What would happen if the two working reactors at the Oi power plant — Japan’s only reactors brought back online since the Fukushima meltdowns last year — are shut down because of a suspected active fault under their critical equipment?
According to Kansai Electric Power Co., the Kansai region would suffer severe electricity shortages this winter because demand is projected to far exceed the utility’s capacity to generate power through other means.
Kepco estimates that the peak demand this February will be 25.37 million kw, while the firm now has a maximum supply capacity of 26.42 million kw — including the Oi reactors.
Without the Oi plant, the capacity drops to 21.96 million kw, or 13.4 percent under its capacity to meet peak demand, Kepco says, because it would lose 2.36 million kw from the two Oi reactors and 2.1 million kw from pumped-storage hydroelectric stations that are charged by electricity from the Oi plant during off-peak nighttime hours.
A pumped-storage hydroelectric plant generates electricity by letting pumped water in a higher reservoir rush through a turbine into another, lower reservoir.
The water is pumped mainly by using nuclear power at night when power demand is low.
Some experts, however, question Kepco’s estimates for its supply capacity, saying power purchased from other firms would let it tide over any shortfalls.
Hideaki Matsui, a senior energy expert at the Japan Research Institute, is one such expert.
Matsui said Kepco could get more electricity from independent power producers around Kansai as well as regional utilities elsewhere in Japan. He also pointed out that Kepco’s supply could be increased by postponing regular inspections of some its thermal power units.
Kepco’s estimates include getting about 4.6 million kw from other sources, including independent power producers and firms with in-house generators. The estimates, however, do not include help from fellow regional utilities.
A Kepco spokesman said depending on the situation, the utility could buy more power from independent producers and will also ask other utilities if they can spare some power.
On Oct. 30, Kepco told the government that if five other utilities in western and central Japan helped out to the point where their own reserves fell to around 3 percent, Kepco would only be 1.7 percent under peak demand.
Kepco also said the No. 3 unit at its Kainan thermal power plant is scheduled for a regular checkup starting Jan. 11, but this might be postponed if the Oi reactors are turned off.
Kepco has already postponed regular checks of some of its thermal units amid the nuclear moratorium.