ML20104A889
| ML20104A889 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 09/09/1992 |
| From: | Devine J GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 5000-92-3066, C321-92-2213, NUDOCS 9209140222 | |
| Download: ML20104A889 (2) | |
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GPU N uclear Corporation
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Wntets Direct Dia! Number.
September 9, 1992 5000-92-3066 C321-92-2213 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Oyster Creek Nuclaar Generating Station (0CNGS)
Docket No. 50-219 Facility Operating Licer.se No. DPR-16 1
Oyster Creek Containment Isolation Valves
References:
(1) GPUN Letter RFW-0620 dated September 24, 1985, t
" Containment Vent and Purge System".
(2) NRC Letter dated October 10,1986, " Containment Purge and Isolttion Vrives (MPA B-24, TAC 59828)".
Reference 1 reiterated GPU Nuclear's commitment to limit the open position of the a
Drywell Purge Valves (V-23-13 and V-23-14) and thu Torus Purge-Valves (V 23-15 and V-23-16) to 30 degrees with closing times not to exceed 15 seconds.
This position was determined to be acceptable in the Reference 2 Safety Evaluation
...until such time as the valves are demonstrated qualified or reolaced by qualified valves". Consistent with this commitment, GPU Nuclear plans a change f
to limit the opening position for valves V-23-13,14,15 and 16 to 75 degrees with closing times not to exceed 60 seconds. The qualification for this change is based upon upgrades being performed to these valves as part of the scheduled 14R Outage hardened vent modification.
Currently, the containment isolation valves V 23-13, 14, 15 and 16 are limited to a 30 degree open position to insure that these isolation valves can-close against the dynamic forces of a Design -Basis-Accident- (DBA).
However, NRC criteria for the hardened vent. design requires venting the primary containment (torus) equivalent to 1% decay heat' during a TW sequence.
Satisfying this criterion necessitates opening of the subject isolation valves to a 75 degree position.
GPU Nuciear has performed a calculation to qualify these valves to close (or open) from tho 75 degree position in the event of an accident during start-up (inerting of the primary containment. This calculation determined that modifications to these valves are necessar)y to qualify the increased valve opening limit.
9209140222 920909 PDR ADOCK 05000219
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h GPU Nuclear Corporation is a subsidiary of Generei Public Utihties Corporation
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5000-92-3066 C321-92-2213 Page 2 The modification, scheduled to be performed during the 14R Outage, consists of replacing the taper pins that hold the disc to the shaft and replacing the shaft key with higher yield strength material. The existing material for the taper pin is 316 stainless steel and for the shaft key is SAE 1035.
Both materials will i
be replaced with 17-4 PH Conditioned H1075, SA564. In addition, to ensure that the containment isolation function of these valves is maintained, the current nitrile seat material will be replaced with viton material which is rated for a temperature of 400 degrees F.
Ail other existing valve components are capaSle of withstanoing the process temperature of 305 degrees F.
l With the valve opening position increased to 75 degrees, the closure time for i
these isolation valves will be longer.
The current actual closure times for these valves are 8.4, 9.0, 3.5 and 12 seconds for V-23-13, 14, 15. and 16 1
respectively.
The new closure time for these valves from the 75 degree open position is expected to be icss than 60 seconds. -Upon implementation of this modification, these isolation valves will-be tested to establish the new actual closure times.
These valves are enly used when inerting the primary containment.
During inerting, the nitrogen inerting pressure is maintained at approximately 60 psig.
In the event a DBA occurs during inerting, the escaping cas through the closing valve will either be pushed backed by the 60_ psig nitrogen nressure or contained in the nitroges piping which is a closed system. Since these isolation valves are connected to a closed system, the new closure time of thel isolation valves
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will not increase the amount of containment -atmosphere 1that _ may be released-durino a DBA before valve closure.
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If you nave say questions or ' comments on this submittal, please contact Mr. Michael Laggart, Manager, Corporate Nuclear Licensing' at (201)_316-7960.
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Very tr ty yours, d
J. C. DeVine,.Jr.
Vice President-and Director Technical functions 1
JC::rz cc: Administrator, Region 1 Senior Resident Inspector Oyster Creek _NRC-Project Manager f
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