Reactor noise and its role in safety of critical and accelerator driven sub-critical systems

Reactor noise methods are important due to their passive nature i.e. one can obtain dynamic information from measurements at steady state. The methods have successfully been utilized for diagnostics of faults in different components of research and power reactors. The recent interest ill accelerator driven sub-critical systems (ADS) and the necessity of monitoring their degree of sub-critically has created a renewed interest in noise methods. Due to statistical properties of the external source, theoretical treatment of reactor noise in ADS is different from that of critical reactors. For such sources, we have developed a new theoretical approach. In this paper, we review the subject of noise in critical reactors and ADS. We also present salient features and some results of the theory developed by us. (author)