Establishment of new regulations for radiological protection for decontamination work involving radioactive fallout emitted by the Fukushima Daiichi APP accident.

In response to the accident at the Fukushima Daiichi Atomic Power Plant (APP) on March 11, 2011, the Japanese government decided to carry out decontamination projects around the plant. For the radiological protection of the decontamination workers, the Japanese government needed to establish new regulations because the existing regulation did not fit into "existing exposure situations" in which radioactive sources were scattered and spread in a wide area around the plant. The new regulations aim to set the appropriate protection standards in accordance with the risk of the ambient dose rate, radioactivity concentration, and type of radio nucleolus resulting from the APP accident, which is equivalent to or more than the typical protection required in planned situations. To maintain practicability, the Japanese government employed a validated and simplified measurement methodology for the internal exposure, ambient dose rate, and radioactivity concentration, considering restrictions in human resources and shortages of supplies in the affected areas. The article also identifies key challenges which require further research.