ALBUQUERQUE, N.M. (AP) — The federal agency that oversees U.S. nuclear research and bomb-making has signed off on the design and cost range for investments needed for a project to manufacture key components for the nation’s nuclear arsenal. The plan calls for making at least 30 plutonium cores per year at Los Alamos National Laboratory in northern New Mexico. The National Nuclear Security Administration says design and construction could cost upwards of $4 billion initially. Watchdog groups have concerns about the lab’s safety and security record. Lab Director Thom Mason during a virtual community meeting Thursday said the goal is not to expand the arsenal but to extend the life of the existing stockpile.