TOKYO — When meltdowns struck Japan’s Fukushima Daiichi nuclear power plant in the wake of a devastating tsunami in 2011, more than 44,000 workers were deployed to take the facility safely offline. The job was messy: Millions of gallons of radioactive water had to be stored on site as the plant’s operator, Tokyo Electric Power Co., known as Tepco, faced a clean-up some priced at $100 billion.

And for the first time, one of the workers involved in that cleanup has been diagnosed with cancer related to his job, as Japan’s NHK reported.

Japan’s ministry of health, labor and welfare announced Tuesday that a recovery worker — a man unnamed in news reports — has been diagnosed with leukemia. The ministry confirmed the man’s cancer was related to his work at Fukushima after he filed a worker’s compensation claim.

Asahi Shimbun, a major Japanese daily newspaper, reported the man, from Kitakyushu, is now 41. He worked at the Daiichi plant near the No. 3 and No. 4 reactors from 2012 to 2013. He was diagnosed with acute myelogenous leukemia — a cancer of the blood and bone marrow, according to the Mayo Clinic — in January 2014. The word “acute” indicates “the disease’s rapid progression,” according to Mayo. The man quit after working at Fukushima Daiichi and developed leukemia, NHK reported.

“We are aware that a case of a cooperating company’s worker who worked at [Fukushima Daiichi] was recognized for worker’s compensation through reports,” Satoshi Togawa, a Tepco spokesman, said in a statement. “As applying for worker’s compensation is done by each employee or each employer, and recognizing this is handled by a labor standards supervision office, we are not in a position to make a comment. We offer our sincere sympathy for the cooperating company’s worker.”

On its Web site, Tepco extensively documents its efforts to shield recovery workers from radiation. The company differentiates between its employees and contractors — who far outnumber the company’s workers at Fukushima. In August, for example, there were more than 9,000 contractors on site, but just about 1,000 employees. Contractors also received more than double the average dose of radiation employees received.

“Keeping firmly in mind that the safety of the workers and employees who are involved in the decommissioning operation is the highest priority,” the Web site reads, “we are addressing the improvement of their work environment to increase efficiency through the reduction of exposure via decontamination, etc., and the reduction of their workload by simplifying protective equipment, and ensuring the thorough provision of facilities to support their physical and mental well being.”

Tepco also provides monthly updates on recovery workers’ radiation exposure to the ministry of health. The dose limit at the site is 1.71 mSv per month; in August, Tepco reported that the average worker was well below that, at .31 mSv. For comparison, people living in the United States receive about 6.2 mSv per year, most “from radon in the air, with smaller amounts from cosmic rays and the Earth itself,” according to the Nuclear Regulatory Commission.

The Fukushima worker diagnosed with cancer experienced accumulation of exposed doses of 16 mSv, according to Asahi Shimbun.

Earlier this month, radiation associated with the Fukushima meltdowns was linked to thyroid cancer in children living near the area.

“This is more than expected and emerging faster than expected,” lead author Toshihide Tsuda told the Associated Press. “This is 20 times to 50 times what would be normally expected.”

This post has been updated.