Kinetic Parameters in a Plutonium Lattice Containing Water Regions

Reactor noise techniques have been used to determine how the quantity B_eff/I changes when water regions of several sizes and shapes are introduced into a light water lattice of plutonium-enriched rods. The measured value of B_eff/l for the unperturbed uniform lattice was 89 ± 2 sec⁻¹. This value was reduced significantly as successively larger water regions were introduced into this lattice. Calculated values of B_eff/l obtained with a typical reactor design calculational method, agree with measured results to within ±5% for these experiments.