Uh, math is retardedly easy through calculus.
It would also be relevant for agencies that regulate nuclear power (Department of Energy, Environmental Protection Agency), agencies that deal with other nations that do nuclear power (Department of State), agencies that invest into 3rd world countries that may relate to nuclear power (United States Agency for International Development), private contractor firms that support all of the above. All of those are aside from things like military.
There's probably also groups that advise the UN, although I would imagine those would be pulled from DOE and such.
Then there's the academic world with more pure research and stuff.