Development of a faulty reactivity detection system appling a digital H estimator

Suzuki, Katsuo; Suzudo, Tomoaki   ; Nabeshima, Kunihiko  

This paper concerns an application of digital optimal H estimator to the detection of faulty reactivity in real-time. The detection system, fundamentally based on the reactivity balance method, is composed of three modules, i.e. the net reactivity estimator, the feedback reactivity estimator and the reactivity balance circuit. H optimal filters are used for these two reactivity estimators, and the nonlinear neutronics are taken into consideration especially for the design of the net reactivity estimator. A series of performance tests of the detection system are conducted by using numerical simulations of reactor dynamics with the insertion of a faulty reactivity for an experimental fast breeder reactor JOYO. The system detects the typical artificial reactivity insertions of 1￠ within a few seconds with the accuracy of 0.1￠, and is satisfactory for its practical use.