ML20107L061
| ML20107L061 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 11/06/1984 |
| From: | VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | |
| Shared Package | |
| ML20107L047 | List: |
| References | |
| NUDOCS 8411130396 | |
| Download: ML20107L061 (1) | |
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3.6.I and 4.6.I SHOCK SUPPRESSORS (SEUBBERS) l f All snubbees.are required operable to ensure that the structural integrity of the Reactor Ccclant System and all other.
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.cafety-related systems is maintained during and following a seismic or other event initiating dynamic loads.
The visual, inspection frequency is based upon maintaining a constant level.of snubber protection to systems.
I Therefore the required inspection interval varies inversely with the observed snubber. failures.and is determined by.
f-f -the number'of inoperable snubbers found during an inspection. Inspections performed before that' interval has elapsed.
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may be used as a new reference point to' determine the next inspection. However, the results of such early inspections F
performed before the original: required time interval has elapsed (nominal time less 25%) may not be used to lengthen the required inspection interval. Any inspection whose results require a shorter inspection interval will override the previous schedule..
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i When the cause of the rejection of,a snubber is. clearly established and remedied for that snubber and for any other i
snubbers that may be generically susceptible, and verified by functional testing, that snubber may be exempted from.
being counted as inoperable. Generically susceptible snubbers are those which are (1) of a specific make or model, (2) of the same design, and (3) similarly located or exposed to the same environmental conditions such as temperature, radiation, and vibration. These characteristics of the snubber installation shall be evaluated to determine if further functional testing of similar snubber installations is warranted.
l When a snubber is found inoperable, an engineering evaluation is performed, in addition to the determination of the j
anubber mode of failure, in order to determine.if-any safety-related component or system has been adversely affected j
by the inoperability of the snubber. -The engineering evaluation shall determine whether or not the snubber mode of l
failure has imparted a significant effect or degradation on the supported component or system.
l To provide assurance of snubber functional reliability, a representative sample of the installed snubbers will be functionally tested once each operating cycle. Observed failures of these sample snubbers shall require functional j
testing of additional units.
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3.6.J THERMAL HYDRAULIC STABILITY j
tot allowing operation in a natural circulation mode will provide additional stability margin, and it will provide l
protection against a reactivity insertion transient due to starting of an idle recirculation pump from the natural circulation mode.
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Amendment No. 2A, 39 125
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