| |
Search Options | |||
| Index | Site Map | FAQ | Facility Info | Reading Rm | New | Help | Glossary | Contact Us | |
|||
ACCESSION #: 9812300224
NSD-NRC-98-5819
December 22, 1998
U.S. Nuclear Regulatory Commission
Attn: Document Control Desk
Washington, DC 20555
Subject: Interim Report of an Evaluation of a Deviation or Failure to Comply Pursuant to 10CFR21.21(a)(2).
The following information is provided pursuant to the requirements of 10CFR Part 21 to submit an Interim Report on issues for which an evaluation of reportability will not be completed within 60 days from the discovery of the deviation or failure to comply. An Interim Report is enclosed for the following Potential Issue under Westinghouse evaluation:
LOCBART Computer Code Error - Interim Report 98-029
If you have any questions regarding this matter, please contact me at 412/374-5282.
| Sincerely,
H. A. Sepp, Manager |
Attachment 0124S
NSD-NRC-98-5819 December 22, 1998
Interim Report No. 98-029
Date: 12/22/98
| SUBJECT: | Interim Report of an Evaluation of a Deviation or Failure to Comply Pursuant to 10CFR21.21(a)(2). |
| TITLE: | LOCBART Computer Code Error |
| BASIC COMPONENT SUPPLIED BY: | Westinghouse Electric Company |
| NATURE OF DEVIATION: | Westinghouse has identified a potential issue related to a logic error discovered in the LOCBART code which causes the cladding zirc-water oxidation calculations to be performed three times per timestep. Preliminary investigation has shown that, while correcting the error is expected to result in a reduction in local cladding oxidation, the corresponding heat deposition in the cladding is expected to increase, which could result in an undetermined increase in large break LOCA peak cladding temperature. |
| DATE OF DISCOVERY OF DEVIATION: | October 23, 1998 |
| EVALUATION STATUS: | Westinghouse is continuing to evaluate the deviation to fully characterize the impact of the deviation. Westinghouse is currently evaluating a possible revision to the model used to interpolate blowdown fluid boundary conditions onto the finer axial nodalization that is modeled in LOCBART. Preliminary studies have shown that the reduction in cladding temperatures resulting from this revision is sufficient to offset the increase in cladding temperatures that results from correcting the error in the zirc-water oxidation logic. |
| In addition, the Westinghouse Owners Group (WOG) PI Core Team has been apprised of this situation. | |
| EVALUATION COMPLETION SCHEDULE DATE: | June 30, 1999 |