TXX-2980, Summary Rept Re Unit 2 Pressure Vessel Misorientation.Caused by Combined Factors,Including Inadequate Communication of Evolving Design Criteria to Designers & Breakdown in Vendor Drawing Review Between Gibbs & Hill & Westinghouse
| ML19263E671 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/30/1979 |
| From: | Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Seidle W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| TXX-2980, NUDOCS 7906200604 | |
| Download: ML19263E671 (3) | |
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TENAS UTILITIES GENERATING COMI%NY 2003 Df4YAN TOWEft
- DALLAS,TEXAM 762ng April 30, 1979 aom TXX-2980
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Mr. W. C. Seidle, Chief Reactor Construction & Engineering Support Branch U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement 611 Ryan Plaza Dr., Suite 1000 Docket Nos. 50-445
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Arlington, Texas 76011 50-446 COMANCHE PEAK STEAM ELECTRIC STATION 1981-83 2300 MW INSTALLATION UNIT N0. 2 PRESSURE VESSEL
Dear Mr. Seidle:
This report summarizes the Unit 2 pressure vessel misorientation, including the causes, the corrective action, and the action taken to prevent recurrence.
How it Happened:
The pressure vessel misorientation was the combined result of several factors including inadequate communication of evolving design criteria to designers and a breakdown in the vendor drawing review inter-face between Gibbs & Hill and Westinghouse.
Initially, Unit 2 was to be a mirror image of Unit 1.
This concept was later modified in certain areas to permit identical components for both units.
The pressure vessel supports were included in this change.
Gibbs & Hill structural designers, however, were not properly informed of.this change in orientation.
Subsequent internal and external communications and vendor drawing review failed to detect the discrepancy. Mechanical and electrical work proceeded on the basis of the correct vessel orientation, and even though the structural drawing passed through these disciplines, as well as Westing-house and TUSI for review prior to issue, the error was never detected.
Corrective Action: Once the problem was identified, a joint review was conducted by Gibbs & Hill, New York, and site construction / engineering personnel. A method of modification was determined that would permit the most reliable and effective means of installing new support foundations in the correct locations while limiting the impact on existing construction.
The full equivalent steel reinforcement of the original structural support has been designed into the replacement support foundations.
This was achieved by coring holes in the appropriate concrete structure for the embed-ment of tie bolts and reinforcing steel. HVAC cooling ducts have been re-routed, as necessary, to complete the necessary design revisions.
2287 H 8 790620064
l P.vge 2 YXX-2980 April 30, 1979
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Preventive Action:
In order to ensure that all other Unit 2 equipment supports and foundations are properly oriented, a review of all applicable drawings was performed. This review confirmed that no other major orienta-tion problems exist. Other examples of misorientation were discovered but not found to have safety implications. These deficiencies have now been corrected or are in the process of correction.
Measures have been taken by Gibbs & Hill to preclude recurrence.
These include the addition of orientation and training workshops to re-emphasize the importance of coordination and interface control in the dispositioning of design information.
The attached sketch illustrates both the original and modified orientations.
More detailed information is available for your review at the jobsite.
Very truly yours,
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R.
. Gary RJG:dla Attachment cc:
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