ML20054G906
| ML20054G906 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/14/1982 |
| From: | Caruso R Office of Nuclear Reactor Regulation |
| To: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| Shared Package | |
| ML20053E474 | List: |
| References | |
| TASK-09-05, TASK-9-5, TASK-RR LSO5-82-06-037, LSO5-82-6-37, NUDOCS 8206220397 | |
| Download: ML20054G906 (13) | |
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June 14, 1982 LS05-82 -g6 y3 Docket No S 9
Mr. James A. Kay Senior Engineer - Licensing Yankee Atomic Electric Company 1671 Worcester Road Framingham, Massachusetts 01701
Dear Mr. Kay:
SUBJECT:
FORWARDING FINAL EVALUATION REPORT OF SEP TOPIC IX-5, VENTILATION SYSTEMS FOR THE YANKEE ATOMIC POWER STATION l
Enclosed is a copy of a final Safety Evaluation Report for Systematic Evaluation Program Topic IX-5, Ventilation Systems. This evaluation is based on our contractor's, The Franklin Research Center, Technical Evaluation Report (TER-C5257-416).
) This assessment compares your facility, as described in Docket No.50-029, with the criteria currently used by the regulatory staff for licensing new facilities. The differences are sumarized as follows:
Auxiliary and Radwaste Ventilation System
~ ~ ~ " Failure of exhaust fan RF-11, which ventilates the radioactively clean i
portion of the primary auxiliary building, may allow area temperatures to rise which could adversely affect operation of safety-related equip-ment located in that vicinity. This ventilation system does not satisfy single failure criterion.
3 4
I Louvers in the upper level of the primary auxiliary building which must
- M open to vent the building in case of a steam line break were not described adequately to enable an assessment of functional redundancy.
g Diesel Generator Building Ventilation System hk 9 4 The licensee's evaluation did not address the effect of the most limiting y
single active failure of the system (four motor-operated dampers, ventilat-g ing unit UV-1, and roof exhaust fcns PRV 1 and PRV 2, actuated by heat-sensitive switches) which ventilates the area containing the safety injection pumps, the No. 3 battery and charger, and switchgear. The systen appears to lack the necessary redundancy.
Battery Room Ventilation System Ine 11censee nas not fubmitted an evaluation of this system.
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, The battery room ventilation system will be evaluated during the integrated assessment. The need to modify this and other ventila-tion systems, which are subject to potential single failures identified above, will be determined during the same integrated assessment. This evaluation will be a basic input to the integrated safety assessment for your facility. This topic assessment may be revised in the future if your facility design is changed or if HRC criteria relating to this topic are modified before the integratdd assessment is completed.
Sincerely, Ralph Caruso, Project Manager Operating Reactors Branch No. 5 Division of Licensing
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. The need to evaluate and modify if necessary, ventilation systems for the potential single failures identified above, will be detennined during the integrated assessment. This evaluation will be a basic input to the integrated safety assessment for your facility. 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, Ralph Caruso, Project Manager Operating Reactors Branch No. 5 Division of Licensing
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. Mr. James A. Kay cc Mr. James E. Tribble, President Yankee Atomic Electric Company 25 Research Drive 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
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ATTN:
Regional Radiation Representative JFK Federal Building Boston, Massachusetts 02203 Resident Inspector Yankee Rowe Nuclear Power Station c/o U.S. NRC Post Office Box 28 Monroe Bridge,* Massachusetts 01350 Ronald C. Haynes, Regional Administrator Nuclear Regulatory Commission, Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 9
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TOPIC IX-5 SEP REVIEW VENTILATION SYSTEMS FOR THE, YANKEE ATOMIC POWER STATION i
s I.
INTRODUCTION To assure that ventilation systems have the capability to provide a safe envirar
.t for plant personnel and for engineered safety features, it.s necessary to review the design and operation of these systems.
