ML20215M825
| ML20215M825 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 10/21/1986 |
| From: | Foster D GEORGIA POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-86-345-000 GN-1124, PT21-86-345, PT21-86-345-000, NUDOCS 8611030332 | |
| Download: ML20215M825 (5) | |
Text
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Georgia Power Cornpany f
Post Office Box 282 Waynesboro, Georgia 30830 Telephone 404 554-9961. Ext. 3360 404 724-8114, Ext 3360 m
Georgia Power D. O. Foster 3,6 0CT 27 P 2 tj l Pres ent October 21, 1986 United States Nuclear Regulatory Commssion Region II File: X7BG03-M102 Suite 2900 Log:
GN-1124 101 Marietta Street, Northwest Atlanta, Georgia 30323
Reference:
Vogtle Electric Generating Plant-Units 1 and 2; 50-424, 50-425; Pipe Support Tolerances and Installation Procedures; Letter GN-890 dated May 1, 1986; Letter GN-989 dated July 11, 1986; Letter GN-1067 dated September 5, 1986 Attention: Mr. J. Nelson Grace In correspondence GN-1067 dated September 5, 1986, Georgia Power Company identified as reportable pursuant to 10 CFR 50.55(e) and 10 CFR 21 some aspects of a condition whereby pipe supports were installed to criteria which were subsequently modified or superseded.
As a result, some as-built conditions did not meet present design requirements.
Georgia Power Company also indicated in GN-1067 that the evaluation of one issue involving optional weld patterns was not completed and that the USNRC would be informed of the results of the remaining portion of the evaluation by October 24, 1986.
Georgia Power Company has completed the evaluation of the optional weld pattern issue and has concluded that this aspect of the overall condition is not reportable pursuant to 10 CFR 50.55(e) or 10 CFR 21.
A supplement to our previously transmitted evaluation summary is attached for your information.
This response contains no proprietary information and may be placed in the USNRC Public Document Room.
Yours truly, D. O. Foster REF/D0F/tdm Attachment Distribution on Page Two p,27 8611030332 861021 PDR ADOCK 050G0424 S
r Page Two xc:
U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 H. G. Baker R. A. Thomas L. T. Gucwa J. P. O'Reilly D. R. Altman C. W. Hayes G. F. Head P. R. Bemis G. A. McCarley R. E. Conway J. A. Bailey R. W. McManus J. T. Beckham
- 0. Batum D. S. Read R. H. Pinson G. Bockhold Sr. Resident (NRC)
P. D. Rice C. E. Belflower C. C. Garrett (OPC)
- 8. M. Guthrie J. F. D'Amico J. E. Joiner (TSLA)
D. E. Dutton E. D. Groover D. Feig (GANE)
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r SUPPLEMENT TO THE EVALUATION OF A POTENTIALLY REPORTABLE CONDITION PIPE SUPPORT TOLERANCE AND INSTALLATION PROCEDURES Initial Report:
On April 3,
1986, Mr.
R.
E.
Folker, Vogtle Project Quality Assurance Engineer, informed Mr. W. H. Rankin of the USNRC Region II of a poten-tially reportable condition concerning pipe support tolerances and in-stallation procedures.
Background Information:
The design of the support system for safety-related piping is based on the piping stress analysis which is performed in accordance with ASME Code Section III, Subsections NB, NC, and ND.
The pipe supports are designed, fabricated, and installed in accordance with ASME Code Section III, Subsection NF and the AISC Code, which is applicable to the pipe support miscellaneous structural steel.
Pipe supports are individually designed and issued for fabrication and installation on engineering drawings which are identified by individual tag numbers.
The pipe supports are installed in accordance with these drawings by Pullman Power Products (PPP).
Construction specification X4AZ01, Division P-5, was prepared by Bechtel Power Corporation and provides engineering criteria applicable to the installation of the pipe supports.
This criteria is converted to construction guidelines by PPP in their field installation procedure IX-50.
Bechtel Power Corporation made changes in the construction specification that controlled the tolerances and installation procedures for pipe supports.
These changes were made between August 1985 and December 1985.
The pipe supports installed prior to the changes could potentially restrict pipe movement beyond that calculated in the pipe stress analysis and could result in loads on pipe support structures in excess of the calculated design loads.
The six criteria in the construction specifica-tion which were revised or superseded and could affect the performance of installed pipe supports are:
1.
Embed plate / penetration separation less than two inches 2.
Less than minimum required restraint gap in box frame pipe support configurations 3.
Non-engineering stop plate installed in axial restraint configuration 4.
Non-engineered filler plate installed in strap restraint configura-tion 5.
Non-engineered weld joint option with reduced lo3d capacity 6.
Non-engineered shape / size substitution of structural steel
4
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Page Two Engineering evaluations for all of the above criteria except item 5 were described in the attachment to Georgia Power Company correspondence GN-1067 dated September 5, 1986.
The evaluation for Criteria 5 is de-scribed in this supplement.
Criteria 5 - Weld Joint Option:
The current construction specification allows substitution of optional weld patterns for the weld pattern shown on the pipe support drawing.
However, the sectional properties of some optional weld patterns for structural angles and channels in the original specification criteria are lower (thus lower weld joint load capacity) than those. properties of the specified pattern. An example is shown in Figure 5.
A random statistical sample of 1,000 pipe supports was selected from the total population of pipe supports which were installed between September 3,1974 and August 7,1985.
This sample was used to identify a sufficient quantity of randomly selected pipe supports which contain attachment of structural angles and/or channels.
By reviewing each of the 1,000 pipe support drawings, the statistically required number of pipe supports (59) were found which made use of struc-tural angles or channels. Accordingly, the 59 pipe supports were reviewed to determine what weld patterns were used for the design basis.
Thirty-eight (38) pipe supports did not use a weld pattern in which weld section properties could be reduced through the use of optional weld pattern.
The remaining twenty-one (21) pipe supports were evaluated under an assumption that the " weakest" cptional weld patterns were implemented during installation.
The result of this evaluation confirms that use of the weakest optional weld pattern for these twenty-one (21) supports results in stresses that are below code allowables.
It is concluded tha. with at least 95% confidence that 95% of the total population of pipe supports with structural angles and/or channels is acceptable and fall into one of the followirig categories:
o Where the optional weld pattern was implemented during installation of structural angles and/or channels, the pipe supports were already designed on the basis of the " weakest" optional weld pattern.
o Although the " weakest" optional weld patterns may have been imple-mented during installation, instead of the design basis weld pattern, the calculated stresses are below code allowables.
This condition has no impact on plant safety and is not reportable.
t r,
~
e Figure 5 WELD PATTERN OPTION I
tamm WELD PATTERN WILO PATTERN SPECWlED ON PtPE OFTION ALLOWED BY SUPPORT ORAWING PECIFICATIOh THE SECTION AL PROPERTIES OF THE OPfl0NAL WE LD PATTERN (ON RIGMTl A RE LOWER TMAN THE PATTERN SPECIFIED ON ORAWING (ON LEFTI.'USE OF OPTIONAL PATTERN RESULTS IN INSTALLEO WELO WITM LNER LDAD CAPACITY TMAN INTENDED BY DESIGN.
i 5
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