Measurement of power in research reactors using the neutron noise technique

A high precision method based on the neutron noise technique in the frequency domain is proposed to measure the stationary power in a research reactor. An expression of the Power Spectral Density (PSD) was obtained using a theoretical modal solution for the detector field of view. The measured PSD data was fitted using the first term of the solution. The principal theoretical hyphotesis verified experimentally was the predominance of both the fission density fluctuation as the correlated source of noise and the fundamental adjoint kinetic eigenfunction in the detectors' field of view. Measurements were made in natural and forced convection in the RA-6 research reactor located at the Bariloche Atomic Center (CAB), Argentina, in different critical arrangements. For practical purposes it was found that the method can be applied between 10 w and 50 Kw and it does not depend on detector locations. The method was used to calibrate other relative methods in order to measure higher power. The measurements agree with the results obtained using a calorimetric method. (Author)