IN-CORE NEUTRON DETECTOR MONITORING UNDER STEADY AND DYNAMIC REACTOR CONDITIONS

Abstract

Background. Reliable operation of in-core neutron detectors improves the quality of measurement data processing and make fields of the neutron and power distributions in the nuclear reactor core more efficient. Materials and methods. The article discusses a new method for monitoring the technical condition of self-powered neutron detector (SPND) that is used to measure neutron flux in the nuclear reactor core. The method is based on the measurement of current values of the detector measuring circuit under steady and dynamic conditions. To monitor the state of this neutron detector, it is proposed to determine not only the insulation resistance of the measuring cable, as it is done in traditional methods, but also the generating capacity of the detector emitter. In addition to the given diagnostic parameters, a new diagnostic feature of the controlled object – capacitance of the measuring circuit of the reactor – has been is introduced in this article. Results and conclusions. Determination of the generating capacity of SPND emitter significantly (by 3–4 orders of magnitude) extends the operating range of the detector by the permissible insulation resistance value (less than 106 Ohms). At the same time, we obtain a new method to estimate the degree of electron emitter burnup caused by neutron flux and to monitor the technical condition of detector by the magnitude of its sensitivity to this flux, which increases the reliability of SPND. Determining the capacitance of the measuring cable of the electrical circuit allows you to properly consider this value when measuring the current signal of the activation detector in order to find the reactor neutron flux under the transient modes of operation.

Keywords

• detector
• monitoring
• nuclear reactor
• neutron flux
• diagnostic system
• diagnostic feature
• electrical circuit