FEASIBILITY STUDY OF LMFBR LOCAL CORE ANOMALY DETECTION BY USE OF TEMPERATURE AND FLOW FLUCTUATIONS.

A series of experiments on LMFBR local core accidents were carried out in an out-of-pile sodium test loop. In the experiments were used 37- and 61-pin bundle test sections which simulated fuel subassemblies. Throughout these experiments temperature and flow fluctuation signals were measured by thermocouples and by an eddy-current type flowmeter that serve to develop an anomaly detection method with high sensitivity. The experimental results indicate that flow fluctuation at the outlet could be more effectively used for the detection of a large local boiling than temperature fluctuation and that a burst type single cladding failure could be detected by use of the flow fluctuation. We proposed a real time anomaly detection algorithm based on the whiteness test for the residual random process. A study was made on the relation between the algorithm and the spectral error measure and its performance. It shows the applicability of the method to a real time system and the effective features of the algorithm.