ML19345C328
| ML19345C328 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek, Callaway  |
| Issue date: | 11/26/1980 |
| From: | Seiken S STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, SLNRC-80-53, NUDOCS 8012040403 | |
| Download: ML19345C328 (8) | |
Text
- D SNUPPS Standardized Nuclear Unit Power Plant System fn.*Z,*,,$,[*d November 26, 1980 20es0 t30118004010 SLNRC 80- 53 FILE: 0491.10.2/M-218 SUBJ: Bergen-Paterson Pipe Snubber Assemblies Mr. Boyce Grier Director, Region I J
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission A
631 Park Avenue King of Prussia, Pennylvania 19406
References:
STN 50-482 STN 50-483
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j STN 50-486
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Dear Mr. Grier:
On October 27, 1980, NRC Region I (Ms. C. Yusko) was informed by the SNUPPS QA Manager (Seiken) of generic design interferences between the Bergen-Paterson furnished pipe clamp assemblies and the mating snubber assemblies supplied by their subvendor, Pacific Scientific Company. As a consequence of these interferences, the final assembly cannot provide the 120 cone of movement necesary to accommodate anticipited thermal and seismic loads. Subsequent examination has reaffirmed earlier SNUPPS conclusions that the nature and scope of these interferences require reporting to the NRC pursuant to 10CFR 50.55(e) regulations.
Enclosed with this letter is a generic report covering the design inter-ferences in the Bergen-Paterson snubbber assemblies, specifically Part 2540 (modified) units. This report provides a chronology of events associated with the discovery of the snubber interferences; sumarizes safety implications associated with this deficiency and outlines a program of follow-up corrective actions planned and/or initiated to fully resolve this matter. The plan provides for design verification and checkout of Type 2540 snubber units currently scheduled for delivery to Callaway and Wolf Creek sites. Defective clamp assemblies identified by Bergen-Paterson as having been furnished to these sites will be tagged and later replaced.
Please note that the enclosed report is being treated as a final report under 10CFR 50.55(e) definition. The corrective action plan will be Soli II i
8012040 W y
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SLNRC 80- 53 Page Two monitored by Bechtel and later by Callaway and Wolf. Creek QA personnel.
In the event additional actions are required, a supplemental report will be prepared and forwarded to the NRC.
In the interim, any questions may be addressed to the undersigned.
Very truly yours,
'b S. J. Seiken Quality Assurance Manager SJS/mtk lbl&2
Enclosure:
Report on Bergen-Paterson Snubber Asssemblies cc: Mr. J. A. Keppler, Director, Region III, USNRC Mr. W. Wescott, Region III, USNRC Mr. Karl Seyfrit, Director, Region IV, USNRC
~s4Mr. Victor Stello, Jr., Director, Office of Inspection and Enforcement, USNRC, Washington D.C.
T. Vandel, Wolf Creek Resident Inspector, USNRC W. Hansen, Callaway Resident Inspector, USNRC y
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10 CFR 50.55(e) REPORT on POTENTIAL BOLT HEAD - PIPE CIAMP INTERFERENCE BERGEN. - PATERS 0!; PIPE SUPPORT' STRUT with MECHANICAL SHOCK ARRESTOR SUPPLIED to SNUPPS UNITS Bechtel Power Corporation Gaithersburg, Maryland November 26, 1980 e
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TABLE OF CONTENTS 1,0 Introduction 2.0 Description of Reportable Deficiency 3.0 Analysis of Safety Implications 4.0-Corrective Action 5.0 Sketch of Bergen-Paterson Snubber Assembly i
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1.0 INTRODUCTION
In accordance with the req 91rements of 10CFR 50.55(e) this report is prepared to provide a suciary of a generic deficiency related to clamp interferences which could hinder the full function of Bergen-Paterson pipe support strut assemblies containing Pacific Scientific mechanical shock arrestors (see attached sketch describing parts).
0 Presently, the pipe support assemblies are designed to provide a 12 cone of movement to accomodate thermal and seismic loads.
This deficiency was initially reported to the NRC Region I Inspection and Enforcement by Bergen-Paterson in a 10CFR Part 21 report dated June 20, 1980. At that time, the deficiency was believed to be Ibnited to two Part Nos. 2541-0.35 and 0.65 snubbers which had been delivered to the Wolf Creek and Callaway jobsites. The Architec t/ Engineer's evaluation of the support designs, which use the two identified enubbers, disclosed that no more than a 50 cone of movement was required. While these two snubbers would permit substantially less than the 120 cone called for in the purchase specificatiotis, sufficient movement was available to accept the snubbers on "as-is" basis. Union Electric verbally informed the NRC on July 2, 1980 of the nature of this problem and followed up with a written report on July 30, 1980. Comparabic reports were made by Kansas Gas and Electric on July 3, 1980 and August 4, 1980. Tne NRC was later notified by Union Electric on October 7,1980 of the proposed resolution concerning the two units in question.
On October 21, 1980, the Callaway site identified additional interference problems with Part No. 2541, size -6 and -15 Bergen-Paterson assemblies.