For example, the function of the spent fuel pool area ventilation system is to provide ventilation in the spent fuel pool equipment areas, to permit personnel access, and to control airborne radioactivity in the area during normal operation, antici-pated operational transients, and following postulated fuel handling accidents.
The function of the engineered safety feature ventilation system is to provide a suitable and controlled environment for engineered safety feature components following certain anticipated transients and design basis accidents.
II.
REVIEW CRITERIA The current criteria and guidelines used to determine if the plant systems meet the topic safety objective are those provided in Standard Review Plan (SRP) Sections 9.4.1, " Control Room Area Ventilation System," 9.4.2, " Spent Fuel Pool Area Ventilation System," 9.4.3,
" Auxiliary and Radwaste Area Ventilation System," 9.4.4, " Turbine 4
Area Ventilation System," and 9.4.5, " Engineered Safety Feature Ventilation System."
In determining if plant design conforms to a safety objective, use is made, where possible, of applicable portions of previous staff reviews.
III.
RELATED SAFETY TOPICS AND INTERFACES The scope of review for this topic was limited to avoid duplication of effort 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 III-l Classification of Structures, Components and Systems (Seismic and Quality)
III-6 Seismic Design Considerations VI-4 Containment Isolation System VI-7.C.1 Independence of Onsite Power VI-8 Control Room Habitability VII-3 Systems Required for Safe Shutdown IX-6 Station Service and Cooling Water Systems XV-20 Radiological Consequences of Fuel Damaging Accidents (Inside and Outside Containment)
TMI III.D.3.4 Control Room Habitability USI-A24, Qualification of Class lE Safety Related Equipment
. IV.
REVIEW GUIDELINES In determining which systems to evaluate under this topic, the staff used the definition of " systems important tn safety" provided in Regulatory Guide 1.105.
The definition states that systems important to safety are those necessary to ensure (1) the integrity of the reactor coolant pressure boundary, (2) the capability to shutdown 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.
V.
EVALUATION The systems reviewed under the topic are the control room area ventilation system, reactor building ventilation system, fuel storage pool area ventilation system, turbine building ventilation systems, radwaste area ventilation systems and engineered safety features ventilation systems.
A.
Control Room Area Ventilation System The function of the Control Room Area Ventilation System (CRAVS) is to provide a controlled environment for the comfort and safety of control room personnel and to assure the operability of control room components during normal operating, anticipated operational transient and design basis accident conditions.
As a result of TMI this system is being reviewed generically (TMI Item III.D.3.4, Control Room Habitability) to assure compliance with Criterion 19, " Control Room" of Appendix A, " General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50.
Therefore, the CRAVS was not reviewed under this topic.
B.
Spent Fuel Pool Area Ventilation System Based on the Franklin Research Center Report, we have determined that this system is non-essential as defined in Section IV.
C.
Auxiliary and Radwaste Area Ventilation System The general function of the auxiliary and radwaste area ventilation system (ARAVS) is to provide a controlled environment during normal operation, and subsequent to postulated accidents, including the loss of offsite power.
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. At the Yankee plant, the auxiliary and radwaste area is divided into three portions:
the radioactively clean portion of the primary auxiliary building, the potentially contaminated portion of the primary auxiliary building, and the waste disposal building.
Each is served by its own ventilation system.
Separate evaluations of the three sections follow.
(1) Primary Auxiliary Building - Radioactively Clean Portion The radioactively clean portion of the Primary Auxiliary Building (PAB) contains the emergency feedwater pumps, component cooling pumps, some containment isolation system equipment, and MCC-4, making the area essential.
The area is ventilated by a roof type exhaust fan, RF-ll, which is mainly required only during the sumer months.
Air is drawn in through windows in the upper level PAB, and through flood control one-way dampers in the lower level PAB.
In the event of a single active failure of exhaust fan RF-li, the system's functional capability will be lost.
Consequently, an unacceptable temperature rise may occur within the area, particularly during summer months. A high temperature may affect the operation of equipment served by the system.
In addition, the upper level PAB also contains steam generator blowdown lines.
