The amount of radioactivity in seawater near the Fukushima Daiichi nuclear power plant is about to hit the highest-ever level recorded in history.According to the Asahi Shimhun on Sunday, officials measured 1-hundred-86 becquerels per liter of radioactive substances in the sea just 34 kilometers from the crippled power plant on April 15th.This level is about 20-thousand times higher than the permissible annual standard set by the Japanese government.The highest level of contamination in history was 2-hundred becquerels per liter in the Irish Sea in the 1970s when a nuclear fuel reprocessing factory discharged cesium-137.Meanwhile, Tokyo is reportedly considering building an underground wall near the Fukushima power plant to contain the spread of radioactive material through soil and groundwater.