It's proving a hard slog. A new, more independent regulator is in place, asking difficult questions and seeking to impose tougher safety rules on powerful utilities that were largely their own masters for the past 50 years.
The Nuclear Regulation Authority (NRA) was created in 2012 and set new safety guidelines in July last year. It now has four teams vetting reactors at nine nuclear power stations on a list of those seeking to re-start. A deadline to complete the checks has been missed as the NRA is still asking for reams of information. No one is able to predict when the first of 48 reactors will be turned back on.
The delays are biting the utilities which are having to spend billions of dollars to import fossil fuels to keep the power on, pushing Japan into a record trade deficit and risking undermining Prime Minister Shinzo Abe's polices to end years of stagnant growth.
"All the utilities are in a similar situation and, unless outstanding issues are resolved, we can't judge that they are in compliance with the standards," Tomoya Ichimura, an NRA director, told Reuters.
The regulator and staff from the utilities and Mitsubishi Heavy Industries Ltd (7011.T), a leading supplier of nuclear plant equipment, are ploughing through mountains of paperwork on the technical specifications of reactors and their vulnerability to natural disasters such as the earthquake and tsunami that knocked out the Fukushima Daiichi station in March 2011.
All lack experience in carrying out such detailed safety checks because of the lax regime that existed before Fukushima.
"Only the framework of the safety criteria was decided, not the details, so the dialogue between the NRA and power companies to work out the specifics is taking time," said Seiichi Nakata, Project Leader, Department of Policy, Communication and International Affairs at the Japan Atomic Industry Forum.
And once the checks are done, reactors must undergo planned inspections, which took as long as two months under the previous regime, as well as get the go-ahead from local authorities before they can be turned back on. The plants are being treated as if they have just been built and are seeking certification to start operating for the first time.
Interviews with utility and nuclear industry staff, regulators and government officials reveal a climate of uncertainty, frustration and long hours.
A taskforce of some 90 NRA inspectors dispatch orders and requests to hundreds of staff from regional utilities seconded to the capital and camped out for months in business hotels near the regulator's headquarters. As many as 2,800 staff at Mitsubishi Heavy are involved in dealing with utilities' requests on specifications and other data, the company said.
Kyushu Electric Power Co (9508.T), Hokkaido Electric Power Co (9509.T), Kansai Electric Power Co (9503.T) and Shikoku Electric Power Co (9507.T) say they have each stationed scores of employees in Tokyo to respond to queries from the regulator.
A typical working day for them lasts from 8 a.m. to 11 p.m. They stay in cheap business hotels within a quick commute of the NRA headquarters in a leafy district of central Tokyo. One of those, the Hotel Unizo in Shimbashi, a bustling district of bars and restaurants, charges 11,000 yen a night. To keep costs in check, some companies offer staff a daily allowance of as little as 1,500 yen for meals, and no laundry, said one person close to the safety review process.
Any downtime not spent returning home to visit families is used to prepare for more meetings with the regulator.
"Everyone involved in the safety reviews is irritated and it is mentally draining," said one staffer at a regional utility, who has been stationed in Tokyo since July and has missed key dates on his children's school calendar.
"I can't read books or watch TV. There's no time to relax," he said, adding he rarely has time even to wash his clothes. "I have 20 sets of underwear and socks bought from convenient stores rolled up like sushi in my office," he said.
PAPER ... AND MORE PAPER
The utilities also rent office space for staff to prepare paperwork for the regulator, said an official who oversees the process at a regional utility. Asked when he expected reactors to be re-started, he replied: "That's what we want to know."
Utilities must submit thousands of pages of documents outlining their compliance and readiness on a checklist of 27 main items required by the NRA, covering everything from quake protection to their emergency responses. Kyushu Electric, which has applied to re-start four reactors, has alone submitted more than 10,000 pages of documents to the regulator, said spokesman Hiroki Yamaguchi.
The regulator is still feeling its way and often changes the criteria for compliance, forcing utilities to submit more documentation, people in the industry said. The utilities then take their requests to Mitsubishi Heavy, which is struggling to meet deadlines.
"Mitsubishi Heavy basically handles safety assessments of the plants, and the utilities vie with each other to get help from them, creating a bottleneck," said the person involved in the checks at a regional utility.
Mitsubishi Heavy declined to comment on claims that it was the reason for some delays.
The cost to Japan's economy and the utilities' finances is heavy. Japan imported a record 87.5 million tonnes of LNG last year, at a cost of $69 billion, according to customs-cleared import data. Imports of thermal coal were also at record levels.
"There's a growing consensus from a purely economic perspective that Japan needs to re-start as many reactors as it can in order to build out the diversification of its power sources and reduce fuel prices," said Tom O'Sullivan, founder of independent energy consultancy Mathyos Japan.
Forecasts that the first nuclear reactor would be back in operation by the middle of this year are misplaced, said Tetsuo Yuhara, a director at The Canon Institute of Global Studies, who previously spent 30 years at Mitsubishi Heavy.
"I have no forecast for re-starts. It's the same situation as a year ago, as two years ago. Nothing has changed."