ML20199E142
| ML20199E142 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 06/26/1985 |
| From: | NRC - COMANCHE PEAK PROJECT (TECHNICAL REVIEW TEAM) |
| To: | |
| Shared Package | |
| ML20199D912 | List:
|
| References | |
| FOIA-86-36 PROC-850626-01, NUDOCS 8606230201 | |
| Download: ML20199E142 (9) | |
Text
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( . COMANCHE PEAK RESPONSE TEAM ACTION PLAN Item Number: V.e
, Installation of Main Steam Pipes Revision No. 0 1 Revised to Feflec';
^'s Description Original Isst.e NRC Coments v-Prepared and Recommended by:
Review Team Leader f '/[
./ jM M Data 3 8$ b 6!PI
( l Approved by:
Senior Review Team b d. /ki_ O* 1.J. hd Date \ l C l l*f 36fff 8606230201 860609 PDR FOIA GARDE 86-36 PDR
Revision:
1 Page .1 of 8 t'~' .
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ITDi NUMBER V.e Installation of Main Steam Pipes
1.0 DESCRIPTION
OF ISSUE IDENTIFIED BY NRC The TRT investigated an allegation that a Unit 1 main steam line had been installed incorrectly and had been forced into proper alignment after flushing operations by use of the main polar crane sud come-alongs. It was also claimed that pipe supports had been modified to maintain the line in its forced position and vibrations following detachment of the flushing line could have damaged the main steam line. Based on its investigation, the TRT determined that the alleged incident pertained to restoration of the Unit 1 Loop 1 main steam line to its initial, correct installation position. (The line had shifted during flushing operations due to the weight of the added water and because the temporary supports sagged.) The TRT also determined that the modifications to permanent pipe supports were necessary to provide proper support to the main steam line in its restored position (initial designs for and construction of the supports had been based on the shifted .
position of the line), and, although the alleged vibrations could not be confirmed, their associated stresses might not have damaged
,_ the main steam line. (The highest stresses would have occurred in the weaker, temporary flushing line.) The TRT review of the TUEC 3, ' analysis, performed 1 year after the incident, concluded that the analysis was incomplete. An evaluation for the full sequence of events leading up to the incident had not been performed. The TRT review of Gibbs & Hill Specification No. 2323-MS-100 indicated that there were inadequate requirements and construction practices for the support of the main steam line during flushing, and for temporary supports for piping and equipment in general. In particular, evaluations to assure the adequacy of temporary supports during flushing and installation were not required. The deficiencies in the analysis, specifications, and construction practice identified above constitute a violation of Criterion V of Appendix B to 10CFR50, 2.0 ACTION IDENTIFIED BY NRC Accordingly TUEC shall:
Modify Gibbs & Hill Specification No. 2323-MS-100, and
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institute procedures for support of the main steam line during flushing and for temporary supports for piping and equipment, in general, to assure that the quality of piping and equipment are not affected.
Perform an assessment of stresses in the portions of the Unit
- 1. Loop 1, main steam and feedwater lines that were affected
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in the sequence of events involved during their initial installation, flushing and final installation. Conditions requiring stress analysis'are:
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y,~ ITEM NUMBER V.e (Cont'd) 2.0 ACTION IDENTIFIED BY NRC (Cont'd)
Flushing condition when the lines were full of water and temporary supports had sagged or settled.
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Disconnecting condition when vibrations of the temporary line could have occurred.
Lifting condition when forces were applied by the polar crane and come-alongs.
These assessments shall be based on appropriate piping configurations involved.
Perform a non-destructive examination of locations in the Unit 1 Loop 1 main steam and feedwater piping where stresses were exceeded during the conditions of concern in 2.2.1 through 2.2.3 above.
Review the existing baseline UT examinations for those portions of the Unit 1, Loop 1. main steam and feedwater r'~'. involved in all the conditions of concern in 2.2.1 through 2.2.3 above, for unacceptable indications.
