ML19211C829
| ML19211C829 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/31/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Arenal A SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 8001150044 | |
| Download: ML19211C829 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION
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,,a WALNUT CREE K, CALIFORNIA 94S96 December 31, 1979 Docket ?!os. 50-206, 50-361, 50-362 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 91770' Attention: Mr. A. Arenal, Vice President Advanced Engineering Gentlemen:
The enclosed IE Infomation Notice No. 79-36 provides infomation on a computer code defect which can result in incorrect stress values for piping elbows.
Sincerely, R. H. Engelken Director
Enclosures:
1.
IE Infomation Notice No. 79-36 2.
List of Recently Issued Infomation Notices cc w/ enclosures:
J. M. Curran, SCE J. T. Head, SCE J. H. Drake, SCE s o c i i s o o4-t 1744 26F
UNITED STATES SSINS No.:
6870 NUCLEAR REGULATORY C0 MISSION Accession No:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250519 WASHINGTON, D.C.
20555 December 31, 1979 IE Information Notice No. 79-36 COMPUTER CODE DEFECT IN STRESS ANALYSIS OF PIPING ELBOW Description of Circumstances:
The NRC was infomed on December 17, 1979 that a computer code, NUPIPE, used in the stress analysis of pipina systems contained a defect which could result in incorrect stress values at one end of pipina elbows. This defect was iden-tified from discussions with a user of NUPIPE and the NUPIPE code developers.
The stress calculation error can occur when a flexible joint is modeled at the end of an elbow (ELB0W-ELAST0JT connection in NUPIPE terminoloay). This defect in the NUPIPE code is in the transformation of the loads in the ELAST0JT coordin-ate axis to the piping ELB0W coordinate axis. The incorrect coordinate axis transfomation may incorrectly interchange the torsion and bendina moment loads on the pipina elbow. This can result in the incorrect assignment of the stress intensification factor for the individual moments. The correct stress may be higher or lower than calculated by NUPIPE, dependina on the loadino condition.
Four conditions must exist for the possibility of the calculation of an incorrect stress in the NUPIPE code:
1.
an USAS B31.1.0 - 1967 Code analysis is being done, and 2.
an ELBOW-ELAST0JT connection exists, and 3.
an absolute sum of two load cases is beina calculated, and 4.
the ELB0W torsional moment axis does not align with the ELAST0JT local x-axis.
Possible users of the NUPIPE code include the code developer, Stone and Webster, EG&G (Idaho Falls), and those using the Cybernet system. The NRC is currently reviewina the extent of usage of the NUPIPE code and the aeneric implications for other facilities. There is a potential for a similar defect to occur in other pipina analysis computer codes.
This Infomation Notice is provided as early notification of a possible sianif-icant matter.
It is expected that recipients will review the information for possible applicability to their facilities. No specific action is reauested in response to this Information Notice.
If NRC evaluations so indicate, further licensee actions may be requested or reouired.
If you have any questions reaardina this matter, please contact the Director of the appropriate NRC Reaional Office.
No written response to this IE Information Notice is required.
1744 269
IE Infonnation flotice No. 79-36 Enclosure December 31, 1979 RECEllTLY ISSUED IE INFORf4ATION NOTICES Information Subject Date Issued To Notice No.
Issued 79-35 Control of fdaintenance 12/31/79 All power reactor facilities and Essential Equipment with an OL or CP 79-3a Inadeauate Desian of 12/27/79 All holders of power reactor Safety-Related Heat OLs and cps Exchangers 79-33 Imoroper Closure of 12/21/79 All power reactor facilities Primary Containment holding OLs and cps Access Hatches 79-32 Separation of Electrical 12/21/79 All power reactor facilities Cables for HPCI and ADS holding OLs and cps 79-31 Use of Incorrect Amplified 12/13/79 All holders of power reactor Response Spectra (ARS)
OLs and cps 79-30 Reoortinq of Defects and 12/6/79 All power reactor facilities Noncompliance, 10 CFR Part 21.
holdina OLs and cps and vendors inspected by LCVIP 79-29 Loss of flonSafety-Related 11/16/79 All porer reactor facilities Reactor Coolant System holdfrio OLs or cps Instrumentation During Ooeration 79-28 Overloadino of Structural 11/16/79 All power reactor facilities Elements Due to Pipe Support with an OL or CP Loads 79-27 Steam Generator Tube
. 11/16/79 All power reactor facilities Ruotures At Two PWR holding Ols and cps Facilities79-12A Attemoted Damaae To New 11/9/79 All Fuel Facilities, Fuel Assemblies research reactors, and power reactors with an OL or CP 79-26 Breach of Containment 11/5/79 All power reactor facilities Intearity holdina OLs and cps 1744 2f6