TXX-6132, Final Deficiency Rept CP-86-26 Re Steam Generator Upper Lateral Restraint Embedment Design.Initially Reported on 850719.Issue Not Reportable Under 10CFR50.55(e)
| ML20215D749 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/03/1986 |
| From: | Counsil W, Keeley G TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| CP-86-26, TXX-6132, NUDOCS 8612170021 | |
| Download: ML20215D749 (2) | |
Text
m Log # TXX-6132
- 3 File # 10110 903.8 TEXAS UTILITIES GENERATING COMPANY SKYWAY TOWER
Mr. Eric H. Johnson, Director Division of Reactor Safety and Projects DEC - 9 G86 U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 y
Arlington, Texas 76012 4
SUBJECT:
COMANCHE FEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS 50-445 UPPER LATERAL RESTRAINT EMBEDMENT DESIGN SDAR: CP-85-26 (FINAL REPORT)
Dear Mr. Johnson:
On July 19, 1985, we verbally notified your Mr. D. Powell of a deficiency regarding the Unit I steam generator upper lateral restraint embedment design.
This is a final report of a potentially reportable item under the provisions of 10CFR50.55(e). Our last interim report was logged TXX-6063, dated October 27, 1986.
The deficiency involves the design / analysis of the steam generator upper lateral (SGUL) beam anchorage. Specifically, the beam end movement contribution to embedment pullout forces was omitted, and an unjustified assumption, that the mobilization of shear friction would resist embedment pullout stresses, was used in the analysis.
Evaluations were performed for LOCA loading under a design bounding assumption where the steam generator compartment platforms are considered removed (resulting in higher pressures in the upper portion of the compartment).
From these evaluations it has been concluded that the pullout stresses in the SGUL beam end anchorage at the 45 degree wall will exceed the ACI allowable when the higher pressure loads are considered. However, local overstress during a LOCA condition is permitted when there is no loss of function of any safety related system (see FSAR Section 3.8.4.3.2).
Confirmatory calculations were performed to demonstrate that the SGUL beam and concrete structure to which it is connected would perform their required function (i.e. support the steam generator during the LOCA).
Furthermore, the above evaluation was in progress before General Design Criterion (GDC) 4 was modified by rulemaking as published in the Federal Register (April 11,1986).
This rule allows the exclusion from the design basis, of the dynamic effects associated with the rupture of primary coolant loop piping. Had this rule been applied to the above analysis, peak LOCA forces would be reduced to approximately cne half.
The values used in this analysis and the SGUL beam embedment stresses would be reduced accordingly.
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w TXX-6132 December 3, 1986 Page 2 of 2 We have concluded that in the event this issue had remained undetected, no condition adverse to safety would exist. This issue is not reportable under the provisions of 10CFR50.55(e).
Records supporting this conclusion are available for your inspector's review at the CPSES project site.
Very truly yours,
&vEGmit W. G. Counsil By:
c'.
G. S. Keeley Manager, Nuclear Li nsing_
BSD/amb c - NRC Region IV (0 + 1 copy)
Director, Inspection & Enforcement (15 copies)
U. S. Nuclear Regulatory Commission Washington, D. C.
20555