ML19262B892
| ML19262B892 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 12/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Linder F DAIRYLAND POWER COOPERATIVE |
| References | |
| NUDOCS 8001160300 | |
| Download: ML19262B892 (1) | |
Text
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UNITED STATES bd 8
NUCLEAR REGULATORY COMMISSION o
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REGION 111 o
799 MOOSEVELT ROAD g
OLEN ELLYN ILI,INOIS 60137 DEC ?.81979 Docket No. 50-409 Dairyland Power Cooperative ATTN:
Mr. F. W. Linder General Manager 2615 East Avenue - South La Crosse, WI 54601 Gentlemen:
The enclosed IE Information Notice No. 79-36 provides information on a computer code defect which can result in incorrect stress values for piping elbows.
Sincerely, Yfu"' '^-
UJames G. Keppler Director
Enclosure:
IE Information Notice No. 79-36 cc w/ encl:
Mr. h. E. Shimshak, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Mr. John J. Duffy, Chief Boiler Inspector, Department of Industry, Labor and Human Relations 1754 336 v
8001160 36d
UNITED STATES SSINS No.:
6870 NUCLEAR REGULATORY COMMISSION Accession No:
0FFICE OF INSPECTION AND ENFORCEMENT 7910250519 WASHINGTON, D.C.
20555 m-December 31, 1979 JwJ au Jlnl b
IE Information Notice No. 79-36 COMPUTER CODE DEFECT IN STRESS ANALYSIS OF PIPING ELB0W Description of Circumstances:
The NRC was informed on December 17, 1979 that a computer code, NUPIPE, used in the stress analysis of piping systems contained a defect which could result in incorrect stress values at one end of piping 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 terminology).
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 transformation may incorrectly interchange the torsion and bending moment loads on the piping 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, depending on the loading 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 being 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 reviewing the extent of usage of the NUPIPE code and the generic implications for other facilities.
There is a potential for a similar defect to occur in other piping analysis computer codes.
This Information Notice is provided as early notification of a possible signit-icant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No specific action is requested in response to this Information Notice.
If NRC evaluations so indicate, further licensee actions may be requested or required.
If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
No written response to this IE Information Notice is required.
Enclosure:
List of Recently Issued Information Notices 1754 337
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 79-34 Inadequate Design of 12/27/79 All holders of power reactor Safety-Related Heat OLs and cps Exchangers 79-33 Improper 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 Peactor facilities Noncompliance, 10 CFR Part 21.
holding OLs and cps and vendors inspected by LCVIP 79-29 Loss of NonSafety-Related 11/16/79 All power reactor facilities Reactor Coolant System holding OLs or cps Instrumentation During Operation 79-28 Overloading 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 reactqr facilities Ruptures At Two PWR holding OLs and cps Facilities79-12A Attempted Damage 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 Integrity holding OLs_and cps 1754 338