Fukushima’s Radioactive Ocean Plume Heading Towards You


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Radiation Plume Across Pacific Ocean

Show here is a map of the Japanese nuclear power plants. Image courtesy of the USA Government.

How much Cesium 137 will reach the Pacific coast of the United States from the Fukushima accident? It’s a complex subject. How the isotope moves through the ocean, and how much gets to the United States, depends not only on the transport mechanism of the Kuroshio-extension currents from Japan but the food chain of marine life. So let’s start with the projections suggested by Deep Sea Research as well as several other studies referenced below.

    • Cs-137 has a half-life of 30.1 years – that means it can travel a very long way before decay.
    • According to simulations,  the Kuroshio Current and Extension, a very active current, strongly dilutes the Cs-137 plume.
    • Projections show that greater than 10 Bq/m3 will reach the U.S. Coast and Hawaiian Islands by early 2014.
    • Projections expect Cs-137 levels between 2014 and 2020 to be 10-30 Bq/m3.
    • The California coast should see slightly lower levels between 2016 and 2025 due to subsurface pathways.
    • Projections show the concentration of the diluted radioactive material well below the WHO’s safety levels.
    • The majority of the North Pacific Gyre, a region of ocean that circulates slowly clockwise, has trapped debris and continues to dilute the radiation.
    • About 25% will eventually travel to the Indian Ocean and the South Pacific over two to three decades.

Fukushima Radiation Plume: How Dangerous Is It?

Comparing radioactive measurements in Becquerels/m3 with the projections of the radiation level from Cs-137 to hit the Pacific coastal areas from the U.S. through Canada clearly shows these levels considerably below human health safety levels of concern – both projected from the Environmental Protection Agency and the World Health Organization. The Fukushima radiation plume looks scary, but the material’s half-life, sedimentation, mixing, and the movement of radioactive material via ocean currents should dilute the impact of the Cs-137 coming from the nuclear disaster in Japan on the United States West Coast for now, and for the generations to come.


Hsu, Jeremy. Fukushima’s Radioactive Ocean Plume to reach US Waters by 2014(2013). Live Science, Accessed November 17, 2013.

Anscombe, Nadya. Fukushima radiation could reach US coast in five years. (2012). Environment Research. Accessed November 17, 2013.

Nuclear Energy Institute. Public Health: Protecting Our Communities, Measuring Radiation. Accessed November 17, 2013.

EPA. EPA Facts about Cesium-137. Accessed November 17, 2013.

Rossi,Vincent, Sebille, Eric, Gupta, Alexander, Garcon, Veronique, England, Matthew. Deep Sea Research Part 1: Oceanographic Research Papers, Multi-decadal projections of surface and interior pathways of the Fukushima Cesium-137 radioactive plume. (2013). Science Direct. Accessed November 17, 2013.

Global Research. Fukushima Radiation Levels Will concentrate in Pickets at Specific US and Canada West Coast Locations. (2013). Accessed November 17, 2013.

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