Radiation levels in seawater at crippled Fukushima plant jump 6,500 times above legal limit ahead of new 5.9 earthquake 17 Apr 2011 Radiation levels have risen dramatically in seawater near the stricken Fukushima nuclear plant in Japan, sparking fears of a new leak, according to the country's government. On Friday, levels of radioactive iodine-131 were found to have spiked to 6,500 times the legal limit. This was up from 1,100 times the limit in samples taken the day before... Plant workers today began dumping sandbags filled with zeolite, a mineral that absorbs radioactive cesium, into the sea to combat the radiation leaks.