page_title: Radiation effects from the Fukushima Daiichi nuclear disaster
section_title: U.S. military
hierarchical_section_title: Radiation effects from the Fukushima Daiichi nuclear disaster / Response in other countries / U.S. military
caption_attribution_description: English: YOKOTA, Japan (March 17, 2011) Senior Airman Eva Gaus, left, and Senior Airman Jonathan Jones, right, both assigned to 374th Civil Engineer Squadron, indicate all clear to the pilot after checking beta and gamma radiation at Yokota Air Base. A C-17 Globemaster III aircraft transported troops from the Japan Ground Self-Defense Force and vehicles from Okinawa for relief efforts. (U.S. Navy photo by Yasuo Osakabe/Released)
context_page_description: The radiation effects from the Fukushima Daiichi nuclear disaster are the observed and predicted effects as a result of the release of radioactive isotopes from the Fukushima Daiichii Nuclear Power Plant following the 2011 Tōhoku 9.0 magnitude earthquake and tsunami. The release of radioactive isotopes from reactor containment vessels was a result of venting in order to reduce gaseous pressure, and the discharge of coolant water into the sea. This resulted in Japanese authorities implementing a 30-km exclusion zone around the power plant and the continued displacement of approximately 156,000 people as of early 2013. The number of evacuees has declined to 49,492 as of March 2018. Large quantities of radioactive particles from the incident, including iodine-131 and caesium-134/137, have since been detected around the world. Substantial levels have been seen in California and in the Pacific Ocean.
  The World Health Organization released a report that estimates an increase in risk for specific cancers for certain subsets of the population inside the Fukushima Prefecture.
context_section_description: In Operation Tomodachi, the United States Navy dispatched the aircraft carrier USS Ronald Reagan and other vessels in the Seventh Fleet to fly a series of helicopter operations. A U.S. military spokesperson said that low-level radiation forced a change of course en route to Sendai. The Reagan and sailors aboard were exposed to "a month's worth of natural background radiation from the sun, rocks or soil" in an hour and the carrier was repositioned. Seventeen sailors were decontaminated after they and their three helicopters were found to have been exposed to low levels of radioactivity.
  The aircraft carrier USS George Washington was docked for maintenance at Yokosuka Naval Base, about 280 kilometres (170 mi) from the plant, when instruments detected radiation at 07:00 JST on 15 March. Rear Admiral Richard Wren stated that the nuclear crisis in Fukushima, 320 kilometres (200 mi) from Yokosuka, was too distant to warrant a discussion about evacuating the base. Daily monitoring and some precautionary measures were recommended for Yokosuka and Atsugi bases, such as limiting outdoor activities and securing external ventilation systems. As a precaution, the Washington was pulled out of its Yokosuka port later in the week. The Navy also temporarily stopped moving its personnel to Japan.
caption: Humanitarian flight is checked for radiation at Yokota
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