Computer-Aided Calibration of a Fine Autorod

A method for accurate calibration of control rods of very small worth starts with a record of flux vs time produced by moving the rod back and forth between its stops a large number of times. This record is converted to reactivity by an inverse-kinetics calculation. The reactivity is fitted to a series of Legendre polynomials in rod position and a series of Gram polynomials in time, the latter to allow for reactor drift.