The trade and industry ministry’s Nuclear and Industrial Safety Agency (NISA) on July 18 ordered Kansai Electric Power Co. (Kepco) and Hokuriku Electric Power Co. to carry out geological surveys, including boring, at the Oi nuclear power plant in Fukui Prefecture and the Shika nuclear power plant in Ishikawa Prefecture, respectively. This is because of suspicions having been raised that fault crushing belts running through the Oi plant site and a fault running through the Shika plant site are active faults.
Even if the two power companies submit benign survey results to NISA, it does not mean that the matter will have been resolved, because the possibility cannot be ruled out that in this quake-prone country, other nuclear power plants are located above or near active faults.
In April, NISA ordered Japan Atomic Power Co. to carry out similar geological surveys in the site of its Tsuruga nuclear power plant in Fukui Prefecture. In early June, before the Oi plant’s Nos. 3 and 4 reactors are restarted, experts pointed out the possibility that fault-crushing belts there, composed of stones formed through fault movements, will move together with nearby faults, causing strata sliding on the ground surface.
NISA’s order is a response to politicians’ and civic groups’ call for geological surveys of the site. NISA should be criticized for letting Kepco restart the Oi reactors before the geological studies are carried out. The government has no plan to stop the reactors despite the need for the surveys. One fault crushing belt at the Oi plant site runs between the Nos. 1 and 2 reactors on one side and the Nos. 3 and 4 reactors on the other. A major pipe used to carry water to cool the Nos. 3 and 4 reactors crosses the belt.
There is the possibility that if the belt moves, the water supply pipe will be destroyed, making it impossible to cool the reactors.
Kepco carried out geological surveys of fault crushing belts in 1982 and 83 at the Oi plant site. But it did not submit photos and other data from the surveys of the belt in question despite NISA’s recent request. Suddenly, however, Kepco on July 13 submitted 15 photos.
Since they do not tell the entire situation concerning the belt, NISA ordered another geological survey. Kepco’s behavior appears suspicious and leaves the impression it may be hiding important data.
The fault at the Shika nuclear power plant cuts through the southwestern corner of the No. 1 reactor building. On July 17, experts told NISA that there is a strong possibility that it is an active fault. If this is true, the reactor must be decommissioned.
The government should order thorough geological surveys at the sites of nuclear power plants throughout Japan. NISA’s approval of the construction of the Shika and Oi plants also must be scrutinized.