSalle County Station Attachment cc:
C. A. Paperiello, Acting NRC Region ill Administrator M. P. Huber, NRC Senior Resident inspector - LaSalle D. M. Skay, Project Manager - NRR - LaSalle F. Niziolek, Office of Nuclear Facility Safety - IDNS l-i i
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Attachment A LaSalle Station Generic Letter 89-13 Program Overview Scone of' L 89-13 Pronram at LaSalle Station G
Comed has defined the scope of the LaSalle Station response to GL 89-13 as encompassing the following systems or portions of systems:
Core Standby Cooling System (CSCS) Pond and intake Structure Core Standby Cooling System - Equipment Cooling Water (CSCS - ECW) system in its e
entirety, including system piping and components (this includes the Residual Heat Removal Service Water (RHR SW) and Diesel Generator (DG CW) Service Water subsystems)
Portions of the Service Water (WS) system (fuel pool cooling heat exchangers and the WS e
piping which crossties to the Fire Protection System)
Portions of the Fuel Pool Cooling (FC) System (fuel pool cooling heat exchangers, fuel pool e
emergency make-up lines along with applicable components from the CSCS)
Portions of the Fire Protection (FP) system e
The CSCS system, along with the Pond and Intake Structure, are clearly open-cycle and fall within the intended scope of the GL 89-13 recommended actions. Although the WS and FP systems are non-safety-related, sections of the systems were included in the LaSalle Station GL 89-13 program in order to improve the reliability of those systems in recognition of the important to safety functions they support.
All of the closed systems at LaSalle Station have been excluded from the scope of GL 89-13 based on the chemistry control related to these systems and their past performance. The ' closed' systems which are cooled by CSCS include all the various Diesel Generator Jacket Water Cooling Systems and primary system cooling water via the RHR heat exchangers. The CSCS system also provides an emergency supply of make-up water to the Fuel Pool system. However, this flow path is normally isolated (a spool piece must be physically connected for the flow path to be opened), and does not encounter CSCS water unless absolutely necessary. With respect to the
' closed systems' interfacing with CSCS, the primary cooling water has very tight chemistry controls and monitoring by virtue ofit being reactor water, and the various Diesel Generator l
Jacket Water systems also have chemistry control. Neither of these systems has exhibited excessive corrosion or fouling due to inleakage. Therefore, the exclusion of these systems from the scope of GL 89-13 isjustified. As an ongoing activity, the chemistry controls and monitoring l
for the applicable closed systems is verified.
Action item I Sodium Hypochlorite or a solution of Sodium Hypochlorite and Sodium Bromide is injected into the 36 inch headers connecting the Lake Screen House to the Service Water Tunnel to maintain the total and free chlorine residuals within guidelines on both Units. With the exception of short maintenance outages of the Chemical Feed System, chemical injection is continuous and all procedures that operate the standby open cycle systems or subsystems have a step to ensure that the Chemical Feed System is operating prior to starting the standby system, or on the rare occasion that a system is staned without the Chemical Feed System in service, that the system will Page 1 of 7 1
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Attachment A i
LaSalle Station Generic Letter 89-13 Program Overview be flushed with chemically treated water as soon as the Chemical Feed System is returned to service and conditions permit such flushing.
In addition to performing a biocide injection function, the Chemical Feed System is also designed to minimize and control silting and scaling in GL 89-13 applicable systems by the injection of a l
l polyacrylic acid solution. With the exception of short maintenance outages of the Chemical Feed j
I System, the chemical to contro! silting and scaling is injected continuously.
Sampling of the lake water used for cooling is performed by the Chemistry Department, which
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monitors, adjusts chemical feed rates based on residual or vendor guidance, and trends the data to determine the optimal injection rates.
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Water samples are taken from the RHR Service Water system headers following the quarterly flush of the RHR Service Water headers. Since the DG Service Water lines do not have sample connections, the RHR Service Water chemistry results will represent all CSCS subsystems that are flushed monthly.
A surveillance is performed each refueling outage to inspect the CW Pump Suction Bays in the Lake Screenhouse. The bypass line butterfly valve is cycled during these inspections. The bypass valve is also included in the ASME Section XI In-Service Testing (IST) program and is cycled quanerly.
Along with the traveling screen bypass line, there are other portions of Lake Screen House that do not receive biocide injection for the control of biofouling. As such, the following equipment and areas are inspected and measured (where appapriate) to determine the extent of biofouling and sediment accumulation, as well as the general condition of the equipment:
CSCS Pond and Intake Flume Surveillance are performed each refueling outage to determine the amount of sediment accumulation in the CSCS Pond and the intake flume.
L,ake Screen House and Associated Systems and Equipment The portion of the Lake Screen House Intake Structure from the area downstrear of the bargrill to the circulating water system pump inlets is inspected for accumulation of silt, corbicula or zebra musselinfestation, biological debris and concrete degradation once each year.
