An earthquake, tsunami, nuclear crisis, and more than 400 aftershock quakes over 5.0 magnitude – now Japan, and the world, face yet another danger: radiation.
Radioactive material, in greater levels than previously thought, has leaked from the stricken Fukushima Dai-Ichi nuclear plant every day since April 5, said data released from the Nuclear Safety Commission of Japan on Saturday, April 23.
Reactor unit 1 has released 154 terabecquerels per day nearly every day of April, the data said. One terabecquerel is one trillion becquerels.
The Fukushima crisis has been rated a maximum level 7 in severity on the international nuclear event scale, the same rating as the 1986 Chernobyl event.
The nuclear complex, containing six reactors units, was dealt several blows over March. For more information on how the crisis happened, visit www.mcccagora.com/features/crisis-evolved/.
Reactor units 1, 3, and 4 suffered hydrogen explosions early in the crisis that tore through parts of the roof. Reactor unit 2 suffered an explosion that ripped through the inner containment vessel.
About 67,500 tons of radioactive water have accumulated at the plant, the utility firm estimates. Some of the water has leaked into the Pacific Ocean.
Radiation spread
The company that owns the nuclear complex, Tokyo Electric Power Co., known as TEPCO, said on Thursday that the radioactive water that leaked for six days into the ocean contained 20,000 times the annual allowable limit for the plant, amounting to 520 tons.
On April 4, TEPCO began dumping 11,500 tons of water with low levels of radioactive iodine into the Pacific Ocean to free space in storage tanks for more toxic water.
The water released had up to 500 times the legal limit for radiation, while the water then stored had about 10,000 times the limit.
In the beginning of the crisis, radioactive materials were first detected in eastern Russia on March 14 and the west coast of the U.S. on March 16.
According to several experts, the levels were magnitudes lower than anything hazardous, the Associated Press reported.
Traces of radiation have even reached the southern hemisphere, according to the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization.
The risk associated with idiodine-131 contamination in Europe is no longer “negligible,” said CRIIRAD, a French research body on radioactivity. Pregnant women and infants in France and Europe have been advised to avoid “risky behavior,” like consuming fresh milk or vegetables with large leaves.
The U.S. Nuclear Regulatory Commission estimated an acceptable level of radiation at 100 millirem a year. The Environmental Protection Agency set a standard of no more than 15 millirem per single site or source.
A chest x-ray gives about 1 to 2 millrem to the whole body. Physical symptoms don’t usually appear until the body has reached 100 rem, or 100,000 millirem, in a single dose.
Levels over 100 microsieverts, or 10 millirem, per hour have been measured at four locations less than two miles from the plant, according to Kyodo News.
The Japan health ministry released a list of 99 different kinds of food found with radiation, including milk, leafy vegetables and fish.
The 12-mile evacuation zone was widened on Friday to include several other towns with high exposure. The change added about 10,500 people to the 70,000 to 80,000 already evacuated.
TEPCO is paying $600 million to 50,000 of the evacuees.
A citizen’s group from Fukushima said that small amounts of radioactive iodine were discovered in the breast milk of four women living east or northeast of Tokyo. The highest sample was from an 8-month-old baby’s mother, at 981 picocuries, or 36 becquerels per kilogram.
The government of Japan has made no radiation safety limit for breast milk consumed by infants under one-year-old, but for tap water the limit of toxicity is 100 becquerels per kilogram.
Resolving the issue
TEPCO announced April 16 that they aim to bring damaged reactors to a stable condition called a cold shutdown in six to nine months, ending the crisis, the Kyodo News reported.
The utility said it would need three months to steadily reduce radiation and another three to six months for radioactive emissions to be controlled.
Fixing the crippled reactors is now at a standstill.
TEPCO sent robots into reactor units 1, 2, and 3 and they discovered that radiation levels are too high for workers to enter. The data obtained found levels to be between 4 and 57 millisieverts per hour.
The government recently changed the ceiling on allowed exposure for workers from 100 to 250 millisieverts. Even with the new amount, workers could only spend about four and a half hours in the No. 3 reactor before they reached the 250 millisieverts ceiling.
The heat and humidity limit time even further.
Repair crews would only be able to stay in reactor units 1 and 2 for 50 minutes and 15 to 20 minutes respectively due to the heat and humidity, a professor from Shinshu University told the Mainichi Daily News on Wednesday.
The company, however, has not released a change in its 6 to 9 month goal.
