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Suzuki, Katsuo; Suzudo, Tomoaki; Nabeshima, Kunihiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.24 - 33, 2004/03
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.
Suzuki, Katsuo; Nabeshima, Kunihiko; Yamane, Tsuyoshi; Fujii, Yoshio*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(4), p.408 - 417, 2003/12
On-line and real-time estimation of time-varying reactivity in a nuclear reactor is necessary for early detection of reactivity anomaly and safe operation. Using a digital nonlinear H estimator, an experiment of real-time dynamic reactivity estimation was carried out in the VHTRC of JAERI. Some technical issues of the experiment are described, such as reactivity insertion, data sampling frequency, anti-aliasing filter, experimental circuit and digitalizing nonlinear H
reactivity estimator, and so on. Then, we discussed the experimental results obtained by the digital nonlinear H
estimator with sampled data of the nuclear instrumentation signal for the power responses under various reactivity insertions. Good performances of estimated reactivity were observed, with almost no delay to the true reactivity and sufficient accuracy between 0.05cent and 0.1cent. From the results of the experiment, it is concluded that the digital nonlinear H
reactivity estimator can be applied as on-line real-time reactivity meter for actual nuclear plants.