A court ruling issued in late March concerning a power reactor in Ishikawa Prefecture has proved both rare and astounding. Saying that there is a problem with the earthquake-resistance design of the reactor, the court ordered a halt to the operation of the nuclear-power station -- the first ruling ordering such a halt from among 30 lawsuits filed by citizens concerned about the safety of nuclear-power stations. As the power company involved has appealed the ruling, the reactor continues to operate. But the ruling could greatly affect the nation's energy policy and power industry. If it is upheld by the Supreme Court, it will call into question the safety foundation upon which the nation's 55 power reactors are built and could lead to their temporary closure. They currently supply about one-third of the nation's electric power.

A total of 135 citizens from 17 prefectures, most of them residents of Ishikawa and Toyama prefectures, filed a lawsuit against the operator of the No. 2 reactor at Hokuriku Electric Power Co.'s Shika nuclear-power station in Ishikawa Prefecture in August 1999, shortly after construction of the reactor began. The 1,358-megawatt, advanced boiling-water type reactor is the nation's 55th nuclear-power reactor and the second largest in output. The plaintiffs contended that the reactor, whose design is based on the quake-resistance design guidelines drawn up in September 1978 by the then Atomic Energy Commission, is vulnerable to damage in a large quake. The March 24 ruling came just nine days after the reactor began operation.

In the trial, the power company explained that the reactor was designed to withstand a magnitude 6.5 earthquake whose focus is just below the reactor, the largest earthquake predicted to hit the area. But the ruling contended the scale and intensity of the largest earthquake assumed in the reactor design is too small.