ML19257C040
| ML19257C040 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 12/31/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| NUDOCS 8001240016 | |
| Download: ML19257C040 (1) | |
Text
'
l'%
ffsin nue,Io u
UNITED STATES g
y,e g
NUCLEAR REGULATORY COMMISSION 3p E
REGION 1 8, i k[
631 PARK AVENUE
+, V
,o' KINO oF PRUSSIA, PENNSYLVANIA 19406 Docket No. 50-213 DEC 311979 Connecticut Yankee Atomic Power Company ATTN: Mr. W. G. Counsil Vice President - Nuclear Engineering and Operations P. O. Box 270 Hartford, Connecticut 06101 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, I i 4V BoyceH.G[e Director
Enclosures:
1.
IE Information Notice No. 79-36 2.
List of Recently Issued IE Information Notices CONTACT:
L. E. Tripp (215-337-5282) cc w/encis:
R. Graves, Plant Superintendent D. G. Diedrick, Manager of Quality Assurance J. R. Hime1 wright, Licensing Safeguards Engineer 1796 265 0 14 8001240 A
ENCLOSURE 1 UNITED STATES SSINS No.:
6870 NUCLEAR REGULATORY COMMISSION Accession No:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250519 WASHINGTON, D.C.
20555 n.
e_,
DwJ 1
Siff IE Information Notic: No. 79-36 Date: December 31, 1979 Page 1 of 1 COMPUTER CODE DEFECT IN STRESS ANALYSIS OF PIPING ELBOW Description of Circumstances:
The N'O 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 (ELBOW-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 ELS0W 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 Notica is providcd as early notification of a possible signif-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.
i 9b 2bb
ENCLOSURE 2 IE Information Notice No. 79-36 Date:
December 31, 1979 Page 1 of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued to Notice No.
Issued 79-12A Attempted Damage to New 11/9/79 All Fuel Facilities, Fuel Assemblies Research Reactors and Power Reactors with an Operating License (OL) or Construction Permit (CP) 79-27 Steam Generator Tube 11/16/79 All Power Reactor Faci-Ruptures at Two PWR lities with an OL or CP Facilities 79-28 Overloading of Structural 11/16/79 All Power Reactor Faci-Elements Due to Pipe Support lities with an OL or CP Loads 79-29 Loss of Nonsafety Related 11/19/79 All Power Reactor Faci-Reactor Coolant System In-lities with an OL or CP strumentation During Operation 79-30 Reporting of Defects and 12/6/79 All Power Reactor Faci-Noncompliances, 10 CFR lities with an OL Part 21 or CP 79-31 Use of Incorrect Ampliffed 12/13/79 All Power Reactor Faci-Response Spectra (ARS) lities with an OL or CP 79-32 Separation of Electrical 12/21/79 All Power Reactor Faci-Cables for HPCI and ADS lities with an OL or CP 79-33 Improper Closure of Primary 12/21/79 All Power Reactor Faci-Containment Access Hatches lities with an OL or CP 79-34 Inadequate Design of Safety-12/31/79 All Power Reactor Faci-Related Heat Exchangers lities with an OL or CP 79-35 Control of Maintenance 12/31/79 All Power Reactor Faci-and Essential Equioment lities with an OL or CP 1796 267