In 1980 Carol Eberhard Kessler was a budding oceanographer at the Marine Biological Laboratory in Woods Hole, Massachusetts. An MIT faculty member encouraged her to supplement her AB in bio-geology from Brown with a master’s degree so she could help research a proposal to store nuclear waste in the sea floor.

“I entered the Technology and Policy Program, with a focus in nuclear science and engineering (NSE), but the waste storage idea was killed, so there went my funding,” says Kessler, who suddenly needed a new career path. “This was right after Three Mile Island—a bad time to get into nuclear energy, but a great time to get into nuclear nonproliferation.”

So Kessler did just that, mentored by NSE professors Marvin Miller and Richard Lester. She credits them with helping her launch a career that includes a 12-year stint as policy developer and negotiator at the U.S. Department of State and leadership positions at the Nuclear Energy Agency in Paris, Pacific Northwest National Laboratory, and Brookhaven National Laboratory, where she currently chairs the Nonproliferation and National Security Department. She earned a master’s in national security policy in 2001 from the U.S. National War College.

Her work has touched on sensitive and far-reaching aspects of nuclear technology: export controls, materials safeguards, reactor safety, and nonproliferation. But she’s most proud of negotiating the disposition of the site of the 1986 Chernobyl disaster.

That Chernobyl effort, which lasted from 1995 to 2000, involved intensive negotiations with G-7 and Ukrainian government officials, regulators, and reactor operators. It led to a decision to re-encase the destroyed reactor, rather than dismantle it—an agreement that likely saved hundreds of workers from radiation exposure. In addition, an adjacent identical reactor was closed in 2000 after a series of replacement energy projects was negotiated through international financial institutions.

“There was a completely different sense of risk in the Soviet psyche,” Kessler recalls. “They felt that if you operate sophisticated equipment, it’s inevitable that people will get hurt and die. It was so ingrained … we had to offer nearly $2 billion in energy replacement grants and loans to convince them that the international community wouldn’t tolerate the risk of operating that type of reactor.”

Kessler’s husband, Chris, also works in nonproliferation; they’ve even held some of the same positions. In her spare time she loves to exercise. At age 50, she completed a half-marathon in Paris. “It was a wonderful experience, one of the hardest things I’ve ever done,” she says.