Much like the voluntary halt on shipment of produce that has tested with radioactive cesium exceeding the national standard. It's up to the producer to abide by the halt, and no government agency is there to enforce it.
From Mainichi Shinbun (12/14/2012):
In a TBS TV program on December 13 evening, Prime Minister Yoshihiko Noda commented on Reactor 2 at Tsuruga Nuclear Power Plant operated by Japan Atomic Power (in Fukui Prefecture), saying "It (decommissioning) will be likely". Prime Minister said, "If the Nuclear Regulatory Authority says there is a safety problem, I will not allow the operation. It will be decommissioned, on the decision by the operator", prompting Japan Atomic Power to decide voluntarily.
In the meanwhile, the same set of geologists and seismologists who unanimously agreed on the possibility of an active fault under the reactor building at Tsuruga Nuke Plant is now in Aomori, studying the trenches dug by Tohoku Electric Power Company at Higashidori Nuclear Power Plant to determine whether the four faults there are active. According to Mainichi, Dr. Shimazaki, who is heading the experts, says what Tohoku Electric calls "swelling" may be due to the active fault.
I do suspect the days of the Nuclear Regulatory Authority may be numbered, particularly when I read LDP may win more than 280 seats in the coming election, and their findings will be nullified.