Suzuki's Fukushima updates

SEPTEMBER 18—On September 15 and 16, Typhoon Man-yi struck the main island of Japan, while strong winds and a huge amount of rainfall hit the Fukushima area. After the typhoon hit on September 15, Tepco sampled water from surrounding tanks and found that the highest contamination level of tritium was 170,000 becquerels per liter—about three times the regulatory standard of 60,000 becquerels per liter of tritium. For example, before the typhoon, the highest contamination level had been found on September 8, when the reading hit 4,200 becquerels per liter; however, since then—due to reasons still unknown—the levels had been steadily climbing to 64,000 becquerels per liter on September 10, and 130,000 becquerels per liter two days later.

On September 17, Tokyo Electric Power (Tepco) announced the status of the contaminated water tanks, as well as the state of the water leakage. Typhoon Man-yi not only had wind gusts of more than 160 kilometers per hour, but the rainfall was double that of the area’s annual rate. Due to such heavy rain, Tepco found that some of the water barriers, standing about 30 centimeters tall around the storage tanks, were close to overflowing. Thus, the company decided to drain the contaminated water that was lower than the regulatory standard. The highest contamination level of mostly strontium 90 was 24 becquerels per liter, which is lower than the regulatory standard of 30 becquerels per liter of strontium 90. Tepco drained into the ground a total of 1,130 tons of water from seven tanks, and it is suspected that some of the water may have leaked into the sea. As for the contaminated water above the regulatory standard that was found inside the water barrier, Tepco pumped it into storage tanks to avoid overflow.

On September 17, Tepco released an English-language video explaining the situation at the Fukushima Daiichi Nuclear Power Station. 

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SEPTEMBER 16, 2013—As there are increasing concerns about the safety of the fishery products due to the leak of contaminated water from the Fukushima Daiichi Nuclear Power Station, it is a good time to look at the latest monitoring results provided by the Fisheries Agency. To keep these new numbers in perspective, however, it is useful to recall that on April 1, 2012, Japan lowered the limits of radioactive contaminants acceptable in food, including seafood, to 100 becquerels per kilogram; this new standard for fisheries replaced the provisional regulation value for radioactive cesium, which had been set at 500 becquerels per kilogram. 

As of the end of August 2013, Japan had collected a total of 37,470 fish samples—14,070 of which were from Fukushima Prefecture. The tests concluded that 92.6 percent of the samples from Fukushima were below the limit of 100 becquerels per kilogram. From outside the prefecture, 98 percent of the tests were below the standard. The percentage of samples beyond the standard was much higher two years ago. That is, from April to June 2011, Fukushima Prefecture saw 53 percent of its fish samples test positive for radioactive contaminants above the standard limit of 100 becquerels per kilogram; however, this rate has steadily declined to only 2.7 percent during the period from July to August of this year. For samples from outside the Fukushima Prefecture, such percentage was much lower. It was 6.5 percent during the period from March to June 2011, but it has stayed below 1 percent since October 2012; and today, it is around 0.4 percent.

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SEPTEMBER 9, 2013—Note: On Friday, September 6, I wrote that the radiation level that was detected near the tanks was 2,200 millisieverts per hour. To clarify, this is the exposure within 5 centimeters of the spot where the reading was taken; because much of this is beta radiation—which can be blocked by clothing, for example—exposure drops as one moves away from the radiation source. In fact, from 50 centimeters away, the measurement was 40 millisieverts per hour.  

Over the weekend, Japanese Prime Minister Shinzo Abe assured the International Olympic Committee that the “situation [at the Fukushima Daiichi Nuclear Power Station] is under control,” and that the contaminated water is “completely contained” within a 0.3 square kilometer area from the nuclear power station. The technical basis of his statement is as follows:

• There are 32 radiation monitoring stations and 85 radiation monitoring points along the coast of the Fukushima, Ibaraki, and Chiba prefectures. The Nuclear Regulatory Authority reports that the seawater contains 0.021 becquerel per liter or less of cesium 134 and cesium 137—far below the acceptable standard of 10 becquerel per liter.
• The contaminated water is limited to the area around the port near the Fukushima Daiichi Nuclear Power Station—an area that is no larger than 0.3 square kilometers.
• The annual radiation exposure from food and water is estimated to be lower than 0.01 millisieverts.

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SEPTEMBER 6, 2013—I have received encouraging feedback and questions to the first column, and would like to express my sincere thanks for your kind support; please excuse me for not responding to those directly through email, Twitter, or Facebook. I will try to respond to your questions in my updates.

 

 

On September 3, 2013, Tokyo Electric Power Company (Tepco) and the Ministry of Economy, Trade, and Industry (METI) announced the following three principle countermeasures against the ongoing contaminated water crisis at the Fukushima Daiichi Nuclear Power Station: removing the source of contamination, isolating ground water from the contamination, and preventing any leaks of the contaminated water. But there are major challenges to the countermeasures that are currently employed or that planned to be employed. These issues are as follows:

 

Removing the source of contamination. On August 22, Tepco started pumping contaminated water from the trench and will have this water isolated by the end of 

October. The multi-nuclide removal equipment—known as the Advanced Liquid Processing System, or ALPS—has three lines and a daily capacity of 750 tons; currently, it is undergoing a “hot test,” which means that the facility uses radioactive materials during the test run. However, two of its three lines are currently shutdown due to technical problems. While ALPS was planned to begin full-scale operation by the end of September, it remains uncertain if this will happen; this is why the government decided to provide financial support for a second and improved facility, which will have a similar function as ALPS, but has not yet been named.

 

Isolating groundwater from the contamination. On July 8, Tepco started injecting sodium silicate into the ground; the company completed enclosing the soil between units 1 and 2 on August 10. Tepco also started enclosing the soil between units 2 and 3 as well as units 3 and 4—the completion date is planned for October. Tepco will examine a freezing method to block the water flow between the turbine buildings and the trenches. This is an expensive operation (first suggested by the government's accident response office in April of 2011, but rejected by Tepco due to high costs); therefore, the government has decided to provide financial support for the effort.

 

Preventing leakage of the contaminated water. Tepco has installed wells—located near the reactor building that faces the mountains—to pump up groundwater so that the water will not flow into the reactor buildings. The company is currently negotiating with local residents and the fishing industry on the details surrounding the startup of these wells. On September 5, Tepco found that the underground water taken from the wells was contaminated—650 becquerel per liter—which implies that contaminated water may have leached into the underground water; heavy rainfalls this summer likely influenced this. Bypassing the underground water may not be effective if it already has been contaminated. Exact routes and the scale of contamination are still not known.