Level of Radioactive Materials Rises Near Japan Plant

Workers have been struggling to deal with contaminated runoff at the plant that resulted from makeshift efforts to cool reactors and spent fuel rod pools after a huge earthquake and tsunami knocked out regular cooling systems.

Much of the tons of water that has been sprayed on the reactors and pools has been stored, but the company that operates the plant, the Tokyo Electric Power Company, recently discovered and eventually plugged a leak that could have been gushing for days. The levels of radioactive materials in the ocean near the plant dropped after that.

But the government said Saturday that levels of radioactive materials in the seawater have risen again in recent days. The level of radioactive iodine 131 jumped to 6,500 times the legal limit, according to samples taken Friday, up from 1,100 times the limit in samples taken the day before. Levels of cesium 134 and cesium 137 rose nearly fourfold. The increased levels are still far below those recorded earlier this month before the initial leak was plugged.

The government said the new rise in radioactivity could have been caused by the installation on Friday of steel panels intended to contain radioactive materials. The construction may have temporarily stirred up stagnant waste in the area, Hidehiko Nishiyama, the deputy director general of Japan’s nuclear regulator, the Nuclear and Industrial Safety Agency, told reporters. However, the increase in iodine 131, which has an eight-day half life, could signal the possibility of a new leak, he said.

“We want to determine the origin and contain the leak, but I must admit that tracking it down is difficult,” he said.

The authorities have insisted that the radioactivity will dissipate and poses no immediate threat to fish outside the waters nearest to the plant or to the people who might eat them. The government has banned fishing close to the shore there.

Both cesium and iodine can increase the long-term risk of cancer with exposures to high levels.

Regardless, plant workers on Saturday began dumping sandbags filled with zeolite, a mineral that absorbs radioactive cesium, into the sea.

via nytimes.com