Exactly... (Associated Press) 
 
 Greenpeace activists and other environmentalists light candles amidst hundreds of paper cranes at the Heroes' Monument in solidarity to the Japanese disaster victims at suburban Quezon city, northeast... (Associated Press) 
 
 This Sunday, April 10, 2011 photo released by Tokyo Electric Power Co. (TEPCO) shows orange colored floats suspending"silt fence," that was installed under water to help prevent contaminated water from... (Associated Press) 
 
 Japanese nuclear regulators said they raised the rating from 5 to 7 _ the highest level on an international scale of nuclear accidents overseen by the International Atomic Energy Agency _ after new assessments of radiation leaks from the Fukushima Dai-ichi plant since it was disabled by the March 11 tsunami. Chernobyl is the only other event to have been given a 7, an accident classified as having a major radioactive release with widespread impact on the environment and public health. Still, Fukushima Daiichi operator Tokyo Electric Power Co. warned Tuesday that since the Fukushima Daiichi plant is still releasing radioactive materials, the total level of radiation released could eventually exceed that of Chernobyl, a spokesman said. "At Chernobyl, the nuclear reactor itself exploded," he said, adding that at the Fukushima plant, the pressure vessel and the containment vessel were largely intact. According to INES, “Such a release would result in the possibility of acute health effects; delayed health effects over a wide area, possibly involving more than one country; long-term environmental consequences.” (Read the IAEA’s glossary of short- to long-term health effects of radiation exposure here.) "Judging from all the measurement data, it is quite under control. (UPDATED) Japanese officials announced on Tuesday morning that they were planning to raise the event level at the Fukushima Daiichi nuclear power plant from 5 to the maximum level of 7, the highest on the international scale for nuclear incidents and the same level assigned to the 1986 disaster at Chernobyl in the Ukraine. “The INES [International Nuclear and Radiological Event Scale] rating itself is not an indicator of a daily phenomena but the assessment after careful consideration and calculation on the event that happened in the past,” Ken Morita of Japan’s Nuclear and Industrial Safety Agency (NISA) tells TIME. A terabecquerel equals a trillion becquerels, a measure for radiation emissions. The release from Fukushima of tens of thousands of terabecquerels of iodine-131, while huge, appears to be smaller than the 5.2 million terabecquerels released from Chernobyl. If the leaks continue, the amount of radioactivity released in Fukushima could eventually exceed the amount emitted by Chernobyl, a possibility that Naoki Tsunoda, a TEPCO spokesman, said the company considers "extremely low." That is the same level reached by the Chernobyl nuclear disaster in the former Soviet Union, which struck almost exactly 25 years ago, on April 26, 1986. INES, designed in 1989 by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development, ranges from 1 (anomaly) to 7 (major accident). About 30 people, mostly workers, died in the immediate aftermath of Chernobyl, though the U.N. has estimated that the long-term death toll due to exposure could eventually be as high as 4,000. The new assessment comes as Japan admits that the effects of the Fukushima Daiichi nuclear accident—which has already caused the evacuation of tens of thousands of people and spread radiation through groundwater and farms over a broad section of eastern Japan—are likely to be long-lasting and grave. Meanwhile, Greenpeace said that in a survey conducted in Fukushima last week, its team of experts found radiation levels 75 times higher than the government recommendation in 11 samples of vegetables from gardens and small farms. The Fukushima plant was damaged in a massive tsunami that knocked out cooling systems and backup diesel generators, leading to explosions at three reactors and a fire at a fourth that was undergoing regular maintenance and was empty of fuel.
– Japan has made the decision to raise the Fukushima Dai-ichi nuclear disaster severity level from 5 to 7. That obviously means "worse." But what else does it mean? Japan finally has an estimate on how much radiation has been released: The level is an indication of the total radioactive materials emitted. Data has revealed that the cumulative amount of radioactive particles released into the atmosphere had reached levels that apply to a Level 7 incident, reports the AP. So what is that estimate? According to two estimates, the equivalent of about 500,000 terabecquerels of radiation from iodine-131 has been released. The Level 7 threshold is "several tens of thousands of terabecquerels." But all 7s are not created alike: The Wall Street Journal notes that officials were careful to say this this is still not a Chernobyl-size disaster. "The amount of released radiation is about a tenth of Chernobyl"—about 5.2 million terabecquerels—said a rep for Japan's Nuclear and Industrial Safety Agency. But it could still top Chernobyl in one regard: TEPCO today warned that the plant continues to release radioactive materials, and that the total levels emitted could eventually top those released by Chernobyl. Level 7 also indicates widespread effects on the environment and health: The Telegraph noted that Japan's safety commission now says radiation in excess of the amount considered safe for humans during an entire year has been found as far as 37 miles from the plant; the evacuation zone is only 18 miles. Is there another big one we haven't been talking about? Sort of. Besides Chernobyl, Time notes that a 1957 accident in Kyshtym, Russia, was the only one that's come close to being a 7; it was a 6. Most nuclear accidents tend to be a 3 or less.