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-KINKI 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$ subcritical, and that the location of neutron source remarkably influences the sub- criticality 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-α measurement suggests that much more samples should be acquired for the reduction of the experimental uncertainty to the same level as that in the above measurements.

KEYWORDS:

• UTR-Kinki reactor
• subcriticality
• reactivity
• spatial dependence
• source-multiplication method
• source-jerk method
• rod drop method
• Feynman-α experiment
• criticality safety
• coupled-core reactor
• detector position