The radiation levels of the first samples of seawater collected by the Environment Ministry since the crippled Fukushima nuclear power plant began to release treated water were below detectable limits, it said Sunday.
Based on the analysis of seawater sampled Friday morning, the concentrations of tritium -- a radioactive material that cannot be removed even after the treatment of contaminated water generated at the Fukushima plant -- were at levels that "would have no adverse impact on human health and the environment," the ministry said.
Amid persistent public concern in neighboring countries such as China, the Japanese government has been stepping up its radiation monitoring efforts since it began on Thursday the decadeslong process to release treated radioactive water from the Fukushima Daiichi complex.
The Fisheries Agency announced Saturday that no detectable amounts of tritium were found in the first fish samples taken in waters near the plant.
Massive amounts of contaminated water have been generated in the process of cooling reactor fuel at the plant, which suffered core meltdowns triggered by the March 2011 earthquake and tsunami.
The water has been kept in tanks after going through the Advanced Liquid Processing System that removes most radionuclides except tritium. But the storage vessels are nearing capacity, resulting in the decision to release the wastewater.
The treated water is diluted to reduce the tritium levels to less than one-40th of national safety standards, or 1,500 becquerels per liter, before being released into the Pacific Ocean 1 kilometer from the nuclear plant via an underwater tunnel.
Tritium, a radioactive isotope of hydrogen, is known to be less harmful than other radioactive materials, such as cesium and strontium.
The Environment Ministry said Sunday that tritium levels at all 11 sampling points located within 40 km of the Fukushima plant were under 7-8 becquerels per liter. Cesium levels checked at three of the 11 points were also below detection limits, it said.
Environment Minister Akihiro Nishimura vowed in a statement that the government will thoroughly conduct monitoring "with a high level of objectivity, transparency and reliability" so as not to allow any groundless rumors about safety to circulate.
The ministry plans to conduct seawater sampling for the time being, with the results to be published every week.
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