A new and efficient method to measure reactivity in a nuclear reactor.

Due to the gamma radiation, the noise of the electronic system, and the environmental radiation, a significant background exists in the electrical current during the measurement of reactivity through the external detectors, resulting in a significant error of the reactivity, especially at a low-power level. Based on an analysis of the inverse kinetics equation which contains the background term, the impact of the background current to the measured reactivity is analyzed, and a method is introduced which calculates the reactivity in an iterative way. The calculation results are compared with the theoretical value and those obtained by other methods. The iterative method is of sufficient precision and has the advantages in efficiency and convenience. It can be applied in the dynamic control rod worth calibration or used independently in the measurement of reactivity in NPPs. [ABSTRACT FROM AUTHOR]