ML20137J377
| ML20137J377 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 08/19/1985 |
| From: | Edelman M CLEVELAND ELECTRIC ILLUMINATING CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| (RDC-121(84)), LER-DEFR-850819, PY-CEI-OIE-0054, PY-CEI-OIE-54, NUDOCS 8508300289 | |
| Download: ML20137J377 (5) | |
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f 'THE CLEVELAND ELECTR P.O. BOX SG)0 - CLEVELAND, OHIO 44101 - TELEPHONE (216) 622-9800 - ILLUMINATING BLOG.
- 55 PUBLICSQUARE Sening The Best Location in the Nation MURRAY R. EDELMAN August 19, 1985 VICE PRESIDENT NucuAR PY-CEI/OIE 0054 L Mr. James G. Keppler Regional Administrator, Region III Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 RE:
Perry Nuclear Power Plant Docket Nos.
50-440; 50-441 Borg-Warner Gate Valves
[RDC 121(84)]
Dear Mr. Keppler:
Our letter of March 15, 1985 reported the failure of a 20" and an 8" Borg Warner gate valve, and detailed inspections planned to assure that the described defects were not generic to other valve models.
Subsequent additional valve failures mandated the expan-sion of our investigation and repair program; the protraction of these activities was reported in our letter of May 15, 1985.
Investigations are now complete and necessary valve repairs and modifications are in progress.
This letter defines the scope of identified valve deficiencies, the corrective action being taken, and serves as our final report pursuant to 10CFR50.55(e).
These activities are documented under Deviation Analysis Report (DAR) 213.
Description of Deficiency Since September 1984, seven (7) Borg Warner gate valves have failed during cycling or examination at the Perry Nuclear Power Plant (PNPP); the two distinct failure modes which have been identified are gate seizure and gate / guide disengagement.
Gate seizure has occurred in four (4) Borg Warner valve models; gate disengagement has occurred in three (3) valve models (applicable valve models are listed in an appendix to this letter).
Gate seizure may be defined as galling of the body guide by the gate bearing surface corner to the extent that further gate travel is impeded.
Gate disengagement is a condition in which the gate drops off the top of body guides in the backseated position, thus prohibiting valve closure.
i o
AUG 2 21985 eq0g e 8
c Mr. Jcmac G. Kappler August 19, 1985 PY-CEI/OIE 8054 L Although, valve failures may be attributed to these two distinct causes, the common factor which has been determined necessary to precipitate failure is installation in a non-standard orientation.
All defective valve models have been found subject to failure when positioned as installed in horizontal piping with stem orientation between 22 1/2 degrees and 157 1/2 degrees off vertical (this range of orientation has been specified by Borg Warner as applicable to 8" valve, Bill of Material RNN-223; PNPP experience indicates that this orientation limitation may be applied to all valves 8" and larger with guides installed by welding).
Ten (10) inch valves (RON-207 and RON-218) have also been demon-strated subject to failure when positioned as in vertical piping.
Susceptibilty to failure in these nonstandard orientations appears to be aggravated by the following parameters:
Gate Seizure 1) sharp corners on the gate surfaces which bear on valve body guides in off-vertical stem orientations 2) excessive clearance between gate and guides which allows increase in angle of attack due to lower gate bearing :arface friction 3) gate bearing surface being hardfaced with stellite while guides are relatively soft carbon steel (not in accordance with approved drawings) 4)
failure of the manufacturer to specify installation orientation limitations as required by specification 5) misalignment of guides due to fabrication without locating fixtures Gate Disengagement 1) inadequate extension of guides into bonnet cavity (bolted bonnet valves only) 2)
excessive clearance between gate and guides and between gate and stem which allows gravitationally induced misalignment in the backseated position Also reported in our letter of November 28, 1984, was a defi-ciency considered extraneous to the valve failures described herein:
inadequately sized guide to body fillet welds for 20" valves subject to differential pressures greater than 600 psi.
Mr. Jcmos G. Koppler August 19, 1985 PY-CEI/OIE 0054 L Finally, a 24" valve, IE12-F105, has also been observed to jam in the closed position due to mispositioning of the guides such that gate / guide friction prevents initial movement in the opening stroke.
This valve is installed in horizontal piping with vertical stem orientation.
This is believed to be an isolated manufacturing anomaly, as no similar failure has been evidenced in Borg Warner gate valves inspected and tested.
