Demonstration of power distribution estimation using ex-core detectors by reactor experiment at UTR-KINKI

Abstract

ABSTRACT A novel core power distribution reconstruction method based on ex-core detectors is demonstrated at the Kindai University Reactor UTR-KINKI. Technology to monitor the interior of the core is critical for assuring nuclear safety. Typical core monitoring systems utilize in-core detectors. However, the harsh environment inside the core degrades detector maintainability and reliability. On the other hand, monitoring using ex-core detectors is difficult due to the lack of information of neutrons. A previous study, therefore, proposed a new power distribution reconstruction method using power correlation between fuel regions, PHOEBE. However, PHOEBE has not been verified experimentally. Thus, the present study demonstrates PHOEBE at UTR-KINKI. The experiment measures the neutron counts using four detectors outside the reflector, and the power distribution was found to be well reconstructed. Furthermore, the present study estimates the power distribution using only two detectors for confirming the effect of power correlation. When the control rod had a large impact on detectors, estimated power distribution was emphasized. By contrast, small control rod effect cases suggested the advantage of PHOEBE. However, a more complex experimental geometry, such as a multi-layered fuel region, is required to more clearly evaluate the effect of considering the power correlation between fuel regions.