Part 21 Report - 1996-043
ACCESSION #: 9607100167
ANSYS ANSYS, Inc.
201 Johnson Road Telephone 412-746-3304
Houston, PA 15342-1200 Facsimille 412-746-3434
July 2, 1996
Thomas Greene, NRC/PECB
U.S. Nuclear Regulatory Commission
Mail Stop: 0-11E4
Washington, DC 20555-0001
Ref: 1. Accession 9601190322
2. ANSYS, Inc. letter dated June 24, 1996
3. Holtec Fax dated June 19, 1996
Subj: Request for a Technical Review of a Draft Information Notice
Regarding Erroneous Results from ANSYS 5.0A and ANSYS 5.1
Dear Mr. Greene:
Per our telephone conversation and the two referenced letters,
ANSYS, Inc. and Holtec International believe that Item 1 of Holtec's 10
CFR 21 Notification has been explained and is therefore not an error. We
recommend that an information notice not be sent out on item 1.
To investigate the second item (i.e. disparate results for forces
and displacements are obtained depending upon the techniques employed to
launch the analysis runs), ANSYS, Inc. has performed various analyses
using the Holtec input and has observed minor changes in the results for
cases run on Personal Computers, but identical results if run on
These changes between personal computer results are observed when
models requiring extreme numerical accuracy are solved. We are presently
investigating why this phenomenon occurs. However, we can only reproduce
these differences using ANSYS Revision 5.1.
To correctly identify the cause and scope of this phenomenon, we are
requesting an additional week to investigate.
William J. Bryan
Quality Assurance Manager
cc: Holtec ANSYS, Inc.
A. Soler D. Looman
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