Protective coating on zircaloy tube by novel chemical vapour deposition process: view and progress

The investigations of the Three Mile Island, United States and Fukushima, Japan accidents found that a stronger cladding material would have better handled the incident's core melting conditions and might have averted some of the problems that arose during shutdown. The unique properties and good record of accomplishment of the zirconium-based metal Zircaloy facilitate its use as a standard fuel cladding in various nuclear reactors. While it has a good record of accomplishment, Zircaloy becomes more liable to failure as its time in service increases, so fuel rods are withdrawn from service preventively despite having substantial remaining capacity to produce energy. It is believed that SiC coatings applied to the Zircaloy cladding can drastically reduce this corrosion and degradation, due to its resistance to corrosive environments at high temperatures and order of magnitude less chemical reactivity with water or steam. Recent reports recommend SiC and SiC/SiC as promising materials for supplementing or replacing Zircaloy cladding and are expected to offer improved safety features, reduced contamination of the primary circuit, and a simplified disposal process. Nevertheless, there remains a need for a process that can produce relatively thick coatings of SiC materials at low temperature and high rates with high-quality and density. Additional advantages could be realized if the deposition process is carried out at atmospheric pressure and with relatively inexpensive equipment