March 30, 2011
Radiation Found In Seawater Near Japanese Plant
Record-high measurements of contaminated seawater were discovered Tuesday near Japan's stricken Dai-Ichi nuclear facility, according to Japan's nuclear safety agency.
Radioactive iodine 131 in seawater near the nuclear plant rose to 3,355 times the legal limit Tuesday afternoon, from 2,572 times earlier in the day, said Hidehiko Nishiyama, a spokesman for Japan's nuclear safety agency, in a briefing with reporters.Scientists say the problem will likely remain localized, but warn that such high levels of radioactive contamination could lead to an exclusion zone if there is a major release of long-term pollutants.
Some 600 workers at the facility have worked diligently over the past two weeks to eliminate the threat of a total meltdown by injecting and streaming water into and on the damaged reactors.
Bloomberg reported that engineers have successfully connected the facility's six units with the power grid as they work to repair or replace the cooling systems damaged in the devastating tsunami.
However, discoveries of hazardous radioactive water in and near the reactors have hindered their work.
"Specialists are considering various possibilities and means to contain the nuclear power plant situation and minimize the radiation impact on surrounding areas and to people's health," Bloomberg quoted Japan's Chief Cabinet Secretary, Yukio Edano, as saying during a news conference on Tuesday.
"We haven't reached a conclusion as to what kind of means are possible or effective."
To date, radioactive iodine 131 has been the biggest contaminant identified by Japanese officials. It can enter the marine food chain, particularly through seaweed, which absorbs this element quickly.
"There is the potential, when you're talking about certain types of seafood, that you can have reconcentration," said Ed Lyman of the Union of Concerned Scientists (UCS), during an interview with the AFP news agency.
"So, even dilute levels of contamination can be enhanced in certain marine life, you know, just like mercury concentrates in large fish like tuna. Also, plants like seaweed are known to concentrate certain isotopes, and so are certain types of shellfish."
Radioactive elements in food are hazardous because, when ingested, the radiation can damage the DNA within cells, potentially causing cancer.
However, the contamination from iodine 131 is short-lived because the element has a half-life "“ the speed at which an element loses half of its radioactivity "“ of just eight days.
"This means that after a few months, it will be harmless, basically," said Simon Boxall of Britain's National Oceanography Centre at the University of Southampton.
"What worries me more is if cesium and plutonium get into the system," he told the AFP, referring to two radioactive heavy metals whose half-lives are approximately 30 years and potentially thousands of years, respectively.
"That's more concerning, because that can build up in the sediments" of the sea bed at Fukushima, Boxall said.
At high levels of contamination, this could ultimately force authorities to create an exclusion zone of catches of fish and seafood for "years and years," he added.
"It's hard to know (how long) until they start taking measurements and determine how extensive the pollution is. You would basically not fish in an exclusion zone, period. And beyond the exclusion zone there would be an additional zone where you would come from time to time and see if there's any radioactivity."
Boxall said that given the enormous size of the Pacific Ocean, the radioactivity in the sea at Fukushima will be flushed out beyond the local area by tides and currents, and dilute to very low levels beyond that.
"It will get into the (ocean) food chain but only in that vicinity," he said.
"Should people in Hawaii and California be concerned? The answer is no."
Meanwhile, the Obama administration said Tuesday that it is sending robots to Japan to assist in efforts to regain control over the crippled plant.
"A shipment is being readied," said Peter Lyons, who oversees nuclear power at the U.S. Department of Energy, during a Senate committee hearing.
"The government of Japan is very, very interested in the capabilities that could be brought to bear from this country."
Lyons said the engineers working at the nuclear complex were making progress in resolving the emergency.
"Current information suggests the plants are in a slow recovery from the accident," he told Senators.
However, he and Bill Borchardt, director of operations for the nuclear regulatory commission, did not offer any predictions about when the crisis might come to an end.
"I really can't even hazard a guess on how long that will be," Borchardt said.
The potential benefits of deploying robots at Fukushima was demonstrated last week, when two workers were exposed to high levels of radiation and burned. The workers were standing in pools of highly radioactive water in a reactor turbine room without adequate protective gear.
Robots, with electronics built to tolerate radiation, can work in areas of the plant where radiation levels would rapidly kill a human engineer. They can also help scientists view damage to the reactor core.
Lyons said the robots the U.S. was sending to Japan would be equipped with cameras as well as devices that measure radiation.
"They could go places where you certainly wouldn't send a person," he said.
Lyons said the U.S. has developed numerous remotely operated robots designed to clear up radioactive waste from department of energy test weapons sites.
The initial versions of the robots were developed in the aftermath of the Three Mile Island accident in 1979, when robots were deployed to get a view of the damaged reactor, and to clean up radioactive water and partially melted fuel.
The U.S. will also send trainers to instruct Japanese workers in the proper operation of the robots. The Energy Department has already sent 40 people and nearly 8 tons of equipment to Fukushima, according to the Guardian newspaper.
Lyons said that U.S. flights would not go within 2.5 miles of the nuclear facility due to the elevated radiation levels near the plant.
On the Net:
- Japan Nuclear Energy Safety Organization
- Union of Concerned Scientists (UCS)
- National Oceanography Centre
- U.S. Department of Energy
- Image Courtesy Wikipedia (CC BY-SA 3.0)