ML20024F097
| ML20024F097 | |
| Person / Time | |
|---|---|
| Issue date: | 08/22/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19292B403 | List: |
| References | |
| NUDOCS 8309080225 | |
| Download: ML20024F097 (4) | |
Text
P TOPICAL REPORT EVALUATION ENCLOSURE.2 Report Nos. and Titles:
WCAP-8821 (Proprietary) and WCAP-8859 (Non Proprietary) TRANFLO Steam Generator Code Description WCAP-8822 (Proprietary) and WCAP-8860 (Non-Proprietary) Mass and Energy Releases Following A Steam Line Rupture Report Date:
September, 1976 Originating Organization: Westinghouse Reviewed By:
Containment Systems Branch, Office of Nuclear Reactor Regulation Summary of Topical Report The above topical reports describe:
(1) a method utilizing the MARVEL code for the calculation of mass and energy releases to the containment following a postulated break in a main steam line, and (2) the TRANFLO
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code which predicts the breakflow quality assumed in the MARVEL calcula-tion. The reports are issued in Proprietary (P) and Non-Proprietary (non-P) versions.
The application of the MARVEL code is discussed in WCAP-8822 (P) and WCAP-8860 (non-P). 'The resulting mass and energy release data calculated using MARVEL are included in Appendix A of the above topical reports as part of Westinghouse Standard 12.2 Rev.1.
i The Westinghouse standard presents data for a spectrum of break sizes as a function of power level. The standard also provides a prescription for modifying the data tables to account for the specific plant conditions of any 3 or 4-loop Westinghouse plant, with Model D or Model 51 steam generators.
The MARVEL code that is used to generate the mass and energy release data for steam line breaks is also used for various 8309080225 830822 PDR TOPRP ENVWEST C
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h1 types of accide'nt and control studies, including startup of an inactive loop, loss of reactor coolant flow, reactivity insertion incidents, steam "line break accident, and steam generator tube rupture accident. A des-cription of the MARVEL code is given in WCAP-8843 which is under a separate review by the NRC.
The MARVEL code provides a multiloop description of the primary system in-cluding the core, pressurizer, coolant loops, and steam generator. The code describes the core power excursion during a stean line break and the resulting heat flow to the primary sytsem which can then be transferred to the steam generator and into the containment.
A specific input to MARVEL for the calculation of mass and energy releases is the quality of the flow emanating from the postualted steam line break as a function of time. This input is calculated by the TRANFLO code, which is described in WCAP-8821 (P) and WCAP-8859 (non-P). Quality is a measure of dryness of the flow, ranging from 1.0 (dry steam) to O (sa-turated liquid).
An increment of 0.1 is conservatively added to the qua-lities predicted by TRANFLO before they are input to MARVEL. TRANFLO is a
multinode blowdown code similar ~to SATAN-VI and RELAP-4.
The code provides a detailed description of a " single steam generator whicb includes the U-tube region, downcomer region, steam dor:ie and steam separation equipment. The integral feedwater preheater of the Westinghouse Model D steam generator is modeled as is the downcomer injection of the MODEL 51 steam generator.
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primary system is not modeled in TRANFLO except in the steam generator. The primary system temperature is input as a table of hot leg temperature versus time, which is calculated using the MARVEL code.
The primary loop flow rate is input and assumed to be constant..
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a Since both MARVEL'and TRANFLO require input from each other, iterations may be required between the two codes to 05tain a-convergent solution.
Summary of Regulatory Evaluation The staff has reviewed the a5ove cited topical reports and prepared a detailed evaluation.
Since portions of the staff's evaluation were considered to be proprietary by Westinghouse, a complete version of the evaluation is presented only in the proprietary version of this report.
The staff has concluded that the TRANFLO and MARVEL codes as described in WCAP-8821 (P)/WCAP-8859 (non-P) and WCAP-8822 (P)/WCAP-8860 (non-P), are ac-ceptable for calculating mass and energy release data following a MSLB. The following model modifications were proposed Ey Westinghouse, and have been reviewed and found accepta51e Ey the staff:
(1) the steam generator water level calculation was modified to include a pressure depedency, and (2) heat transfer to steam during tube 5' ndle uncovery has been accounted u
for.
l The mass and energy release data in Appendix A to WCAP-88?2 (p)/WCAP-8860 (non-P) should b~e revised to reflect these changes. The impact of these modifications on earlier plants that used th~e TRANFLO-MARVEL method has been evaluated.
Based on the sensitivity study performed by Westinghouse, we con-clude that the second modification could result in higher temperatures in the lower compartment of an ice condenser plant.
Consequently, additional analysis may be required to justify th'e adequacy of equipment qualification in ice con-denser containments.
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- The MA'RVEL code as described in WCAP-8843, used in performing transient analyses, is currently under a separate review by the NRC.
Following the canpletion of that review, we may require additional analysis to be performed by Westinghouse.
With the exception of the above considerations, we have con ~cluded that the TRANFLO-MARVEL method described in WCAP-8821 (P)/WCAP-8859 (non-P) and WCAP-8822 (P)/WCAP-8860 (non-P), provides a conservative method for cal-culating mass and energy release to the containnent following a main steam-line break.
Our review of the TRANFLO code has Eeen confined to the acceptability of the model to provide input for long term containment analysis and did not include consideratioas for use of the code for other purposes.
In the calculation of mass and energy release data in Appendix A to WCAP-8822 (P) and WCAP-8860 (non-P), Westinghouse has listed the assumptions made for initial steam generator inventory and feedwater system operation during the accident, and has provided a prescription for calculation of steam system op-eration. We' require that applicants using these mass and energy release data l
provide justification By comparing the in-plant design with the assumptions made by Westinghouse, and provide and justify any modifications made to the tables to account for the specific design of their systems. i L