CSCS Bvoass Line The CSCS Screen Bypass line between the bargrill and the CSCS Bypass Line Isolation Valve is visually inspected for accumulation of sediment, fouling and corbicula or zebra mussel infestation each Unit I refueling outage. This inspection also includes the cycling of the CSCS Bypass Line Isolation valve through its full range of travel.
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Attachment A I
LaSalle Station Generic Letter 89-13 Program Overview Service Water Tunnel i
Even though chemically treated, the Service Water Tunnel is visually inspected periodically for l
corbicula or zebra mussel infestation, fouling and siltation. This inspection includes the portion of l
the CSCS Cooling Water Screen Bypass Line downstream of CSCS Bypass Line Isolation Valve.
l One half of the Service Water Tunnel, as determined by the centerline (4 line) of the Lake Screen House, is inspected each refueling outage on a rotating outage basis, with each Unit's applicable half (Unit 1, South Half, Unit 2 North Half) inspected during the applicable Unit outage.
System Components. Structures. and Piping Unless a visual inspection is already performed along with the activity at hand, the System Engineer for GL 89-13 applicable systems will perform a visual inspection. Each such " inspection of opportunity" is documented by the System Engineer and retained in the GL 89-13 program I
files. These inspections will be used to assess the condition of the system components and piping and help in determining the etTectiveness of the biocide and corrosion monitonng program.
q System Flushing New procedures have been put in place or existing procedures have been revised to require and document periodic flushing and Oow testing ofinfrequently used or stagnant lines in the CSCS:
Redundant, stagnant, or infrequency used cooling loops in the CSCS-ECW, WS, Fuel Pool Cooling, and Fire Protection systems are flushed on a monthly basis, and flow tested on a refueling outage basis at maximum design flow to ensure that they are not fouled or clogged.
The CSCS, WS, Emergency Fuel Pool Make-Up, and Fire Protection systems all draw from the chemically treated Service Water Tunnel, therefore all receive benefits from the biocide and silt / scale control during flushing.
The non-safety Service Water system (WS) flows continuously with the standby heat exchangers on the Fuel Pool Cooling System either rotated monthly or laid up in a drained and dry condition. Therefore, dedicated flushing procedures are not required for WS. A monthly rotation of the inservice fuel pool cooling heat exchanger is performed to ensure regular flushing and re-chlorination of the idle heat exchanger. The heat exchanger may be laid up in a drained and dry condition on the service water side in lieu of monthly rotation.
Action Item II The previous responses to item 11 of GL 89-13 have been re-evaluated and a new testing program has been developed for LaSalle Station. The heat exchanger performance monitoring program at l
LaSalle Station consists of the following key elements:
Heat Transfer Testing Cleaning and Inspection Eddy Current Testing e
Lay-up/ Flushing Page 3 of 7
Attachment A LaSalle Station Generic Letter 89-13 Program Overview e Flow Verification Performance Trending A unique combination of these program elements will be applied to each heat exchangers in the l
scope of the GL 89-13 program. The specific elemcats app;ied to each heat exchanger have been l
selected based on the unique service corJitions. configuration limitations and performance requirements of each and are summarized as follows:
1 Cubicle Area Coolers (NW, SW, SE, and NE)
Tube-Side (Chemical) Cleaning on condition Air-Side CoilInspection Component Flushing Air-Side Flow Verification Cooling Water Flow Verification Cooling Water dP Monitoring DG Heat Exchangers (Standby and IIPCS)
Thermal Performance Testing Tube-Side Clean & Inspect Tube-Side Eddy Current Testing Component Flushing Cooling Water Flow Verification RHR Heat Exchangers Thermal Performance Testing Tube-Side Clean & Inspect Tube-Side Eddy Current Testing Component Flushing Shell-Side Flow Verification Cooling Water Flow Verification RHR Pump Seal Coolers Shell-Side Clean & Inspect Component Flushing Cooling Water Flow Verification LPCS. Pump Motor Coolers Tube-Side Clean on condition Component Flushing Cooling Water Flow Verification I
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Attachment A i
. LaSalle Station Generic Letter 89-13 Program Overview Fuel Pool Heat Exchangers Thermal Performance Testing l
Tube-Side Clean & Inspect Tube-Side Eddy Current Testing Component Flushing Shell-Side Flow Verification Cooling Water Flow Verification Action Item III Degradation of components as a result of corrosi an, erosion, silting, coating failure, and microfouling is assessed at selected areas of the CSCS-ECW and portions of the Service Water, Fuel Pool Cooling, and Fire Protection systems. The methods used to identify each of these degradation mechanisms are periodic inspections and Non-Destructive Examination (NDE) as discussed l'elow.
