High Strength, Oxidation Resistant Fuel Claddings for Improved Accident Tolerance

The recent events at the Fukushima nuclear power plant highlight the need for enhanced accident tolerance. Of particular concern is the overheating of standard zirconium alloy cladding material in a loss of coolant accident (LOCA). One of the leading, high-risk/high-reward candidates for future claddings is a silicon carbide (SiC) composite material. However, the inherent open porosity present in fibrous based composites leads to an intrinsic lack of hermiticity for a fully- composite cladding. Some SiC clad designs seek to overcome this issue through use of one or more ceramic coatings, though such coatings are also intrinsically brittle; thus, raising the question as to the ability to withhold fission products. While fission product retention is still an open question in the community, recently published work suggests that a fully-ceramic design has serious issues. This suggests that exploring a design alternative is prudent. One such design is the so-called hybrid design, which suggests the use of a thin ductile coating either on the interior or exterior of the composite. During this investigation, Plasma Processes, a leader in the fabrication of advanced coatings and components, will partner with Oak Ridge National Laboratory (ORNL) to develop leak tight metallic coatings for SiC composite nuclear fuel claddings. During Phase I, the techniques for producing dense, well-bonded metallic coatings on SiC composites will be developed. Samples will be produced for preliminary steam testing and analysis at ORNL. During Phase II, the fabrication techniques will be optimized. Prototypical fuel rods with the improved cladding will be fabricated and tested at relevant reactor conditions. Commercial Applications and Other Benefits: Fuel rods for safe commercial nuclear power in USA and throughout the world. Other applications include naval nuclear power.