11 Aug (NucNet): Units 4 and 5 of Japan’s Hamaoka nuclear power plant in Shizuoka prefecture were automatically shut down earlier today when an earthquake hit the region.
The Japan Atomic Industrial Forum (JAIF) said there was no serious impact to the plant as a result of the earthquake, which was provisionally measured by the US Geological Survey as being 6.4 on the Richter scale.
The epicentre of the earthquake, which struck just after 05.00 hours local time, was about 85 kilometres from the plant in Suruga Bay at a depth of about 26 kilometres.
Of the other units at the plant, Hamaoka-1 and -2 are shut down for decommissioning while unit 3 is undergoing a periodic inspection.
According to JAIF, Japan’s Nuclear Industrial and Safety Agency said the maximum seismic acceleration observed at Hamaoka-5 was 426 Gal (centimetres per second squared) – below the licensed design seismic motion of 582 Gal.
All units at the plant are boiling water reactors. In December 2008, JAIF said voluntary measures had been completed that would lead to an increase in seismic tolerance margins at units 3, 4 and 5 of the plant to margins of about 1,000 Gal.
>>Related reports in the NucNet database (available to subscribers)
Chubu Electric Extends Periodic Outages For Two Hamaoka Units (News No. 26, 31 January 2006)
Non-Operational Japanese Units Are Formally Closed Down (News in Brief No. 16, 4 February 2009)
Sixth Unit Proposed For Japan’s Hamaoka Plant (News No. 101, 29 December 2008)
