Experts commissioned by the operator of a Japanese nuclear plant that faces possible closure because of a suspected active seismic fault say a decision should wait, citing insufficient data. Operator Japan Atomic Power Co. disputes that view. The decision is being closely watched as the pro-nuclear government moves to restart plants suspended since the Fukushima nuclear crisis. The plant’s owners plan to appeal the regulators’ decision. Still, the development comes as a number of other plants are awaiting determination whether their sites contain active faults. The decision could also be viewed as a setback for Prime Minister Shinzo Abe’s government, which took office in December. Mr. Abe’s administration effectively wants to reverse a decision to eventually phase out nuclear power, a move taken by the previous government that was in office during the 2011 Fukushima Daiichi nuclear plant accident. For the company, which is jointly owned by Japan’s major utilities, the closure of the Tsuruga plant would eliminate its only source of revenue and pose large-scale costs for a permanent decommissioning of the facility.