On 20 July 2011, Japan’s Science Ministry released a radiation map of Japan.  It showed that radiation levels 150 kilometers (93 miles) from Fukushima Daiichi nuclear plant, are just as high as areas just 50 kilometers (31 miles) from the damaged plant.

This means Fukushima Daiichi nuclear plant is putting out enough radiation to cover the northern half of the main island Honshu.  It explains the extensive contamination to cattle feed and cows, among other things.

The radiation map is based on airborne radiation samples taken from 22-23 June 2011.