In the event of a steam line break, ventilation louvers in the upper level PAB will open to vent the building and prevent the formation of a harsh environment in the lower level PAB, where the majority of the essential equipment is located.
The degree of redundancy and the mechanism that activates the ventilation louvers are not sufficiently defined by the licensee and cannot be determined from available sources of information.
Therefore, there is a concern that a single active failure may result in a loss of the ventilation system's functional performance capability.
Thus, in the event of a steam line break, a harsh environment may form l
in the lower level PAB.
Therefore, the licensee should evaluate the consequences of the most limiting single active failure, under both normal i
and accident conditions, to determine its impact on essential equipment and operating personnel.
I (2) Primary Auxiliary Building - Potentially Contaminated Portion The potentially contaminated portion of the PAB, the cubicle area, contains mostly primary plant support equipment required for manual plant operation.
The motors associated with the charging pumps and shutdown cooling pump are the major electrical components that would be required post-accident and may be effected by a loss of ventilation.
This area would, therefore, be con-sidered essential.
Filtered outdoor air is supplied by a unit ventilator, UV-5, and distributed by ducting to the various equipment cubicles.
Air is exhausted from the various equipment cubicles through a high efficiency filter unit consisting of prefilters, charcoal and HEPA filter, and an exhaust fan, FN-19, to the primary vent stack.
The vapor container purge system filter assembly and fan function as a backup for the PAB exhaust system.
It follows from the above evaluation and the fact that each of the four vapor container purge fans is rated at 30,650 cfm, while the exhaust fan, FN-19, is rated at 23,000 cfm, that the ventilation system is redundant.
It also appears to direct air flow from areas of lower radioactivity to areas of progressively higher radioactivity.
A loss of offsite power reduces the building's heat load and ventilation requirements.
Generated heat will be dissipated within the building.
In addition, necessary loads and the ventilation system can be connected to the onsite emergency power, if required and the original heat removal ability of l
the ventilation system will be restored.
Based on the fore-l guing consideration, we find the design of this system acceptable.
(.3) Waste Disposal Building Based on the Franklin Research report, we have determined that this system is non-essential as defined in Section IV.
D.
Turbine Area Ventilation System Based on the Franklin Research report, we have detennined that this system is non-essential as defined in Section IV.
1 E.
Engineered Safety Feature Ventilation Systems The engineered safety feature ventilation system (ESFVS) is designed to provide a suitable and controlled environment for engineered safety feature components following certain anticipated transients and design basis accidents.
Four separate areas at the Yankee plant house engineered safety feature components and their own ventilation systems:
the heating boiler room, the switchgear room, the battery rooms, and the diesel generator building.
These four systems are evaluated separately below.
(1) Heating Boiler Room Ventilation System The Heating Boiler Room Ventilation System (HBRVS) services the heating boiler room.
The only piece of equipment located in this room which may be required post-accident or for safe shutdown is the steam driven emergency feed pump.
The steam driven emergency feed pump is manually operated, and its operation is not affected by a lack of ventilation.
Ventilation would be required for the operator.only. The heat load of this pump is so low that adequate ventilation can be achieved by opening the doors to the room.
Therefore, the HBRYS system is not an essential system.
(2) Pump and Switchgear Rooms Ventilation System The switchgear room is considered to be essential, because it houses No. 1 and 2 batteries, the battery chargers and inverter, vital instrumentation power supplies, emergency MCC 1, and the vapor container hydrogen analyzer and sample station, all of which are important to safety.
The pump and switchgear room ventilation system (PSRVS) contains two supply fans (FN-13-1 and -2), which supply air through a common duct to both portions of the ventilation system.
Each fan supplies half the required air, and each portion of the system requires half of all available air.
The duct configuration indicates that, in the event of a fan faihre, the non-safety-related portion of the ventila-tion system serving the pump room can probably be isolated either manually or automatically.
This' action would direct a suitable amount of the ventilating air to the essential
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portion of the PSRVS, thus providing redundancy.
