Goshi Hosono, an adviser to the prime minister and member of his nuclear crisis management task force, said the government would closely monitor TEPCO's implementation of its crisis plan and hoped it could be carried out ahead of schedule.
The timetable's first step focuses on cooling the reactors and spent fuel pools, reducing radiaen plant and stem radiation leaks.
"There is no shortcut to resolving these issues. Though it will be difficult, we have to go step by step to resolve these problems," he said.
Even with the announcement of the timeline, it remained unclear when evacuees might be able to return home.
The area would need to be decontaminated, including removing and replacing the soil, Nishiyama said.
Hosono said the evacuees would not have to stay in gymnasiums for such a long period, but would be moved into temporary housing.
Some evacuees were unswayed by TEPCO's plan.
"I don't believe a word they say," said Yukio Otsuka, 56, a private school owner whose home is about three miles (five kilometers) from the power plant. "I don't trust them. I don't believe it is possible. We have really drawn the short stick on this one."
Activists criticized the delay in the roadmap's announcement.
"TEPCO has taken far too long to provide an indication of the direction it plans to take to bring the situation at Fukushima Dai-ichi under control," said Philip White of the Tokyo-based Citizens' Nuclear Information Center, a group of scientists and activists who have opposed nuclear power since 1975. "We hope TEPCO meets its targets, but there are many challenges ahead and many uncertainties."
The unveiling of the roadmap came two days after TEPCO - also under pressure from Kan's government _ announced plans to give 1 million yen ($12,000) in initial compensation to each evacuated household, with much more expected later.