Here's the story of one worker, who videoed some of his experience:
In reviewing Fukushima working conditions, Reuters interviewed more than 80 workers, employers and officials involved in the unprecedented nuclear clean-up. A common complaint: the project's dependence on a sprawling and little scrutinized network of subcontractors - many of them inexperienced with nuclear work and some of them, police say, have ties to organized crime.
Tepco sits atop a pyramid of subcontractors that can run to seven or more layers and includes construction giants such as Kajima Corp and Obayashi Corp in the first tier. The embattled utility remains in charge of the work to dismantle the damaged Fukushima reactors, a government-subsidized job expected to take 30 years or more.
Outside the plant, Japan's "Big Four" construction companies - Kajima, Obayashi, Shimizu Corp and Taisei Corp - oversee hundreds of small firms working on government-funded contracts to remove radioactive dirt and debris from nearby villages and farms so evacuees can return home.
Tokyo Electric, widely known as Tepco, says it has been unable to monitor subcontractors fully but has taken steps to limit worker abuses and curb the involvement of organized crime.
"We sign contracts with companies based on the cost needed to carry out a task," Masayuki Ono, a general manager for nuclear power at Tepco, told Reuters. "The companies then hire their own employees taking into account our contract. It's very difficult for us to go in and check their contracts."
The unprecedented Fukushima nuclear clean-up both inside and outside the plant faces a deepening shortage of workers. There are about 25 percent more openings than applicants for jobs in Fukushima prefecture, according to government data.
Raising wages could draw more workers but that has not happened, the data shows. Tepco is under pressure to post a profit in the year to March 2014 under a turnaround plan Japan's top banks recently financed with $5.9 billion in new loans and refinancing. In 2011, in the wake of the disaster, Tepco cut pay for its own workers by 20 percent.
With wages flat and workers scarce, labor brokers have stepped into the gap, recruiting people whose lives have reached a dead end or who have trouble finding a job outside the disaster zone.
The result has been a proliferation of small firms - many unregistered. Some 800 companies are active inside the Fukushima plant and hundreds more are working in the decontamination effort outside its gates, according to Tepco and documents reviewed by Reuters.
When he arrived in Fukushima, Hayashi received instructions from five other firms in addition to the labor broker and RH Kogyo. It was the sixth contractor up the ladder, ABL Co. Ltd that told him he would be working in a highly radioactive area. ABL Co reported to Tokyo Energy & Systems Inc, which in Fukushima manages some 200 workers as a first-tier contractor under Tepco.
Hayashi says he kept copies of his work records and took pictures and videos inside the plant, encouraged by a TV journalist he had met before beginning his assignment. At one point, his boss from RH Kogyo told him not to worry because any radiation he was exposed to would not "build up".
"Once you wait a week, the amount of radiation goes down by half," the man is seen telling him in one of the recordings. The former supervisor declined to comment.
The statement represents a mistaken account of radiation safety standards applied in Fukushima, which are based on the view that there is no such thing as a safe dose. Workers are limited to 100 millisieverts of radiation exposure over five years. The International Atomic Energy Agency says exposure over that threshold measurably raises the risk of later cancers.
After Hayashi's first two-week stint at the plant ended, he discovered his nuclear passbook - a record of radiation exposure - had been falsified to show he had been an employee of larger firms higher up the ladder of contractors, not RH Kogyo.
Reuters reviewed the passbook and documents related to Hayashi's employment. The nuclear passbook shows that Hayashi was employed by Suzushi Kogyo from May to June 2012. It says Take One employed Hayashi for ten days in June 2012. Hayashi says that is false because he had a one-year contract with RH Kogyo.
"My suspicion is that they falsified the records to hide the fact that they had outsourced my employment," Hayashi said.
ABL Co. said Hayashi had worked with the firm but declined to comment on his claims. Tepco, Tokyo Energy & Systems, Suzushi Kogyo and RH Kogyo also declined to comment. Take One could not be reached for comment.
In September 2012, Hayashi found another job with a subcontractor for Kajima, one of Japan's largest construction companies. He didn't want to go back home empty-handed and says he thought he might have been just unlucky with his first bad experience at the plant.
Instead, his problems continued. This time a broker who recruited several workers for the subcontractor insisted on access to his bank account and then took almost a third of the roughly $160 Hayashi was supposed to be earning each day, Hayashi says.
The broker, according to Hayashi, identified himself as a former member of a local gang from Hayashi's native Nagano.
Ryo Goshima, 23, said the same broker from Nagano placed him in a crew doing decontamination work and then skimmed almost half of what he had been promised. Goshima and Hayashi became friends in Fukushima when they wound up working for the same firm.
Goshima said he was fired in December after complaining about the skimming practice. Tech, the contractor that had employed him, said it had fired another employee who was found to have skimmed Goshima's wages. Tech said Goshima left for personal reasons. The firm paid Goshima back wages, both sides say. The total payment was $9,000, according to Goshima.
Kajima spokesman Atsushi Fujino said the company was not in a position to comment on either of the cases since it did not have a contract with Hayashi or Goshima.
"We pay the companies who work for us and instruct those companies to pay the hazard allowance," the Kajima spokesman said in a statement.