On 5/10/2013, the video to measure the highly radioactive material was posted on Youtube.
The location is assumed to be in Namie-machi. The details are not clear but Fukushima Diary post this for the reference of the potential study in future.
170,000 CPM of γ and β dose was detected on the black substance accumulate on asphalt. With the shield of 3mm thickness, it decreased to be 40,000 CPM. The substance contains significant level of β nuclide of 130,000 ~ 140,000 CPM.
The researcher claims he/she named it Black substance.