ML18136A420
| ML18136A420 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 12/31/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 8001240084 | |
| Download: ML18136A420 (4) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION REGION II Q
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101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 In Reply Refer To:
RII:JPO 50-338, 50-339 REG~fi.l~Y DOCKET FILE CO:PY 5===04, 50-40==-
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Virginia Electric and Power Company Attn:
W. L. Proffitt Senior Vice President, Power P. 0. Box 26666 Richmond, Virginia Gentlemen:
23261 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.
Enclosures:
- 1.
IE Information Notice No. 79-36
- 2.
List of Recently Issued Information Notices Sincerely,
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James P. O'Reilly Director
Virginia Electric and Power Company cc w/encl:
W.R. Cartwright, Station Manager Post Office Box 402 Mineral, Virginia 23117 P. G. Perry Senior Resident Engineer Post Office Box 38 Mineral, Virginia 23117 W. L. Stewart, Manager Post Office Box 315 Surry, Virginia 23883 DEC 3 1,g7g
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, n.c.
20555 December 31, 1979 SSINS No.:
6870 Accession No:
7910250519 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 computer code, NUPIPE, used in the stress analysis of pip{ng 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 coordi-nate axis to the piping ELBOW c_oordinate axis.
The incorrect coordinate axis transformation may intorrectly 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-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 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 othe{ 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, f1,1rther 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.
IE Information Notice No. 79-36 December 31, 1979 Information Notice No. 79-36 79-35 79-34 79-33 79-32 79-31 79-30 79-29 79-28 79-27 79-12A 79-26 79-25 RECENTLY ISSUED IE INFORMATION NOTICES Date Subject Issued Computer Code Defect In 12/31/79 Stress Analysis of Piping Elbow Control of Maintenance and 12/31/79 Essential Equipment Inadequate Design of Safety-12/27/79 Related Heat Exchangers Improper Closure of Primary 12/21/79 Containment Equipment Access Hatches Separation of Electrical 12/21/79 Cables for HPCI and ADS Use of Incorrect Amplified 12/13/79 Response Spectra (ARS)
Reporting of Defects and 12/6/79 Noncompliances, 10 CFR Part 21 Loss of NonSafety-Related 11/16/79 Reactor Coolant System Instrumentation During Operation Overloading of Structural 11/16/79 Elements Due to Pipe Support Loads Steam Generator Tube Ruptures At Two PWR Facilities Attempted Damage To New Fuel Assemblies Breach of Containment Integrity Reactor Trips At Turkey Point Units 3 And 4 11/16/79 11/9/79 11/5/79 10/1/79 Enclosure Issued To All holders of power reactor OLs and CPs All holders of power reactor OLs and CPs.
All holders of power reactor OLs and CPs All holders of power reactor OLs and CPs All power reactor facilities holding OLs and CPs All power reactor facilities holding OLs and CPs All power reactor facilities holding OLs and CPs and vendors inspected by LCVIP All power reactor facilities holding OLs or CPs All power reactor facilities with an 01 or CP All power reactor facilities holding OLs and CPs