A method is described for diagnosing the water-water power reactor core components using self-powered neutron detector (SPND) readings. Self-powered neutron detectors are part of the incore instrumentation system. The method monitors both the detector itself and fuel element. The paper’s authors suggest using both steady state and dynamic reactor core conditions for interpretation of SPND readings. Dynamic conditions can be used to determine the coefficients of neutron flux dynamics that are calculated by analogy with determination of reactivity values from output signals of ion chambers in the reactor control and protection system.