Yes. See Article 56 of Protocol I of the 1949 Geneva Conventions: "1. Works or installations containing dangerous forces, namely dams, dykes and nuclear electrical generating stations, shall not be made the object of attack, even where these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population. Other military objectives located at or in the vicinity of these works or installations shall not be made the object of attack if such attack may cause the release of dangerous forces from the works or installations and consequent severe losses among the civilian population."

Note that the United States, Israel, Iran, Pakistan, India, and Turkey have not ratified this Protocol. (The US, Iran, and Pakistan all signed in 1977 but none ratified it.)

Article 15 of Protocol II also apparently relates to this. Some more information here.