The supplier was notified of interferences and subsequently directed to examine all sizes of Part 2541 snubber assemblies scheduled for use with Pacific Scientific Mechanical shock arrestors to determine the scope and extent of these interferences. The supplier developed scale layouts of all sizes and configurations of the Part 2541 snubber / clamp assemblies for purposes of verifying in a 3 dimensional mode, functions and fit. From l
the layouts, Bergen-Paterson verified that a total of sixteen (161 Size -6,
-15, and -120 delivered assemblies (8 per SNUPPS unit), when used in i
conjunction with various pipe sizes, contain interferences which may hinder the function of the units. These interferences were not detected previously because Bergen-Paterson's interference checks for 12 total movement were performe' in only two directions rather than in a 3-dimensional " cone" configuration. When triaxial checking was performed, the presence of the interference was confirmed.
On the basis of these findings, a telecon 50.55(e) report of a generic design deficiency of Bergen-Paterson snubber assemblies was made by the SNUPPS QA Manager to the NRC Region I Office on October 24, 1980. The supplier, Bergen-Paterson, filed a follow up 10 CFR Part 21 report with the Commission on October 29, 1980. A list of identification numbers of the 16 assemblies that had been shipped to the SNUPPS sites has been compiled and the jobsites notified accordingly. These assemblies will be placed on hold. Othe'r units in manufacture at lergen-Paterson are also involved; holds have also been placed on these units.
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2.0 DESCRIPTION
OF REPORTABLE DEFICIENCY The Bergen-Paterson snubber assemblies being supplied to the SNUPPS i
sites employ a Bergen-Paterson Part No. 2640 pipe clamp in combination with a Pacific Scientific end bracket assembly. Many of these snubber assemblies are employed in safety-related piping systems.
The Part 2541 snubber assemblies in question contain an interference between the pipe clamp and and snubber assembly in the end bracket assembly which does not permit the required 120 cone of movement under i
seismic and thermal loadings.
3.0 ANALYSIS OF SAFETY IMPLICATIONS h
Snubbers that are employed in seismically designed piping systems must permit the pipe to move thermally in the direction of the support and 4
l provide a rigid-restraint during a seismic event. The snubber must also permit motion of the piping transversely perpendicular to the end brackets. This is achieved by allowing a 120 cone of travel at both i
ends of the snubber, utilizing ball bushings.
1 The snubbers in question permit 00 to 6 cone of movement of the clamp j
end versus the full 12 cone specified in Bergen-Paterson's Load Capacity Data Sheets. The restriction of pipe movement could overstress the pipe.
The action of the clamp locking up with the snubber body could also overstress the snubber during piping movement.
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j 4.0 CORRECTIVE ACTION 1
The interference in these snubber assemblies has been attributed to a i
i breakdown in Bergen-Patterson's design control practices. The vendor l
is preparing detailed written procedures for use in performing interference checks of all new or modified snubber assemblies.
Individuals designated
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to perform interference checks will receive training in the use of the i
new procedures. The Part 2541 assembly, as well as all other snubber assemblieg will continue to be checked for proper clearance and placement i
by means of three dimensional layouts. These additional controls will I
be in place at Bergen-Paterson by December 1,1980.
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1 The Part 2640 clamps will be modified to eliminate the interferences.
Defective clamps identified by Bergen-Paterson as having been furnished to
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the sites will be tagged and later replaced. No further shipments of the affected sizes will be made until the Architect / Engineer has confirmed that the ' committed corrective actions required of Bergen Paterson have been taken and further independently verified design acceptability of all size units. Follow up site actions will also be taken to assure the required modifications and replacements are made.
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9 5.0 BERGEN-PATERSON SNUBBER ASSEMBLY shock Arrestor (Snubber)
Pipe Ciamp (Part 2640)
Supplied by Pacific Scientific supplied by Bergen Paterson Part 2541 (Modified Part 2540)
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0 12 cone of t--
Tevement
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t=t End Bracket x
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Bechtel Power Corporation Engineers-Constnactors 15740 Shady Grow Road
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Gaithersburg, Maryland 20760 301-258 3000 November 26, 1980 Mr. Nicholas A. Petrick Executive Directo'r, SNUPPS S Choke Cherry Road Rockville, Maryland 20850
Dear Mr. Petrick:
BI4A-80/0009 File: M-218A/0490.3 10CFR50.55(e) Report Related to Interferences in Bergen-Paterson Snubber Assemblies - Final Version Enclosed is the 50.55(e) report for the Bergen-Paterson interference problem.
The version dated November 17,1980.was reviewerTrith UE and KG & E Technical Co=:sittee representatives via telecon on NovembsT 24,1980 and now inc6rttrrates their consnents.
Should you have any questions, please let me knov.
Sincerely,
/
John Kroehler, Jr.
Project QA Manager JKJ:jt
Enclosure:
10 CFR 50.55(e) Report
-cc:
S. J. Seiken SNUPPS w/a E. W. Creel KG&E w/a i
~ W. G. Eales KG&E w/a F. D. Field UE w/a D. W. Capone UE w/a j
J. A. Bailey KG&E w/a
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