Heavy rains from the tail end of a weakened typhoon have pushed levels of highly radioactive water at Fukushima to near overflowing. Enormous quantities of radioactivity, 720,000 terabecquerels, are contained in 28 million gallons of contaminated water according to TEPCO. TEPCO is rushing to install a water decontamination system by June 15 because they calculate that water will overflow by June 20 if additional decontamination and storage systems aren't installed. With Japan's rainy season beginning, TEPCO will be challenged to keep large amounts of radioactive water from overflowing directly into the ocean.
Bloomberg reports that the water contains the largest amount of radioactivity released from a reactor since the Chernobyl accident, more than Fukushima has released to the atmosphere.
The amount of contaminated water rose to about 105 million liters (28 million gallons) from 100 million liters on May 18, and may start overflowing after June 20, the company known as Tepco said in a statement today. Radiation in the water is estimated at 720,000 terabecquerels, general manager Junichi Matsumoto said at a media briefing in Tokyo.
Today TEPCO released data that show that radioactive cesium is building up to dangerous levels in multiple sediment samples 3 km (1.8 miles) offshore. Because Cs-137 has a half life of 30 years, sediment offshore will likely continue to be contaminated at dangerous for one hundred years even if no more radioactive water is released to the sea.
The additional overflow of large amounts of highly contaminated water could be disastrous to the local marine environment. Note, that I have been saying for weeks that TEPCO needed to urgently install ion exchange equipment to decontaminate the growing volumes of contaminated cooling water. I am not alone. TEPCO's slow response is endangering the marine environment.
“The risk of overflow is as serious as the meltdown of reactor fuel rods that’s already happened,” Tetsuo Ito, the head of the Atomic Energy Research Institute at Kinki University in western Japan, said in a phone interview. “Tepco should’ve acknowledged this risk weeks ago and could’ve taken any urgent measures.”
Moreover, radiation levels in water inside the silt fence near reactor 2 are high and rising, despite large amounts of dilution. Continued very high levels of Iodine 131 with a half life of 8 days are very hard to explain for a reactor that has been "shut down". Normally Iodine levels would drop several orders of magnitude below cesium activity levels over the sixty day period shown in the graph, but instead they continue to track each other. The level of 10,000 Bq/liter I-131 is very problematic. It is much higher than would be expected for a reactor in cold shut down for 2 1/2 months.
Update: The data from the quay near Fukushima shows the expected divergence of Cs-137 and Cs-134 radioactivity levels from those of I-131 based on the 8 day half life of I-131. This is the rate of decay of I-131 levels that will occur after a cold shut down. Something anomalous appears to be happening near reactor unit 2.
