Human World

Traces of Fukushima fallout reached SF Bay Area in March 2011

Atmospheric chemists have another quantitative measurement of radiation leaked from the Fukushima Dai-ichi reactor accident in Japan following the March, 2011 earthquake there. In a study published September 21, 2011 in the online journal PLoS ONE, researchers at the University of California at Berkeley report that fallout from the damaged reactor extended as far as the San Francisco Bay Area, resulting in elevated levels of radioactive material that were nonetheless very low and posed no health risk to the public.

The Berkeley study comes about a month after researchers in Southern California announced a similar finding, using an instrument at the end of a pier at the University of California at San Diego’s Scripps Institution of Oceanography.

Three of the reactors at Fukushima Dai-ichi overheated, causing meltdowns that eventually led to explosions, which released large amounts of radioactive material into the air. Via Wikimedia

Following the magnitude 9.0 earthquake and resulting tsunami in Japan on March 11, 2011, researchers from the Department of Nuclear Engineering at UC Berkeley collected rainwater samples in Berkeley, Oakland, and Albany, California. Collection dates were from March 16 to March 26. The researchers examined their samples for the presence of above-normal amounts of radioactivity, and they did measure elevated levels of radioactive isotopes of cesium, iodine, and tellurium. The first sample that showed elevated radioactivity was collected on March 18, and levels peaked on March 24 before returning to normal.

After the researchers published their findings, they did similar gamma-ray counting measurements on samples of weeds collected in Oakland and on vegetables and milk sold commercially in the Bay Area. In some of these samples, they detected low levels of the same fission products observed in the rainwater. The levels of activity observed in these samples also pose no hazard to the public.

San Francisco Bay Area landscape. Researchers detected radioactive fallout in rainwater samples from Berkeley, Oakland, and Albany, California from March 16 to March 26. The levels posed no risk to the public. Image Credit: jdnx

Bottom line: Following the March 11, 2011, earthquake in Japan, the Fukushima Dai-ichi nuclear power plant was severely compromised. Radioactive material was found in the water in many surrounding areas in Japan. There was speculation at the time that the radiation would travel across the ocean as far as California, which it did, but only in trace amounts, according to research teams in both southern and northern parts of the state. UC Berkeley researchers found elevated levels of radioactive material in San Francisco Bay Area rainwater, peaking one week after the Fukushima Dai-ichi reactor accident. These levels were very low and posed no health risk to the public. Results of the study appear in the September 21, 2011, issue of PLoS ONE.


Scientists calculate radiation release from Fukushima

September 21, 2011
Human World

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