One year ago, a series of events began with an earthquake off the cost of Japan that culminated in the largest accidental release of radioactivity into the ocean in history.
We have to be careful and say “accidental” because in the late 1950s and early 1960s, 50 to 100 times more radioactivity was released worldwide as fallout from the intentional testing of nuclear weapons. The word “ocean” is also important, since Chernobyl in 1986 was hundreds of miles inland, so it had a smaller impact on the concentrations of radionuclides in the sea than was measured directly off Japan in 2011.
One year later, we have to ask, what do we know about Fukushima’s impact on the ocean and levels of radioactive contaminants in water and fish?
Japan’s prime minister made his first visit to the country’s tsunami-devastated region on Saturday as officials grappling to end the worst nuclear crisis since Chernobyl said they may have discovered why radiation has been leaking into the sea.
Tokyo Electric Power Co (TEPCO) said it had found a crack in a concrete pit that was leaking water at its No.2 reactor in Fukushima, measuring 1,000 millisieverts of radiation per hour.
"With radiation levels rising in the seawater near the plant, we have been trying to confirm the reason why, and in that context, this could be one source," said Hidehiko Nishiyama, deputy head of the Nuclear and Industrial Safety Agency (NISA).
He cautioned, however: "We can’t really say for certain until we’ve studied the results."
TEPCO has begun pouring concrete into the pit to stop the leak, he said.
Japan’s effort to contain the crisis at the Fukushima Daiichi nuclear plant suffered a setback, an official said on Friday, citing evidence that the reactor vessel of the No. 3 unit may have been damaged.
The development, described at a news conference by Hidehiko Nishiyama, deputy director-general of the Japan Nuclear and Industrial Safety Agency, raises the possibility that radiation from the mox fuel in the reactor — a combination of uranium and plutonium — could be released.
One sign that a breach may have occurred in the reactor vessel, Mr. Nishiyama said, took place on Thursday when three workers who were trying to connect an electrical cable to a pump in a turbine building next to the reactor were injured when they stepped into water that was found to be significantly more radioactive than normal in a reactor. The No. 3 unit, the only one of the six reactors at the site that uses the mox fuel, was damaged by a hydrogen explosion on March 14. Workers have been seeking to keep it cool by spraying it with seawater along with a more recent effort to restart the reactor’s cooling system.
In another development on Friday, the Japanese government said it would help people who wish to leave the area around the crippled plant, a sign that efforts to reassure frightened residents have failed to persuade people to stay.
Radiation leaking from Japan’s tsunami-damaged nuclear power plant has caused Tokyo’s tap water to exceed safety standards for infants to drink, officials said Wednesday, sending anxiety levels soaring over the nation’s food and water supply.
Residents cleared store shelves of bottled water after Tokyo Gov. Shintaro Ishihara said levels of radioactive iodine in tap water were more than twice what is considered safe for babies. Officials begged those in the city to buy only what they needed, saying hoarding could hurt the thousands of people without any water in areas devastated by the March 11 earthquake and tsunami.
"I’ve never seen anything like this," clerk Toru Kikutaka said, surveying the downtown Tokyo supermarket where the entire stock of bottled water sold out almost immediately after the news broke, despite a limit of two, two-liter bottles per customer.
The unsettling new development affecting Japan’s largest city, home to around 13 million people, added to growing fears over the nation’s food supply.
Japan warned radioactive levels had become "significantly" higher around a quake-stricken nuclear power plant on Tuesday after explosions at two reactors, and the French embassy said a low level radioactive wind could reach Tokyo by the evening.
Prime Minister Naoto Kan urged people within 30 km (18 miles) of the facility north of Tokyo to remain indoors, underscoring the dramatic worsening of Japan’s nuclear crisis, the world’s most serious since the Chernobyl disaster in Ukraine in 1986.
As concern about the crippling economic impact of the nuclear and earthquake disasters mounted, Japanese stocks plunged 13 percent – heading for their biggest drop since 1987 — compounding a slide of 7.6 percent the day before. The two-day fall has wiped $720 billion off the market.
In a sign of mounting fears about the risk of harmful radiation, Air China said it had canceled flights from Beijing and Shanghai to Tokyo, but there was no sign that people were rushing en masse to the capital’s airports to leave.
"There has been a fire at the No. 4 reactor and radiation levels in the surrounding area have heightened significantly. The possibility of further radioactive leakage is heightening," a grim-faced Kan said in an address to the nation.