In May, the Department of Energy’s National Nuclear Security Administration successfully removed two U.S.-origin radioactive sources from retired cancer therapy machines at a healthcare facility in Guatemala – ensuring that radioisotopes such as the Cobalt-60 in these machines could not be weaponized or improperly handled. These types of initiatives to protect and dispose of global radiological materials from sources as innocuous as hospitals that could fall into the wrong hands are all in a day’s work for Corey Hinderstein. This trailblazer was sworn in on Dec. 6, 2021, as Deputy Administrator for Defense Nuclear Nonproliferation at the National Nuclear Security Administration, where she leads NNSA’s efforts to prevent state and non-state actors from developing nuclear weapons or acquiring weapons-usable nuclear or radiological materials, equipment, technology, and expertise. Prior to her current role, she was vice president of International Fuel Cycle Strategies at the Nuclear Threat Initiative based in Washington, D.C., where she focused on international nuclear fuel cycle and nonproliferation policy, global nuclear security, and arms control and nonproliferation monitoring and verification. From February 2015 through November 2017, Hinderstein was senior coordinator for nuclear security and nonproliferation policy affairs at the Defense Nuclear Nonproliferation office of the NNSA. Here, she led DOE’s preparations for the 2016 Nuclear Security Summit and worked on other projects related to nuclear security and illicit trafficking, Iran’s nuclear program, and international monitoring and verification. Prior to her service at DOE, Hinderstein had been with NTI since 2006 and earlier was deputy director of the Institute for Science and International Security. Hinderstein is a past president and fellow of the Institute of Nuclear Materials Management and served on the board of directors for the World Institute for Nuclear Security. She also has served in advisory capacities for multiple national laboratories and has published widely on nuclear nonproliferation, verification and monitoring and nuclear security.