At Fukushima Daiichi Nuclear Power Station, all monitoring posts (8
places) and transmitters were unable to use due to blackout caused by
the Tohoku-Chihou-Taiheiyou-Oki Earthquake. Until those equipment 
were resumed, we temporally measured the radiation dose by monitoring 
cars (mobile measuring vehicle) and radiation administrators 
collected, sorted and recorded the data by hand. During that time, it 
was not good condition for monitoring as communication line and
intra-LAN were frequently down and the collected data were sometimes 
handed over person to person.
Under such circumstance, after the Tohoku-Chihou-Taiheiyou-Oki 
Earthqake, as it was confirmed that part of the data of Fukushima 
Daiichi Nuclear Power Station which has been disclosed at our website 
were lacking, we have reviewed disclosed those data during Mar 11 to 
March 21.
(announced on May 28th)

Today, we will announce the result of investigation of the reason for 
part of the data remained undisclosed on our website after the 
Tohoku-Chihou-Taiheiyou-Oki Earthquake and for the delay of the 
statement, the result of review of the data during March 22 to June 1.

We, TEPCO, will continuously do utmost efforts to stabilize current 
situation and to conduct appropriate disclosure of information 
including monitoring data.

Attachment1:Regarding the result of investigation in relation to the
            undisclosed monitoring data at Fukushima Daiichi Nuclear
            Power Station(PDF 150KB)
Attachment2:Result of MP Data review(2011/03/11 - 03/21)(PDF 296KB)
Attachment3:Result of MP Data review(2011/03/22 - 06/01)(PDF 68.7KB)