Nuclear Science User Facilities 116 techniques involving ultrasonic or laser interrogation will require similarly thick materials. Likewise studies on welding or corrosion are best conducted using thick specimens. Other studies on mechanical proper- ties or physical properties are better studied using thinner specimens.The current hex-block specimen inventory covers this full range of sizes. Before sectioning of the two blocks at Westinghouse, each was extensively measured using non-destructive profilometry techniques to assess carbide-induced shrinkage, void- induced swelling, and block bending. Non-destructive time-of-flight ultrasonic measurements were then used to identify the average levels of void swelling and carbide precipita- tion across opposing flats of the two blocks.The first round of cutting to produce 0.5 and 1.0 inch thick “hex-coins” was followed by density measurements and more ultrasonic measurements across the new cut faces. Subsequent sectioning of the hex-coins was followed by addi- tional density measurements and the production of specimens for measure- ment of various mechanical and physical properties, microstructure and microchemistry. Figure 3 provides an example of the second stage of cutting of one coin, to be followed later by cutting of smaller specimens for microscopy, shear punch, and other tests. The original major goal of the hex- block program was to demonstrate that ultrasonic measurements could be used to assess the internal distribu- tion of void swelling and carbide densification in thick components. It was successfully demonstrated that ultrasonic measurements were in full agreement with density-change and microscopy measurements. Some examples of these results are shown in Figures 4-6. Figure 4. Average through- thickness swelling determined between flats 1 and 4 of Block 3 using time-of-flight ultrasonic measurements. Dotted lines indicate the cutting locations that will be used later to produce the 2.5-cm-thick hex coins.