No abstract

Under the influence of marine conditions on nuclear powered ships, the liquid storage in the Pressurizer shake violently, which affects the normal operation of the Pressurizer and even causes safety accidents. Therefore, it is extremely urgent to design an anti-wave device for the Pressurizer. This paper studies a Pressurizer model with a ring-shaped plate. Using numerical simulation software, the VOF method is used to couple the k-ε model to simulate the liquid level fluctuation of the two Pressurizers with and without anti-wave device under different external excitation cycles. The phenomenon of internal liquid level fluctuation during movement was analyzed, and the pressure transient change characteristics of the pressure monitoring points arranged on the pressurizer were analyzed, so as to compare the different axial sections and the overall water level shaking amplitude. By comparing the simulation results, it is found that when the external excitation period is T = 2∼2.5s, the ring-shaped plate studied in this study can suppress the shaking of the liquid storage in the Pressurizer significantly.

Liquid sloshing will occur in liquid storage tanks such as accumulator of floating nuclear power plant (FNPP) subjected to additional inertial forces under motion conditions. The study carried out measurement experiments based on the 6-DOF platform to study the sloshing characteristics and pressure variation rule of the accumulator. The results show that surging will induce many kinds of nonlinear free surface sloshing forms, it can be seen that the law of pressure variation is mainly dominated by natural frequency and excitation frequency based on time and frequency domain analysis. Then the study combines the automatic encoder and extreme learning machine to build the deep extreme learning machine (DELM) network to predict the pressure in time series. Based on the phase space reconstruction of the time sequence, the pressure results of the next time are output after the last 15 pressure data are input. The prediction results show that the DELM model has fast speed and high precision and the predicted value is in good agreement with the experimental data. So this study can provide a reference for the pressure monitoring and the artificial intelligence application of FNPP.

In case of core emergency cooling safety injection, the boron containing coolant injected externally and dilution water mass will be mixed in the pressure vessel. The uneven mixing of boron containing coolant and dilution water mass may lead to the return of the core to criticality. Therefore, it is of great significance to accurately measure the boron concentration distribution in the pressure vessel and study the mechanism affecting the mixing process for the safe operation of the reactor. In this paper, combined with the structural characteristics of HPR1000 pressure vessel, a visual experimental device is built through proportional modeling design, and the flow mixing process of diluted water mass, safety injection solution and coolant in the pressure vessel under double loop operation is obtained by using plane laser-induced fluorescence technology, the effects of different Reynolds numbers on the diffusion of boric acid were experimentally studied. The experimental results show that under the condition of double loop, the two inlets divide the circumferential direction into good arc and bad arc. The velocity distribution of fluid flowing through the bad arc is more uniform, while the vertical flow of fluid flowing through the good arc is uneven; The fluid flows downward rapidly after the intersection on the inferior arc side, and the intersection height is positively correlated with the cold pipe flow, while the fluid on both sides shows obvious mixing after the intersection on the superior arc side; Clear water mass cannot be avoided at the core inlet, but increasing the cold pipe flow and safety injection flow can reduce the time of clear water mass flowing through the core.

The pressurizer of floating reactor moves dramatically with the of ocean waves, and liquid in pressurizer will slosh when subjected to additional inertial force. To study the hydro characteristics of the liquid in pressurizer, this paper analyzed the flow field and pressure variation of pressurizer under typical moving conditions. Combined with the influence factors of typical motion on the transient pressure variation characteristics at monitoring position under different working conditions, optimize the differential pressure measuring method of liquid level through numerical simulation, result in reduce the liquid level measuring deviation. Traditional numerical approach of liquid sloshing is improved based on the modified motion equation and coordinate transformation matrix approach. Combined with the moving grid and modified algorithm. Through comparison. The results show that the liquid level measuring deviation of heave motion with vertical additional acceleration and the pressure variation of rolling motion is mainly caused by the spatial position variation of the model and the liquid free surface. The mechanism of coupling of heave motion and rolling motion can be comprehensively considered in combination with the influences of every individual motion. In addition, through verification, the liquid level measuring can be corrected according to the attitude data and geometric information of pressurizer.