ML19324C167
| ML19324C167 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 11/06/1989 |
| From: | Feigenbaum T PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEIN-89-038, IEIN-89-38, NYN-89142, NUDOCS 8911150109 | |
| Download: ML19324C167 (4) | |
Text
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j New Hampshire-Ted C. FOtre l
Senior Vice President and Chief Operating Officer 1
NYN-89142 l
November 6, 1989
.i United States Nuclear Regulatory Commission Washington, D.C.
20555
' Attention: Document Control Desk i
References:
(a) Facility Operating License NPF-67. Docket No. 50-443 (b) USNRC Information Notice 89-38, dated April 5, 1989,
" Atmospheric Dump Valve Failures at Palo Verde Units 1, 2, and 3'
Subject:
Modifications to Atmospheric Steam Dump Valves-Gentlemen:
New Hampshire Yankee (NHY) has reviewed the information provided in USNRC Information Notice 89-38, dated April 5, 1989, " Atmospheric Dump Valve Failures at Palo Verde Units 1, 2, and 3."
As a result, the Control
' Components. Incorporated (CCI) supplied atmospheric steam dump valves (ASDVs) utilized at Seabrook Station will be enhanced to ensure operability.
Accordingly, NHY has developed a design change to the valve actuator to ensure the proper functioning of these valves. A description of the design change is provided as an enclosure to this letter.
The design change to ensure operability of these valves will be completed prior to plant heatup to Mode 3.
l Following this modification valve testing at normal operating conditions will be required to verify the operability of these valves.
Seabrook Station Technical Specification 3.7.1.6 requires at least four atmospheric relief valves and associated manual controls including the safety related. gas supply systems to be operable in Modes 1, 2, 3 and in Mode 4 when steam generators are being used for decay heat removal. New Hampshire Yankee will submit a license t.mendment request under separate cover to allow this post-modification testing to be performed in Mode 3.
If you have any questions regarding this matter, please contact Mr. Richard Belanger at (603) 474-9521, extension 4048.
Very truly yours,
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Ted C. Feigenbaum
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New Hampshire Yankee Division of Public Service Company of New Hampshire P.O. Box 300
- Seabrook, NH 03874
- Telephone (603) 474 9521
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' United States Nuclear Regulatory Commission November 6, 1989 Attention: Document Control Desk Page 2 L
cca Mr. William T. Russell Regional Administrator l
United States Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, PA 19406 Mr. Victor Nerses, Project Manager Project Directorate I-S United States Nuclear Regulatory Commission Division of Reactor Projects Washington, DC 20555 Mr. Antone C. Cerne NRC Senior Resident Inspector P.O. Box 1149 Seabrook, NH 03874 i
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9 New Hampshire Yankee November 6. 1989 l
ENCLOSURE 1 TO NYN-89142 MODIFICATIONS TO ATMOSPHERIC STEAM DUMP VALVES i
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4 New Hampshire Yankee November 6, 1989 L
Enclosure to NYN-89142 l
Background
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USNRC Information Notice 89-38 provided notification of potential failures of atmospheric steam dump valves (ASDVs), specifically, pilot operated ASDVs manufactured by Control Components. Incorporated (CCI). The failure mechanism involved excessive bonnet pressure resulting from H
abnormally high leakage past the main valve plug piston ring.
This results
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in the valve actuator being unable to overcome the forces holding the main i
plug on the valve seat.
j Discussion To open the valve, the actuator must operate against the sum of the packJng friction, piston ring friction, actuator spring force, bonnet pressure, and the plug weight. An analysis performed by CCI indicates that with maximum piston ring leakage an actuator differential pressure of 149 i
psi is required to operate the valve as compared to the 66 psi required l
assuming design leakage.
.l CCI has developed two modification options for the Seabrook Station ASDVs. Option 1 consists of increasing the pilot valve capacity, utilizing
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a two-piece, wedge-style piston ring to reduce leakage, and replacing the
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actuator spring, reducing its load from 2,800 pounds to 1,520 pounds. This results in a required actuar.or itifferential pressure of 61 psi.
Option 2 l
consists of replacing the actuator spring as described in Option 1 and modifications to the actuator air supply to accomodate the resulting higher actuator differential pressure of 137 pai.
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Design Enhancement To ensure operability of the Seabrook Station ASDVs New Hampshire Yankee will install the CCI recommended replacement springs described in i
Option 2 above. The control scheme associated with the actuators for these i
valves includes a safety related backup air supply.
The regulator on the 1
backup air supply will be adjusted to approximately 140 psi to ensure that the valves will operate to perform their safety function in the event of I
adverse piston ring leakage.
These modifications will be completed prior to plant heatup to Mode 3.
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