Transitional Reactivity Variation from Natural to Forced Circulation

In order to study the disciplinarian of reactivity variation in the transient state from natural to forced circulation,a calculation model was established for the reactor and primary coolant system based on MATLAB.The calculation results indicate that the coolant flux changes in conformity to hyperbolic tangent curve in the transient state.The coefficient k and flux rising multiple,W∞/W0,determine the flux grads and time for flux to steady.It can effectively improve the minimum reactor period to choose appropriate value of coefficient k in reactor design.And reducing the flux grads of transient state can decrease the peak value of reactivity and increase the security of reactor.