Periodic Inspections of Eauioment Internal Surfaces The condition of system internal surfaces are assessed during inspections of opponunity afforded by equipment maintenance (i.e., components opened or removed for maintenance activities). The data obtained from these inspections is evaluated by the System Engineer in conjunction with the GL 89-13 Program Manager and, where necessary, corrective actions are developed and implemented.
A visual inspection was performed on several sections of CSCS buried pipe during the extended Unit 1 and Unit 2 shutdown between 1996 and 1998. The CSCS Division I and Division 11 common discharge lines (3125 feet of buried piping each) and 100 feet of buried piping immediately downstream of the CSCS discharge stop valves (lE12-F068A, IE12-F068B,2E12-F068A, and 2E12-F0688) were visually inspected. The buried CSCS suction lines have not been f
visually inspected. However, based on the ASME Section XI pump testing which measures and trends pump suction pressure, the suction line is verified to be acceptable (i e., no flow blockage caused by silting, fouling, collarsing pipe walls, etc.).
Non-destructive examination LaSalle Station is currently developing a procedure to formalize the NDE inspection process (developing basis for location selection and data trending) for components in the open cycle l
service water systems. For the purpose of evaluating the rate of erosion and/or corrosion, several l
piping locations will be selected for NDE:
Areas oflow flow conditions or stagnant conditions -- Four locations have been identified as experiencing low flow velocities. A baseline inspection consisting of ultrasonic gage thickness measurements have been performed. Periodic inspections will be performed at these same locations every refueling outage. Results of these inspections will be evaluated against the i
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Attachment A LaSalle Station Generic Letter 89-13 Program Overview baseline inspection. The results of these inspections are trended by the System Engineer.
Appropriate action is taken when trending results indicate that unacceptable deviation from anticipated corrosion levels is indicated, Areas of high flow conditions -- High flow locations are undesirable because of the potential e
for erosion of piping. No locations were found in the CSCS-ECW system where high flow velocities are present. Therefore, no inspections are currently performed for this criteria. This position will be re-evaluated upon completion and implementation of the formal component inspection procedure.
Large bore piping sections -- For the purpose ofidentifying the extent and severity of general and localized corrosion in large bore piping, a representative sample oflocations will be selected by the System Engineer and the Program Manager. Data will be taken at the selected locations and evaluated to determine the rate of corrosion. The inspection areas will be marked in accordance with approved procedures. Subsequent inspections will be performed at these locations and the rate of corrosion determined. The frequency ofinspections will be determined by the inspection program and the rate of corrosion or degradation.
Future inspection locations will also be chosen based on a computer program being developed via a tailored collaboration between Comed and the Electric Power Research Institute (EPRI). This program will contain a flow model of the CSCS system and will predict which areas are most susceptible to corrosion and fouling.
Action item IV A design review for each Safety-Related Service Water System has been performed. The design review consisted of the following five areas of study:
System Configuration Review
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Single Failure of Active Component Review I
e Field Verification of P&lD's e
Flood Protection Review Pipe Support Review e
No open items were identified during the design review.
The NRC System Operational Performance Inspection (SOPI) and the System Functional Performance Review (SFPR) provided a technical supplement to the original design review completed in response to GL 89-13. Following implementation of all corrective actions resulting I
from these reviews, there is greater assurance of design basis adequacy as reflected in the field and j
in design documents.
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Attachment A
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LaSalle Station Generic Letter 89-13 Program Overview In addition to the actions described above, further detailed analyses are currently being pe >
ned:
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Re-definition of individual heat exchanger heat loads and cooling water flow requirements; e
l and Re-evaluation of the CSCS system hydraulic capabilities through development of and analysis l
with a co'mputerized hydraulic model of the system.
I Specifically, the system is being flow balanced while ensuring that it continues to be hydraulically capable of meeting the specified heat load demands under worst-case conditions.
In terms of continuing configuration control, several actions will be performed to better define, evaluate, and maintain the design basis of the CSCS system. First, the Design Control Program at LaSalle Station ensures that the design basis is maintained as hardware and operational changes are made to the plant. Second, the lieat Load /llydraulic Evaluations mentioned above will be l-maintained current such that there is continued assurance that the balanced CSCS system can meet the worst case required heatload/ hydraulic demands.
Action Item V Maintenance practices, training programs, and operating and emergency procedures have been evaluated to assure that the CSCS Service Water Systems will function as intended and that operators will perform effectively.
Comed developed and used a set of checklists to evaluate maintenance practices, training programs, and operating and emergency procedures. These checklists were completed by the Maintenance, Training, and Operating Departments.
The ongoing activities related to this item include procedure reviews and training program l
reviews. These actions are already built into LaSalle Station procedures, and therefore do not l
require further actions specifically for the GL 89-13 program.
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