The major electric utilities are again expected to secure their minimum power capacity requirements by the time demand peaks in August, with or without nuclear power, their estimates showed Thursday.

But the electricity situation in the west will be tougher because Kansai Electric Power Co. and Kyushu Electric Power Co., which relied more on atomic power before the nationwide reactor shutdowns, will only have a supply buffer of 3 percent — the minimum level for ensuring stable electricity supply.

The estimate is based on the assumption that the two utilities will be able to tap other utilities that have spare capacity, including Tokyo Electric Power Co., which runs the crisis-stricken Fukushima No. 1 nuclear plant.

Tepco was estimated to have a spare capacity of 5.5 percent.

A panel is studying the estimate so the government can decide which energy-saving measures are necessary to ride out the summer if none of the dozens of nuclear power plants are restarted.

One nuclear plant operated by Kyushu Electric is taking the lead in the state safety assessment process that started last July, after nuclear regulations were stiffened following the multiple core meltdowns in Fukushima in 2011. But it is not yet clear exactly when the process will finish or whether plant will be allowed to restart.

Extra supply capacity at the nine regional monopolies, excluding Okinawa Electric Power Co., stood at an average of 4.6 percent. Okinawa Electric is the only utility without any nuclear plants.