Information Notice 1980-16, Shaft Seal Packing Causes Binding in Main Steam Swing Disc Check & Isolation Valves

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 Notice No. 80-16 Enclosure

April 29, 1980

RECENTLY ISSUED

IE INFORMATION NOTICES

Information Subject Date Issued To

Notice No. Issued

80-15 Axial (Longitudinal) 4/21/80 All light water reactor

Oriented Cracking In facilities holding power

Piping reactor OLs or CPs

80-14 Safety Suggestions From 4/2/80 All power reactor

Employees facilities with an

OL or CP

80-13 General Electric Type SBM 4/2/80 All light water reactor

Control Switches - Defective facilities holding power

Cam Followers reactor OLs or CPs

80-12 Instrument Failure Causes 3/31/80 All holders of power

Opening of PORV and Block reactor OLs and CPs

Valve

80-11 General Problems with ASCO 3/14/80 All holders of Reactor

Valves in Nuclear Application OL, CP, fuel fabrica- Including Fire Protection tion and processing

Systems facilities

80-10 Partial Loss of Non-Nuclear 3/7/80 All power reactor

Instrument System Power facilities holding

Supply During Operation OLs and CPs

80-09 Possible Occupational 3/7/80 All holders of

Health Hazard Associated power reactor OLs

with Closed Cooling Systems and near term CPs

80-08 The States Company Sliding 3/7/80 All power reactor

Link Electrical Terminal facilities with an OL

Block or a CP

80-07 Pump Shaft Fatigue Cracking 2/29/80 All Light Water Reactor

Facilities holder power

reactor OLs and CPs

80-06 Notification of Significant 2/27/80 All holders of Reactor

Events OLs and to near term

OL applicants