The Japanese company running a nuclear power plant where four workers died on Monday is to gradually close all 11 of its reactors for safety checks.
Experts from Japan's nuclear safety agency are at the site
Kansai Electric Power Co (Kepco) said it would start procedures immediately to take three units off line.
The country's number two power firm, was asked to carry out the work by the government of Fukui prefecture.
Workers died when non-radioactive steam escaped from a ruptured pipe at Kepco's Mihama plant.
The incident was the nation's deadliest nuclear industry accident.
The Mihama No 3 reactor, where the fatalities took place, is already closed while two others are shut for regular maintenance.
Kepco, which provides power to the heavily industrialised region around Osaka, said no power shortage would result from the phased closures.
To make up for the shortfall in power the company said it would restart two oil-fired generators.
Japan has a total of 52 nuclear reactors and relies on
atomic energy for more than one-third of its energy needs.
No other of Japan's power companies have as yet followed Kepco's lead of announcing closures for safety checks.
Media reports in Japan have said Kepco president Yosaku Fuji is likely to resign to take responsibility for Monday's accident.
But a Kepco spokesman said there were no plans for its president to resign and no discussion of it.
"We currently are putting our top priority on finding out the cause of the accident," the spokesman said.
Experts from the national Nuclear and Industrial Safety Agency were at the accident site on Friday.
Power companies have been instructed by the country's nuclear watchdog to check documentation, in order to ensure inspections on pipes similar to the one that ruptured at Mihama have been carried out properly.
Similar checks have also been ordered at thermal plants.