It took about 15 to 16 months for the Ministry of Education and Science
or MEXT (the very name is a joke at this point) to announce radioactive
strontium (Sr-90) was widely dispersed from the broken reactors at
Fukushima I Nuclear Power Plant last year in 10 prefectures in Kanto and
Tohoku, to the levels last seen in the Chernobyl accident.
Caveat is that it excludes Fukushima and Miyagi, probably the two most
contaminated with radioactive fallout from the Fukushima accident.
MEXT's excuse is that the stations in these prefectures have been
damaged by the earthquake/tsunami.
プルトニウム検出が発表されたScientific reportsの記事 Isotopic evidence of plutonium release into the environment from the Fukushima DNPP accidentのリンクはこちら
以下は日本の大手メディアの報道です(青字化筆者)。