Experimental Study of Quenching Process During Bottom Reflooding Using “Queen” Test Section

Phenomenon of quenching of hot fuels in core during bottom reflooding following loca event is investigated in order to understand the performance cooling process. the study is conducted experimentally using queen test section which allow study of rod surface temperature histories based on which the heat fluxes are estimated. the visual observation is also done to study the boiling regimes. the test variables are initial rod temperature, i.e. 400oc, 500oc and 600oc, and coolant flow rate, i.e. 0,01kg/s, 0.02 kg/s and 0.04 kg/s with constant water inlet temperature of 30oc. the results shows different heat transfer regimes such as film boiling, transition boiling, nucleate boiling and convective single phase heat transfer regimes. for specified initial rod temperature, the higher flow rate provides high rewet velocity and higher maximum heat flux, then quenching process is more effective

Simulation of Operational Conditions of Fassip-02 Natural Circulation Cooling System Experimental Loop

The natural circulation is considered in the design of emergency passive core cooling system in a nuclear power plant. In that context, in order to investigate the characteristics of the natural circulation, FASSIP-02 experimental loop is designed. This paper simulates the various operational conditions with different condition of the heater power, the pipe insulation and the expansion tank's valve using RELAP5 code. The objective is to obtain the best operational conditions of FASSIP-02 once it is built. The simulation results show that the until 50,000 s the steady state condition could not be achieved yet when the heater power greater than 10 kW. The pipe insulation reduced the heat loss to the environment and in turn it causes faster increase of the water temperature inside the pipe. While, if the expansion tank's valve is closed during the operation, the pressure inside the loop would increase, faster when the heater power is higher. It is concluded that in all cases to avoid the saturation condition, the heater power should be maintained lower than 10 kW, especially when the loop pipe is insulated

STUDI EKSPERIMENTAL QUENCHING PADA CELAH SEMPIT.

STUDI EKSPERIMENTAL QUENCHING PADA CELAH SEMPIT. Proses quenching sangat banyak dijumpai di berbagai bidang industri, termasuk bidang nuklir. Khususnya, proses quenching pada celah sempit terkait erat dengan fenomena kecelakaan parah di mana diasumsikan teras yang meleleh dapat terkumpul di bagian bawah bejana reaktor. Eksperimen dan analisis data hasil eksperimen proses quenching pada celah sempit ukuran 0,5 mm dan 7 mm telah dilakukan untuk memahami proses quenching berdasarkan perbedaan lebar celah. Untuk celah ukuran 7 mm, hasil eksperimen dapat digambarkan secara baik untuk beberapa korelasi yang ada, termasuk korelasi untuk pendidikan kolam, sedangkan untuk celah 0,5 mm, sebagian besar korelasi belum dapat menggambarkan hasil eksperimen. Proses quenching pada celah sangat sempit tersebut sangat dibatasi oleh CCFL dan kapilaritas yang sangat berbeda dengan pendidihan kolam. Oleh karena itu pula, quenching pada celah sempit terjadi lebih lama daripada celah yang lebih lebar.Koefisien perpindahan panas maksimum rata-rata untuk celah 7 mm dan 0,5 mm berturut-turut adalah 15 kW/m2k dan 3 kW/m2k

Experimental and Numerical Simulation Investigation of Single-Phase Natural Circulation in A Large Scale Rectangular Loop

In order to anticipate station blackout, the use of safety system based on passive features is highly considered in advanced nuclear power plant designs, especially after the Fukushima Dai-ichi nuclear power station accident. An example is the application of natural circulation in the emergency cooling system. To study the reliability of such an application, a research project on natural circulation was carried out. This paper describes the investigation results on the natural circulation phenomena obtained using a large rectangular experimental loop named FASSIP-01. The experiments were conducted at two different heat source powers. The experimental results are analysed using existing correlation and numerical model simulation. The RELAP5 system code is applied to model the natural circulation. FLUENT computational fluid dynamic code is used to visualize the flow distribution. The experimental results show the establishment of stable natural circulation in all heat power input with the mass flow rate of about 0.0012 kg/s. Calculation using the existing correlation shows that the experimental Reynold numbers are lower than predicted by the correlation. The computational fluid dynamics-based tool could show the three dimensional distribution of the temperature, while the model of RELAP5 predict well the dynamic of the single-phase natural circulation established in the experimental loop. It is concluded that the stable natural circulation have been established in the large rectangular loop and the model of the RELAP5 could simulate the observed natural circulation phenomenon reasonably well