ML20050C871
| ML20050C871 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde, Humboldt Bay, 05000000 |
| Issue date: | 03/31/1982 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| Shared Package | |
| ML20050C861 | List: |
| References | |
| NUDOCS 8204090425 | |
| Download: ML20050C871 (1) | |
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March 31,1982 Docket Nos. 50-528, 50-529, 50-530 Arizona Public Service Company P. O. Box 21666 Phoenix, Arizona 85036 Attention: Mr. E. E. Van Brunt, Jr.
Vice President, Nuclear Projects IE INFORMATION NOTICE NO. 82-10: FOLLOWING UP SYMPT 0MATIC REPAIRS TO ASSURE RESOLUTION OF THE PROBLEM Gentlemen:
The enclosed Information Notice provides notification of events that may have safety significance.
It is expected that recipients will review the Information Notice for possible applicability to their facilities.
If you have any questions regarding this matter, please contact this office.
Sincerely, Originet signed 53 R. H. Engelken R. H. Engelken Regional Administrator
Enclosure:
IE Infonnation Notice No. 82-10 cc w/ enclosure:
F. W. Hartley, APS G. C. Andognini, APS M[j409 K o$hyg,31 G
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Accession No.:
8202040126 IN 82-10 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 31, 1982 IE INFORMATION HOTICE NO. 82-10:
FOLLOWING UP SYMPTOMATIC REPAIRS TO ASSURE RESOLUTION OF THE PROBLEM Discussion:
There have been a number of instances in which licensees have attempted to correct valve problems by treating the symptoms rather than the underlying cause. This failure to distinguish between the problem and its symptomt has resulted in recurrence of the problem and further damage to or destruction of the valve or operator. Symptomatic repairs provide for a return to operability without addressing the underlying problem, earning the label " quick and dirty fixes." The industry jargon recognizes not only that the immediate needs are met, but also that the underlying problem remains to be corrected.
It is this second pnint which is emphasized: the underlying problem remains to be corrected.
j Specifically, valves that leak beyond Technical Specification limits have be.en restored to operability by allowing additional stem travel. The direct result of this symptomatic solution has been damage to or destruction of the valve or operator.
One licensee has routinely backseated valves with Limitorque operators using the full motor torque in order to stop stem packing leakage, resulting in damage to the valve backseat. Bypassing the open limit switch allowed over-travel in the open direction resulting in binding of the. stem in the stem nut.
Because the unthreaded portion of the stem galled in the threads of the stem i
nut, the threads deformed and the nut cracked. The valves involved were 600 psi class, Anchor 10-inch integral backseat gate valves with pressure seal bonnets. Stem and body were type 316 stainless steel.
On a larger scale, in a survey of Licensee Event Reports (LER) for 1978 through 1980, 444 valve operator events were identified for 66 plants. Of these,193 were identified as motor operator events. Corrective actions which involved torque switches comprised the largest single corrective action group.
The principal means of corrective action identified was the adjustment of torque switch setting. This solution was applied to valves in similar service and,
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IN 82-10 March 31, 1982 Page 2 of 2 repetitively, to the same valve at several plants. This indicates that the problem was not being corrected.
l The second major corrective action group was limit switch adjustments. This was a common solution to problems involving valve operation within a time limit.
The cause for the problem is repeatedly given as instrument drift which is undoubtedly true as far as it goes; however, repetit'on of the events points to the need for a wider ranging solution which will prevent recurrences and improve system reliablity.
During the survey period, there were 16 reported instances of motors replaced in motor operators in the high-pressure coolant injection (HPCI), reactor core isolation cooling and residual heat removal systems of boiling water reactors.
This was the third largest corrective action group. The damage that required i
replacement of some of the 16 motors resulted from thermal overload protection being bypassed and may be another indication that the underlying valve problem was not corrected.
The common thread in the events as reported by LERs surveyed is the repetition of the problem or the solution, either of which can indicate that a symptomatic -
repair has been made.
Symptomatic repairs become of concern to the NRC where they impact upon the reliability of the system and where they may adversely affect the health and safety of the public.
When considering the solution to a valve problem, it must be recognized that a symptomatic repair may cause damage to the valve or operator which could impair the safety function of the system to which it is applied. Consideration should be given to the kind of damage that can occur as a result of the repair and the consequences should a valve fail in a nonconservative direction. A mechanism should exist to identify and resolve the underlying problem when symptomatic repairs are applied.
When the possibility exists for degradation of a safety system as a rescit of a temporary symptomatic repair to restore operability, prudence dictates a closer surveillance of the system so affected.
This information notice is provided as notification of a potentially significant matter.
It is expected that recipients will review the information for apolica-bility to their facilities. No specific action or response is required at this time.
If you have any questions regarding this matter, please contact the Regional Administrator of the appropriate NRC Regional Office.
Attachment:
Recently Issued Information Notices
o Attachment IN 82-10 March 31, 1982 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 82-09 Cracking in Fiping of Makeup 03/31/82 All power reactor Coolant Lines at B&ll Plants facilities holding an OL or CP 82-08 Check Valve Failures on 03/26/82 All power reactor Diesel Generator Engine facilities holding Cooling System an OL or CP 82-07 Inadequate Security Screening 03/16/82 All power reactor Programs facilities holding an O'. or CP 82-06 Failure of Steam Generator 03/12/82 All power reactor Primary Side Manway Closure facilities holding Studs an OL or CP 82-05 Increasing Frequency of 03/10/82 All power reactor Drug-Related Incidents facilities holding an OL or CP t
82-04 Potential Deficiency of 03/10/82 All power reactor Certain AGASTAT E-7000 facilities holding Series Time-Delav Relays an OL or CP l
82-03 Environmental Tests of 03/04/82 All power reactor Electrical Terminal Blocks facilities holding an OL or CP 82-01 Auxiliary Feedwater Pump 02/26/82 All power reactor Rev. 1 Lockout Resulting from facilities holding Westinghouse W-2 Switch an OL or CP Circuitry Modification l
l 80-32 Clarification of Certain 02/26/82 All facility, j
Rev. 1 Requirements for Exlusive-materials and-Use Shipments of Radio-Part 50 licensees active Materials 1
OL = Opera +.ing License i
CP = Construction Permit i
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