ML19270H465
| ML19270H465 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/02/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19270H464 | List: |
| References | |
| NUDOCS 7908270095 | |
| Download: ML19270H465 (1) | |
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SAFETY EVALUATION MODIFICATION TO SURVEILLANCE REQUIREMENTS OF CONTAINMENT ATMOSPHERE DILUTION SYSTEM - BROWNS FERRY NUCLEAR PDWER PLANT - UNITS 1, 2 & 3 TAC 11916 I.
_ INTRODUCTION The licensee Tennessee Va11ey Authority, in its submittal of July ll,1979 proposed changes to the Technical Specifications regarding surveillance requirements for the Containment Atmosphere Dilution (CAD) System solenoid operated air / nitrogen valves for the Browns Ferry Nuclear Power Plant, Units 1, 2 and 3.
The CAD system is used to ensure that a combustible gas mixture does not fonn inside containment following a loss-of-coolant accident. Operation of the CAD system following an accident requires the overriding of contain-ment isolation signals.
The present surveillance requirements, to verify system operability, require that at least once per month, each solenoid operated air / nitrogen valve be cycled through at least one complete cycle of full travel and that each manual valve in the flow path be verified to be open. To accomplish this during power operation, containment isolation signals must be bypassed with a key-lock switch. Therefore, upon receipt of a containment isolation signal, containment integrity is lost during the testing of these valves.
The licensee has proposed the following changes to Section 4.7.G.1 of the Technical Specifications to alleviate this situation.
II.
EVALUATION The proposed modification to the surveillance requirements consists of cycling each solenoid operated air / nitrogen valve with its hand switch (no containment isolation override) through at least one complete cycle of full travel and verifying that each manual valve in the flow path is open, at least once per month. Also, at each cold shutdown, it would be verified that each solenoid operated air / nitrogen valve in the flow path could be opened with a containment isolation signal present (containment isolation override). The proposed modification prevents the loss of containment integrity while testing these valves during power operation, and provides an adequate test interval for testing the containment isolation override capability.
III. CONCLUSION This does not complete our review of the generic purg, alve bypass matter for the Browns Ferry Nuclear Power Plants, however, based on our review of the licensee's submittal, we conclude that the modifications to Section 4.7.G.1 of the Technical Specifications are acceptable.
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