ML19323D715
| ML19323D715 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay, Diablo Canyon |
| Issue date: | 04/29/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8005220205 | |
| Download: ML19323D715 (1) | |
Text
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UNITED STATES e
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NUCLEAR REGULATORY COMMISSION g.
tj REGION V o
1990 N. CALIFORNIA BOULEVARD
- [4 SUITE 200, WALNUT CREEK PLAZA WALNUT CREEK, CALIFORNI A 945%
April 29, 1980 Docket Nos. 50-133, 50-275, 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
The enclosed IE Information flotice No. 80-16 provides informatic on two instances of main steam swing check or isolation valves binoing due to shaft packing.
Sincerely, tfiTim C-a R. H. Engelken Director
Enclosures:
1.
IE Information flotice No. 80-16 2.
Recently Issued IE Information flotices cc w/ enclosures:
W. Barr, PG&E W. Raymond, PG&E R. Ramsay, PG&E, Diablo C;r.ye..
E. Weeks, PG&7, Humboldt Bay E. B.1.angley, Jr., PG&E 8005220 2.0 6
SSINS flo.: 6870 Accession No.:
UNITED STATES 8002280667 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTI0fl Afl0 ErlFORCEMErlT WASHIrlGT0ft, DC 20555 April 29, 1980 IE Information flotice No. 80-16 SHAFT SEAL PACKING CAUSES BINDIrlG IN MAlfi STEAM SWING DISC CHECK AND ISOLATI0ft 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.
flain 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.
1 During testing in the hot standby mode at the Trojan Nuclear Plant on April 15, 1980, tnree 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 sm'all 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
-l taken.
No written response to this IE Information flotice is required.
IE Information flotice flo. 80-16 Enclosure April 29,1980 RECEllTLY ISSUED IE It!FORMATI0ft NOTICES i
Information Subject Date Issued To Notice flo.
Issued 80-15 Axial (Longitudinal) 4/21/80 All light water reactor 3
Oriented Cracking In facilities holding power i
Piping reactor OLs or cps 1
1 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 I
Control Switches - Defective facilities holding power Cam Followers reactor OLs or cps 80-12 Instrument Failure Causes 3/31/80 All holders of power d
Opening of PORV and Block reactor OLs and cps Valve 80-11 General Problems with ASCO 3/14/80 All he'Jers of Reactor Valves in Nuclear Application OL, CP, fuel fabrica-1 Including Fire Protection tion and processing Systems facilities j
)
80-10 Partial Loss of flon-Nuclear 3/7/c0 All power reactor Instrument System Power facilities holding i
Supply During Operation OLs and cps 1
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
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