ML19260E187
| ML19260E187 | |
| Person / Time | |
|---|---|
| Issue date: | 12/26/1979 |
| From: | Levine S NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19260E186 | List: |
| References | |
| RR-NRR-79-20, NUDOCS 8002130629 | |
| Download: ML19260E187 (4) | |
Text
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UNITED STATES
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DEC 2 61373
'.MEM'ORANDUM FOR: Harold R. Denton, Director Office of Nuclear Reactor Regulation FROM:
Saul Levine, Director Office of Nuclear Regulatory Research
SUBJECT:
REGUEST FOR ENDORSEMENT OF PROJECT WORKSCOPE
Reference:
Memo fm Denton to Levine dtd Aug. 17,1979, Subj:
Request for Confirmatory Research on LWR Heat Transfer (RR-NRR-79-20)
Enclosed is a project workscope shich addresses some of the high priority data needs identified in the reference. Upon your approval, we will initiate a request for bid acticn to perform this work. The high priority items from the referenre that are addressed by this workscope include the developme,nt of a pest-CHF film boiling heat transfer model for bundles at both high and low flow rates. Discussions on this work have been held between NRR staff (B. Sheron, N. Lauben and Z. Rosztoczy) and WRSR (Y. Y. Hsu, N. Zuber, L. Thompson and H. Sullivan).
Background
Post-CHF hect transfer can be encountered in various stages of postulated reactor accidents. Because of the complexity of the flowing film boiling processes involved, better data, heat transfer models and analysis of the post-CHF heat transfer phenomena are still needed. Much of the complexity is due to the fact that the heat transfer is largely governed by thermal nonequilibrium in the two phase flow.
It is believed that a nonequilibrium heat transfer model is required to provide an adequate description of the nonequilibrium phenomena occurring in a rod bundle.
Nonequilibrium models have been developed in the past and have shown improvements over the present post-CHF correlation, but this work needs to be extended.
This request for bid action would extend this type of he.at transfer model formulation and provide a bundle heat transfer model for both high and low flow rates. Because of the lack of data in certain areas, it will be necessary to provide a data base for correlation development.
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Harold R. Denton DEC 2 01579 Objectives To develop an experimentally and phenomenologically based nonequilibrium heat transfer model for post-CHF heat transfer applicable to both high and low flow rates in rod bundles. The project should include measurement on nonequilibrium conditions existing under controlled flow conditions.
Two phase flow measurement techniques should be developed generically to provide technical support of large scale research projects which will provide nonequilibrium heat transfer data for use in model development.
Estimated Cost The estimated cost is $200,000 per year for a three-year time period.
We believe that the proposed workscope adequately addresses an identified need.
If you agree, please indicata your concurrence by signing in the space provided below and return the original of this memorandum to me.
(W 1
aul Levine, Director Office of Nuclear Regulatory I,esearch
Enclosure:
As stated cc w/ encl:
L. E. Phillips, NRR Endorsement:
I agree that the proposed research is adequate and useful to the NRC regulatory process.
See memorandum Denten to Budnitz, dated January 1980.
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//d/FD Harold R. Denton, Director Date
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Office of Nuclear Reactor Regulation
WORKSCOPE The project involves experiments on heat transfer, modeling of heat transfer phenomena, and some instrumentation development work. The objective of the post-CHF experiments (Item 1) is to provide parametric studies of heat transfer so that a phenomenologically-based model can be developed.
Improved physical understanding and a model are the goal rather than a compilation of heat transfer coefficients. The post-CHF model (Item 2) must be applicable to a large bundle geometry although it may be developed with a simple test geometry and generalized.
Existing bundle data from sources such as THTF, Semiscale and LOFT should provide the bulk of the data to be used for this purpose.
The objectives of the instrumentation development are to provide some support for large scale reflood tests (Item 3.1) while providing needed support for the post-CHF heat transfer experiments (Items 3.2 and 3.3).
1.0 Post-CHF Heat Transfer Experiments 1.1 Utilize proven capability to make heat transfer and nonequilibrium fluid temperature measurements in tubes under controlled condition:;, and perform experiments in the range of low pressure, low mass flow and low to moderate quality, where there are no current data.
Measurements must be taken in a test section of sufficient length so that flow is well developed at the point of measurement.
1.2 The effect of spacers on nonequilibrium film boiling heat transfer and vapor nonequilibrium should be investigated.
1.3 Reflood and quenching phencmena should be studied with emphasis on non-equilibrium phenomena.
Data should be adequate for use in the assessment of nonequilibrium models in best estimate codes such as TRAC.
l.t Nonequilibrium post-CHF heat transfer should be investigated under the conditions expected in a small break accident.
2.0 Hodel Development 2.1 An improved heat transfer model and logic for dispersed flow film boiling should be developed. The model should be phenomenological in nature.
It may include, but is not limited to wall-vapor, wall-drop and drop-vapor heat transfer.
The model should be first assessed with data obtained in this project.
The model should be readily incorporable into the NRC best estimate codes, such as TRAC.
- 2. 2 Existing data from integral experiments should be compared with predictions of post-CHF models, including models developed in this project.
Data sources may include THTF, Semiscale and LOFT, using the local thermal hydraulic conditions supplied by other analysis groups.
Enclosure
.. New data or information that may be needed to allow verification of the 2.3 post-CHF model for bundle geometrics in low flow and low to moderate qua'lity regions should be identified.
A conduction model for the external thermocouple on a fuel rod should be 2.4 This task will include parametric calculations to determine provided.
under what conditions the fin effect and the potential for an induced local quench are greatest.
3.0 Development of Various Instrumentation Techniques Existing probes using capacitance and conductance concepts should be 3.1 refined for measurement of the film thickness and velocity during film Capacitance and boiling with the presence of an interfacial shear. Air-water tests should be conducted conductance concepts should be used.
up to the flood limit in order to determine the effectiveness of the Technical support should be supplied to assure effective use of probe.
film probes in the large scale reflood tests.
The techniques used in Task 1.1 should be applied to the problem of 3.2 measuring the wetted to dry surf ace area ratio during post-CHF nonequilibrium transition boiling.
Non-intrusive instrumentation should be developed as a calibration standard 3.3 for the temperature measurement of superheated vapor.
4.0 Report Schedule A report is required at the end of each year, and it must include a recorrendation for a best-estimate post-CHF model for interim use baseu on information available at that time. A topical report is required in the second year of the contract period. A final model which has been validated by bundle data from large facilities such as THTF should be provided in a topical report due at the end of the contract period.