February 27, 2014

Fukushima’s Radioactive Waters Reach Canada, Pose No Radiological Threat

April Flowers for redOrbit.com - Your Universe Online

Radioactive cesium isotopes from Japan's Fukushima nuclear power plant — severely damaged in the 2011 tsunami and earthquake — have made their way to the waters just off the coast of Canada.

The announcement was made at the annual American Geophysical Union's Ocean Sciences Meeting in Honolulu this week, but the scientists noted that the concentrations of the two isotopes were still well below safe drinking levels, reports Brooks Hays for UPI.

The waters off the coast of Vancouver, British Columbia, have been continuously sampled since 2011 by scientists from the Bedford Institute of Oceanography, UPI reports. The scientists have sampled waters for almost 1,200 miles due west of Vancouver. BBC News reports that the first radioactive waters were detected by June of last year.

“These levels are still well below maximum permissible concentrations in drinking water in Canada for caesium-137 of 10,000 becquerels per cubic meter of water -- so, it’s clearly not an environmental or human-health radiological threat,” Bedford’s Dr. John Smith said according to BBC's Jonathan Amos. A becquerel (Bq), named after Henri Becquerel who shared a Nobel Prize with Pierre and Marie Curie for their work in discovering radioactivity, is an internationally-agreed-upon unit used to measure radioactivity.

According to Ken Buesseler of the Woods Hole Oceanographic Institution (WHOI), none of the Fukushima water has reached beaches in the US yet.

Several hundred tons of radioactive water leaked into the ocean when the Fukushima plant was damaged by the tsunami and earthquake, and several smaller leaks have been discovered since. Initial tests of water in the plant's immediate vicinity after the event revealed a measurement of 10 million Bq per cubic meter (Bq/m3).

While it is true that the two radioactive isotopes — cesium-134 and cesium-137 — have appeared in the waters around British Columbia, the saturation level is somewhere below 1Bq/m3. As the plume of Fukushima water moves slowly across the Pacific, however, researchers are projecting that number to go up — just not drastically.

The arrival of the isotopes has been beneficial in one way. It has allowed researchers to validate the two computer models being used to forecast the possible future progression of the plume.

The computer models predict future cesium-137 at no greater than 27 Bq/m3, and future levels of cesium-134 at 2 Bq/m3 by mid-2015. Both of these predictions are below what the World Health Organization, the EPA and Canada's Department of the Environment consider safe for human consumption.

Last month, Discovery News reporter Trace Dominguez posted a video explaining why viewers should not worry about Fukushima radioactivity in the West Coast or anywhere else in the US.

At the meeting, Buesseler described the citizen science effort now under way to record radioactivity in beach waters of the western United States. WHOI is recruiting members of the public to gather water samples from California to Washington state, as well as Alaska and Hawaii. The privately funded sampling project is organized at the website ourradioactiveocean.org.

“What we have to go by right now are models, and as John Smith showed these predict numbers as high as 30 of these becquerels per cubic meter of water,” he told reporters.

“It’s interesting: if this was of greater health concern, we’d be very worried about these factors of ten differences in the models. To my mind, this is not really acceptable. We need better studies and resources to do a better job, because there are many reactors on coasts and rivers and if we can’t predict within a factor of 10 what cesium or some other isotope is downstream - I think that’s a pretty poor job."

As yet, no cesium-134 has been detected in US waters. Cesium-137 was already present in the environment because of the A-bomb test in the 1950s and 1960s. Dr. Bruesseler expects that a specific Fukushima signal from both radionuclides will be evident in US waters very shortly, however.