Strontium 89, 90 detected on site from samples taken 3 weeks ago

Concentrations for this particularly dangerous isotope were quite high, as NHK points out:

"The utility detected up to 480 becquerels of radioactive strontium 90 per kilogram of soil. That's about 100 times higher than the maximum reading recorded in Fukushima Prefecture following atmospheric nuclear tests carried out by foreign countries during the Cold War era."

Sr-89 was also found, and though it has a relatively short half-life (50.57 days), the activity was as at "2,800 becquerels of strontium 89 per kilogram of soil at the same location".

The plant operator mentions that these levels are not much cause for concern.

"Yoshihiro Ikeuchi of the Japan Chemical Analysis Center says strontium tends to accumulate in bones, like calcium. But he also says its levels in the air are thought to be lower than those for soil and even if people inhale the substance, no health problems will be caused by such internal exposure to radiation."

Don't expect any accurate absorbed dose estimations out of Tepco for plant workers. Slow lab results, poor participation and lousy safety measures will make it almost impossible to get within 30% of the real number.