ML20073E224
| ML20073E224 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 04/25/1991 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-73771, TAC-73772, NUDOCS 9104300107 | |
| Download: ML20073E224 (10) | |
Text
{{#Wiki_filter:* fr hr 1%uri Gntl a.tv Af s lo nv u h !rar lklat livn Urtti ln o }% u,la nt ,l'Il Itm l@! % frar verratwu, 8 %rtetta. % C.N'HI 1:% t @lCli1 %I DUKE POWER April 25, 1991 U. S. Nuclear Regulatory Commission ATTNt Document control Desk Washington, D. C. 20555 Subjects.McGuire Nuclear Station Docket Numbers 50-369 and -370 catawba Nuclear Station Docket Numbers 50-413 and -414 Response to Conditions Relative to the Use of Topical Report BAW-10173; Supplement (TAC Nos. 73771/73772) By letter dated February 20, 1991, Mr. Robert Martin transmitted the-NRC staff's Safety Evaluation Report (SER) for topical report BAW-10173. -The SER.found the Tcpical Report to be acceptable for referencing in support of future reloads, provided 5 conditions ~which the Staff requested be addressed were met. By letter dated March 14, 1991 responses to these conditions were provided. - In a-subsequent telephone conversation between members of the NRC staff, B& W Fuel. Company, and Duke,- it was determined that additional analysis was necessary to completely address the Staff's concern relative to Condition 1. Accordingly,. a revised response to Condition 1 is provided'in the Attachment. If-there are any questions, please call Scott Gewehr at (704) 373-7581.. Very truly yours, Ow-M. S.- Tuckman topcond/ sag a 910430o107 910425 ~ xN r; PDR-.-ADOCK 05000369 (/ O P-PDR ]/f
t 4 Nuclear Regulatory Comm:.asion April 25, 1991 Page 2 cci Mr. T. A. Reed, Project Manager Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 9H3, OWFN Washington, D. C. 20555 Mr. R.E. Martin, Project Manager Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 9H3, OWFN Washington, D. C. 20555 Mr. S. D. Ebneter, Regional Administrator U.S. Nuclear Regulatory Commission - Region II 101 Marietta Street, NW - Suite 2900 Atlanta, Georgia 30323 Mr. Frank McPhatter B&W Fuel Company 3315 Old Forest-Road P. O. Box 10935 Lynchburg, VA 24506-0935 l
Attachment I Additional Response to Condition 1 for use of BAW-10173 1 Condition 1: A benchmark analysis should be performed to verify appropriatonoss i of the LYNXT modificatic ns and modeling for the analysis of steam lino break with loss of of fsito power (SLB-LOOP). The benchmark analysis should be provided for staff review to confirm the acceptability of the SLB-Loop analysis results. Rosponso: An analysis of the steamlino break transient with offsito power available was provided in reference 1. In response to a staff question, an analysis without offsito power (loss of of fsito power, or LOOP case) was provided in references 2 and 3. For the case whero offsito power is available, full reactor coolant flow is maintained during the entire transient, and the analysis was performed with the single-pass 5-channol 1/8-coro LYNXT model, which had boon reviewed previously as an acceptablo LYNXT coro model. For the LOOP caso, the core thermal-hydraulic conditions are charactorized by natural circulation coolant flow with strong gradients in inlet temperature and power peaking conditions. Thorofore, for this caso a modification was mado to the LYNXT code by incorporating the implicit pressuro-velocity (PV) algorithm to ensure a convergent solution. In addition, a nino-channel, half-core model was used with the coro modeled as three distinct regions, i.e. , a cold region to represent the faulted quadrant, a hot region to represent the combined intact quadrants, and a mix region to provido an interface betwoon the hot and cold core -arnas. As discussed above, analysis of the SLB-LOOP caso required a
- larger, more detailed model than the full-flow caso and an alternato solution scheme, the PV algorithm.
Reference 4 provided a benchmark in which the two modifications woro testod separately by analyzing the SLB transient with offsito power availablo (the full-flow caso), the most limiting SLB transient. The results showed that the difference in results between the two solution schemos is lose than 3% in predicted DNBR while there is no practical difference betwoon the two models for this case (actual calculated difference 0.2%). The benchmark analysis provided in referenco 4 demonstrated that, for the limiting SLB caso, the alternativo models and solution schemes used in LYNXT produce equivalent results. - As an additional demonstration of equivalence, the SLB-LOOP caso has now boon analyzed with the nine-channel model and the SCHEME algorithm. That is, the PV and SCHEME algorithms (SCHEME is the original LYNXT solution algorithm) woro compared for the same low flow SLB transient statopoint, with tne only difference being in the 4
thermal-hydraulio algorithm used for the solution. Figuros 1 through 5 compare the results of the two cases. Figuros 1 and 2 compare the flow rates of each channel. Figures 3 and 4 compare the channel enthalples. Figure 5 shows that the minimum DNDR of the most limiting channel and rod differs by approximately 1 DNB point or 0.5% between the two cases. Analysis with the PV algorithm resulted in a minimum DNBR of 1.88 versus a value of 1.89 found using the SCHEME algorithm. The benefit of using the PV algorithm for this analysis is in the speed of problem execution and its ability to handle the arbitrary flow direction which can occur in some low flow problems. However, for this particular case both algorithms produced virtually equivalent results. l ...~
References 1. Letter transmitting Topical Report DAW-10173, Revision 0, H. B. Tucker to U. S. Nuclear Regulatory commission, March 30, 1989. 2. Letter transmitting Topical Report BAW-10173, Revision 1, H. B. Tucker to U. S. Nuclear Regulatory Commission, October 22, 1990. 3. Letter transmitting Topical Report BAW-10173, Revision 2, M. S. Tuckman to U. S. Nuclear Regulatory Commission, November 28, 1990. 4. latter transmitting Response to Conditions Relative to the Use of Topical Report BAW-10173, M. S. Tuckman to U. S. Nuclear Regulatory Commission, March 14, 1991.
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