We have been measuring and evaluating the external and internal exposure 
doses of the site workers engaged in emergency work at Fukushima Daiichi 
Nuclear Power Station. 
Today we have submitted reports to the Ministry of Health, Labor and 
Welfare regarding the evaluation results of the external exposure doses of 
the site workers engaged in emergency work before the end of March 2011 
and the primary evaluation results*1 of the internal exposure doses of 
workers who were measured with whole-body counters (WBC) before the end of 
May out of the said workers per the annex. 

Subsequently, as for the workers whose primary evaluation results are 
showing significant values*2, we will carry out a reevaluation based on 
the exact dates when they took in radioactive materials, which will be 
determined through a hearing investigation. Moreover, workers whose 
results indicate relatively high values will be subjected to a more 
detailed WBC administered by the Japan Atomic Energy Agency. 

*1: Primary evaluation of internal exposure doses
Prior to the official evaluation based on the exact period when workers 
took in radioactive materials, a tentative evaluation may be conducted in 
the event that each worker took in all amounts of radioactive materials 
only on the date when the worker started work at the site (March 12, if 
engaged initially) when the exposure dose amounts were at their peak. 
*2: Significant values 
It is regarded as 2mSv which is equivalent to the recorded level. 

Annex: Site Workers' Exposure Doses during Emergency Work at Fukushima 
       Daiichi Nuclear Power Station (PDF 81.4KB)