Abstract: The one-dimensional large leakage sodium-water reaction analysis program LLEAK was used to analyze the pressure distribution in the sodium-water reaction test system under large leakage conditions. The results show that the bursting discs at inlet and outlet of reaction vessel have no action on the system peak pressure of 0.92 MPa, when the water leakage rate is 57 g/s and the sodium circulation flow rate is 10 m³/h or 20 m³/h. Therefore, the bursting disc action setpoint should be reduced from 1.0 MPa to 0.8 MPa to ensure the system pressure is at a low level. Otherwise, the system pressure peak reaches 1.4 MPa at the water leakage rate of 290 g/s. To meet the safety of the equipment, the equipment should be able to withstand at least 2.0 MPa. With the increase of sodium circulation flow rate, the influence of sodium-water reaction on the pressure of buffer tank is reduced at the condition of larger water leakage. And with the increase of sodium circulation flow rate, the influence of sodium-water reaction on the pressure of buffer tank is deteriorated at the condition of smaller water leakage.