IAEA: Japan puts restrictions on drinking water in 4 Fukushima areas

Japanese authorities have placed restrictions on drinking water in at least four areas in Fukushima prefecture, where a nuclear plant was crippled by a magnitude-9 quake last March 11, the International Atomic Energy Agency has said. The IAEA also indicated concentrations of plutonium in the area are similar to those from nuclear weapons. "As of 28 March information on radioactivity in drinking water collected mainly from the Japanese Ministry of Health, Labor and Welfare indicates that recommendations for restrictions based on I-131 concentration remain in place only in four locations in the prefecture of Fukushima. To date, no recommendations for restrictions have been made based on Cs-137," the IAEA said. Also, it cited Japanese limits for the ingestion of drinking water by infants is 100 Becquerel per liter. It also said five soil samples, collected at distances between 500 and 1,000 meters from the exhaust stack of Unit 1 and 2 of the Fukushima Nuclear Power Plant on 21 and 22 March, were analyzed for plutonium-238 and for the sum of plutonium-239 and plutonium-240. Plutonium-238 was detected in two of the five samples, while plutonium-239/240 was detected in all samples as expected. "Concentrations reported for both, plutonium-238 and plutonium-239/240 are similar to those deposited in Japan as a result of the testing of nuclear weapons," it said. It added the ratio of the concentrations of plutonium-238 and plutonium-239/240 in two of the samples indicates that very small amounts of plutonium might have been released during the Fukushima accident, but this needs further clarification. Food contamination As far as food contamination is concerned, 63 samples taken from March 24 to 29 and reported on from March 27 to 29 for various vegetables, fruit (strawberries), mushrooms, eggs, seafood and pasteurized milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Miyagi, Niigata, Tochigi and Yamagata), stated that results for iodine-131, caesium-134 and caesium-137 were "either not detected or were below the regulation values set by the Japanese authorities." The Joint FAO/IAEA Food Safety Assessment Team met with local government authorities in Ibaraki prefecture last Monday and provided advice related to contamination of food and the environment, including the mechanisms and persistence of such contamination, examples of remediation strategies, international standards and sampling plan designs and radionuclide transfer from soil to plants, particularly as related to rice production in the area. Local government authorities briefed the FAO/IAEA Team on the extent of contamination in Ibaraki, the principal agricultural products affected, the main production areas and production methods (greenhouse, open-air) and levels of contamination found. The FAO/IAEA team is also meeting with the local authorities in Tochigi prefecture and will meet with local government officials in Gunma. Marine organisms Initial analysis carried out by the National Research Institute of Fishery Research showed contamination of fish samples. The samples were collected from the port of Choshi (Chiba prefecture) and 4 of 5 samples showed Cs-137 concentrations below limit of detection. "In one sample Cs-137 was found with 3 Bq/kg (fresh weight) and it was reported that it was slightly above the limit of detection. This concentration is far below any concern for fish consumption," IAEA said. "It is still too early to draw conclusions for expected concentrations on marine food, because the situation may change rapidly, however, it is expected that the detected initial concentrations of seawater will soon drop to lower values by dilution and the levels in marine food will most likely not reach levels above given limits for consumption, (presuming that discharges of contaminated seawater from the reactor will not continue)," it added. The IAEA said it is not expected that fish or other marine food will be collected in a close area to the NPP Fukushima at the present situation. Some marine algae are known to accumulate in particular I-131 and Tc-99m. However, these values will soon be of no concern due to the short half-lives of the radionuclide mentioned. Plant situation still very serious The IAEA said the situation at the Fukushima Daiichi plant remains very serious. It said accumulated contaminated water was found in trenches located close to the turbine buildings of Units 1 to 3. Dose rates at the surface of this water were 0.4 millisieverts/hour for Unit 1 and over 1 000 millisieverts/hour for Unit 2 as of 2:30 a.m. Sunday (Manila time). "The Nuclear Safety Commission of Japan suggests that higher activity in the water discovered in the Unit 2 turbine building is supposed to be caused by the water, which has been in contact with molten fuel rods for a time and directly released into the turbine building via some, as yet unidentified path. An investigation is underway as to how the water accumulated in the trenches," it said. Measurements could not be carried out at Unit 3 because of the presence of debris. Fresh water has been continuously injected into the Reactor Pressure Vessels (RPVs) of Units 1, 2 and 3. Radiation On Monday, deposition of iodine-131 was detected in 12 prefectures, and deposition of cesium-137 in nine prefectures. The highest values were observed in Fukushima with 23,000 becquerel per square meter for iodine-131 and 790 becquerel per square meter for caesium-137. In the other prefectures where deposition of iodine-131 was reported, the range was from 1.8 to 280 becquerel per square meter. For caesium-137, the range was from 5.5 to 52 becquerel per square meter. In the Shinjyuku district of Tokyo, the daily deposition of both iodine-131 and cesium-137 was below 50 becquerel per square meter. No significant changes were reported in the 45 prefectures in gamma dose rates. Seawater samples New analyses in seawater 330 meters east to the discharges point of NPP Units 1 to 4 were made available for March 27. These concentrations show a significant decrease from 74,000 Becquerel per liter of iodine-131, 12,000 Becquerel per liter of cesium-137, and 12,000 Becquerel per liter of cesium-134 on March 26 to 11,000 Becquerel per liter of iodine-131 and 1,900 Becquerel per liter of cesium-137 on March 27. Seawater samples were also collected daily at a location 30 m from the common discharge point for Units 5 and 6. These results also show an increase in the radionuclide concentrations on March 26. The seawater samples collected on March 27 show as well a decrease of the radionuclide concentration. "It can be expected that the data will be quite variable in the near future depending on the discharge levels. In general, dilutions by ocean currents and into deeper waters as well decay of short lived radionuclide e.g. I-131 or I-132 will soon lead to lower values," IAEA said. — LBG, GMA News