Proton irradiation is commonly used to mimic neutron irradiation since it is more easily accessible, easier to control and faster/cheaper. However, it is not clear that the proton irradiation reproduces the same microstructural evolution (SPP dissolution, segregation, defects, etc.) as neutron irradiation. Temperature is often used to compensate for the differences and this study aims at studying the effect of temperature and proton dose on the evolution of Zircaloy-4. Two techniques with outstanding capabilities to analyze materials at small length scale are Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT). TEM offers atomic-scale insight to local structure and interactions at surfaces and interfaces such as grain boundaries. On other hand, APT offers access to information on chemical identification and 3-D distribution of trace elements at nano-scale. Thus, individually both techniques are unique in elucidating materials down to sub nano-scale. To carry out comprehensive research on chemical and microstructural changes in Zr alloys, one needs to combine merits of both techniques. This project will focus on the APT part.Since the material microstructure is fundamental to performance of the materials, understanding the correlation between microstructure and macrostructure may explain radiation-induced growth uncertainties and discrepancies. The present proposal plan to pursue understanding microstructural changes, precipitation behavior and mechanical properties of Zr-4 alloys1) Role of solute elements (Fe, Cr and Sn) 2) Role of dosage (0.5, 1.6, and 5 dpa)3) Role of temperature (T=280 C, 350 C) Current materials irradiation by neutrons tests require long exposure times, costly infrastructures and time-consuming post-irradiation examination (PIE). On the other hand, ions irradiation offers high levels of radiation damage on short time scales and inexpensive way to emulate neutron irradiations effects. For these studies, samples have been already irradiated at Michigan Ion Beam Facility (MIBL), University of Michigan.
In-reactor behaviour of Zr-based alloys are very important to the current fleet of reactors. Phenomena like hydrogen pickup, oxidation and growth creep depends on the alloying elements added, neutron dose, the temperture and chemistry of the reactor coolant, etc. This project aims at understanding how irradiaiton changes the material and how well protons can be used to mimic neutron irradiation.
The work performed in this Project directly supports the current fleet of reactors with fundamental research and ties directly into the work performed in the light water reacto sustainability program. Futhermore, the data generated in this project will support modeling of these types of alloys suring irradaition.
