Sens. Barbara Boxer (D-Calif.) and David Vitter (R-La.) heatedly clashed Wednesday during a hearing on nuclear power safety. Boxer, the chairwoman of the Environment and Public Works Committee, was criticized by Vitter, the ranking Republican, for her treatment of a witness. At one point, she gaveled down Vitter and told him he is powerless to stop her, saying, “When you have this gavel, you make the rules.” The quarrel started when Boxer repeatedly asked Nuclear Regulatory Commission (NRC) Chairwoman Allison Macfarlane whether her agency has implemented any of the recommendations from a task force set up after the 2011 Fukushima...