Physical and mechanical metallurgy of zirconium alloys for nuclear applications: a multi-scale computational study

Technical Report · Wed Oct 01 00:00:00 EDT 2014

DOI:https://doi.org/10.2172/1170305· OSTI ID:1170305

Glazoff, Michael Vasily ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

In the post-Fukushima world, the stability of materials under extreme conditions is an important issue for the safety of nuclear reactors. Because the nuclear industry is going to continue using advanced zirconium cladding materials in the foreseeable future, it become critical to gain fundamental understanding of the several interconnected problems. First, what are the thermodynamic and kinetic factors affecting the oxidation and hydrogen pick-up by these materials at normal, off-normal conditions, and in long-term storage? Secondly, what protective coatings (if any) could be used in order to gain extremely valuable time at off-normal conditions, e.g., when temperature exceeds the critical value of 2200°F? Thirdly, the kinetics of oxidation of such protective coating or braiding needs to be quantified. Lastly, even if some degree of success is achieved along this path, it is absolutely critical to have automated inspection algorithms allowing identifying defects of cladding as soon as possible. This work strives to explore these interconnected factors from the most advanced computational perspective, utilizing such modern techniques as first-principles atomistic simulations, computational thermodynamics of materials, diffusion modeling, and the morphological algorithms of image processing for defect identification. Consequently, it consists of the four parts dealing with these four problem areas preceded by the introduction and formulation of the studied problems. In the 1st part an effort was made to employ computational thermodynamics and ab initio calculations to shed light upon the different stages of oxidation of ziraloys (2 and 4), the role of microstructure optimization in increasing their thermal stability, and the process of hydrogen pick-up, both in normal working conditions and in long-term storage. The 2nd part deals with the need to understand the influence and 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, a description of the advanced plasticity model is outlined featuring the non-associated flow rule in hcp materials including Zr. The 3rd part describes the kinetic theory of oxidation of the several materials considered to be perspective coating materials for Zr alloys: SiC and ZrSiO₄. In the 4th part novel and advanced projectional algorithms for defect identification in zircaloy coatings are described. In so doing, the author capitalized on some 12 years of his applied industrial research in this area. Our conclusions and recommendations are presented in the 5th part of this work, along with the list of used literature and the scripts for atomistic, thermodynamic, kinetic, and morphological computations.

• Research Organization: Idaho National Lab. (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1170305
• Report Number(s): INL/EXT-14-32426; TRN: US1500017
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
REACTOR ACCIDENTS
FUKUSHIMA DAIICHI NUCLEAR POWER STATION
ZIRCALOY 2
ZIRCALOY 4
PROTECTIVE COATINGS
OXIDATION
SOLUBILITY
HYDROGEN
HYDRIDES
SENSITIVITY
THERMAL DEGRADATION
SILICON CARBIDES
SILICON OXIDES
ZIRCONIUM OXIDES
ALGORITHMS
CLADDING
HCP LATTICES
ZIRCONIUM
PLASTICITY
SLIP
TWINNING
MORPHOLOGY
FUEL RODS
DEFECTS
COMPUTERIZED SIMULATION
IMAGE PROCESSING
NUCLEAR INDUSTRY
PHYSICAL METALLURGY
STABILITY
SPENT FUEL STORAGE
THERMODYNAMICS
CALCULATION METHODS
CRYSTALLOGRAPHY
DIFFUSION
INSPECTION
CHEMICAL REACTION KINETICS
MICROSTRUCTURE
OPTIMIZATION
REACTORS
RECOMMENDATIONS
REACTOR SAFETY
ZIRCONIUM ALLOYS