Noise analysis estimation of the moderator temperature coefficient for a PWR fuel cycle

Measured neutron and thermocouple noise performed close to the beginning and end of a 1400 MW pressurized water reactor cycle are presented. A lower coherence between the neutron and temperature fluctuations was measured for most of the analyzed signals close to the end of the fuel cycle, showing therefore the H \ and H2 moderator temp(~rature coefficient estimations a higher scattering. This behaviour is interpreted as being caus(~d by changes of the space dependent neutron response to the temperature fluctuations according to variations of the fuel composition and operation conditions throughout the fuel cycle. The bias due to the different axial position of the neutron and temperature sensors is reduced using a 10 model of temperature fluctuations inside as ell as outside the core. The resulting moderator temperature coefficient magnitudes are compared with the design-predicted values for the beginning and end of the fuel cycle