DETERMINATION OF THE MTC BY NOISE ANALYSIS METHODS

摘要

Determination of the moderator temperature coefficient (MTC) in Pressurized Water Reactors (PWRs) has been the matter of interest for a long time. The MTC should be within certain limits at all times; it should be negative, but its absolute value should not exceed a certain limit either. Since the MTC changes continuously during the fuel cycle with burnup and the corresponding change in the boron concentration in the water, a monitoring of its value is necessary. The traditional methods that are used to measure the MTC are time consuming and expensive (see Ref. 1). The noise based methods are more flexible but so far they were rather inaccurate with a systematic underestimation of the MTC (see Ref. 1 for a complete list of references in this matter). In recent work we have pointed out that the main weakness of the noise based method is the poor knowledge of the driving source, by measuring the temperature fluctuations only in one radial point whereas those fluctuations are highly space-dependent (see Ref. 1).