W3P88-0907, Application for Amend to License NPF-38,requesting Change to Tech Spec Bases Section to Better Reflect Control Room Air Conditioning Sys Design.Fee Paid
| ML20148K491 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 03/28/1988 |
| From: | Burski R LOUISIANA POWER & LIGHT CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20148K497 | List: |
| References | |
| W3P88-0907, W3P88-907, NUDOCS 8803310171 | |
| Download: ML20148K491 (8) | |
Text
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LO UISI AN A / 317 BARONNE STREET P. O. BOX 60340 (504) 595 3100 POWE R & LiG HT NEW ORLEANS, LOUISIAN A 70160 NNIVsi[O March 28, 1988 W3P88-0907 A4.05 QA U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555
SUBJECT:
Waterford SES Unit 3 Docket No. 50-382 Request for a Change to the Bases Section
_of the Waterford 3 Technical Specifications Gentlemen:
The purpose of this letter is to submit a change to the Waterford 3 Technical Specification Bases Section to better reflect the Control Room Air Conditioning System design.
This change is being made as a result of a recent conversation with the NRC Resident Inspector.
It is hoped that this change will clarify any confusion which may arise with respect to the Control Room Air Conditioning System configuration and operability determination.
Please find attached a justification for the proposed Bases change as well as a marked up copy of the change for subsequent processing.
Should you have any questions or comments on this matter, please feel free to contact Larry Laughlin at,,(504) 595-2845.
Yours very truly, 4M-R.F. Burski Acting Manager Nuclear Safety & Regulatory Affairs RFB/LWL/pim Attachments:
LP&L check - $150.00, Attachments A & B cc E.L. Blake, W.M. Stevenson, J.A. Calvo, D.L. Wigginton, R.D. Martin, NRC Resident Inspector's Office (W3)
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8803310171 880328 W EQUAL OPPORTUNITY EMPLOYER" P,
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Attachment I to Technical Specification 3.7.6 Bases Change
System Description
The Control Room Air Conditioning System is designed to:
a) limit control room doses due to airborne activity to within 10CFR50 limits, b) maintain the ambient temperature required for personnel comfort during normal plant operating conditions, c) permit personnel occupancy and proper functioning of instrumentation and controls during all normal and design basis accident conditions assuming a single active failure coincident with a loss of offsite power, d) withstand a safe shutdown earthquake without loss of function, e) permit personnel occupancy in the control room during a toxic chemical accident.
The Control Room Air Conditioning System consists of two full capacity redundant air handling units (AH-12), a computer room supplementary air i
handling unit (E-31) two exhaust fans (E-34), and a conference room and l
kitchen exhaust fan (E-42).
Two full capacity, redundant Engineered Safety Features (ESF) air filtration units (S-8) provide continuous filtration following a design basis accident.
During normal operation, outside air enters an air intake louver located in the. Reactor Auxiliary Building. Two safety-related 100 percent capacity air handling units (AH-12) are provided.
One unit operates on a continuous
(
-basis while the second unit will be automatically started by Class IE instrumentation should the first unit fail (see Figure 1).
Upon receipt of a toxic chemical signal, the Control Room Air Conditioning I
System is automatically transferred to the emergency operation mode (see l
Figure 2).
Outside air isolation valves V-13 and V-14 and exhaust l
isolation valves V-9, V-10, V-11, and V-12 isolate all air flow paths into and out of the control room areas. Exhaust fans E-42 and E-34 trip while both pairs of recirculation dampers D-18 and D-19 associated with the operating air handling unit AH-12 open to automatically recirculate all air supplied to all control room areas.
In the event of a radiological emergency (see Figure 3), the automatic features described above apply and both Emergency Filtration Units (S-8) start to provide filtration of recirculated air and all outside air (if selected).
In addition, plant operators have the option of manually initiating filtered pressurization and recirculation by opening V-1, V-3, V-5, or V-7 (this option was selected in Figure 3).
1 NS30914 I
i
From the system operation described above, the Control Room Air Conditioning System consists of two distinct and diverse parts. The Control Room Air Handling Units and the Emergency Filtration Units are designed such that they can be operated together or separately as the situation dictates. The Control Room Air Handling Units, for example, are designed to cool and/or heat the Control Room Envelope while the Emergency Filtration Units are design to remove radioactivity from the Control Room Envelope atmosphere.
