“For pressurized water reactors (PWRs), which are the most common reactor type in the US as well as the type of reactor at the Taishan Nuclear Power Plant, the biggest causes of fuel leaks are debris and grid-to-rod fretting, which occurs when a nuclear fuel rod rubs against the metal spacer grids that hold the rods in place,” Katie Mummah, a nuclear engineering PhD student at the University of Wisconsin-Madison, told The Register.