Fukushima nuclear accident
The Fukushima Daiichi nuclear disaster was a series of equipment failures, nuclear meltdowns and releases of radioactive materials at the Fukushima nuclear power plant in northeastern Japan, following a devastating earthquake and tsunami on 11 March 2011 which claimed nearly 19,000 lives. It is the largest nuclear disaster since Chernobyl in 1986 and only the second disaster to measure Level 7 on the International Nuclear Event Scale.
Fukushima clean-up ‘more difficult than Three Mile Island’
US adviser says operation is bigger than one at Three Mile Island in 1979, but concerns over leaks of radioactive water 'out of proportion'
A former US nuclear regulator says cleaning up Japan's wrecked Fukushima plant is a bigger challenge than the work he led in the US after the partial nuclear meltdown at the Three Mile Island plant in Dauphin County, Pennsylvania, in 1979.
He also said that the ongoing radioactive water leaks at Fukushima were just a minor part of that task.
Lake Barrett was appointed this month by plant operator Tokyo Electric Power (Tepco) as an outside adviser for the decommissioning process.
He led the clean-up after the Three Mile Island accident - the worst in US commercial nuclear power plant history - for nearly a decade as part of the Nuclear Regulatory Commission.
He said that the meltdowns in three of the reactors, massive radiation leaks and the volume of contaminated water at the Fukushima Daiichi plant on Japan's northeast coast make it a more complicated clean-up.
"In comparison to Three Mile Island, Fukushima is much more challenging, much more complex a job," Barrett said in Tokyo.
Compared to the magnitude of that task, the leakage problem is a "very low health impact and not a concern", he said.
The attention on the contaminated water leaks is "out of proportion" and is hurting the overall clean-up process by slowing things down, he said.
The Three Mile Island accident involved one reactor. All the radioactivity was contained in one building, where 8,000 tons of toxic water was trapped.
In Fukushima, the catastrophe was precipitated by a massive earthquake and tsunami, the effects of which were further adding to the difficulties of containing and cleaning up after the meltdowns of the three reactors.
Moreover, buildings at the Japanese plant were destroyed or damaged by hydrogen explosions, which released massive radioactive elements into the air and to the sea.
Japanese officials have acknowledged that radioactive ground water has been leaking from the plant since soon after the nuclear disaster. Recent leaks from tanks holding radioactive water have added to concerns.
But despite worries over the massive quantities of water needed to cool the melted reactors, the risk of radiation-contaminated water to public health is minimal, Barrett said.
Vapour was seen rising again from a reactor at the power plant yesterday, more than two-and-a-half years after its core melted down.
Tepco said it believed the steam was coming from a puddle sitting on top of the reactor and was not dangerous, but it has not been able to clarify why vapour started appearing occasionally from July this year.
The company said the plant remained stable, with sensors in and around it showing no increase in the levels of radioactivity released. Tepco acknowledged on Thursday that samples of underground water from near a tank where a major leak occurred last month showed high levels of radioactive tritium.
Massive amounts of contaminated water - a combination of water leaking from the three damaged reactors and inflows of underground water - have also accumulated inside reactor and turbine basements and threaten to leak into the Pacific.
The most toxic water gathers in the basements, Barrett said, but this had so far been "adequately controlled".
The Nuclear Regulation Authority has estimated the amount of that water at a substantial 90,000 tons.
It urged Tepco to quickly increase anti-leak measures to the basements to minimise the risk of the toxic water spreading.
Additional reporting by Agence France-Presse