ML20054F499
| ML20054F499 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/11/1982 |
| From: | Caruso R Office of Nuclear Reactor Regulation |
| To: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| References | |
| TASK-09-03, TASK-9-3, TASK-RR LSO5-82-06-028, LSO5-82-6-28, NUDOCS 8206170025 | |
| Download: ML20054F499 (8) | |
Text
f-e June 11,1982 Docket No. 50-29 LS05 06-028 Mr. James A. Kay Senior Engineer - Licensing Yankee Atomic Electric Company 1671 Worcester Road Framingham, Massachusetts 01701
Dear Mr. Kay:
SUBJECT:
FORWARDING EVALUATION REPORT OF SEP TOPIC IX-3,
" STATION SERVICE AND COOLING liATER SYSTEMS" YANKEE NUCLEAR POWER STATION Enclosed is a copy of our evaluation of Systematic Evaluation Program Topic IX-3, Station Service and Cooling Water Systems..This evaluation is based on your safety assessment of this topic.
This evaluation compares your facility, as described in Docket No. 50-29, with the criteria currently used by the regulatory staff for licensing new facilities. The differences are sununarized as follows:
1.
The licensee has not demonstrated that adequate procedures exist to ensure that either the Component Cooling System or Service Water
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System will be manually loaded to a energency power source in a j
timely manner after an accident.
I 2.
The licensee has not addressed the effect of a passive failure in the Component Cooling Systen.
This evaluation will be a basic input to the integrated safety assessment for your fscility. This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.
Sincerely, gg pd: t't &
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()g gigg k Ralph Caruso, Project Manager
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Operating Reactors Branch No. 5 nas l
Division of Licensing
Enclosure:
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,e Yank:e Docket N]. 50-29 Mr. James A. Kay Revised 3/30/82
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CC Mr. James E. Tribble, President Yankee Atomic Electric Company j
25 Research Drive
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Westborough, Massachusetts 01581 Chairman Board of Selectmen Town of Rowe Rowe, Massachusetts 01367 Energy Facilities Siting Council 14th Floor One Ashburton Place Boston, Massachusetts 02108 U. S. Environmental Protection Agency Region I Office ATTN:
Regional Radiation Representative JFK Federal Building Boston, Massachusetts 02203 Resident Inspector Yankee Rowe Nuclear Power Station c/o U.S. NRC Post Off. ice Box 28 Monroe Bridge,* Massachusetts 01350 Ronald C. Haynes, Regional Administrator Nuclear Regulatory Commission, Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 l
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SYSTEMATIC EVALUATION PROGRAM TOPIC IX-3 YANKEE NUCLEAR POWER STATION TOPIC:
IX-3, Station Service and Cooling Water Systems I.
INTRODUCTION The safety objective of Topic IX-3 is to asisure that the cooling water systems have the capability, with adequate margin, to meet design
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objectives 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 ade-quate provisions for makeup are available; C.
tank overflow cannot be released to the environment without moni-toring 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 non-seismic dlass 1 fluid systems.
II.
REVIEW CRITERIA The6 current criteria and guidelines used to determine if the'p' ant
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systems meet the topic safety objective are those provided in Stac.dard 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 confirms to a safety objective, use is made, where possible, of applicable por-tions of other staff reviews.
For example, safety ob-jective D, identified above, is being reviewed as part of SEP Topic III-5.B. " Pipe Breaks Outside Containment. Therefore, it is not addressed in this topic.
III.
RELATED SAFETY TOPICS AND INTERFACES The scope of review for this topic was limited to avoid duplication of efforts since some aspects of the review were performed under related topics.
The related topics and the subject matter are identified'below.
Each of the related topic reports contains the acceptance criteria and review guidance for its subject matter.
II-2. A - Severe Weather Phenomena II-3.B.1 - Flooding of Equipment III-3.B - Flooding of Equipment (Failure of Underdrain System)
VI-7.D - Flooding of Equipment (Long-Term Passive Failures)
III-3.C - Inservice Inspection of Water Control Structures III-4.C - Internally Generated Missiles III Mass and Energy Releases (High Energy Line Break)
VI-2.D - Mass and Energy Releases III Seismic Qualification III Environmental Qualification VI-7.8 - ESF Switchover From Injection to Recirculation Mode VI-7.C.1 - Independence of Onsite Power VII Systems Required for Safe Shutdown VIII-2 L Diesel Generators IX Fuel Storage IX Fire Protection XV LOCAs Resulting From Spectrum of Postulated Piping Break Within the Reactor Coolant Pressure Boundary IV.
