Reactor noise in accelerator driven systems

• Published in: Annals of nuclear energy 2003, Vol.30 (2), p.223-243
• Main Author: Degweker, S.B.
• Format: Article
• Language: English
• Subjects: Acoustic noise; Actinides; Fission products; Protons; Radioactive wastes; Reaction kinetics
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/S0306-4549(02)00051-8

Reactor noise methods have long been used for measuring reactor kinetics parameters in low power critical and sub critical reactors. The recent interest in accelerator driven sub critical systems (ADS) and the necessity of monitoring their degree of sub criticality has created a renewed interest in these methods. In this paper we derive formulae for interpreting some of the classical noise methods such as Rossi alpha, the variance to mean, auto correlation and power spectral density, as well as some recently proposed methods, such as the cross power spectral density between the proton current and the neutron detector signals for systems driven by periodically pulsed sources having a large multiplicity. It is shown that the rather high contribution due to the large multiplicity of the accelerator driven source to the variance (or any other measure of the noise) is significantly different for a periodically pulsed source as compared to that for Poisson source events.