ML20053D297
| ML20053D297 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/25/1982 |
| From: | James Shea Office of Nuclear Reactor Regulation |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TASK-09-03, TASK-9-3, TASK-RR LSO5-82-05-052, LSO5-82-5-52, NUDOCS 8206040276 | |
| Download: ML20053D297 (11) | |
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't 4.3 A-May 25, 1982 Docket No. 50-245 LS05 05-052 Mr. W. G. Counsil, Vice President Nuclear Engineering and Operations Northeast Nuclear Energy Company Post Office Box 270 s
lbrtford, Connecticut 06101
Dear Mr. Counsil:
SUBJECT:
FORWARDING DRAFT EVALUATION REPORT OF SEP TOPIC IX-3,
" STATION SERVICE AND COOLING WATER SYSTEMS" FOR TE MILLSTONE NUCLEAR POWER PLANT, UNIT 1 Enclosed is a copy of our draft evaluation of Systematic Evaluation Program Topic IX-3, Station Service and Cooling Water Systems. This draft evaluation is based on your safety assessment of this topic.
i This draft evaluation compares your facility, as described in Docket No.
50-245, with the criteria currently used by the regulatory staff for licensing new facilities.
Please inform us if your as-built facility differs from the licensing basis assumed in our assessment within 30 days of receipt of this letter.
This evaluation will be a basic input to the integrated safety assessment for your facility unless you identify changes needed to reflect the as-built conditions at your facility. This topic assessment may be rcvised in the future if your facility design is changed or if NRC criteria relating to i
this topic are modified before the integrated assessment is completed.
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Sincerely, i
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James J. Shea gg Operating Reactors Branch f5 Q
Division of Licensing no g[.
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Enclosure:
l Draft SEP Topic IX-3 I'[8 l
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See next page SEPB1.)
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Millstone' Unit 1 Docket No. 50-245 Revised 3/30/82 Mr. W. G. Counsil cc William H. Cuddy, Esquire State of Connecticut Day, Berry & Howard Office of Policy & Management Counselors at Law ATTN:
Under Secretary Energy One Constitution Plaza Division Hartford, Connecticut 06103 80 Washington Street Hartford, Connecticut 061i5 Ronald C. Haynes, Regional Administrator
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Nuclear Regulatory Commission Region I Office 631 Park Avenue King of Prussia, Pennsylvania 19406 Northeast Nuclear Energy Company ATTN:
Superintendent Millstone Plant P. O. Box 128 Waterford, Connecticut 06385 Mr. Richard T. Laudenat Manager, Generation Facilities Licensing Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Resident Inspector c/o U. S. NRC P. O. Box Drawer KK Niantic, Connecticut 06357 First-Selectman of the Town of Waterford Hall.of Records 200 Boston Post Road Waterford, Connecticut 06385 John F. Opeka Systems Superintendent Northeast Utilities Service Company 7
P. O. Box 270 Hartford, Connecticut 06101 U. S. Environmental Protection Agency Region I Office ATTN:. Regi3nal Radiation Representative JFK Federal Building Boston, Massachusetts 02203
ENCLOSURE SEP REVIEW 0F STATION SERVICE AND COOLING WATER SYSTEMS TOPIC IX-3 FOR THE MILLSTONE hUCLEAR POWER PLANT, UNIT 1 l
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I.
INTRODUCTION The safety objective of Topic IX-3 is to assure that the cooling water systems have the capability, with adequate margin, to meet design objec-tives and, in particular, to assure that:
a.
systems are provided with adequate physical separation such that there are no adverse interactions among those systems under any mode of operation; b.
sufficient cooling water inventory has been provided or that adequate provisions for makeup are available; c.
tank overflow cannot be released to the environment without monitoring and unless the level of radioactivity is within acceptable limits; d.
vital equipment necessary for achieving a controlled and safe shutdown is not flooded due to the failure of the main condenser circulationg water system.
II.
REVIEW CRITERIA The current criteria and guidelines used to detennine if the plant systems meet the topic safety objective are those provided in Standard Review Plan (SRP) Sections 9.2.1, " Station Service Water System," and 9.2.2, " Reactor Auxiliary Cooling Water Systems." In determining if plant design conforms to a safety objective, use is made, where possible, of applicable portions of previous staff reviews.
For example, safety objective d, identified above, is being reviewed as a part SEP Topic III-5.B.
Pipe Breaks Outside Containment. Therefore, it is not addressed in this topic.
III.
