Lance Lewis Snead

Investigations of Aluminum-Doped Self-Healing Zircaloy Surfaces in Context of Accident-Tolerant Fuel Cladding Research

We present here some important results investigating aluminum as an effective surface dopant for increased oxidation resistance of zircaloy nuclear fuel cladding. At first, the transport behavior of aluminum into reactor grade zircaloy was studied using simple diffusion couples at temperatures greater than 770xa0K. The experiments revealed the formation of tens of microns thick graded Zr-Al layers. The activation energy of aluminum in zircaloy was found to be ~175 kJ/mol (~1.8xa0eV), indicating the high mobility of aluminum in zircaloy. Subsequently, aluminum sputter-coated zircaloy coupons were heat-treated to achieve surface doping and form compositionally graded layers. These coupons were then tested in steam environments at 1073 and 1273xa0K. The microstructure of the as-fabricated and steam-corroded specimens was compared to those of pure zircaloy control specimens. Analysis of data revealed that aluminum effectively competed with zircaloy for oxygen up until 1073xa0K blocking oxygen penetration, with no traces of large scale spalling, indicating mechanically stable interfaces and surfaces. At the highest steam test temperatures, aluminum was observed to segregate from the Zr-Al alloy under layers and migrate to the surface forming discrete clusters. Although this is perceived as an extremely desirable phenomenon, in the current experiments, oxygen was observed to penetrate into the zirconium-rich under layers, which could be attributed to formation of surface defects such as cracks in the surface alumina layers.

The HFIR 14J irradiation SiC/SiC composite and SiC fiber collaboration

A short introduction with references establishes the current status of research and development of SiC{sub f}/SiC composites for fusion energy systems with respect to several key issues. The SiC fiber and composite specimen types selected for the JUPITER 14J irradiation experiment are presented together with the rationale for their selection.

Technology Implimentation Plan - ATF FeCrAl Cladding for LWR Application

Technology implimentation plan for FeCrAl development under the FCRD Advanced Fuel program. The document describes the activities required to get FeCrAl clad ready for LTR testing

Strength Evaluation of PyC for TRISO Particles: Development of Equibiaxial Flexural Test

For the purpose of evaluating fracture strength of inner pyro-carbon (IPyC) for TRISO particles, a disc equibiaxial flexural test technique was developed and IPyC-relevant specimens fabricated in a test-run of fluidized-bed chemical vapor deposition were evaluated. It was demonstrated that the test technique developed is effective to determine the apparent fracture strength of thin specimen of PyC. Moreover, true strength was estimated from the acquired apparent strength values based on the result from finite element analysis. The estimated true strength values appeared reasonable for flexural strength of dense PyC. The influence of geometrical features introduced to the specimens due to the specific preparation procedures appeared insignificant.