Review records of hydrostatic testing of the main steam and feedwater line to verify the quality of piping involved in the incident.
Provide similar assessments for circumstances involved in a lifting incident identified during the TRT inspection for the Unit 1, Loop 4, main steam line.
Provide assessments of effects on quality of safety-related piping and equipment which were involved in similar incidents of sagging, settlements and failures, if any, of temporary supports.
Submit the results of analysis, examinations and reviews in a documented report for NRC review.
3.0 BACKGROUND
3.1 Information Supplementing NRC Description The preliminary review of the main steam line installation issue shows that the NRC description of the situation is generally correct. The allegation itself appears to be
, misleading based upon current knowledge.
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C' ' ITEM NUMBER V.e .
(Cont'd)
3.0 BACKGROUND
(Cont'd)
In the normal course of completing the installation of the i line, it was found that the main steam line as installed on
, its temporary supports was out of position approximately 3-1/4" vertically and 3" horizontally with respect to the Steam Generator nozzle to which it was to be welded.
l Engineering was informed and, subsequently, calculations were reviewed to determine the weight of the line that was out of 1
position. The line was lifted into position in a controlled manner, using a load measuring dynamometer in series with the main book on the polar crane. The dynamometer was clearly visible and was observed by the field support engineer and other personnel during the lift. The maximum load was approximately 15 tons. This was consistent with previously 1
calculated estimates of the weight of the line being lifted.
The one lift plus the horizontal displacement with a come-along resulted in satisfactory alignment. No further adjustments by bending, heating, or cutting were necessary to obtain a fit.
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- - ' A related issue identified by the TRT concerns the welding of temporary supports without a weld procedure specification or by an unqualified welder. The TRT reviewed the requirements for temporary supports, and made walkthrough inspections in both Unit 1 and Unit 2. The TRT established that temporary supports are employed during construction to maintain the required positions and alignments of components during installation until designed supports are permanently installed. Such supports are essentially made up on the site by construction personnel from available materials which are i
assembled in a manner to provide the necessary support function. Based on its investigation, the TRT determined j that, except for attachment welds to components or permanent plant structures, no written requirements existed addressing weld fabrication of temporary supports.
The TRT included the following required action statement in NUREG-0797 Supplement No. 10. TUEC shall modify Gibbs & Hill Specification 2323-MS-100 requirements and provide procedures for the fabrication and installation of temporary supports to
' assure that the quality of piping and equipment so supported
.is not adversely affected. This action is related to that required for Mechanical and Piping Category II, allegation AP-13, item 1 (installation of main steam pipes -- See
- paragraph 2.0 above).
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Revision: 1 Page 4 of 8
' ITEM NUMBER V.e (Cont'd)
3.0 BACKGROUND
(Cont'd) 3.2 Preliminary Determination of Root Cause and Generic Implications It is observed at this point that, in construction practice, it is not at all uncommon to perform adfestments in pipe position prior to final welding, particularly when permanent supports are installed subsequent to the final ficup.
Construction practice and related codes and standards do not prohibit such adjustments because of the resiliency and damage insensitivity of welded steel piping to small displacements.
From a technical viewpoint, the possibility of damage to the steam line or the plant generally must be related to any permanent strain induced during the lif t at.d the effect of any associated residual stress in the pipe and supports.
Potential for further damage due to cracking or other flaws
- induced by the deformation needs to be assessed. There are no other engineering effects. This action plan has been developed on the above basis.
The issue will be studied generically to determine the, extent of the practice and to establish the potsibility and degree of damage in other piping systems in the plant.
4.0 CPRT ACTION PLAN 4.1 Scope The scope of the plan is twofold. A specific engineering investigation will be performed on the main steam line and supports including the connection at the SG nozzle to ,
determine the detrimental physical effects if any, of the adjustment of the line to achieve final ficup.
The second part of the plan vill. identify the extent of construction practices at the site related to the specific main steam installation and to the more general area of temporary supports. Then the nature and extent of detrimental physical effects in other important piping systems will be determined.
