Advanced digital signal processing technique for neutron flux measurement in a nuclear power plant

In a Nuclear Power Plant (NPP), the developed power is proportional to the emitted neutron flux. The concept we introduce is a new wide range neutron monitor, called Marine, which delivers both neutron flux and reactor period information. The basic idea of this work is that the signal coming from the sensor is continuously processed by three lines, each one being dedicated to one third of the 12 decades whole range: respectively pulse, Campbelling, and current modes for the low, intermediate and upper ranges. The main innovations lie in the use of linear electronics together with a very early signal digital conversion followed by an advanced signal processing technique: an extended Kalman filter. We precisely describe this algorithm, and analyse its performance in terms of response time and accuracy for both the flux and the reactor period measurement. We first used a simulation framework, and then real signals measured on an experimental facility. We show here that both are consistent and present a real enhancement in comparison with the existing analogue neutron monitors. These excellent results, together with the intrinsic flexibility of digital techniques led the developers to launch an industrial version.