TOKYO Nov 28 (Reuters) - The head of Japan's Fukushima Daiichi nuclear plant, site of the world's worst atomic accident in 25 years more than eight months ago, has been hospitalised and will be replaced in his post, plant operator Tokyo Electric Power Co said on Monday.
Masao Yoshida, 56, was in charge when a massive earthquake and tsunami struck on March 11, knocking out cooling systems and triggering reactor meltdowns at the plant, 240 km (150 miles) northeast of Tokyo.
A Tokyo Electic Power Co (Tepco) official declined to give details of Yoshida's illness but told a news conference there was no indication that it was caused by radiation exposure.
"The government intends to watch the situation carefully so this would not not affect the plan to bring the plant under control," Chief Cabinet Secretary Osamu Fujimura told a separate news conference.
Yoshida, in his first public appearance since the accident, apologised earlier this month for failing to prevent the meltdowns. But he said conditions at the plant were improving to the point where a "cold shutdown" -- when temperatures are stabilised below boiling point -- would be possible by year-end.
He added, however, that radiation levels in the compound were high and it was still dangerous for workers at the site.
The disaster prompted the government to declare a 20 km (12 miles) no-entry zone around the plant, forcing the evacuation of about 80,000 residents.
A cold shutdown is one of the conditions that must be met before the government considers lifting its entry ban.
Recalling the early days after the disasters struck, Yoshida told the reporters: "Several times during the first week of the crisis, I thought I would die soon."
Yoshida was a focus of controversy in May when Tepco admitted that he had kept injecting seawater into one of the damaged reactors, contradicting the operator's report that it had suspended the procedure due to concerns at the prime minister's office.
Experts approved of Yoshida's decision but the confusion fanned doubts about whether Tepco, criticised for a cover-up culture, was telling the public the truth about the crisis.
As an emergency measure early on, Tepco tried to cool the damaged reactors by pumping in huge volumes of water, much of it from the sea, only to leave a vast amount of tainted runoff that threatened to leak out into the ocean.
It solved the problem by building a cooling system to clean the radioactive runoff, using some of the water to cool the reactors. (Reporting by Linda Sieg and Kiyoshi Takenaka; Editing by Tomasz Janowski)