RELATED SAFETY TOPICS AND INTERFACES l
Only those portions of the SRP which are not covered by other reviews are I
applied in this review. Therefore, this report does not address the following areas which are reviewed under other SEP topics or staff generic reviews:
III-4 Protection from missiles, pipe whip, jet impingement, and fires III-5 (physical separation).
IX-6 I X-5 Ventilation Systems, III-1 Quality and Seismic Classification, IV-1.A N-1 Loop Operation, III-7 Inservice Inspection and Testing, VI-10. A IX-1 Fuel Storage IX-3 Systems Required for Safe Shutdown,
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Adverse environmental phenomena (tornadoes, floods, etc.)
B VI-10.B Sharing of systems.
. IV.
REVIEW GUIDELINES In determining which systems to evaluate under this topic, the staff used the definition of " systems important to safety" provided in Reference 1.
The definition states systems important to safety are those necessgry to ensure (1) the integrity of the reactor coolant pressure boundary.
(2) the capability to shut down the reactor and maintain it in a safe condition, or (3) the capability to prevent, or mitigate the consequences of, accidents that could result in potential offsite exposures comparable to the guidelines of 10 CFR Part 100, " Reactor Site Criteria." This definition was used to determine which systems or portions of systems were " essential."
Systems or portions of systems which perform functions important to safety were considered to be essential. It should be noted that this topic may require reevaluation if future SEP reviews of design basis events identify additional cooling water systems that.are important to safety.
V.
EVALUATION The systems reviewed under this topic are the turbine building closed cooling water system, reactor building closed ccoling water system, turbine building secondary closed cooling water system, service water system, and energency service water system.
1.
Turbine Building Closed Cooling Water Systen The Turbine Building Closed Cooling Water System (TBCCW) is a closed loop system with three 33% capacity heat exchangers and three 50% capacity pumps.
The system contains a surge tank which provides net positive suction head for the pumps and surge volume to accommodate system fluid expansion and contraction.
The TBCCW system cools the following equipment:
Generator H2 Coolers (4)
Stator Windings and Rectifier Coolers (2)
Turbine Lube Ol'1 Coolers (2)
Alternator Cooler (1)
Generator Leads Cooler (1)
Recirculating Pump MG Coupling Coolers (2)
Evaporator Yacuum Pump (1)
Priming Pump Coolers (3)
The only safety function performed by equipment serviced by the TBCCW, is that of the recirculating pump MG coupling coolers. The coolers help maintain seal integrity.
However these pumps are not required to operate e I Reactor Coolant Pressure Boundary is defined in 10 CFR Part 50 and 50.2 (v),
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. as part of the plant's shut down scheme nor post incident, and the licensee has indicated that cooling is not required for seal integrity once pumps are secured. Therefore, based on this and our review of the TBCCW system, wer have determined that the TBCCW system is not important to ' safety as defined in reference 1.
2.
Reactor Building Closed Cooling Water System The Reactor Building Closed Cooling Water System (RBCCW) is a closed loop system with two 100% capacity pumps and three 50% capacity heat exchangers.
The system also contains a surge tank which provides net positive suction head for the pumps and a surge volume to accommodate system fluid thermal expansion and contraction.
The RBCCW system cools the following equipment:
Fuel Pool Heat Exchangers Recirculation Pumps and Motors Drywell Air Coolers Reactor Water Clean-up Nonregenerative Heat Exchangers Reactor Building Equipment Drain Tank Filter Recirculation Coolers Waste Concentrator Condenser Sparging Air Compressors Drywell Sump Cooler Three Concentrator Waste Surge Tanks Cleanup and Precoat Pump Coolers Shutdown Cooling Heat Exchanger Shutdown Cooling Pump Cooler Xenon / Krypton Equipment No credit is taken for the containment drywell coolers in accident analyses for the Millstone Unit 1 plant, and, therefore, they are not necessary for safe plant shutdown.
RSCCU flow to the coolers is not essential.
The specific equipment and/or systems to which the RBCCW supplies cooling water which are considered safety related are the fuel pool coolers, recir-culation pumps (pressure boundary integrity only), and shutdown cooling system.
Cooling is not required to the recirculation pumps to maintain pressure boundary integrity in the short term. This has been documented by the General Electric BWR Owners Group in response to TMI Action Plan Item II.K.3.25, Effect of Loss of Power on Pump Seals.
Resolution of this issue is being pursued as part of the TM1 Action Plan. Spent fuel pool cooling can be accomplished by other methods along with sufficient time being available to reestablish cooling. The capability to provide long term cooling to the spent fuel pool is being addressed as part of SEP Topic I X-1, Fuel Storage. The shutdown cooling system is not required to bring the plant to safe shutdown or to achieve cold shutdown conditions, as delineated in SEP Topic VII-3, Systems Required For Safe Shutdown.
