REACTIVITY EFFECTS OF LARGE VOIDS IN THE REFLECTOR OF A LIGHT-WATER-MODERATED AND -REFLECTED REACTOR

摘要

Reactivity effects of large voids in the reflector of the Pool Critical Assembly (PCA), an enriched-uranium, light-water-moderated and -reflected reactor, were investigated experimentally and theoretically. The three principal effects which were studied experimentally were:the variation of reactivity with the size of a void located at the center of one face of the core (including a void covering the entire face), the variation of reactivity with void position on the core face, and the superposability of the reactivity effects of voids. The effect of the largest void on the thermal-neutron flux distribution was also measured.