Abstract
Accurate prediction of steam volume fraction and of the boiling crisis (either DNB or dryout) occurrence is a key safety-relevant issue. Decades of experience have been built up both in experimental investigation and code development and qualification; however, there is still a large margin to improve and refine the modelling approaches. The qualification of the traditional methods (system codes) can be further enhanced by validation against high-quality experimental data (e.g., including measurement of local parameters). One of these databases, related to the void fraction measurements, is the pressurized water reactor subchannel and bundle tests (PSBT) conducted by the Nuclear Power Engineering Corporation (NUPEC) in Japan. Selected experiments belonging to this database are used for the OECD/NRC PSBT benchmark. The activity presented in the paper is connected with the improvement of current approaches by comparing system code predictions with measured data on void production in PWR-type fuel bundles. It is aimed at contributing to the validation of the numerical models of CATHARE 2 code, particularly for the prediction of void fraction distribution both at subchannel and bundle scale, for different test bundle configurations and thermal-hydraulic conditions, both in steady-state and transient conditions.
Highlights
Accurate prediction of steam volume fraction and of the boiling crisis occurrence is a key safety-relevant issue
Selected experiments belonging to this database are used for the OECD/NRC pressurized water reactor subchannel and bundle tests (PSBT) benchmark
The activity presented in the paper is connected with the improvement of current approaches by comparing system code predictions with measured data on void production in PWRtype fuel bundles
Summary
A system code shall demonstrate that it is reliable in simulating and predicting the key phenomena of properly selected scenarios. There is still a large margin to improve and refine the modelling approaches taking advantage of more recent techniques that focus on microscopic mechanisms rather than on macroscopic effects, so that more accurate predictions can be obtained and reduction of uncertainties can be achieved In this view, the qualification of the traditional methods (system codes) can be further enhanced by validation against highquality experimental data (e.g., including measurement of local parameters), while in parallel more sophisticated 3D techniques (such as CFD) are developed and assessed. The qualification of the traditional methods (system codes) can be further enhanced by validation against highquality experimental data (e.g., including measurement of local parameters), while in parallel more sophisticated 3D techniques (such as CFD) are developed and assessed One of these databases, related to the void fraction measurments, is the pressurized water reactor subchannel and bundle tests (PSBT) conducted by the Nuclear Power Engineering Corporation (NUPEC) in Japan. Subjected subchannel Heated rod Thimble rod (a) Test sections for sub-channel void distribution measurement
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