ML17053B321
| ML17053B321 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/31/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rhode G NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8001150090 | |
| Download: ML17053B321 (6) | |
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Docket No. 50-410 UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA19406 DE'C 3 y 197g Niagara Mohawk Power Corporation ATTN:
Hr.
G.
K.
Rhode Vice President System Project Management 300 Erie Boulevard, West
- Syracuse, New York 13202 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, "Boyce H. Grier 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/encls:
Eugene B. Thomas, Jr.,
Esquire
l e
ENCLOSURE 1
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT MASHINGTON, D. C.
20555 SSINS No.:
6870 Accession No:
'910250519 IE Information Notice No. 79-36 Date:
December 31, 1979 Page 1 of 1 COMPUTER CODE DEFECT IN STRESS ANALYSIS OF PIPING ELBOM Description of Circumstances:
The NRC was informed on December 17, 1979 that a computer
- code, NUPIPE, used in the stress analysis of'iping 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-ELASTOJT connection in NUPIPE terminology).
This defect in the NUPIPE code is in the transformation of the loads in the ELASTOJT 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 831.1.0 - 1967 Code analysis is being done, and 2.
an ELBOM-ELASTOJT 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 ELASTOJT local x axis.
Possible users of the NUPIPE code include the code developer, Stone and Mebster, EGLG (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 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.
ENCLOSURE 2 IE Information Notice No. 79-36 Date:
December 31, 1979 Page l of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Notice No.
Subject Date Issued to Issued 79"12A Attempted 0'amage to New Fuel Assemblies 11/9/79 All Fuel Facilitie's, Research Reactors and Power Reactors with an Operating License (OL) or Construction Permit (CP) 79"27 Steam Generator Tube Ruptures at Two PMR Facilities 11/16/79 All Power Reactor Faci-lities with an OL or CP 79"28 79"29 Overloading of Structural ll/16/79 All Power Reactor Faci-Elements Due to Pipe Support lities with an OL or CP Loads 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 79-31 79-32 79-33 Reporting of Defects and Noncompliances, 10 CFR Part 21 Use of Incorrect Amplified
Response
Spectra (ARS)
Separation of Electrical Cables for HPCI and ADS Improper Closure of Primary Containment Access Hatches 12/6/79 12/13/79 12/21/79 12/21/79 All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lit'ies with an OL or CP All Power Reactor Faci-lities with an OL or CP 79-34 79"35 Inadequate Design of Safety-Related Heat Exchangers Control of Maintenance and Essential Equipment 12/31/79 All Power Reactor Faci-lities with an OL or CP 12/31/79 All Power Reactor Faci-lities with an OL or CP
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