ML20008G177
| ML20008G177 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 06/26/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-81-471-000 10CFR-050.55E, 10CFR-50.55E, PT21-81-471, PT21-81-471-000, NUDOCS 8107020393 | |
| Download: ML20008G177 (2) | |
Text
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June 26, 1981 3
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J si Mr. J s P. O'Reilly, Director 2 JUL 011981
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U.S. Nuci Regulatory Commission k.t, Region II - uite 3100
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101 Marietta treet Atlanta, Geor 30303
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - STEAM GENERATOR BLOOOWN LINE - LOOP NO. 2 PIPING ANALYSIS 3RROR - SQRD-50-328/81 REVISED FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. V. Celenjak on May 6, 1981 in accordance with 10 CFR 50.55(e) as NCR SQN CEB 8112. A final report was submitted on May 26, 1981. Enclosed is our revised final report as discussed with R. V. Crlenjak on June 24, 1981. We consider 10 CFR 21 applicable to this deficiency.
If you have any questicos, please get in touch with D. L. f.aabert at FTS 857-2581.
Very truly yours, TENNESSEE VALLET AUTHORITT L. M. L'. ills, Manager Nuclear Regulation and Safety Enclosure
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cc:
It'. Victor Stallo, Director (Enclosure)V Office of Inspection and Enforcement U.S. Ntrl:a'* Regulatory c - hsion Washiruton, DC 20555 8107020393 Y
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ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT '2, STEAM GENERATOR BLOWDOWN LINE --LOOP NO. 2 PIPING ANALYSIS ERROR SQRD-50-328/81-34 4
REVISED FINAL REPORT Description of Deficiency Piping movements of the steam generator blowdown line, loop No. 2, l
- were greater during hot functional testing than anticipated in the j
design; consequently, certain snubbers would have bottomed out. TVA discovered that' a lateral support that had been installed before hot functional testing had been inadvertently omitted from the thermal load c.se analysis. Omitting the lateral support from the analysis resulted in smaller mov3ments of the piping in the analysis than l
actually occurred.
Safety Implications i
l Snubbers bottoming out due to pipe movements greater than anticipated i
in the design would greatly increase the stresses in the pipe.
L Inordinate increases in these stresses could cause the pipe to break, resulting in a LOCA.
Corrective Action l
As stated in our last report, TVA performed a reanalysis of the I
steam generator blowdown line and found that by omitting the support the analysis would result in acceptable design stress levels for ali postulated load cases. Although our last report stated that modifications would be completed before fuel loading, we have subsequently determined that the support removal is not required until initial system heatup following fuel loaaing. The unacc.eptable condition does not occur until the thermal mode of operation, ana the affected piping and components are not in a thermal transient at fuel loading. Thus, the modification will' be l
completed before system heatup following fuel loading.
TVA has instructed the contractor to ensure that existing check I
procedures, which are designed to catch deficiencies of this nature, are more closely adhere t to.
In addition, TVA has developed an independent checklist to be completed by TVA which reviews the contractor's analyses. This checklist will be attached to the analysis reports, documenting TVA's review.
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