Equivalence method and transient flow characteristics of the integrated valve

As a new kind of built-in control rod drive technology, the control rod hydraulic drive system (CRHDS) is applied to the 200 MW nuclear heating reactor (NHR-200). The integrated valve (IV) is the key flow control component of CRHDS, realizing the stepping function of control rod. During operation, the rapid action of IV can trigger the water hammer, which can lead to system vibration, noise and instrument damage. Therefore, it is necessary to investigate the transient flow process. The composition and working principle of IV were presented, and the transient flow experiments were conducted. An equivalence method was proposed innovatively, and the transient flow model of IV was established, whose results were in good agreement with the experimental data. Finally, the model was applied to variable parameter conditions. The analysis results show that: IV can be simplified as flow capacitance, flow resistance, internal connecting pipe and closing valve. The water hammer pressure fluctuation amplitude decreases with the increase of valve closing time, cavity volume and system pipe diameter. The water hammer period increases with the increase of cavity volume and system pipe length. The research results provide guidance for the optimization and engineering application of CRHDS.