Variation of ambient gamma dose rate in Tokai, Ibaraki after the accident of Fukushima Daiichi Nuclear Power Plant

Okura, Takehisa ; Omori, Shuhei; Kawasaki, Masatsugu 

Ambient gamma dose rate has monitored at the several sites around nuclear facilities of Nuclear Science Research Center, JAEA in Tokai, Ibaraki. Effect of the Fukushima accident prevents from monitoring of influence from the nuclear facilities. Chronicle variation of ambient gamma dose rate for 5 years after the Fukushima accident was analyzed statistically by dividing components of the Fukushima accident and extracting environmental factor of it. Variation of the environmental factor was evaluated quantitatively and verified. This result will be basic material to optimize the monitoring of the dose rate by distinguishing influence from nuclear facilities from the effect of the Fukushima accident.