In fast-neutron reactors, fuel is sealed in ~7 millimeter diameter steel tubes called cladding. When a high-energy "fast" neutron strikes an atom in the steel, it can knock the atom out of place, like a cue ball striking another billiard ball. This leaves two types of damage in the metal: an empty spot where the atom was, and the displaced atom wedged between other atoms. Over time, these defects typically drive undesirable rearrangement of the microstructure, potentially reducing the life of the cladding.
On October 22, the U.S. Nuclear Regulatory Commission (NRC)granted Tennessee Valley Authority's (TVA's) Watts Bar Nuclear Generating Station a 40-year operating license for its new Unit 2 reactor. This is the first nuclear reactor to be granted an operating license by the NRC in two decades.
Pressurized water nuclear reactors in the United States generate about 13 percent of U.S. electricity. Though efficient, these reactors face a unique challenge with stress corrosion cracking (SCC). This type of corrosion is one of the primary life-limiting degradation mechanisms of nickel-base alloy pressure boundary components, such as instrumentation and control rod nozzles, the welds that attach these nozzles to the reactor vessel, and welds that connect feedwater piping to the reactor vessel. As interest grows in a more sustainable and efficient fleet of nuclear reactors across the world, there is increasing interest in characterizing SCC initiation response.
School's out, which means a new group of interns is settling into summer research assignments with mentors at the Department of Energy's Pacific Northwest National Laboratory in Richland.
