Abstract:
Control rod of JRR-3M is composed of follower type fuel and hafnium neutron absorber. The control rod worth (CR worth) is used as important and basic data for management of reactor operation. However, because the control rod worth would be affected by the change of burn up of follower fuel, the reliability of the measured CR worth would be degraded when the burn-up would be different. In order to evaluate the effect, the CR worth in different burn-ups are calculated by simulating the measurement with IK method, and compared with the measured one. This report shows the results of evaluation and also proposes a convenient method to estimate the CR worth with higher reliability.