Analysis of Safety Implications CEI has determined that none of the valve models subject to gate disengagement are installed in Unit 1 in an " active" application, as defined in Regulatory Guide 1.48.
These non-active valves are not required to perform a mechanical motion while accomplishing their safety function, and are in fact maintenance valves. Thus, failure of these valves would have no impact upon the safe operation or shutdown of the plant.
However, of models determined subject to gate seizure, three (3)
Unit 1 valves (lE12-F008, and 1B21-F065A&B) installed in a suscep-tible orientation are classified as active and intended to perform a containment isolation function.
Two (2) of these valves (lB21-F065A&B) were also supplied with inadequate guide to body fillet welds for their design differential pressure (1500 psid).
The 24" valve observed to jam in the closed position is also classified active and intended to perform a containment isolation function.
Failure of these active valves would result in degradation of their ability to perform their intended containment isolation function.
Corrective Action In order to identify the valves potentially subject to the foremen-tioned failure modes, the installation orientation of all Unit 1 Borg Warner gate valves was determined.
Representative samples of all valves installed in nonstandard orientations were inspected for physical configuration and percent engagement when backseated.
l These representative samples were also cycled in orientations similar to installed valves, or in orientations more susceptible to failure; installed valves of Bills of Material exhibiting failure in sample inspections were repaired by installation of hardfaced guides which also reduced operating clearance and increased gate engagement at both travel extremes.
Additionally, CEI is installing new hardfaced lower guides (as a minimum) in all Unit 1 valves having welded guides and installed in horizontal piping with stem orientation between 22 1/2 degrees and 157 1/2 degrees off vertical; lE12-F072A was repaired by instal-lation of longer non-hardfaced guides and by chamfering of gate bearing surface corners.
Both guides are being replaced in the RON-218 valves installed in vertical piping.
Mr. Jcmea G. KIpplor Augu;t 19, 1985 PY-CEI/OIE 8054 L All other valves determined susceptible to failure which are installed in horizontal piping with stem orientation lees than 22 1/2 degrees off vertical have been exercised through multiple cycles to verify operability.
The 24" valve which jammed closed was repaired by simple tapering of a lower guide to alleviate initial cycling friction.
All Unit 2 and warehoused valves determined susceptible to failure have been identified on Nonconformance Reports and tagged as requiring repair.
Finally, guide to body fillet weld size was increased as directed by the manufacturer in all 20" valves determined to be subject to differential pressures greater than 600 psid.
It is deemed that the-described inspections, repairs, and associ-ated functional testing provide adequate assurance that valve deficiencies have been fully identified and addressed.
This is our final report on this matter.
Please call if there are any questions.
Sincerely, Murray R. Edelman Vice President Nuclear Group MRE:sab cc:
Mr. J. A. Grobe USNRC, Site Office (SBB50)
Mr. D. E.
Keating USNRC, Site Office Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 U.S. Nuclear Regulatory Commission c/o Document Management Branch Washington, D.C.
20555 Records Center, SEE-IN Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339
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PY-CEI/OIE 9954 L APPENDIX Failure Borg Warner Seal l Nonconformance Characteristic MEL B/M Size (inches)
Drawing No.
Design Report Gate Seizure N/A RNN-223 8
81130 BB OPQC-1531 IN27-F560A ROU-2g42 20 81040-2 PS SCG-062 N/A RNN-227 24 81170 BB OPQC-1429 N/A RON-207 3 10 80990 BB OPQC-1614 Gate lE12-F072A
RON-206 8
80980 BB NTS-283 Disengagement IE12-F099A RON-2073 la 80990 BB NTS-422 N/A RON-2073 la 80990 BB CQC-3973 Other 1E12-F0085 RNU-210 20 81230 PS 00C-2001 lE12-F105 RNN-227 24 81170 BB NTS-711 1
BB - Bolted Bonnet PS - Pressure Seal 2
RNU-213/81040 is identical Bill of Material and Borg Warner Drawing No.
3 RON-218 is identical Bill of Material and Borg Warner Dwg No.
4 This non-active valve was repaired by installation of longer non-hardfaced guides, and chamfering of the gate bearing surface corners.
5 Guide galled but gate did not seize; RNU 211 is identical Bill of Material and Borg Warner Dwg. No.
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