STUDIES ON SOURCE EFFECT IN EXPERIMENTAL DESIGN FOR PASSIVE COOLING IN LARGE CAVITIES UNDER LOCA CONDITIONS

摘要

In recent years, most of the advanced Pressurize Water Reactor (PWR) design contains passive cooling features, especially for the containments, which are functioning as the final radioactive emission barriers. To evaluate the best estimation codes for containment design, large scale thermo-hydraulic experimental facilities will be necessary for Code Verification and validation (V&V). Normally, the multi-phase jet is the main source for containment thermo-hydraulic processes under Loss of Coolant Accident (LOCA) conditions. This paper presents the scaling studies of source effects in large cavity experiment facility design. The similarity in core safety features, such as cavity temperature and pressure, is preserved firstly in the scaling and some dominant design parameters are given. Some primary design features are decided. The jet mass flow rate and heat sink surface ratios are provided for the prevailing parameters for system transient simulation. Based on mass and energy conservative equations, the parameters ratio for jet mass flow rate, jet time scale, jet integral energy, break size and expansion structures size are determined. Furthermore, some transient multidimensional phenomena are also considered. A novel six regions hierarchical model is similarly provided specially for cavity space scaling. The interaction between jet and space natural circulation was modeled. The local heat and mass transfer simulation and system level evaluation are coherence in the experimental design. Based on the preceding results, estimation for distortion on experiments can also be made to evaluate the experimental data deviations from prototype design.