The measurement of neutron diffusion parameters in heavy and light water concentrations by the pulsed neutron technique

Abstract

Neutron diffusion parameter measurements have been made at 21°C in 20, 50, and 80 percent concentrations of heavy and light water, including pure H20 and D2 0 as moderators. Pulsed neutron techniques were used with a 250-kv Cockcroft-Walton accelerator as the pulsed source. The range of bucklings used was from 0.05 cm⁻² to 0.70 cm⁻². The values for the diffusion coefficient, Dₒ; the diffusion cooling coefficient, C; and the transport mean free path, Atr, were determined from the expansion of the decay constant to second order using iteration procedure. The values of Dₒ, C, and Atr are tabulated below for the various concentrations, including pure H₂O and D₂O.

Percent D₂0 Dₒ x 10⁻⁴ (cm²sec⁻¹) C x 10⁻⁵ (cm⁴sec⁻¹) λtr (cm)

0 3.634±0.048 0.161±0.008 0.443

20 3.779±0.017 0.170±0.032 0.515

50 6.964±0.044 0.74±0.12 0.915

80 11.75±0.68 2.19±0.42 1.602

100 19.66±1.37 3.56±1.08 2.670