ML20216H997

Responds to Region IV 961113 Memo Requesting Review of Licensee Position on Compliance W/General Design Criteria for Dual Function air-operated Containment Penetration Valves

ML20216H997
Person / Time
Site:	Waterford
Issue date:	04/10/1997
From:	Berlinger C NRC (Affiliation Not Assigned)
To:	Beckner W NRC (Affiliation Not Assigned)
References
TAC-M97234, NUDOCS 9709170131
Download: ML20216H997 (5)

Text

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\ ,, ,,, # April 10, 1997 MEMORANDUM TO: William D. Beckner. Cirector Project Directorate IV-1 Division of Reactor Projects II/IV FROM: Carl H. Berlinger. Chief ogNS Containment S stems and Seve Accident ranch ,

Division of S stems Safety and Analysis

SUBJECT:

TASK INTERFACE AGREEMENT (TIA) - WATERFORD 3 REQUIREMENTS FOR THE CAPABILITY OF CONTAINMENT ISE ATION VALVES TO CLOSE TO MAINTAIN CONTAINMENT INTEGRITY (TAC N0. M97234)

The purpose of this memorandum is to respond to a Region 1.V request dated November 13, 1996. The request was to review the licensee's position on compliance with the General Design Criteria for dual function (i.e..open safety function on a safety injection actuation signal and/or containment function to isolate the containment) air-operated containment penetration valves.

Before address 1rg the specific designs one needs to understand the roles of a system safety function and containment isolation function. In general, a-system which penetrates containment has an important role to play in the overall operation of the plant. Some perform a safety function in a pre / post LOCA manner while others are important to the overall operation of the plant, in either case, however, the requirement to perform a containment isolation function is the same. Containment isolation is always considered to be a safety function. The only remaining question is when the isolation function needs to be performed.

Let us reverse the order and first discuss the role of the containment isolation valves for a non-safety system. For this system class, it is normally assumed that the need for the system function ceases when the need for containment isolation is identified. Receipt of a containment isolation signal will cause the containment isolation valves to automatically actuate.

This satisfies the containment function while at the same time ending the nornial functioning of the system.

The safety system containment isolation philosophy is quite similar. The difference relates to the priority of the function. Unlike for a non-safety system, the safety system function dces not cease when the need for containment isolation is identified. The safety function simply takes priority over containment isolation. As long as the system is able to provide

Contact:

J. Kudrick. SCSB/DSSA 415-2871 1 0 9709170131 970410 i

PDR ADOcK 05000302

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e 4-Equally limportant'to the ability to change valve position is knowing when- ,

to initiate containment isolationi Sufficient instrumentation should be available to the operator for-this purpose. This would include leak . .

detection as well as sufficient discrimination to determine which system  !

is leaking.

QUESTION 4 If the answer to Question 3 is yes. are manual actions an acceptable

-means of meeting this requirement?

BESPONSE Manual action is an acceptable means for meeting this requirement. But.

it should be remote manual and normally from the control room.

With respect to the acceptability of the accumulators that exist within the ,

plant we are currently discussing this issue with the licensee. We will report resolution in a future amendment, I DJSTRIBUTION:

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its safety function, containment isolation should.not be implemented.

However, if the system is not able to perform its safety function, then containment isolation becomes its number one priority.

By having the safety system function take first priority eliminates the need for automatic containment isolation. Remote isolation 1s-the accepted mode for this type of system. With remote isolation capability, however, comes the need to know when isolation is needed. This generally means leak detection and some means to determine system operability.

Once it is determined that the safety function is not operable, containment isolation becomes the number one priority. The operator is trained to properly isolate the system which means closing bcth containment isolation valves.

Now let us look at the requirements to isolate. The function must be fully safety grade. This means that the instrumentation, motive power, actuator, and valve must be all safety grade. If the valve is motor operated. it should be Class lE powered. For air power. the valve should either close upon loss of air supply or the supply should be considered essential which generally implies an adequately sized accumulator that will assure valve closure for 30 days.

Therefore, for systems with a dual requirement, the valves can and probably will have a two )osition criteria, To satisfy the safety system function, the valve position s1ould be o)en. However, to satisfy the containment isolation function, valve position slould be closed. Tn simply look at the safety system function to establish valve position meets only half of the valve requirements. Additionally, to power the valve actuator with a non-safety air supply is unacceptable when the failure position is open since the containment isolation function cannot be satisfied.

With this brief background, one can now discuss the specific questions contained with the TIA request. Specifically, Region IV has identified the following questions:

OUEST10N 1 Does the licensee comply with the requirements of Criterion 57 (i.e., do the containment spray and component cooling water containment penetration valves have a closed safety function? In particular, are the air-operated valve accumulators required to maintain the valves closed on a loss of non-safety related instrument air?

RESPONSE

The valves in question have dual requirements. For the system safety function, the valves have an open function to assure the operability of the system when needed. However, the valves also have a containment isolation function when called upon. Under this sequence, the valves have a closed function. As discussed above, the system safety function has first priority. Therefore the fail open design is appropriate. But.

the containment isolation function is equally important when the c

This means that the air supply should be-situation calls for isolation.

safety. grade to minimize the times when one loses the air sup)ly to the T1e design valve which also loses the containment isolation function.

needs safety accumulators to assure an air supply in the event of loss of non-safety instrument air, for this reason. It is unacceptable to have non-safety instrument-air without a safety backup system.

OUEST10N 2 Would similar valves for containment penetrations subject to the requirements of Criteria 55 and 56 also have a closed safety function for containment isolation, even if, the position of greater safety of the valve is to open?

RESPONSE

'All containment isolation valves subject to the requirements However, ofit is quite Criteria 55 and 56 have a closed sbfety function.

misleading to state that the position of greater safety of the valve is to open. These valves under discussion have a dual requirement; performance of the system safety function and the containment isolation Therefore for the function. Each function is a separate responsibility.

But for system safety function, the position of greater safety is open.

the containment 1 solation function, the position of greater safety is ariority the valve should closed. Since the system function has first fail open upon loss of air. However, since tie containment isolation position of greater safety is closed, the air supply should be as reliable as possible to minimize the probability of the loss of air.

This is translated to mean safety grade.

QUESTION 3 1s the licensee required to have the capability of remote manual closure of the containment penetration valves with a safety injection actuation si.gnal and/or containment spray actuation signal present?

RESPONSE

The simple response is yes. The licensee is required to be able to remotely close the valve at any time during the transient. This is particularly important if the safety system has a burned in signal to stay open to maintain the safety system function. The solution is to design the logic such that a switch in the control room can be actuated to over ride this open signal. An example of such a design can be found on the containment isolation valves connected to an external recombiner.

Normally the valves are in a closed position. To allow the recombiner to become operational, these valves must be opened even though there exists a containment isolation signal. This override logic eliminates the need to jumper the connections within the control cabinet which would be necessary without this control logic.

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4 Equally important to the ability to change valve position is knowing when.

to initiate containment isolation. Sufficient instrumentation -should be available to the operator for this purpose. This would include leak detection as well as sufficient discrimination to determine which system is-leaking, t OUrSTION 4 If the answer to Question 3 is yes, are manual actions an acceptable means of meeting this requirement?

RESPONSE

Manual action is an acceptable means for meeting this requirement. But, it should ha remote manual and normally from the control room.

With respect to the acceptability of the accumulators that exist within the plant, we are currently discussing this issue with the licensee. We will report resolution in a future amendment.

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