b'Figure 3. Ring hoop tensionA variety of mechanical tests willbeing absorbed in the Zircaloy matrix. test, specimen and grip fixturebe used to evaluate the strength andHowever, the distribution of the design along with finite element predictions of strain distribution fracture toughness properties of thecladdings hydrogen content along in the gauge region.hydride cladding, among them thethe 8-inch axial length was highly ring hoop tension test. The goal of thenon-uniform, with peak concentrations ring hoop tension test is to replicatebeing 2-3 times that of the average. the stress state of a uni-axial tensionIt was determined that temperature test with a cladding geometry. Severalnon-uniformities in the furnace were specimen designs, grip designs, andthe main cause of this non-uniformity. loading arrangements were modeledEfforts were undertaken to flatten the using finite element software totemperature profile in the furnace and, determine an optimum configuration.centering features were added to the Loading grips and sample specimensquartz tube to ensure that the center were then fabricated according to theof the cladding always aligned with designs that performed best in thethe hottest location in the furnace. This finite element simulations.successfully reduced the variation in Accomplishments:hydrogen contents to less than 30%. The preliminary results of theThe procurement of a longer furnace hydrogen charging were promising.is also expected to further improve the Removal of the native oxide layerhydrogen uniformity. successfully resulted in the hydrogen 140 2019|AFC ACCOMPLISHMENTS'