If detrimental effects are found in either the main steam line or other systems, the need for remedial action will be determined. If necessary, a suitable program to remedy the I damage will be formulated and implemented.
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Revision: 1 Page 5 of 8 s l ITEM NUMBER V.e (Cont'd) 4.0 CPRT ACTION PLAN (Cont'd) 4.2 MethodoloEY l The specific engineering investigation of the steam line adjustment will be performed as follows:
Review procedures for pipe erection and placement of temporary and permanent pipe supports.
Interview personnel involved with the steam line adjustment.
Evaluate engineering significance of procedures and practices.
Perform an analytical evaluation of stresses and support load changes during steam line movement for Unit 1. Loop 1, including full parametric variations of possible inputs.
p Establish engineering significance of stresses and v support loads from previous step. .
Review the existing UT examinations and hydrostatic tests for the affected piping on Unit 1. Loop 1.
Determine the need for reinipection of portions of the line that may have been highly stressed and identify location for reinspection. If appropriate, recommend and implement reinspection program.
A generic study of possible damage in other piping, including the Unit 1. Loop 4 main steam line, will be performed as p follows:
Review procedures and specifications for pipa erection l and placement of temporary and permanent pipe supports.
Review NCRs and Piping Deviation Request Forms (PDRFs) with circumstances similar to the steam line.
Interview pipe installation personnel to determine other piping that had location adjustments made during l fitup.
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Review all other sources that would contribute residual stresses to piping systems such as bending in place, v etc.
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Revision: 1 Page 6 of 8 ITEM NUMBER V.e (Cont'd) 4.0 CPRT ACTION P1.AN (Cont'd)
Evaluate the engineering significance of residual stress due to fitup adjustments. Perform comparative l evaluations relative to other sources of residual stress. Considur guidance from codes and standards, ASME, ANSI, SRP, etc.
If required after the above evaluations, specific additional samples of piping ficup will be chosen and specific engineering evaluations performed as with the steam line.
Where required, modify Gibbs & Hill Specification and/or related procedures, to insure that piping in general (and the main steam piping in particular) and associated equipment are not adversely affected during flushing activities and/or by use of temporary supports.
g- The attached logic diagram identifies tasks and the inter-I relationship of taska for resolution of this action plan.
C 4.3 Responsibilities 4.3.1 Comanche Peak Projec*. Engineering
. 4.3.1.1 Scope Modification (as required) of procedures and specifications for control of pipe erection, temporary support, hydro / flushing.
Provide documentation for process and procedure review.
Assist in preparation of Results Report 4.3.1.2 Personnel Mr. C. Noehlman Project Mechanical Engineer I
Mr. H. Harrison Technical Services j.
Supervisor v
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Revision: 1 Page 7 of 8 ITEM NUMBER V.g (Cont'd) 4.0 CPRT ACTION PLAN (Cont'd) 4.3.2 Third-Party Activities l 4.3.2.1 Scope All activities identified in section 4.2 except those identified in 4.3.1.1 will be performed by third-party.
TERA Corporation verification of work perforned by RLCA 4.3.2.2 Personnel Mr. H. A. Levin TERA Corporation - CPRT 4
Mechanical Review Team Leader
,s Dr. J. R. Honekamp TERA Corporation - TRT Issues Manager v
Mr. P. Streeter TERA Corporation - Senior Mechanical Engineer Dr. R. L. Cloud
- Principal RLCA Mr. C. I. Browne* Project Manager RLCA 5.0 SCHEDULE Historical Review: Complete Procedural Review: Complete Analysis of MS Line Complete Evaluation of NDE/ PSI Records: Complete
Conclusions:
07/08/85 Dr. Cloud and Mr. Browne have recently assumed responsibilities assisting the project in the area of piping design. Accordingly, these individuals are no longer associated with the third-party s ,,- team. Their prior work will be verified in detail by TERA Corporation. -
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