. Based on our review of the RBCCW system, we have detemined that this system is not important to safety as defined in Reference 1.
3.
Service Water System Four (4) service water pumps provide seawater for cooling the station systems listed below. The service water pumps are vertical centrifugal pumps each capable of delivering 10,000 gpm. Any three of the pumps are capable of supplying sufficient cooling water flow for full power operation of the plant. The heat exchangers are of various capacities depending on the cooling loads of the system. Temperature and pressure indicators located near the heat exchangers indicate a malfunction in the system. The service water system supplies cooling for the following equipment:
Normal Flow Heag Transfer Salt Water (10 Btu /hr)
Location (gpm)
Turbine Building Closed Cooling Water 9,900 34.0 Reactor Building Closed Cooling Water 12,000 78.34 Diesel Generator 700 5.0 Turbine Building Secondary Closed Cooling Water 5,000 8.8 Evarcrator (one in operation) 1,350 t
The heating loads included in the turbine building, the reactor building, I
and the turbine building secondary cooling water systems are listed in the applicable review for each of the associated systems in this topic.
The Service Water S,, tem is considered essential because it services the Emergency Diesel Generator and the Turbine Building Secondary Closed l
Cooling Water System, which are both essential systems.
1 In the event of loss of nomal power one service pump is supplied from each emergency power source (i.e., emergency diesel generator, gas l
turbine). All non-essential loads are automatically shut off (i.e.,
l TBCCW, RBCCW and evaporators) und essential load cooling capability is maintained.
During normal operation, if one of the service water pumps j
fail, the spare pump take s up the pumping load until repairs can be made.
During accident or abnormal conditions, one service water pump is required l
. to cool the diesel generator and the turbine building secondary cooling water system. The immediate and long-term effect of losing the service water system results in shutting down the diesel generator. In this event, the gas turbine generator is used to supply emergency power since its cooling requirements are independent of the service water. The loss
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of service water results in the loss of the turbine building closed cooling water system; the consequences of which are described in Section V.S.
Any flooding that could result in either the reactor building or intake structure as a result of SWS leakage will be assessed in SEP Topic III-5.B. Pipe Break Outside Containment. Based upon our review of the service water system, we have concluded that the design of the SWS provides sufficient redundancy to ensure reliable operation, with the exception of common piping. The licensee should evaluate the effect of a passive system failure.
4.
Emergency Service Water System The station errargency service water system provides cooling water from the Long Island Sound to the low pressure core injection (LPCI) system heat exchangers.
The emergency service water system consists of four (4) pumps, two heat exchangers, piping, and control and support equipment. The four pumps are grouped into two sets of two pumps.
Each set of pumps provides 5,000 gpm (2,500 gpm/ pump) of seawater to one LPCI heat exchanger.
Either set of pumps and heat exchanger is capable of handling the heat l
load of the LPCI system.
Each set of pumps is individually piped to the respective heat exchanger, resulting in two completely segregated j
emergency service water systems.
Support equipment includes two self-cleaning strainers, one in each line to the heat exchangers. In the event of loss of normal AC power, power for either set of emergency service water pumps can be supplied from the energency power sources.
This system power alignment is a manual operation.
Should either set of pumps or the respective heat exchanger fail, the other set of pumps are placed in operation until repairs are made.
The pressure of the emergency service water system is maintained at a 20 psi differential above the LPCI cooling system pre!!sure over the entire range of operation with a differential pressure control valve.
This is dor so that if a leak occurs in the LPCI cooling system, the leakage is into the cooling system instead of permitting the release j
of possibly radioactive contaminants to the service water and thereby into the Long Island Sound.
Isolation of leaking ESWS components is accomplished by securing the associated pumps either manually by isolating the containment spray /
cooling heat exchanger, or closing the motor operation discharge valve of the affected loop. Any flooding that could result in either the
reactor building or intake structure as a result of ESWS leakage will be assessed in SEP Topic III-5.B. P5pe Breaks Outside Containment. The perfomance of an operating ESWS loop would not be significantly impaired by a moderate energy line break as a result of the leakage rate calcu-lated in accordance with Branch Technical Position MED 3-1 appended to Standard Review Plan 3.6.2 (550 gpm) being small relative to the total loop flow rate of 5,000 gpm with two ESW pumps in service. In addition, a redundant ESW loop is available in the event a line break significantly impairs the performance of a loop.
The LPCI pumps are activated on either a signal of reactor low water level and low reactor pressure, or a signal of high dry-well pressure. The containment cooling function can be performed with the LPCI system after the core is flooded.
