Radiation levels within 80 kilometers of Fukushima Daiichi have dropped 40%. Readings were taken 1 meter from the ground on November 16 (2012). These were compared readings taken Nov. 5, 2011. The reductions are due to a combination of things. First, half of the decrease is due to the radioactive decay of the Cesium contamination. Cs-134, comprising about half of the total for the element, has a 2 year half-life. Thus Cs-134 decay was about a third of what existed in 2011 due to natural decay. The Cs-137 isotope has a 30 year half-life, so its rate of decay had not changed much over the year.
And much more:
http://www.hiroshimasyndrome.com/fukushima-accident-updates.html
And much more:
http://www.hiroshimasyndrome.com/fukushima-accident-updates.html