ML20205A194
| ML20205A194 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/01/1986 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8608110320 | |
| Download: ML20205A194 (3) | |
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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401 SN 157B Lookout Plac',"q g?
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AUG O 1886 U.S. Nuclear Regulatory Comission Region II ATTN:
Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Dr. Grace:
BROWNS FERRY NUCLEAR PLANT UNITS 1, 2, AND 3 - NRC-OIE REGION II INSPECTION REPORT 50-259/86-02, -260/86-02, -296/86 SUPPLEMENTAL INFORMATION By my letter to you dated April 17, 1986, we submitted our response to the subject Browns Ferry violation.
Enclosed is supplemental information on violation item 1 concerning pipe support and restraint systems. This supplemental information reflects our current status with regard to system walkdowns and engineering analysis. This was verbally requested by your staff.
If you have any questions, please get in touch with M. J. May at (205) 729-3566.
To the best of my knowledge, I declare the statements contained herein are complete and true.
Very truly yours, TENNESSEE LEY AUTHORITY R. G idley, Di cector Nuclear SafetM and Licensing Enclosure cc:
Mr. James Taylor, Director,(Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission l
Washington, D.C.
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RESPONSE
NRC INSPECTION REPORT NOS.
50-260/86-02 AND 50-296/86-02 J. A. OLSHINSKI'S LETTER TO S. A. WHITE DATED MARCH 4, 1986 Item 1 10 CFR 50, Appendix B, Criterion III, requires that measures shall be established to assure that regulatory requirements and design basis for those systems, and components are correctly translated in drawings and procedures.
These measures shall assure that appropriate quality standards are specified and included in design documents and that deviations from such standards are controlled. The design control measures shall also provide for verifying or checking the adequacy of design.
Contrary to the above, the requirements identified above had not been met in that an inspection of pipe support and restraint systems revealed the following discrepancies:
Unit 3 Reactor Building Closed Cooling Water (RBCCW) System, isometric a.
drawing NI-370-4R contained six pipe supports.
Licensee's representative could not identify any of the design calculations for the above supports or the stress analysis for the piping system.
Pipe support drawing 48N1221-2 in the RBCCW system contained nine pipe supports that were classified as seismic restraints. No design calculations for these supports were found for review.
b.
Unit 2 RBCCW system,. support 9-R209, contained an incorrect assumption of shear force calculation for which the total shear force should have been used instead of one-half the shear force. Calculation sheets 12A, 12B, 12C, and 12D were not checked. The overall calculations for the support t
l appears to be less than satisfactory in terms of thoroughness, clarity, consistency, and accuracy.
Portions of the design calculations and sketches were not checked for 28 pipe c.
supports in the unit 2 RBCCW system. As a result, the adequacy of these supports cannot be assured for safe operation of the plant during a seismic
. event.
This is a Severity Level IV violation (Supplement I) and is applicable to
" units 2 and 3 only.
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Supplemental Information to Item 1 (a) l
--Isometric drawing N1-370-4R was a preliminary drawing to bo used in tIhe reverification walkdown to be performed by TVA on this piping and for all class I piping systems under the 79-14 program.
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TVA is currently engaged in reverifying the as-built condition of the 79-14 scope of work by walkdowns. After the walkdowns, the as-built data gathered will be used to perform reanalysis of all of the 79-14 scope of work. This piping reanalysis will be performed by a T-pipe computer program which will be fully documented and microfilmed. Support design calculations will subsequently be reevaluated to the reanalysis loads for code compliance.
Fully documented support design calculations and drawings will be prepared, checked, and microfilmed for each support.
This work is considered part of TVA's Phase II of the implementation of the 79-14 bulletin to meet code compliance.
Since the subject isometric drawing was the initial step in TVA's Phase II program, the resulting design calculations were not yet prepared to those referenced documents.
However, pipe support drawing 48N1221-2 is an issued drawing, and calculations for these supports could not be located during the inspector's visit; subsequently, the existing calculations were located which reflected a load comparison from unit 2 versus unit 3, evaluated to the unit 3 piping and support configuration.
Under TVA's current Phase II 79-14 program plan, these supports will have separate design calculations documented.
IVA is currently involved in securing sufficient manpower and resources to i
perform this work. All work will be performed by personnel with experience in performing piping analysis and pipe support designs.
In addition, the 79-14 program plans are to tag each support with a unique 2
identifier, and that number will be used as the unique number to be identified on support drawings, support calculations, etc., such that all design documents can be retrieved by that number.
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Supplemental Information to Item 1 (b) and (c)
After review of the identified error, TVA reevaluated all seismic restraints on the unit 2 RBCCW system and performed a detailed reanalysis to determine stress levels in the piping. Although some supports were determined to be inadequate for the design loadings with a safety factor of two, the piping stress levels tenain below the rode allouable w!.ttout these supports. Therefore, the as-built l
condition of the supports and associated piping is acceptable for continued operation.
This specific evaluation by analytical technique reconfirms the engineering judgement made during our 79-14 Phese I 1.rogram for continued operation for the same RBCCW piping system.
As stated above for item 1 (a), TVA is committed to generate the documentation to justify our piping analysis and piping support designs to meet code compliance for all three units for the 79-14 scope of work for BFN.
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