The machine showed the radiation level there was between 5 and 10 microsieverts per hour, which is more than 100 times that of Tokyo.

Invited by Tokyo Electric Power Company Holdings Inc. (TEPCO), Hua, along with some other foreign journalists, paid a visit to the crippled Fukushima Daiichi nuclear power plant.

As the car he took approached the power plant, the radiation level rose quickly. Being 24 km away from the nuclear plant, the reading was about 0.114 microsieverts per hour, twice the amount of Tokyo, whereas being 15 km from the plant, the reading was 20 times higher.

Inside the power plant and close to one of the crippled reactors, the machine showed that the radiation level there was as high as 150 microsieverts per hour.

Dozens of workers wearing protection suits were spotted working by the No. 2 reactor, and according to a guide from TEPCO, the radiation level there was as high as 1,000 microsieverts per hour. Currently, some 6,000 staff are working in the Daiichi nuclear power plant.

A magnitude-9.0 earthquake in 2011 triggered a massive tsunami which destroyed the emergency power and then the cooling system of Fukushima Daiichi nuclear power plant, and caused a serious nuclear disaster, forcing some 300,000 people to evacuate.

Almost six years later, the nuclear nightmare still continues in that part of Japan.

Inside the power plant, only the No. 2 reactor looked almost intact, while other reactors which suffered from hydrogen explosions were unrecognizable.

The operator of the crippled power plant said earlier this month that levels of radiation as high as 650 sieverts per hour were detected inside the No. 2 reactor, much to the consternation of Japan's nuclear watchdog and the local and international public.

The level was much higher than an earlier reading of 73 sieverts per hour in 2012, with the amount of radiation enough to kill a person, even after being exposed for just a brief period of time.

Even robots sent to gather information from the damaged reactor suffered malfunctions and failures, possibly due to extremely high levels of radiation.

For a long time, a number of TEPCO's gaffes and communication blunders regarding the nuclear disaster have attracted massive criticism from the public.

A report from the International Atomic Energy Agency shows that the potential damage of the Fukushima nuclear disaster to the health of the people and the environment in the area was hard to estimate due to a lack of information.

Meanwhile, messages from the Japanese government have always been "positive," stating that the nuclear disaster caused limited damage and the aftermath is being dealt with, despite some data made public by different bodies of the government being contradictory to each other.

The area around the crippled nuclear plant is like a ghost city with abandoned houses, bags of contaminated soil piled up along a railway and in the fields, weeds growing wildly and madly.

After the nuclear disaster, the government designated an area 20 km around the Fukushima Daiichi nuclear plant as a restricted area.

At a place called Narahamachi, the restriction has been lifted, and residents are allowed to go back home since Sept. 2015. However, according to Yuuichi Okamura, a manager from TEPCO, by now only 10 percent of the residents have come back home.

After the accident happened, TEPCO claimed that the reactor's core was damaged, but did not admit that the core had melted until two months later, though according to TEPCO's own standards, when 5 percent of a core is damaged, it means the core has melted.

A report from a third-party investigation committee showed that TEPCO's then-President Masataka Shimizu instructed officials not to use the specific description under alleged pressure from the Prime Minister's Office, though then-Prime Minister Naoto Kan and then-Chief Cabinet Secretary Yukio Edano both strongly denied it.

TEPCO's President Naomi Hirose apologized for keeping the fact from the public in June, 2016. "I would say it was a cover-up," he told a news conference. "It's extremely regrettable."

According to Yuuichi Okamura, the No. 1, No. 2 and No. 3 reactors all had melted cores, and TEPCO still has no way to take out the melted nuclear fuel rods from the reactors. The over 1,500 nuclear fuel rods in No. 4 reactor have been successfully taken out and transferred to a safe place.

The Fukushima nuclear disaster ranked seven, the highest level on the international nuclear events scale, and was the most serious disaster since the former Soviet Union's Chernobyl nuclear disaster in 1986.

Six years on, the crisis has yet to be fully brought under control, with no precise timeline for the full decommissioning of the plant, or a precise blueprint for the technological processes necessary for it to take place.

For TEPCO, the difficult tasks of dealing with the unprecedented problems such as processing contaminated water, cooling the reactors, and removing nuclear fuels, all continue to pose serious challenges.