HIROSHIMA, Japan: Sunao Tsuboi was 20 years old when he suffered terrible radiation burns in Hiroshima's atomic inferno.

More than 65 years later, the crisis at the disaster-hit Fukushima No. 1 nuclear power plant is forcing him to relive the horror.

“This terrifies me from the depth of my heart,” Tsuboi, who is one of the dwindling group of survivors of the US nuclear bomb attack on Hiroshima in the final days of World War II, told AFP.

The leak of radioactive material from the complex northeast of Tokyo has “reawakened our deep-seated fears”, he said.

“Radiation damages genes and DNA. This is something that no doctor can fix. There is no proper remedy for radiation exposure.”

In his office near the Hiroshima peace memorial park, Tsuboi pulls a photograph from his desk, showing him and other students on August 6, 1945, just hours after the explosion. Their shredded skin is falling off.

To ease their unspeakable pain, soldiers daubed them with cooking oil. The apocalyptic scenes behind them hint at the nightmare that fell from the sky.

Tsuboi props his glasses on the nubs of his damaged ears. His forehead is bleached white from the radiation. His impeccable pinstriped suit covers a body riddled with cancer.

The ongoing drama at the Fukushima plant, located 800 kilometres from Hiroshima and where three workers were exposed to high levels of radiation this week, has reignited Tsuboi's anti-nuclear passions.

“Nuclear technology cannot coexist with human beings,” he said. “We need to turn our value system upside down. Life is more important than the economy.”

“The government repeatedly says that the level of radiation that has leaked from the Fukushima plant is not dangerous. But for those of us who understand what it's like to be irradiated, it's very dangerous,” Tsuboi added.

“People must be told that the after effects last for years, decades. We've lived through it.”

Other “hibakusha” — survivors of the nuclear bombings of Hiroshima and Nagasaki — say the same thing.

Hashizume Bun, the 80-year-old author of “The day the sun fell. I was 14 years old in Hiroshima”, was less than 1.5 kilometres from the hypocentre of the explosion.

“I've had health problems ever since. I still have radioactive elements in my body,” Bun, who has spoken in 70 countries about her ordeal, told AFP.

I had three sons, and now have four grandchildren. Every time one of them is sick, we're afraid. This is what awaits the victims of Fukushima,” she said.

“I hope that the Fukushima incident will reverse the global shift towards nuclearisation,” said the peace activist, explaining her sadness about the “renaissance” of nuclear energy as a clean alternative to coal-fuelled plants.

“If we don't stop this, the world will end up completely irradiated,” Bun warned.

“Nuclear technology is uncontrollable and has no borders.”

At the Hiroshima Peace Memorial Museum, dozens of sombre visitors wander through the exhibits. Some photos and objects — like blackened, misshapen fingernails lost in the streets — are hard to look at.

One display explains food contamination, the dangers of radiation exposure and how radioactive elements spread in the air and beyond — the same questions people living near the Fukushima plant in northeast Japan are now asking.

Shoji Kihara, a telecoms engineer, is a second-generation hibakusha, born in 1949.

His father, mother and sister — who was in utero at the time of the Hiroshima bombing — have all died.

He is furious about the government's reassurances that the situation at Fukushima poses no “immediate” danger to human health.

“They keep saying that there will be no immediate effects such as skin lesions, or fatal illnesses. But such symptoms come from serious exposure to radiation. They say it's not serious,” Kihara told AFP.

“But there will surely be consequences in the medium and long term.”

Hiroshima — today a thriving modern city — only has one building left that was not demolished after the bombing — the Atomic Bomb Dome, preserved as a memorial.

Between the A-Bomb Dome and the peace museum is the Cenotaph, a giant arch above a tomb inscribed with the names of the victims. Visitors bow their heads in silence.

In the stone is engraved a promise: “Let all the souls here rest in peace; for we shall not repeat the evil.”