2011 Japanese Nuclear Incident
The EPA RadNet system was operating on March 11, 2011, when a tsunami inundated the Fukushima Daiichi power plant and knocked out the reactors' emergency cooling systems. The reactors overheated, damaging the nuclear fuel and producing hydrogen explosions which breached the reactor buildings and released radioactive elements to the environment. In response to the Japanese nuclear incident, EPA deployed additional air monitors to Hawaii, Alaska, Guam and Saipan.
From late March to late July 2011, RadNet sample analysis detected very low levels of radioactive material in the United States consistent with expected radionuclide releases from the damaged nuclear reactors at Fukushima Daiichi. All of the levels detected were very low, and were always well below any level of public health concern. After a thorough data review showing declining radiation levels in these samples, EPA returned to the routine RadNet sampling and analysis schedule for precipitation, drinking water and milk on May 3, 2011. The last time the EPA detected radioactive elements associated with Fukushima was July 28, 2011 in Hawaii.
You can view EPA news releases related to the Japanese Nuclear Incident by visiting, 2011 Japanese Nuclear Incident: EPA News Release by Date. The EPA also launched a Japan 2011 website which displayed near real-time air monitoring results and associated laboratory analysis data from the RadNet monitoring network. Search the EPA Archives for the EPA Japan 2011 website.
The sortable table below provides RadNet air, milk, precipitation and drinking water data from March 11, 2011 - June 30, 2011. In the data reports below, "ND" or "Non-detect" indicates that the radionuclide in question was not detected in EPA's analysis. If a cell is blank, the nuclide was either not detected or an analysis for that nuclide was not conducted.