Application of noise analysis in determination of moderator temperature coefficient of reactivity in Candu

In Pressurized Light Water Reactors (PLWR) the at-power Moderator Temperature Coefficient (MTC) of reactivity represents a major safety parameter, important in licensing of these reactors. Recently, there have been advances in applications of noise analysis technique in determination of the (MTC of reactivity for PLWR's (Demaziere, 2002.) using 'on-line' measurements. The main benefit of the calculation of MTC with the noise analysis technique is that it does not require interruption of reactor operation. The noise analysis technique utilizes the fact that MTC is 'hidden' in correlations (Holbert and Venkatesh 1995.) between the noise in the moderator temperature signal and the noise in the reactivity (estimated through point-kinetics theory). There is an interest to extend the application of the noise analysis methods into a computation of reactivity coefficients in CANDUs. Also, it should be noted that Candu reactors are equipped with reactivity control devices called Light water Zone Controllers (LZC), which are used under normal operating conditions to control core excess reactivity. Light water level in these devices is known to be highly correlated with the core reactivity and is easily and constantly measured. The present study demonstrates that it is possible to use station measurements in order to estimate the moderator temperature coefficient during normal reactor operation using existing instrumentation. (authors)