Determination of PWR Control Rod Position by Core Physics and Neural Network Methods

A method is described by which the axial position of a control rod can be determined. The method is based on the influence of a partially inserted control rod on the axial flux profile. By measuring this flux profile, the control rod position can be in principle unfolded. One problem is however that the relationship between rod position and flux profile is rather implicit and cannot be explicitly inverted. Thus, it is suggested here to use neural network techniques to unfold the rod position from the measured flux profile. For training of the network, a large number of flux profiles are needed, corresponding to various known rod positions. These data can be generated by advanced core calculational codes. In this study, the Studsvik core master system SIMULATE was used. The method was tested with good results on both fully simulated data as well as on a measurement taken at the Swedish pressurized water reactor Ringhals 4.