ML19211C828
| ML19211C828 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 12/31/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 8001150043 | |
| Download: ML19211C828 (1) | |
Text
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0 UNITED STATES d
g y y ) _,-,7 ' j NUCLEAR REGULATORY COMMISSION r
REGION V
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1990 N. CALIFORNIA BOULEVARD h#
,o SUITE 202, WALNUT CREEK PLAZA
- ,,,a WALNUT CR E E K, CALIFORNIA 94$96 December 31, 1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin, Jr.
Assistant Vice President Gentlemen:
The enclosed IE Infomation Notice No. 79-36 provides information on a computer code defect which can result in incorrect stress values for piping elbows.
Sincerely,
&'$L R. H. Engelken Director
Enclosures:
1.
IE Infomation Notice No. 79-36 2.
List of Recently Issued Infomation Notices cc w/ enclosures:
C. P. Yundt, PGE F. C. Gaidos, PGE 1744 278 8001150C O
UNITED STATES SSINS No.: 6870 NUCLEAR REGULATORY C0ta1ISSION Accession No:
0FFICE 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 informed on December 17, 1979 that a comouter code, NUPIPE, used in the stress analysis of oipina 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 ELBOW 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 hiaher or lower than calculated by NUPIPE, dependina on the loadina 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 ELBOW 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 oossible sianif-icant matter.
It is expected that recipients will review the information for possible acolicability to their facilities. No specific action is requested in response to this Information Notice.
If HRC evaluations so indicate, further licensee actions may be requested or reauired.
If you have any questions reaardino this matter, please contact the Director of the appropriate NRC Reaional Office.
No written response to this IE Information Notice is required.
1744 271
IE Information Notice No. 79-36 Enclosure December 31, 1979 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued To Notice No.
Issued 79-35 Control of Maintenance 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 Reporting 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 7n Loss of NonSafety-Related 11/16/79 All power reactor facilities Reactor Coolant System holding OLs or cps Instrumsntation During Operation 79-28 Overloadina 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 Attempted 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 27ji