小编摘要：日本福岛第一核电站（Fukushima Daiichi nuclear complex）因受损释放出大量辐射，政府划定核电站周围19公里以内为疏散区。根据一项最新评估，该疏散区以外部分地区的辐射水平超出了政府规定的婴儿可接受上限。该评估
日本福岛第一核电站（Fukushima Daiichi nuclear complex）因受损释放出大量辐射，政府划定核电站周围19公里以内为疏散区。根据一项最新评估，该疏散区以外部分地区的辐射水平超出了政府规定的婴儿可接受上限。该评估引发了国际社会就民众应与该核电站保持多远距离展开争论。
Levels of radioactivity from Japan's damaged Fukushima Daiichi nuclear complex are above government limits for infants in some areas outside the plant's 12-mile evacuation zone, according to the latest estimate to fuel an international debate over how close civilians should be allowed to the plant.
The new estimate, by a state-funded monitoring body, came as fears over Tokyo's tap water eased. Tests Thursday showed radioactive material in a major plant supplying water to the capital has fallen beneath the level the government says could pose long-term health risks to infants. Elevated levels at the plant Tuesday and Wednesday sparked official warnings and bottled-water sales.
政府监管机构日本原子力安全技术中心（Nuclear Safety Technology Center）于周三晚发布了这项有关福岛第一核电站周边地区累计辐射剂量的评估。评估涵盖了自3月11日发生地震和海啸以来12天的记录。这次灾难导致核电站多次失火、爆炸和辐射水平升高。
Japan's Nuclear Safety Technology Center, a government monitoring group, released the estimate late Wednesday of the cumulative exposure to radiation in zones surrounding the Fukushima Daiichi complex. The estimate covered the 12 days since Japan's March 11 earthquake and tsunami spurred fires, explosions and spikes in radioactivity levels at the complex.
The estimate -- produced by modeling radiation readings collected at various points around the plant -- suggested that most areas with radiation that exceeded government thresholds fell within the 12-mile evacuation zone.
But the model showed that areas where cumulative exposure over 12 days reached 100 millisieverts -- the government's maximum for infants -- extended beyond the evacuation zone. A map based on the data showed areas that received a cumulative 100 millisieverts extended as far as about 25 miles northeast and south from the plant.
Government officials said the center's estimate didn't require a larger evacuation, under even the most conservative standards. They said a person would have to have been in the area, and outdoors for the entire time since the March 11 earthquake, to receive that full dose.
Still, the test results demonstrate the uncertainty surrounding the measuring of radioactive emissions from the power plant.
Elevated levels of radioactive elements have been found as far away as Tokyo in its tap water, prompting worries over the nation's food and water supplies.
In Japan's capital on Thursday, new tests showed a sharply lower level of radioactive iodine-131 at the northern Tokyo water-purifying plant where tests earlier this week revealed levels roughly twice those recommended for infants.
The Thursday test showed the plant's water contained 79 becquerels per kilogram -- a measure of radioactive events -- below the 100 becquerels per kilogram level considered acceptable for infants. Tokyo officials Thursday lifted the city's warning about consumption by infants.
Iodine-131 has a half-life of about a week, meaning that levels in water could fall quickly if new doses aren't introduced. Tokyo metropolitan government officials have posited, but have not proved, that recent rains could have flushed airborne iodine-131 into rivers that supply the vast majority of Tokyo's water, and also increased radiation levels in Tokyo.
On Thursday, Tokyo's government said radioactive cesium exceeding the government's limit was detected in komatsuna, or Japanese mustard spinach, in a sample taken in Tokyo. It is the first time a radioactive substance exceeding the government limit has been found in farm products in Tokyo since the beginning of the crisis.
有关电站危险情况的数据和估计结果各不相同，曾让日本、美国和其他国家的监管机构犯难。新泻大学（Niigata University）核化学教授工藤久昭（Hisaaki Kudo）说，即使是在一个不大的区域，辐射水平也可以是非常不均衡的。他列举的变量包括风力、地点、不同种类的设备和放射性物质等。
Regulators in Japan, the U.S. and elsewhere have grappled with differing data and estimates of the plant's dangers. 'Even within a small area, radiation levels can be very uneven,' said Hisaaki Kudo, nuclear chemistry professor at Niigata University, citing variables ranging from wind to location to different types of equipment and radioactive material.
Wednesday's estimate by Japan's Nuclear Safety Technology Center differs from daily data that Japan's Ministry of Science and local governments have been releasing since March 11. Those daily measures have shown radioactive material at slightly elevated levels of generally under 10 microsieverts per hour.
The Nuclear Safety Technology Center's estimate Wednesday judges the full amount of exposure over the period since the radioactive material was released, which health experts say could be a better gauge of health threats. Its computer simulation estimates how far radioactive materials have spread based on factors including landscape, weather and the direction and speed of winds.
Officials stressed that the simulation is based on an unlikely scenario of a person staying outside the entire time to be exposed to radioactive.
2011-03-28 11:48 编辑：icetonado
TOKYO, Mar 17 （Reuters） - Japan may build robots to play the violin, run marathons and preside over weddings, but it has not deployed any of the machines to help repair its cripp