Space-Dependent Effect Observed in Subcriticality Measurements for Loosely Coupled-Core System

Abstract

The results of the subcriticality measurements by various techniques performed for the UTR-KINK1 reactor, a light-water-moderated and graphite-reflected coupled-core reactor, are presented. The result of the source-multiplication measurement indicates that the apparent dependence of the subcriticality on the detector position is significantly observed even under a condition 2 8 subcritical, and that the location of neutron source remarkably influences the subcriticality obtained. On the other hand, the spatial dependence in the source-jerk measurement is slight relative to that in the source-multiplication and the rod drop measurements. Furthermore, the result of the Feynman-a measurement suggests that much more samples should be acquired for the reduction of the experimental uncertainty to the same level a s that in the above measurements. Kinki reactor, aubcriticality, reactivity, spatial dependence, source-multiplication method, source-jerk method, rod drop method, Feynman-a experiment, criticality safety. coupled-core reactor, detector position K E Y WORDS: UTR-