ML20207R752
| ML20207R752 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 03/09/1987 |
| From: | Kober R ROCHESTER GAS & ELECTRIC CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8703180095 | |
| Download: ML20207R752 (7) | |
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ROCHESTER GAS AND ELECTRIC CORPORATION e 89 EAST AVENUE, ROCHESTER, N.Y. 14649-0001 ROGER W. KODE'R T E LE FwCNE VK E F9tESDE NT
- *u coor 7 s 546-2700 cu c rmc monuc rm March 9, 1987 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Failure of "B" Main Stealt Isolation Valve (MSIV) To Close While Plant Was Shutdown R.E. Ginna Nuclear Power Plant Docket No. 50-244 The above event was reported to the NRC in accordance with 10 CFR 50.72 (b)(2), four-hour notification.
The attached follow-up description and evaluation of this event for further reportability, cause and corrective action is hereby submitted.
This event was evaluated to be non-reportable per 10 CFR 50.73, Licensee Event Report System.
Vr truly yours, l
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l Ro r W. Kober xc:
U.S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 l
Ginna USNRC Resident Inspector l
0703100095 870309 PDR ADOCK 0500 4
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3 ROCHESTER CAS AND ELECTRIC CORP.
SHEET NO. 2 DATE March 9, 1987 TO U.S. Nuclear Regulatory Ccanission DESCRIPTION OF EVENT On February 7, 1987 at 0150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> the unit was in the process of being cooled down for the Annual Refueling and Maintenance Outage.
At this time the operator, per procedure, was instructed
-to close both MSIV's.
The "A" MSIV closed as required but the "B" MSIV failed to close.
Repeated attempts to close this valve from the main control board failed.
No immediate cause for the failure was determined and the plant continued to cool down with the valve open.
The On-Duty Shift Supervis6r declared the event reportable per 10 CFR 50.72 (b) (2) and at 0434' hours February 7, 1987 made the appropriate notifications,to the NRC Operations Center.
I CAUSE OF EVENT a
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The MSIV's are 30" self-aligning, swinging disb, inclined seat check valves manufactured by Atwood and Morrills The valves are straight-through-type and have a swinging disc rotating on a heavy shaft;with bushed bearings.
Each of the valves has an
. external air-operated cylinder which requires80-100 psig to hold i
the valve open.
Two series solenoid valves control the air
-supply which maintains the valve in the open position during operation.
These series solenoid valves are closed upon receipt of a main steam isolation signal.
Two parallel piped, normally closed, energize to open-solenoid valves, are provided for l
venting air upon receipt of an isolation signal.
When air is vented, the valve closes by spring assist as well as steam flow impinging on the back of the disc.
In order to determine the cause of the event'and provide _appro-priate corrective action, a systematic. approach in diagnosing the problem was developed.
This approach consisted of step by step, trouble shooting as follows:
l.
All electrical solenoids involved with the "B" MSIV'were checked out and found to be operating normally.
l 2.
The air-operated actuator spring assist to close was checked by disconnecting the linkage.
Actuator traveled close as designed.
The "B" MSIV remained open.
3.
All shaft packing was removed to assure the problem was not packing friction.
The "B" MSIV remained open.
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.r4 ROCHESTER GAS AND ELECTRIC CORP.
SHEET NO. 3
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DATE March 9, 1987' To U.S. Nuclear Regulatory Commission 4.
The top access cover to the "B" MSIV'was removed and the internals inspected with the following results:
A visual inspection revealed no abnormal conditions.
a.
b.
After removing the shaft. bushing bolts the "B"
MSIV-closed.
c.
The shaft bushings were removed and inspected.
The inspection revealed dimensions within manufactured tolerances and no abnormal conditions (i.e. galling, tearing, or rubbing).
d.
The shaft was removed and inspected.
This inspection revealed dimensions within manufactured tolerances and no abnormal conditions (i.e.' galling, tearing, or rubbing).
e.
The valve disc was removed and inspected.
This inspection revealed no abnormal conditions.
f.
Non-destructive examinations were performed on the shaft, valve disc, and valve seating surface with no abnormal conditions detected.
g.
The internals of the valve body were inspected.
This inspection revealed that the valve disc had been binding on what remained of a partially removed valve stop.
This valve stop had been partially removed back in 1975 because the valve disc was operating in the region of the steam flow and occasionally would drop further into the steam flow and the valve would close.
h.
The actuator was disassembled and the closing spring replaced.
The root cause of the "B" MSIV failure to close on demand was the binding of the valve disc on what remained of a partially removed valve stop.