' REVIEW GUIDELINES In addition to the guidelines of SRP Sections 9.2.1 and 9.2.2, 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 neces-sary to ensure (1) the integrity of the reactor coolant pressure bound-ary, (2) the capability to shutdown the reactor and maintain it in a s.afe condition, or (3) the capability to prevent, or mitigate the con-sequences 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 sys-l tems 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 will be' updated if future SEP reviews identify I
additional cooling water systems that are important to safety.
V.
EVALUATION The systems.which were reviewed under this topic are the Component Cooling System and the Service Water System.
These are the only two cooling water systems at Yankee.
They supply all cooling water requirements.
A.
Component Cooling System l
i The Component Cooling System removes heat from various plant systems and components and transfers this heat to the Service Water System.
An intermediate cooling system is utilized to insure that there are no radioactive releases to the environment via the service water system.
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The component cooling system consists of two coolers, two circulating pumps, a surge tank, a chemical addition tank and associated piping, systemrand instrumentation piping, valves, fittings and instruments.
This equipment is connected to two main piping headers which are loca-ted outside the vapor container.
Independent lines, provided with isolation valves located outside the vapor container, are connected from the hecder to the vaious components inside the vapor container.
Each component cool'ing pump and cooler can accommodate full' heat re-moval loads.
For increased reliability of the system, each unit can be operated singularly or in parallel and each pump and cooler can be cross connected.
To maintain the desired level.i6 the Component Cooling Surge Tank, manual make-up of demineralized water is used, level controls and t alarms are provided in the surge tank.
Large amounts of make-up to the component cooling surge tank are provided from an interconnection to the condensate pump discharge line.
The component coolant fluid is circulated by either or both pumps. A pressure switch, a pressure alarm,~ and pressure indicators are provided in the pump discharge to ensure that the system pressure remains within assigned limits.
Check valves prevent backflow through the idle pump.
The heat loads on the system are:
1.
Main Coolant Pumps 2.
Neutron Shield Tank Cooling coils
.. y3.
Sampie Cooler 4.
Waste Evaporator and Heat Exchangers 5.
Waste Gas Compressor and Heat Exchangers 6.
Shutdown Cooling System Heat Exchanger 7.
Low Pressure Surge Tank Cooling System Heat Exchanger ew 8.
Spent Fuel. Pit Cooling System Heat Exchanger The specific equipment and/or systems to which the component cooling system supplies cooling which are considered safety-related are the Shutdown Cooling System Heat Exchanger,and the Low Pressure Surge Tank Cooling System Heat Exchanger.
During normal plant operation, the component cooling system has one pump and one heat exchanger in operation with the second pump in standby.
Each l
pump and heat exchanger have 100% capacity, therefore, the system has com-l plete redundancy in these major components.
Component cooling system pump No.1 is powered from 2400 volt bus No. 3, and component. cooling system l
pump No. 2 is powered from 2400 volt bus No. 2.
Each 2400 volt bus is i
normally powered by separate off-site power supplies.
These pumps are not required immediately post-accident; therefore, they are not powered by emergency power.
However, the licensee has stated that the electrical sys-tem can be realigned to power them post-accident.
The adequacy of these procedures should be evaluated in the integrated assessment.
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Each heat exchanger is designed to remove the decay heat removal capacity of the Shutdown Cooling System at 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after a plant shutdown, the steam generators are used prior to initiation of the Shutdown Cooling System on the SES.
The main coolant pumps are an essential load for normal plant -
operation.
These pumps are of the canned-motor type, requiring component cooling water to an external cooling jacket which re-.
moves stator and rotor heat from the internal cooling water.
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Operation of the pumps is not permitted when component cooling. water is lost, and this requires a plant shutdown.
This event is included in existing plant procedures and the plant can be safely shutdown with a loss of main coolant pumps.
Also, main coolant pump. operation is not required for plant response to any postulated accidents.
l During post-accident conditions, thp only heat loads which are essen-tial are the shutdown cooling heat [exc)iangers and low pressure surge tank cooling systems. The shutdown cooling system is designed to be placed in service when the main coolant system temperature has been reduced to less than 330*F and the pressure to less than 300 psig for normal. plant operation.
