ML17296A925
| ML17296A925 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/21/1980 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | |
| Shared Package | |
| ML17296A924 | List: |
| References | |
| ANPP-15971-TEC, NUDOCS 8008270226 | |
| Download: ML17296A925 (8) | |
Text
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U.
S. Nuclear Regulatory Commission Region V
Walnut Creek Plaza Suite 202 1990 North California Boulevard Walnut Creek, California 94596 Attention:
Mr. G.
S. Spencer, Chief Reactor Construction and Engineering Support Branch
& <QCSEQEHR53'F P. O. BOX 2I666 PHOENIX'RIZONA85036~ii/ I
~>> tf July 21, 1980 ANPP-15971-JEC/BSK
Subject:
A 50.55(e)
Reportable Condition Relating to Inadequately Design Reinforcing Steel in the Walls of the Main Steam Support Structure for Unit 1
File:
80-019-026
Reference:
Telephone Conversation between G. Hernandez and B.
S. Kaplan on June 20, 1980 (DER 80-17)
Dear Sir:
Attached, is our final written report of the reportable deficiency, under 10CFR50.55(e),
referenced above.
Very truly your 5-F. ~l n~
E. E. Van Brunt, Jr.
APS Vice President Nuclear Projects ANPP Project Director EEVBJr/JEC:skc Attachment
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t U. S. Nuclear Regulatory Commission Attention:
Mr. G.
S.
- Spencer, Chief ANPP-15971-JEC/BSK July 21, 1980 Page 2
CC'ictor Stello, Jr., Director Office of Inspection and Enforcement U.
S. Nuclear Regulatory Commission Washington, D. C.
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Robb Pasnacht Ide Kaplan Rogers Allen Wilson Bingham Stubblefield Bashore Welcher Hawkinson Brand
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FINAL REPORT REPORTABLE DEFICIENCY 50.55(e)
ARIZONA PUBLIC SERVICE COHPANY (APS)
PVNGS UNIT i/1 I
Descri tion of Deficienc The five-way restraints for the Main Feedwater (hfFN) lines are supported by the walls of the main steam support struc-ture (HSSS).
These structural steel restraints had to be designed elastically for postulated pipe break loads in order to minimize the movement of the HFW pipe.
A dynamic load factor (DLF) of 2.0 is conservatively selected whenever a constant force is suddenly applied to a linear elastic support system.
This DLF was utilized in the design of the five-way restraints.
- However, a DLF inadvertently was not used in the design of the concrete walls of the MSSS.
This condition was discovered during a final design review.
II Anal sis of Safet Im lications The HSSS and its five-way restraint is required to restrain and to minimize the movement of the HFW line in the event of a postulated pipe break.
In an investigation of the HSSS walls to resist the postulated pipe break loads with a DLF of 2.0, one local area of the exterior wall was shown to be overstressed. with regard to elastic stress limits.
While this condition does not necessarily mean that the wall would fail, it does imply that there would be local yielding of the wall, which could result in unacceptable movement of the pipe.
This condition is considered a reportable deficiency based on two considerations:
- l. If the condition were not detected and corrected, it is possible that it would be significant to safety.
2.
This condition was not detected during the initial design review.
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Final Report Page 2
III Corrective Action For Units f/2 and f/3, a design change was made by adding additional reinforcing steel and increasing the design strength of the concrete, so that the NSSS meets the established design criteria (Drawings 13-C-ZCS-700, Revision 6; 701, Revision 6, DCN //6 and //7; and 702, Revision 4, DCN
/36 and /f7).
For Unit i/1, a design change package will be implemented so that the design meets all established criteria, by adding an adequately supported steel beam under the wall so that the original design basis for the wall is satis-fied.
All engineering personnel responsible for the design have been instructed to carefully check to assure that all applicable criteria are included in the design.
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