Scientists have found a mix of radioactive materials around the damaged Fukushima nuclear plant in east Japan that could mean the environmental impact from the fallout may last much longer than previously expected.

The new evidence of materials including uranium, cesium and technetium in the area of the disaster seven years ago has been published in the Environmental Science & Technology journal.  

“It was previously thought that only volatile, gaseous radionuclides such as cesium and iodine were released from the damaged reactors. 

“Now it is becoming clear that small, solid particles were also emitted, and that some of these particles contain very long-lived radionuclides; for example, uranium has a half-life of billions of years, radioactive materials like uranium have a half-life of billions of years," said the study by a team of international researchers from institutions including Japan’s Kyushu University and the UK’s University of Manchester.

The scientists looked at extremely small pieces of debris, known as micro-particles, which were released into the environment during the initial disaster in 2011. 

“The particles found measure just five micrometers or less; approximately 20 times smaller than the width of a human hair. The size of the particles means humans could inhale them,” according to the study. 

The reactor debris fragments were found inside the nuclear exclusion zone, in paddy soils and at an abandoned aquaculture center several kilometers from the nuclear plant.

An earthquake with a magnitude of 9.0 struck Japan on March 11, 2011, triggering a tsunami in the coastal belt. The tsunami inundated about 560 square kilometers and killed 19,000 people. Around 11 reactors at four nuclear power plants operating in the region were shut down automatically when the quake hit. 

A series of inspections showed no significant damage to reactors from the earthquake. But it was later revealed that three of the six reactors had partial meltdowns leaking radioactive materials. 

The government has deputed Tokyo Electric Power Company (TEPCO) to clean up and safely handle radioactive materials at the Fukushima Daiichi site and in the surrounding exclusion zone.

Satoshi Utsunomiya, associate professor at Kyushu University, who led the study, said, “Having better knowledge of the released micro-particles is also vitally important as it provides much-needed data on the status of the melted nuclear fuels in the damaged reactors.” 

“This will provide extremely useful information for TEPCO’s decommissioning strategy,” Utsunomiya added.

In a separate survey of nearly 2,000 Fukushima Prefecture residents, the Asahi Shimbun and Fukushima Broadcasting Co. found that 66 percent of them still feel anxiety over radioactive substances spewed out of the plant.