Information Notice 1980-16, Shaft Seal Packing Causes Binding in Main Steam Swing Disc Check & Isolation Valves
| ML031180306 | |
| Person / Time | |
|---|---|
| Site: | 05000000 |
| Issue date: | 04/29/1980 |
| From: | NRC/OI |
| To: | |
| References | |
| IN-80-016, NUDOCS 8002280667 | |
| Download: ML031180306 (2) | |
SSINS No.:
6870
Accession No.:
UNITED STATES
8002280667
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, DC 20555
April 29, 1980
IE Information Notice No. 80-16 SHAFT SEAL PACKING CAUSES BINDING IN MAIN STEAM SWING DISC CHECK AND ISOLATION
VALVES
Description of Circumstances
Recently two instances of binding of swing check valves have occurred. During
disassembly of the main steam isolation valves at Indian Point 2, it was
observed that all four reverse flow check valves were stuck at or near fully
open. These 28" valves are manufactured by Atwood & Morrill Co.
Investigation revealed that this condition was apparently caused by excessively
tight shaft packing which did not allow free movement of the valve disc.
This condition was reported on January 31, 1980.
An evaluation determined
that with the existence of the reported condition in event of a main steam
line break upstream of a main steam isolation valve together with coincident
single failure of a main steam isolation valve to close in another loop, the
potential existed for blowdown of the contents of two steam generators.
Main steam line break analyses applicable to Indian Point 2 have been performed
assuming blowdown of the contents of one steam generator and have not considered
multiple steam generator blowdown.
Therefore, it is possible that the reported
condition could have contributed to the exceeding of a safety limit as defined
in the Unit 2 Technical Specifications if a main steam line break had occurred.
The reported condition was corrected by adjusting the packing of these valves
in all four loops and verifying that valve disc movement is not restricted.
During testing in the hot standby mode at the Trojan Nuclear Plant on April
15, 1980, three of the four main steam line isolation valves failed to close
when manually actuated. The cause of the occurrence was binding in the shaft
packing. The valve is air opened and is closed by gravity, steam flow and a
small spring force; the valves were manufactured by Atwood & Morrill Co.
The
licensee believes that the valves would have closed during actual operations
with steam flow in the line.
The valves were repaired and tested satisfactorily.
Modifications to the valves to install air operators to help close the valves
are being investigated by the licensee.
This Information Notice is provided as notification of a possible significant
matter.
It is expected that the recipients will review the information for
possible applicability to their facilities and appropriate corrective action
taken.
No written response to this IE Information Notice is required.
IE Information
April 29, 1980
Notice No. 80-16 Enclosure
RECENTLY ISSUED
IE INFORMATION NOTICES
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Notice No.
Subject
Date
Issued
80-15
80-14
80-13
80-12
80-11
80-10
Axial (Longitudinal)
Oriented Cracking In
Piping
Safety Suggestions From
Employees
General Electric Type SBM
Control Switches - Defective
Cam Followers
Instrument Failure Causes
Opening of PORV and Block
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General Problems with ASCO
Valves in Nuclear Application
Including Fire Protection
Systems
Partial Loss of Non-Nuclear
Instrument System Power
Supply During Operation
Possible Occupational
Health Hazard Associated
with Closed Cooling Systems
The States Company Sliding
Link Electrical Terminal
Block
Pump Shaft Fatigue Cracking
Notification of Significant
Events
4/21/80
4/2/80
4/2/80
3/31/80
3/14/80
3/7/80
3/7/80
3/7/80
2/29/80
2/27/80
Issued To
All light water reactor
facilities holding power
All power reactor
facilities with an
All light water reactor
facilities holding power
All holders of power
All holders of Reactor
OL, CP, fuel fabrica- tion and processing
facilities
All power reactor
facilities holding
All holders of
power reactor OLs
and near term CPs
All power reactor
facilities with an OL
or a CP
All Light Water Reactor
Facilities holder power
All holders of Reactor
OLs and to near term
OL applicants
80-09
80-08
80-07
80-06