The personal dose equivalent for 36 Marumori residents living in wooden houses was evaluated using optically stimulated luminescent dosemeters after the Fukushima nuclear accident. The cumulative doses to residents over 200 d from 1 September 2011 ranged from 536 to 1490 μSv. In each resident's house, the indoor and outdoor ambient dose equivalents were measured with an NaI scintillation survey meter. A linear relationship with a slope of 0.5 was found between them; however, the ratio of the indoor to the outdoor ambient dose equivalent varied from 0.36 to 1.0. A better linear relationship was observed between the personal dose equivalent and the indoor ambient dose equivalent compared with that between the personal dose equivalent and the outdoor ambient dose equivalent. These results indicate that the individual exposure dose depends on the indoor ambient dose equivalent rather than the outdoor ambient dose equivalent. These results should be very helpful in obtaining the countermeasures to reduce residents' exposure dose.
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