The operation of the air handling units, therefore, are not dependent on the operation of the filtration units.
This has led to confusion with respect to system operability.
Ja_nuary 9, 1988 Event On January 9,1988, the inlet damper to Control Room Ventilation Emergency Filtration Train A was removed from service for maintenance. This nece;si-tated declaring the A train inoperable.
Later that day, Essential Chiller B wes removed from service due to a damaged start switch. The chillers provide cooling water to the Control Room Air Conditioning System AH-12 units for temperature control of the Control Room Envelope.
(The S-8 filtration units, however, are not dependent upon the chillers.) Plant operators, after reviewing the equipment out-of-service log and Technical Specification 3.7.6, Control Room Air Conditioning System, entered Technical Specification 3.0.3.
Their decision was based on an inoperable Train A S-8 unit and an inoperable Train B AH-12 unit -
i.e., although the Train A AH-12 unit and the Train B S-8 units were operable, control room personnel inter-preted the definition of operability as requiring an operable AH-12 and S-8 unit in a single air conditioning train. As a result, a plant shutdown was initiated. Shortly thereaf ter, the B chiller was declared operable and the plant shutdown was discontinued.
Potential Reportable Event (PRE)-88-004 was written to document the event.
The NRC and industry has recognized that determinations of operability are not always obvious and straightforward.
In the situation described above, a person knowledgeable in Technical Specification interpretation would i
naturally assume that requiring an operable AH-12 and S-8 unit in a single i
l train is the minimum acceptable configuration necensary to remain in the l
action statement of Technical Specification 3.7.6 without invoking Technical Specification 3.0.3.
In other words, one operable Control Room Air Condi-tioning Train provides the safest operating basis during the 7 days allowed for restoration of the inoperable components.
This, however, is not the case for the Waterford 3 Control Room Air Conditioning System.
In order to identify the safest configuration during the action statement of Technical Specification 3.7.6, it is necessary to drop below the system level and examine the two primary functions of the air conditioning system provided by the AH-12 and S-8 units.
2 NS30914
Having entered the action stctement, the air conditioning system, by defini-tion, is vulnerable to a single failtire. Efforts should be addressed to minimizing thir vulnerability to the extent possible. For the case of an AH-12 and S-8 unit in the same train, postulating the loss of that train's diesel generator (under loss of offsite power conditions) defeats both the air handling and filtration functions of the Control Room Air Conditioning System.
On the other hand, for the case of an AH-12 and S-8 unit in opposite trains, the loss of a diesel generator could not defeat both air conditioning functions.
In that case, either the air handling unit or the emergency filtration unit would continue to provide some control of the Control Room Envelope atmosphere in contrast to the loss of all function for the single train case. The conservative approach, therefore, would be to satisfy the operability requirements by crediting an AH-12 and an S-8 unit in different trains. This is the configuration that existed at Waterford 3 on January 9,1988.
When faced with multiple alternatives or interpretations, the intent of Technical Specifications is not to prohibit choosing the more safe alterna-tive.
If operable AH-12/S-8 units in one air conditioning train are considered sufficient to remain in the action statement of Technical Speci-fication 3.7.6, the more conservative condition of a single unit in separate trains should not lead to a plant shutdown.
While the January 8, 1988 decision to enter Technical Specification 3.0.3 may have appeared at the time to be the most conservative approach, on closer examination the Control Room Air Conditioning System had been in the safest configuration consistent with the action statement of Technical Specificatica 3.7.6.
In addition, each Control Room Air Conditioning train contains an electric heater. The heater provides personnel comfort during normal operation.
During emergency conditions, however, temperatures on the low end of the scale are of no concern.
Since the heaters perform no safety function, they are not needed for system operability.
This point of clarification is, therefore, being included in the attached Bases change.
Proposed Change In order to avoid confusion in the future and document this unique aspect i
of the Waterford 3 Control Room Air Conditioning System, LP&L proposes to l
amend the Bases for Technical Specification 3.7.6 to explicitly allow credit for an AH-12 unit in one train and an S-8 unit in another train, l
when determining operability. Attachment A reflects the present Bases for Technical Specification 3.7.6, while Attachment B contains the proposed 1
revision. Based on the discussions provided above, the proposed change leads to a more conservative air conditioning configuration while in the action statement of Technical Specification 3.7.6 than the traditional approach to Technical Specification interpretation of operability.
3 NS30914
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