Patent Number: 
Section: abstract

A moderator temperature coefficient measurement apparatus includes: an input section receiving plant data including a coolant temperature signal being time series data on a temperature of a coolant of a light water reactor, and a reactivity signal indicating time series data on a reactivity calculated based on a detection value of a neutron flux in the light water reactor; a singular value decomposition section decomposing the coolant temperature signal into N components T′1 (t) to T′N (t), and the reactivity signal into M components ρ′1 (t) to ρ′M (t) by a singular value decomposition method; a combination section generating a selected combination being a combination of T′i (t) selected from the N components T′1 (t) to T′N (t) and ρ′j (t) selected from the M components ρ′1 (t) to ρ′M (t); and a temperature coefficient calculation section calculating a moderator temperature coefficient based on auto and cross power spectral density functions obtained by applying a Fourier transformation to the selected combination. The moderator temperature coefficients can be detected at high precision without changing states of the plant.