For a man who has spent almost every waking hour over the past half year shepherding Japan through one of the world's worst nuclear disasters, Goshi Hosono wears his worries lightly.

The youthful and telegenic government pointman on the Fukushima clean-up has been in his post since shortly after the earthquake and tsunami of March 11.

He has outlived one prime minister and counts as a survivor in the revolving door world of Japanese politics, a place peopled largely by faceless men in grey suits who are all but unknown in the world outside the debating chamber.

Despite a series of setbacks at Fukushima, including the revelation this week that spontaneous fission had been detected inside a reactor that was supposed to be all but extinct, Hosono is upbeat.

"We have come a long way in our efforts to control the accident," he told AFP in an interview.

"It was the emergency workers at the plant who have contributed to it the most. We are finally seeing the goal of cold shutdown in sight. The workers' efforts must be highly applauded."

Hosono says the government and plant operator TEPCO (Tokyo Electric Power Company) -- the villain of the piece for many in Japan -- are on course to declare this phase of the recovery to be over by the end of the year.

He says the focus is now shifting from stabilising damaged reactors to cleaning up the environment after leaks and explosions spewed radiation into the air, soil and sea, and disposing of tonnes of nuclear waste.

The atomic crisis -- the worst the planet has seen since Chernobyl exploded 25 years ago -- has not directly killed anyone, but the natural disaster that sparked it claimed 20,000 lives.

With thousands of people still unable to return to their homes in a large area around the plant, and suspicions over the safety of food produced in the wider region, a weary public remains sceptical about the government's efforts.

Hosono, who will allow journalists to enter the battered plant for the first time next week, said: "The immediate challenge still is to confirm the cold shutdown.

"Until then, we will ensure we go on step by step without letting our guard down."

A bright star in the ruling Democratic Party of Japan firmament, Hosono became an adviser to the then prime minister Naoto Kan this January. About a month after the towering waves of March 11 tore into Fukushima he was moved to the nuclear brief.

He was appointed to the rather prosaically titled role of State Minister in Charge of Nuclear Accident Settlement and Prevention in late June.

When the unpopular Kan fell on his sword in August, Hosono was one of the few members of the cabinet to survive the transition to life under new premier Yoshihiko Noda.

The 40-year-old Hosono, a graduate of the prestigious Kyoto University and married father-of-one, is a relative youngblood in Japan's often turgid political arena.

He is also verbally nimble in a world where grey political heavyweights have an almost jaw-dropping ability to say the wrong thing and get themselves into trouble.

But Hosono's 12-year political career has not been without incident. An extramarital fling with an attractive TV anchor saw him adorning the pages of gossip magazines for all the wrong reasons in 2006.

He is upfront about the fact that the Japanese government has not always done -- or been seen to do -- desperately well since the crisis erupted.

"In retrospect we had a pretty tough time in the immediate aftermath of March 11," he said.

"Frankly speaking, I don't think the disaster preparations before the accident were good enough," he said. "The power company lacked substantial preparation, and the administration had many flaws in its system."

"I think such difficult times are now behind us," he added.

He admits though that the sticky problem of exactly what should be done with the radioactive waste from the plant and the debris in the 20-kilometre (12-mile) exclusion zone around it is far from solved.

"Japan will have a great deal of (radioactive) waste. It is not an option for us to send it overseas and leave it there as if Japan had nothing to do with it."

But finding somewhere at home that can take it is not going to be an easy task and one that, like many politicians, Hosono seems keen to kick into the long grass.

The Japanese government has plans to build a new facility in Fukushima prefecture, where radioactive waste will be stored temporarily for at least 30 years until its final destination is determined.

However, with authorities yet to identify land that could store the waste even in the medium term because of opposition from people living near potential sites, Hosono is hoping science -- and time -- might help.

"We will need new technologies to be developed to reduce the total mass of nuclear waste, which will take quite a long time, before we can start moving radioactive waste to another location," he said.