AbstractAn extended series of exponential experiments was carried out utilizing233UO2-ThO2fuel elements in uniform arrays in light and heavy water. In this series the principal parameters measured were material buckling (), reflector savings (λ), dysprosium disadvantage factor (ζDy), ratio of epicadmium to subcadmium capture in thorium (), and ratio of232Th fission to233U fission (). A total of 29 clean and poisoned lattices was measured.