Japan’s nuclear crisis escalated as helicopters and riot-control water cannons were enlisted in an effort to prevent radioactive pollution spreading from the nuclear industry’s worst catastrophe since Chernobyl.
Helicopters doused 30 metric tons of water on pools used to cool spent fuel rods. No change in radiation was reported after four bombing runs by the aircraft, Kyodo News said citing plant operator Tokyo Electric Power Co. A plan to have police shoot a high-pressure stream of water at the reactor structure was called off tonight. Tokyo Electric may connect a power cable to the plant later today, a company official said.
“We are still reviewing the result of water spraying by helicopters,” said Akiteru Kobayashi, head of nuclear facility management.
Tokyo Electric’s failure to end the threat of radiation from the Fukushima plant has prompted the U.S., U.K., France, Germany and Australia to advise their citizens to consider leaving Tokyo. About 2.3 trillion yen ($29 billion) has been wiped from Tepco’s market value since the March 11 quake, subsequent tsunami and a series of explosions and fires devastated the 40-year-old power station, 135 miles (220 kilometers) north of Tokyo.
Japan’s Nuclear and Industrial Safety Agency said today there is a possibility of no water at the No. 4 reactor’s spent- fuel cooling pool. If exposed to air, the fuel rods could decay, catch fire and spew radioactive materials into the air. The agency has detected no smoke or steam rising from the reactor, spokesman Hidehiko Nishiyama said.
Exposure of spent-fuel rods to air “could result in fracturing of the fuel rod cladding and escape of dangerous radioactive fission products” such as iodine-131, cesium-137 and strontium-90, said Stephen Lincoln, an environmental chemist at the University of Adelaide.
All water in the No. 4 reactor’s spent-fuel pond has drained, U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko told a congressional panel in Washington yesterday. Fuel rods stored in three reactors at the Tokyo Electric plant are exposed and releasing radiation, Yukiya Amano, head of the International Atomic Energy Agency, said in Vienna before departing for Tokyo. The plant has six reactors, three of which have been damaged by explosions following the March 11 quake.
Helicopters are also being used to determine radiation readings, water levels in the pool and damage to the reactors, Tepco spokesman Kaoru Yoshida told reporters in Tokyo today. Technicians were unable to inspect the facilities because of high levels of radiation.
More than 320 workers are at the plant site today, from a group of 50 engineers yesterday. Tokyo Electric evacuated 750 employees on Tuesday when radiation levels at Dai-Ichi spiked.
The recent increase in employees at the Dai-Ichi plant could indicate that a work rotation is being implemented to minimize radiation exposure. Japan’s health ministry raised the cumulative maximum legal exposure for nuclear workers to 250 millisieverts from 100 millisieverts on March 15 to enable workers to stay longer on the site to prevent a nuclear disaster.
Radiation levels have reached 10 millisieverts per hour in some parts of the plant, said John Price, a Melbourne-based consultant on industrial accidents and former member of the safety policy unit at the National Nuclear Corporation U.K.
“That means they have an access time of 10 to 25 hours at the most,” Price said in a telephone interview today. “At that rate, you are going to go through workers very fast.”
Lack of Information
“We haven’t been able to get any of the latest data at any spent fuel pools,” Tepco official Masahisa Otsuku said yesterday. “We don’t have the latest water levels, temperatures, none of the latest information for any of the four reactors.”
Tepco said it’s building a power line to the Dai-Ichi plant’s cooling systems, which were knocked out by the quake, but was unable to say when the cable would be completed.
The failure of backup generators used to pump cooling water caused explosions in at least three of the structures surrounding the station’s reactors, as well as a fire in a pond containing spent fuel rods.
The NRC’s Jaczko said radiation at the Japanese site is fluctuating and at peak levels “would be lethal within a fairly short period of time.”
His information came from NRC staff who were dispatched to Japan to help with the response and have been in contact with industry officials there, he said. Jaczko’s assessment prompted the U.S. to recommend American citizens leave Japan. France and Germany have already told their citizens to depart.
There have been more than 450 aftershocks since the magnitude-9 temblor left hundreds of thousands stranded and without power, with disruptions to food and water supplies. The Japanese government has dispatched 100,000 troops to the northeastern region.
The official death toll at 2 p.m. Tokyo time was 5,321 people, with 9,329 missing and 2,383 injured, the National Police Agency said. The tsunami and fears of a meltdown at the plant forced 451,059 people from their homes, and 385,549 were evacuated, the police said.