Two of the LPCI pumps can then be shut down and two containment cooling energency service water pumps will be started manually to provide cooling water to the containment spray / cooling heat exchangers.
In addition, the suppression chamber is equipped with temperature alarms at approximately 850F; after receiving these alarms operator action is required to establish emergency service water flow through the heat exchangers.
Based upon our review of the emergency service water system we have concluded that the design of the ESWS provides sufficient redundancy to ensure reliable operation, in the event that it is required to supply cooling to the containment spray / cooling heat exchangers following an accident.
5.
Turbine Building Secondary Closed Cooling Water System The turbine building secondary cooling water system supplements the turbine 0
building cooling system by providing 80 F cooling water to other auxiliary equipment in both the turbine and reactor buildings.
The system consists of two pumps, two heat exchangers and control and support equipment.
Each of the two full capacity cooling water pumps delivers 1800 gpm, which is sufficient to supply all cooling for the following equipment.
Reactor Building Space Cooler (1)
Condensate Pump Motors (3)
Station Air Compressor (1)
Instrument Air Compressor (1) l Condensate Booster Pump 011 Coolers (3) l Reactor Feed Pump 011 Coolers (3)
Turbine Building Sample Coolers (9) i Reactor Building Sample Coolers (2)
Cleanup Pump Space Cooler (1)
Motor Generator Set Space Coolers (3)
Spray Pump Space Coolers (2)
Rod Drive Space Cooler (1)
Control Rod Drive Pumps (2)
Condensate Pump Space Coolers (1)
. Reactor Feed Pump Space Coolers (2)
Diesel Generator Space Coolers (2)
Air Conditioning Units (2)
Condensate Booster Pump Space Cooler (1)
Steam Tunnel Space Coolers (2)
Makeup to Diesel Generator Expansion Tank The turbine building secondary cooling water system is considered essential because of the dependency of both the plant's ventilation and feedwater coolant injection systems.
The two half-capacity heat exchangers are capable of removing the maximum expected heat lgad from the system.
Each heat exchanger is designed to remove 4.9 x 10 Btu per hour.
Either heat exchanger is capable of handling the reduced cooling loads during accident conditions.
A single tank is located above the highest point in the system to handle system fluctuations and to supply makeup when necessary. A low level alarm is provided for the head tank. A chemical feeder is provided for addition of corrosion inhibitor. Control equipment is supplied as needed.
All equipment is supplied with flow control devices for regulation of flow through the heat exchangers.
Water level is manually maintained in the expansion tank with makeup being supplied from the demineralized water transfer system. A low level alarm is provided for the expansion tank.
l As indicated previously, each secondary closed cooling water pump of the l
system handles 100% load; therefore, system redundancy is provided. A signal is annunciated in the control room upon loss of a pump. This alerts the operator, who manually actuates the alternate pump. The pumps are supplied by emergency power from either the diesel generator or gas turbine.
Based on review of turbine building secondary cooling water system, we have concluded that the design of this system provides sufficient redundancy to ensure reliable operation except for common piping. The licensee should evaluate the effect of a passive system failure.
VI.
CONCI.USION Based on our review of service and cooling wat'er system, we have concluded that the essential sy:tems and functions are:
Service Water System: Diesel Generator and Turbine building secondary closed cooling water heat exchanger.
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, Emergency Service Water System: Low pressure core injection heat exchanger Turbine Building Secondary Closed Cooling Water System: Plant ventilation systems and feedwater core injection system We have determined that these systems are in conformance with current criteria for this topic except for non-redundant piping as was done for the Emergency Service Water System, which is found in both systems. To resolve this issue the licensee should either demonstrate that these systems are non-essential (by method described below) or show for each system that a passive failure in non-redundant pipe runs will not result in loss of system function.
The licensee may demonstrate that a cooling system function is non-essential, by showing that the systems it serves can function without being cooled, as follows:
1.
For the Service Water System; show that both the diesel generator and, the turbine building secondary closed cooling water system are non-essential.
2.
For the turbine building secondary closed cooling water system; show that the ventilation function performed is non-essential (this may be done in conjunction with SEP Topic IX-5) and that the pumps associated with the feedwater coolant injection system would be unaffected by a loss of cooling.
The consequences of flooding should' be addressed in SEP Topic III-5.B.
VII. REFERENCES 1.
Regulatory Guide 1.105, Systems Setpoints 2.
Millstone Unit No.1 FSAR 3.
Standard Review Plan Section 9. 2.1, 9. 2. 2 4.
Licensee's Topic IX-3, Safety Assessment Report, submitted by letter dated November 24, 1 981
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