Physical And Mechanical Metallurgy Of Zirconium Alloys For Nuclear Applications

In the post-Fukushima world, thermal and structural stability of materials under extreme conditions is an important issue for the safety of nuclear reactors. Because the nuclear industry will continue using zirconium (Zr) cladding for the foreseeable future, it becomes critical to gain a fundamental understanding of several interconnected problems. First, what are the thermodynamic and kinetic factors affecting oxidation and hydrogen pick-up by these materials at normal, off-normal conditions, and in long-term storage? Secondly, what protective coatings could be used in order to gain valuable time at off-normal conditions (temperature exceeds ~1200°C (2200°F)? Thirdly, the kinetics of the coating's oxidation must be understood. Lastly, one needs automated inspection algorithms allowing identifying cladding's defects. This work attempts to explore the problem from a computational perspective, utilizing first principles atomistic simulations, computational thermodynamics, plasticity theory, and morphological algorithms of image processing for defect identification. It consists of the four parts dealing with these four problem areas preceded by the introduction. In the 1st part, computational thermodynamics and ab initio calculations were used to shed light upon the different stages of zircaloy oxidation and hydrogen pickup, and microstructure optimization to increase thermal stability. The 2nd part describes the kinetic theory of oxidation of the several materials considered to be perspective coatings for Zr alloys: SiC and ZrSiO4. The 3rd part deals with understanding the respective roles of the two different plasticity mechanisms in Zr nuclear alloys: twinning (at low T) and crystallographic slip (higher T's). For that goal, an advanced plasticity model was proposed. In the 4th part projectional algorithms for defect identification in zircaloy coatings are described. Conclusions and recommendations are presented in the 5th part. This integrative approach's value is in developing multi-faceted understanding of complex processes taking place in nuclear fuel rods. It helped identify several problems pertaining to the safe operations with nuclear fuel: limits of temperature that should be strictly obeyed in storage to retard zircaloy hydriding; understanding the benefits and limitations of coatings; developing in-depth understanding of Zr plasticity; developing original algorithms for defect identification in SiC-braided zircaloy. The obtained results will be useful for the nuclear industry.

The Metallurgy of Nuclear Fuel: Properties and Principles of the Technology of Uranium, Thorium and Plutonium is a systematic analysis of the metallurgy of nuclear fuel, with emphasis on the physical, mechanical, and chemical properties as well as the technology of uranium, thorium, and plutonium, together with their alloys and compounds. The minerals and raw material sources of nuclear fuel are discussed, along with the principles of the technology of the raw material processing and the production of the principal compounds, and of the pure metals and alloys. Comprised of three parts, this volume begins with an introduction to the history of the discovery of uranium and its position in the periodic system; its use as a nuclear fuel; radioactivity and isotopic composition; alloys and compounds; and physical, mechanical, and chemical properties. The effect of mechanical and thermal treatment, thermal cycling and irradiation on the physicochemical properties of uranium is also examined. The next two sections are devoted to thorium and plutonium and includes chapters dealing with their uses, alloys and compounds, and methods of recovery and purification. This book is written for university students, but should also prove useful to young production engineers and scientific workers who are concerned with problems in the metallurgy of nuclear fuel.