2.17μSv/hr ~ 19 millisieverts per year, approx 214km south west of Fukushima Daiichi nuclear power plant:
From Sugar Nat
Present radiation hotspots in Nagareyama city, Chiba Prefecture (near Tokyo)
Measure taken at 1m from the ground : 0.57μSv/h
Measure taken at 50cm from the ground : 0.89μSv/h
Measure taken at ground level : 2.17μSv/h
Read more in Japanese :
http://hotspot-i-t.blogspot.fr/2017/06/blog-post_11.html?m=1
20 millisieverts per year 