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 Computer Codes 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 workstations. 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. Sincerely, ANSYS, Inc. William J. Bryan Quality Assurance Manager cc: Holtec ANSYS, Inc. A. Soler D. Looman M. Imgrund J. Bittner D. Conover *** END OF DOCUMENT ***

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