Material Bucklings for 1.002, 1.25, and 1.95 wt% Uranium-235-Enriched Uranium Tubes in Light Water

Material bucklings and extrapolation distances were measured for several slightly enriched uranium-metal tube lattices and tube-in-tube assembly lattices in light water. The tubes measured were: 1.002 wt% ²³⁵U enriched uranium (2.34-in. o. d.; 1.79-in. i. d.); 1.25 wt% ²³⁵U enriched uranium (2.37-in. o. d.; 1.80-in. i. d.); and 1.95 wt% ²³⁵U enriched uranium (2.28-in. o. d.; 1.41-in. i. d.). The tube-in-tube assemblies measured were: 1.002 wt% ²³5U outer tubes (2.34-in. o. d.; 1.79-in. i. d.) containing 1.002 wt% ²³⁵U inner tubes (1.18-in. o. d.; 0.49-in. i. d.); and 1.25 wt% ²³⁵U outer tubes (2.37-in. o. d.; 1.80-in. i. d.) containing 0.95 wt% ²³⁵U inner tubes (1.18-in. o. d.; 0.48-in. i. d.). Maximum bucklings for the tubes were found to be 25.00, 47.00, and 83.00 m^-2 , respectively; and for the tube-in-tube assemblies, 23.50 and 38.50 m^-2 , respectively. Based on the measurements, critical parameters for use in nuclear safety analyses were calculated.