NAGOYA – Chubu Electric Power Co. has reported to the government that its Hamaoka nuclear power plant in Shizuoka Prefecture would be safe even if it were hit by a 21-meter-high tsunami after a massive earthquake.
The operator compiled its report on the assumption that the plant could be flooded by such high waves hitting the Pacific coast while it is still offline and the reactors are kept cool.
But the report, submitted Monday to the Nuclear and Industrial Safety Agency, does not mention whether the plant could survive such a huge tsunami if it is in operation.
NISA ordered the utility to file the report by Monday based on a new projection by the Cabinet Office’s expert panel anticipating a tsunami of up to 21 meters near the Hamaoka plant in the event that a huge quake occurs in the Nankai Trough off central and western Japan.
Chubu Electric said in the report it would be able to resume water supply to the plant’s cooling system for reactors and spent fuel pools even if the cooling functions are lost in the wake of a huge tsunami, by using equipment including mobile pumps located at a higher place in the plant.
It would take at least six days before the water in a reactor’s core fell below the fuel level even if the cooling system broke down, the report says.
The plant in the city of Omaezaki has been suspended since May. Then Prime Minister Naoto Kan asked Chubu Electric to shut it down based on a prediction that a magnitude 8 quake could hit the region sometime in the first half of this century.
50 reactors ‘operable’
Tokyo Electric Power Co. will classify four of the crippled reactors at its Fukushima No. 1 nuclear power plant as defunct on Thursday, reducing the nation’s “operable” commercial reactors to 50 from 54.
Reactors 1 through 4 at the six-reactor complex sustained major damage in the March 11, 2011, earthquake and tsunami and subsequent hydrogen explosions. Three reactors suffered meltdowns.
The Electricity Business Law requires utilities to seek the permission of the industry minister in changing the output of a nuclear power plant. Tepco filed an application over the scrapping of the four reactors on March 30.
The Fukushima Prefectural Government is demanding the utility also decommission the plant’s reactors 5 and 6, as well as all four reactors at the nearby Fukushima No. 2 nuclear plant.
Tepco has not decided what it will do with those reactors, company officials said.
The company also operates seven reactors at the Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture. Those seven reactors, like 49 of the nation’s 50 operational nuclear reactors, are now idled.
Only the No. 3 reactor at Hokkaido Electric Power Co.’s Tomari plant is currently operating.
Just before last year’s devastating quake and tsunami, roughly 30 percent of the total electricity generated in Japan was supplied by nuclear power.
The total number of operational commercial reactors could further decrease as aging reactors are expected to be retired and plans to build new ones have been suspended.