During post-accident operation, the plant would be cooled down as low as possible using the steam generators and the post-LOCA recirculation system prior to placing the shutdown cool-ing system in operation. When it is placed in operation, the heat loads will be greatly reduced, and therefore, the component cooling system will be well within design limits. This mode of operation will Be verified during the review of T6 pics VI-7.B. "ESF Switchover From Injection to. Recirculation Mode" and XV-19, "LOCAs Resulting From hSpectrum of Postulated Pipe Breaks Within the Reactor Coolant Pressure Boundary."
The Low Pressure Surge Tank Cooling System heat exchanger is identic'ai to the shutdown cooling system heat exchanger. The two systems are de-signed so that each heat exchanger can be lined up to function as a i backup for the other.
Based on our revie'w of the component cooling system we have determineil that sufficient component redundancy exists; however, the piping associ-ated with this system is non-redundant. The licensee's topic assessment did not acequately address passive failures for systems with non-redundant piping.
The capability of the plant to withstand the effects of postulated flooding from a component cooling system pipe leak will be addressed in SEP Topic III-5.B, " Pipe Breaks Outside Containment."
B.
Service Water System The service water system provides Sherman Pond water for cooling systems throughout the plant, supply for the water treating plant, and for washing the traveling water screens.
The service water system consists of three 2,500 gpm vertical deep well type centrifugal pumps that take suction from a common intake well in the Circulating Water Pump House.
The pumps discha'rge to a common 12 in.. header which is continued as a service water sup-ply loop, two 12 ine lines running parallel, to the southern corner of the turbine room basement.
These'two headers can be manually cross-connected so, that,;any combina. tion. of. pumps can supply the necessary loads.
Th'e h~ea,t loadsj,n' t'hil s}yst'ein. a_re': ~l'[ _
1.
Component cooling system 2.
Vapor container coolers 3.
Steam generator blowdown coolers 4.
Miscellaneous primary plant services, including charging pumps, cooling, purification pump cooling, low pressure surge tank pump ccoling, shutdown cooling pump cooling, waste disposal building and hose connections.
5.
Traveling water screen washing 6.
Water treating plant 7.
Turbine oil cooling 8.
Generato.r hydrogen cooling 66 9.
Main transformer cooling
- 10. Miscellaneous secondary services, including air compressor cooling, boiler feed pump cooling, heater drain pump cooling, circulating water vacuum priming pump sealing, sample coolers in turbine area and hose connections.
The specific equikent:and/or systems to which tile service water system supplies cooling which are considered safety =related are the component cooling system, the low. pressure surge tank cooling pump and the shutdown cooling pump.
As discussed in section V.A the shutdown cooling system heat removal capacity equals reactor decay heat at 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after shutdown.
This requires a service water system flow rate of 2500 gpm, or one pump.
Cooling water to the shutdown cooling system pump is also supplied by the service water system. The low pressure surge water tank cooling pump is identical to the shutdown cooling pump and can be lined up to" function as -
a backup.
It is also cooled by the service water system.
These pumps only require a few gpm for cooling.
The licensee should verify the existance of procedures which would ensure that system flow requirements are balanced.
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During normal plant operation, two pumps are running and the third pump is in standby. On low pressure in the common discharge header, the standby pump will start automatically, and an alarm will sound in the control room.
The power supplies for SWS pumps flo.1, 2 and 3 are the station 2400 volt buses fio. 3,1 and 2, respectively.
The licensee has stated that the electrical system can be realigned,to power any pump post-accident from emergency sources if required.
The capability of the plant to withstand the effects of postulated flooding from a -
' service water system pipe leak will be addressed in SEP Topic III-5.B.
I VI.
C0tlCLUSION Based on our review of the service and component cooling water systems we have concluded that the essential systems and functions are:
A.
Component Cooling System: shutdown cooling system heat exchanger,+.
le pressure surge tank cooling and ' tank cooling system heat exchanger.
B.
Service Water System:
component cooling system, shutdown coolihg. system pump cooling and low pressure surge tank cooling system pump cooling.
We find the design of these systems acceptable with the following exceptions:
A.
Component Cooling System The licensee should verify that adequate proeddures exist to ensure that emergency power is provided to this system.inrthetevent of an accident.
The need for system modifica. tion to el.iminate potential passive single - '
failures will be evaluated during the integrated assessment.
B.
Service Water System
.The licensee should verify the existence of procedures whichiould en'sure
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that sys. tem flow requirements are balanced.
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