Plutonium (Fukushima Prefecture)

Based on the Plan for the Radiation Monitoring of Soil in Fukushima Prefecture, nuclide analysis for Pu-238 and Pu-239+240 was conducted for soil samples collected in Fukushima Prefecture from August 10 to October 13, 2011. Radioactive materials detected in all samples collected at monitoring points (48 locations) were within their ranges in past measurements conducted nationwide before the accident and the ratio between Pu-238 and Pu-239+240 was almost the same as the national average (0.0261) before the accident. Therefore, detected Pu-238 and Pu-239+240 in the current analysis are considered not accident-derived.

At one location (Ottozawa, Okuma Town) out of seven reference monitoring points around TEPCO's Fukushima Daiichi NPS, the ratio between detected Pu-238 and Pu-239+240 was 0.214, one digit higher than the national average (0.0261). It suggests that the location has the influence of the accident at TEPCO's Fukushima Daiichi NPS.

• Included in this reference material on March 31, 2013
• Updated on January 18, 2016