A study on the jet pump characteristic curve in boiling water reactor

The jet pump models of RELAP5/MOD2, RETRAN-02/MOD3, and RELAP4/MOD3 are compared. From the investigation of the momentum equations, it is found that the normal quadrant jet pump models of these codes are essentially the same. In this paper, it is found that the relationship between the flow ratio, M, and the heat ratio, N, is uniquely determined for a given jet pump geometry provided that the wall friction and gravitational head are neglected. In other words, under the given assumptions the M - N characteristic curve will not change with power level, recirculation pump speed and loop flow rate. The effect of the gravitational head on the M - N curve has been found to be significant for low flow conditions. As a result, a guideline has been given to the definition of the specific energy (or the head ratio). Sensitivity studies on the key parameters have been performed. It is found that the generic M - N curve should not be used for a jet pump which does not have the same nozzle to throat area ratio as that of the generic jet pump