Simulation Study of Neutronic and Acoustic Methods of Boiling Detection

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J.Shima*; Y.Fujii*; Y.Shino*; H.Araki*

J.Shima*; Y.Fujii*; Y.Shino*; H.Araki*

None

As a part of the work on the development of a diagnostic system for detecting anomalies in the core of a fast breeder reactor, a study is being made on the methods of detecting abnormal reactivity and coolant boiling on the basis computer simulation. The objective of the present simulation study is to obtain some basic information useful for developing sensitive method of signal processing suitable for boiling detection. Neutronic, acoustic and measurement noises as well as reactor kinetics and reactivity estimator are simulated on a hybrid computer and analyzed for various noise conditions using correlation, spectral and coherence analyses. It has been confirmed that the cross-spectral and coherece analyses between neutronic and acoustic signals are effective method for boiling detection provided that the void coefficient of reactivity is sufficiently large and that detection capability is slightly improved by using a discriminator of signal level before making spectral analysis. A simulated boiling detection experiment using a zero power thermal reactor is also planned in order to check the validity of computer simulation.