In addition, the system can be connected, either automatically or manually to emergency power, the system's power source is also redundant.
Therefore, we find this design of the system acceptable.
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. (3) Battery Rooms Vcntilation System The ventilation system for battery rooms 1 and 2 is essential since the ventilation system services a system essential to safety as defined in the review criteria.
Since the licensee is currently reviewing this system, further evaluation is deferred.
It should be noted that the existing BRVS does not appear to comply with the acceptance criteria.
(4) Diesel Generator Building Ventilation System The Diesel Generator Building Ventilation System (DGBVS) services the diesel generator building which contains the emergency diesel generators, the switchgear, the safety injection system pumps, the No. 3 battery and charger.
This equipment is required post-accident and for safe shutdown, requiring the DGBVS system to be classified as essential.
The three diesel generators are located in individual cubicles.
The ventilation system for each cubicle is separate and independent to that cubicle.
Air is supplied to the cubicle by an intake hood on the roof with a motor operated damper that is actuated by the diesel starting circuit. Air is exhausted outside through an exhaust louver on the front of the cubicle.
The exhaust ducting also includes a motor operated damper that is also actuated by the diesel starting circuit. The diesels are air cooled, and the diesel cooling fan also serves as the cubicle exhaust fan.
It is driven directly off the diesel.
We find this arrangements acceptable.
The Diesel Generator Building Ventilation System (DGBVS) services the diesel generators and switchgear, the No. 3 battery and charger, and the safety injection system pumps.
This equipment is required post-accident and for safe shutdown, requiring the DGBVS system to be classified as essential.
. The area containing the safety injection pumps, the No. 3 battery, and switchgear is ventilated by a system consisting of four motor-operated dampers, one ventilating unit (UV-1),
and two roof exhaust fans (PRV 1, 2). This ventilation equip-ment is actuated by temperature switches when the temperature rises.
The equipment can also be powered by an onsite emergency power source through MCC-2.
However, the system does not appear to have the necessary redundancy, to accomodate the effect of a single active failure, the licensee should review the ventilation system in this area to ensure that a single active failure would not result in an unacceptable temperature rise.
VI.
CONCLUSIONS Yankee ventilation systems satisfy NRC acceptance criteria with the following exceptions:
Auxiliary and Radwaste Ventilation System Failure of exhaust fan RF-ll, which ventilates the radioactively clean portion of the primary auxiliary building, may allow area temperatures to rise enough, particularly during the summer, to adversely affect operation of safety-related equipment located in that vicinity. There-fore, this ventilation system does not satisfy single failure criterion.
Louvers in the upper level of the primary auxiliary building which must open to vent the building in case of a steam line break were not described adequately to enable an assessment of functional redundancy.
If the ventilation system is vulnerable to a single active failure of the louvers or their operating mechanism, a steam line break might cause the formation of a harsh environment around safety-related equip-ment located in the lower level of the building.
The system would thus not satisfy the single-active-failure criterion.
The licensee should submit clarifying information about the louvers to resolve this question and propose corrective action if required.
Diesel Generator Building Ventilation System The licensee's evaluation did not address the effect of the most limiting single active failure of the system (four motor-operated dampers, ventilating unit UV-1, and roof exhaust fans PRV 1 and PRV2,.
actuated by heat-sensitive switches) which ventilates the area containing the safety injection pumps, the No. 3 battery and charger, and swtich-gear.
The system appears to lack the necessary redundancy.
The licensee should review the system that ventilates this area to ensure that a single active failure cannot result in an unacceptable temperature rise.
. 4 Cattery Rooms Ventilation System This ventilation system services which battery rooms 1 and 2 and should be evaluated for compliance with relevant acceptance criteria. The licensee has not yet submitted an evaluation of this system.
The battery room ventilation system will be evaluated during the integrated assessment.
The need to modify this and other ventilation systems, which are subject to potential single failures identified above, will be determined during the same integrated assessment.
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