See drawing Attachment A.
CORRECTIVE ACTION The following corrective actions were completed:
j-1.
Removed all remaining disc stop material not required in the "B" MSIV.
2.,
Cleaned and reassembled the "B" MSIV.
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ROCHESTER GAS AND ELECTRIC CORP.
SHEET NO. 4 DATE March 9, 1987 To U.S. Nuclear Regulatory Comunission 3.
Tested the "B" MSIV with positive results.
4.
Completely disassembled the "A"
MSIV and inspected it as was done to the "B" MSIV.
Found that the lower portion of the valve disc stop had been completely removed during the 1975 modification discounting any chance of common mode failure to both valves.
5.
Cleaned and reassembled the "A" MSIV.
6.
Tested the "A" MSIV with positive results.
7.
Inspected both main.steamline check valves.
No abnormal conditions were found.
In summary, the corrective actions completed will preclude any recurrence of the problem experienced with the "B"
MSIV.
This corrective action also proved that the "A" MSIV was not vulnerable to the same problem.
No further corrective action is planned.
ANALYSIS OF EVENT An evaluation of the event for further reportability requirements yielded the following results:
1.
Technical Specification violations reportability:
a.
Section 3.6.3, Table 3.6.1 (Containment Isolation Valves) addresses the MSIV's but in a subsequent note clarifies that the MSIV's are not considered to be containment boundary isolation valves.
==
Conclusion:==
not reportable as a Technical Specification Violation.
b.
Section 4.7 applicability only applies to the periodic testing of the Main Steam Isolation Valves.
The MSIV's were being closed for a normal operation and not a periodic test.
==
Conclusion:==
not a violation of this section thus not reportable as a Technical Specification Violation.
2.
10 CFR 50.73, Licensee Event Report System, reportability:
a.
Paragraph 50.73 (a) (2) (ii) requires reporting of:
Any event or condition that resulted in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded, or that resulted in the nuclear power plant being:
a
~ OCHESTER GAS AND ELECTRIC CORP SHEET NO. 5 R
DATE March 9, 19877 70 U.S. Nuclear Regulatory Commissioin (A)
In an unanalyzed condition that significantly.
compromised plant safety.
(B)
In a condition that was outside the design basis of the plant; or (C)- In a condition not' covered by the plants opera-ting and emergency procedures.
Review of the Ginna/UFSAR, accident analysis, Section 15 for the steam break accident and the Steam Generator Tube Rupture Accident concludes these accidents could be mitigated with the failure of one MSIV.
The Loss of Coolant Accident does not apply because the MSIV's are not containment boundary isolation valves.
Review of the plant's Emergency Operating Procedures concludes that the failure of one MSIV was considered for the involved accidents and contingencies actions l
are addressed.
==
Conclusion:==
this event is not reportable under 10 CFR 50.73 (a) (2) (ii) because it did not place the plant. within the envelope of the above 50.73 (a) (2) (ii) criteria.
b.
Paragraphs 50.73 (a) (2) (v) and (vi) requires reporting of:
(v)
Any event 'or condition that alone could have prevented the fulfillment of the safety function of structures or systems that are needed to:
(D)
Mitigate the consequences of an accident.
(vi) Events covered in paragraph (a) (2) (v) of this section may include one or more personnel errors, eauioment failures, and/or discovery of design, analysis, fabrication, construction, and/or procedural inadequacies.
- However, individual comoonent failures need not be reported oursuant to this caracraoh if redundant eauioment in the same system was ooerable and available to perform the reauired safety function.
Redundant equipment was available and operable in the system to perform the required safety function.
This equipment was the check valve in the steam line with the failed MSIV and the alternate steam line's as found operable MSIV.
==
Conclusion:==
this event is not reportable under 10 CFR 50.73 (a) (2) (v) and (vi).
ROCHESTER GAS AND ELECTRIC CORP.
SHEET NO. 6 DATE March 9, 1987 To U.S. Nuclear Regulatory Commission All other paragraphs of 10 CFR 50.73 were reviewed for c.
applicability and found not to apply to this event.
A safety assessment of this event indicates that the failure of one MSIV to close does not prevent the fulfill-ment of the safety function of the system.
There are other rcdundant components available to fulfill the safety function.
Based on this there was no compromise to plant safety or the health and welfare of the general public.
ADDITIONAL INFORMATION This event has been reported on NPRDS for industry dissemination of root cause.
Data March 9, 1987 Shast_ No_,_.7
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