ML20206L961
| ML20206L961 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/23/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206B161 | List: |
| References | |
| GL-83-11, NUDOCS 8811300325 | |
| Download: ML20206L961 (3) | |
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- o,, UNITED STATES 8~ o NUCLEAR REGULATORY CC'MMISSION .
- f. I wAsHiNo TON, D. C. 20S55
- %,.....,l fNCLOStMF. I SAFETY EVAtVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 4
RELATING TO THE USE OF RETRAN COMPUTER CODE !
F0" SYSTEMS TRANSIENT ANALYSIS i PEACH BOTTOM ATCPIC POWER STATION UNITS ? AND 3 '
PHILADELPHIA ELECTRIC COMPANY !
DOCKET NOS. 50-?77 AND 50-178 i
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1.0 INTRODUCTION
The Philadelphia Electric Company (PEco or the licensee) Topical Report PEC0-FMS-0004. "Methods for Performing BW2 Systems Transient Analysis." wis ;
submitted to demonstrate PEco's technical competence to use the RETRAN computer code to perform systems transient analysis for the Peach Bottoa Units 2 and 3. This submittal was made in response to NRC Generic letter 83-11 l (Licensee Qualification for Performing Safety Analyses in Support of Licensing. f Actions. February 4.1983). !
The sub,iect topical report was submitted by PECo in a letter dated September 28, 1987. The licensee's objectives were to demonstrate the adecuacy of the plant modeling techniques and the technical competence of the PEco staff to apply l the RETAAN code and the,aby obtain approval for the RETRAN models to be used for non-LOCA licensing analysis for the Peach Bottom Units.
l In response to staff requests for additional infoNation, supporting material l was provided in PEco's letters of June 6,1988 arid October 11. 1988. The ;
staff has completed its review of the PECo submittals with technten1 assistance from its consultan . International Technical Services. Inc.
(ITS). The staff evaluation is addressed below. A technical evaluation [
report prepared by ITS to support this evaluation is attached.
8011300326 PDR 8G1123 I P ADOCK 05000277 PNV
2 2.0 EVALVATION PEco developed a base plant nodalization for the Nach Bottom Units. The model contains one six-volume steam line, a steam separator, and a non-equilibrium volume representing the upper downcomer. The algebraic slip option and subcooled void medel with one-dimensional kinetics option were selected in the core volumes. The RETRAN separator option utiliziro a non-equilibrium method was selected for a separator component representing the 211 individual steam separators. A non-equilibrium pressurizer model simulates the upper downcomer region wher:. d steam-water interface exists.
The base model also contains two recirculation loops driven by one control system. The centrifugal pump model was used in the recirculation pump volumes and the jet pump model was silected based upon plant measured data for jet pumps. Safety valves were modeled using a fill table based on a standard ASME coefficient of discharge calculational method. The turbine was modeled not by a fluid volume but through use of control logic to compute the turbine speed and steam flow via a f411 PECo has used the RETRAN02 M00004 code for transient analyses presented in the topical report. This version of the code has been modified by the licensee to incorporate changes for user convenience; those modifications do not impact the analyses. The M00004 version of RETRAN02 has been reviewed and found acceptable for use in licensing applications ("RETRAN-02: Acceptance for Referencing of Topical Report EPRI-NP-1850/CCM-A, Revisions 2 and 3 Regarding RETRAN 02/M00 003 and MOD 004 " Octeber 19, 19#8). For benchmarking tne code the ' censee has analyzed three series of startup tests, a safety / relief valve test, trree plant turbine trip tests and an NCC-specified test problem. All analyses were performed with the code and plant model under consideration for approval. The analysis and discussion contr!.buted favorably to PECo's demonstration of proficiency in the use of the code and plant model.
PECo will w:= the RETRAN02 MOD 004 code in the performance of analyses required to support the overall methodology in licensino applications. These results and a sensitivity study will be reported in a future licensing topical report, PECO-FMS 0006, which will provide the overall PECo reload nethodology s .
3 apprrach. Since the present evaluation of PECO-FMS-0004 se.ves only to 4
demonstrate the licensee's technical capability and understanding of the RETRAid code and models in a best-estimate sense, the staff requires additional discussion and justification of the models fnr licensing purposes. This information, as detailed in the attached ITS Technic:1 Evaluation report, includes the following:
(a) a discussion and justification for the use of (1) the jet cump model with a flow t tversal, (ii) the one-dimensienal kinetics option, (iii) the feedwater system model with ability to simulate rapid feeowater flow excursion such as encountered in turbine tests, and (iv) a qualification of the algebraic slip model for licensing transients; (b) a justification of the licensing conditions and safety margins; and (c) a statisticel analysis to determine the uncertainty allowance applied to the delta-CPP calculations.
It is expected that this information will be provided during the review of DECO-FMS-0006. .
3.0 CONCLUSION
The staff concludes that PECo has demonstrated knowledge of the use of the RETRAN code and plant models for best-estimate calculations. The topical i
) report PECO-FMS.0004 and supplemental information may be generally referenced ;
with regard to nodalization and phenomenological modils to support licensing submitttls for the Peach Bottom Units 2 and 3. We find that the licensee has demonstrated technical competency to perform non LOCA analyses using the [
RETPAN code in conpliance with Generic Letter 83-11. Prior to approval of the overall methoda!ngy for licensing applications, however, the licensee should provide justi-*~
- ion for the code and models on a transient-by-transient basis with licensing input conditions and a statistical uncertainty analysis as discussed in Section 2.0 of this Safety Evaluation, i
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