TOKYO -- After helping shape nuclear policy in post-Fukushima Japan, Shunichi Tanaka, a former chief of the country's nuclear watchdog, took on another tough assignment -- moving to a village still struggling from the 2011 nuclear disaster to help with its recovery effort.

In February, Tanaka, who chaired the Nuclear Regulation Authority until last September, became a reconstruction adviser in the tiny village of Iitate, Fukushima Prefecture. Like many in surrounding localities, Iitate residents were ordered to evacuate after a powerful earthquake and tsunami on March 11, 2011, led to meltdowns at Tokyo Electric Power Co. Holdings' Fukushima Daiichi nuclear power plant. To date, only around 10% of residents have returned.

"It won't be easy to make life like it was before the disaster," Tanaka said. Nonetheless he will help the village move forward by offering advice on nuclear decontamination and the ongoing dangers of radiation. He also acts as a go-between for the village and the national government.

"I'm a jack of all trades," he says.

In his former role at the NRA, Tanaka spearheaded an overhaul of Japan's nuclear regulatory scheme, setting tough new standards for nuclear power operations intended to prevent another Fukushima-like accident. To date, 12 reactors have cleared the new standards. And yet the public remains largely distrustful of nuclear power -- a problem Tanaka believes he can address by building up trust in the areas directly affected by the Fukushima disaster.

Shunichi Tanaka, former chairman of the Nuclear Regulation Authority.

Challenges in that region, however, remain immense, none more so than decommissioning the damaged power plant. This involves the unprecedented feat of removing and safely storing the plant's nuclear fuel, part of which has melted and escaped from the reactors it originally powered.

Back in September, Tepco and the national government reaffirmed their previous timeline for the cleanup, estimating the decommissioning process would take 30 to 40 years to complete. But the herculean nature of this task is becoming increasingly apparent. Nuclear fuel is too radioactive for humans to approach even when wearing protective gear, and must be handled by remotely controlled robots. But precision machinery is sensitive to radiation, and developing technology able to withstand conditions at the Fukushima site has proved intensely challenging.

"I truly cannot say" whether decommissioning can be wrapped up on a 30- to 40-year timeline, and "it is important to be honest," said Hajimu Yamana, head of the government-backed Nuclear Damage Compensation and Decommissioning Facilitation Corporation.

The process is also extremely costly. The Ministry of Economy, Trade and Industry in 2016 pegged costs such as decommissioning and victims' compensation related to the disaster at 21.5 trillion yen ($202 billion at current rates), nearly double its initial estimate of 11 trillion yen.

Work to remove and store melted fuel, set to begin as soon as 2021, and assorted other decontamination tasks could pile on additional expenses, depending on how they progress. The Japan Center for Economic Research believes the real cost could be as high as 70 trillion yen. Much of this would be borne by taxpayers, who require a convincing explanation of why costs are so high.

Decontaminating the soil poses another thorny problem. Roughly 640,000 cu. meters of contaminated soil, divided into 1-cu.-meter packages, has been delivered to an interim government storage facility between October and January. Yet up to 22 million cu. meters of contaminated earth remains to be treated in Fukushima Prefecture alone, a far larger amount than can be adequately handled at the current pace of work.

The government has not even locked down the roughly 1,600 hectares of land needed to complete the facility, which is itself only a temporary solution. Tokyo has pledged that Fukushima Prefecture will not be the final resting place for any of this soil, and looks to move it to a more permanent home elsewhere within 30 years. But even initial steps toward choosing such a site remain to be taken.

"It would be difficult and unrealistic to ask other prefectures to shoulder the burden," Tanaka said. He has proposed decontaminating the soil and using it to fill in wetlands, turning them into farmland or meadowland that would provide a living for residents returning to evacuated areas. An influx of foreign engineers working on decommissioning the Fukushima plant could also give rise to new industry. But whatever plans emerge, the highest and most important hurdle could be simply getting started.