A correlation-based approach for evaluating mechanical properties of nuclear fuel cladding tubes

Mechanical properties of Zircaloy cladding tubes and contributions to M.E.T.A. mechanical property database

“…Mechanical tests with SSJ3 specimens at 300°C will be performed in the future. The stress-based correlation properties from ATT to SSJ3 in this work as compared to those reported in Gussev et al [16] are shown in Figure 5a, and the strain-based properties are shown in Figure 5b. For UTS, UE, and TE, the new properties from both rolling and transverse direction tube specimens fell directly on the property curves, and for YS, both specimen machining directions fell acceptably close, suggesting that the anisotropic nature of the Zircaloy plate does not affect its correlations.…”

“…Unfortunately, many of these methods test the tubing as a complicated structure, making mechanical property information difficult to obtain through strain gradients or complex loading paths [2,4]; require precise measurement techniques that are difficult to implement in hot cell environments [6,8]; or consume large amounts of valuable irradiated material [8,11]. As a result, when characterizing the mechanical properties of a tube component, many researchers have machined tensile gauges in the axial or hoop directions [12,13,14,15,16] to perform a more conventional mechanical test to obtain the mechanical properties of the tube in its principal coordinates.…”

“…In some configurations, plastic hinges and bending stresses can saturate once the tensile specimen straightens, which leads to a complex load path on the specimen that is difficult to remove its bias on mechanical test data, especially in a hot cell environment. Furthermore, because the mandrels are loaded along the inside surface of the specimen, frictional forces bias the stress measurements to higher values, and specimens with longer gauge lengths often produce necks at two locations [13,16], making it difficult to relate measured elongation from a mechanical test to real specimen elongation. To overcome these challenges, Oak Ridge National Laboratory developed millimeter-scale axial tension test (ATT) and ring tension test (RTT) specimens that minimize strain gradients across the specimen gauge [18] and consume less material than previous test methods did.…”

“…Despite the successes of the mechanical test methodology, some challenges remain in establishing the testing techniques for wider use. For instance, the data used to correlate mechanical properties between specimen types in Gussev et al [16] were taken from iron-or aluminum-based alloys that are dissimilar to the anisotropic, textured zirconium-based alloys used in the nuclear industry-except for one Zircadyne material tested. To further focus the approach employed by Gussev et al on nuclear materials, work documented in this FY report included the testing of recrystallized, rolled Zircaloy-4 plate, which is a closer analog to industry nuclear claddings, to add that material to the current dataset.…”

“…Mechanical tests with the fully recrystallized Zircaloy-2 plate were performed to obtain correlation factors for the shorter gauge length RTT specimen using a procedure similar to that used in Gussev et al [16] to determine any anisotropy sensitivity to the correlation factors and to investigate potential temperature sensitivity to the correlation factors. Mechanical test results of the ATT, SSJ3, and RTT specimens are shown in Figure 3.…”