On April 4th, 2011, we reported on the preventive measures to be taken 
after receiving severe verbal warning from Nuclear and Industrial Safety 
Agency (NISA) on April 1st in regard to the results on nuclide analysis at 
Fukushima Daiichi Nuclear Power Station.
                                             (announced on April 4th, 2011)

Accordingly, we would like to inform the results of re-evaluation on 
nuclide analysis in regard to samples collected before March 30th from 
accumulated water in the turbine building, water in the sub-drain 
(subsurface water) near the turbine building and accumulated water detected
in the Process Main Building of Centralized Radiation Waste Treatment 
Facility. 

The preventive measures are as follows and re-valuation was conducted based
 on such measures.

<Preventive measures>
1. Evaluation of nuclide analysis based on experts' opinion
 Experts from third-party institution verified the concept of nuclide 
 identification and evaluation was conducted after reflecting such experts'
 opinions.

2. Deliberation on the method of cross-check
 Experts from manufacturer confirmed the adequacy of nuclide library in the
 analytical equipment. In addition, experts from third-party institution 
 confirmed the adequacy of concept in regard to program used for nuclide 
 analysis evaluation.

3. Improvement of accuracy achieved by support from other institutions, such
   as electric utilities
 We attempted to improve the accuracy of nuclide analysis evaluation by 
 asking other electric utilities and third-party institutions for support 
 on reviewing data and reasonableness.

4. Preparation of preliminary report and definite report
 In order to achieve good balance between accuracy and promptness, we made 
 announcement in 2 stages. Firstly, we released a preliminary report 
 (determination of radioactivity density regarding the 3 major nuclides, 
 while providing them as reference data in the results of nuclide analysis)
 and thereafter a definite report (determination and announcement of 
 radioactivity density regarding major nuclides as well as other nuclides).
                                            (announced on April 20th, 2011)

We re-evaluated the results on nuclide analysis of air collected within the
site boundary, seawater close to the power station, seawater at the bar 
screen of Unit 1 to Unit 4, sub-drain water around the turbine building, 
sub-drain water at the Centralized Radiation Waste Treatment Facility which
were collected during May 8th to may 20th, accumulated water in the 
underground floor of turbine building of Unit 4 those collected on April 
21st, accumulated water in the underground floor of turbine building of 
Unit 3 those collected on April 22nd, and sea water of offshore of Ibaraki 
Prefecture those collected on April 29th, May 11th, and May 18th 
respectively and report as a definite figure.

We will re-evaluate the results on nuclide analysis in regard to samples 
collected from the air at the site of power station and seawater near the 
power station after May 21st. We will announce the results of such 
re-evaluation accordingly. 

Appendix: [Definite Report]Result of Nuclide Analysis of Radioactive 
          Materials at the Site of Fukushima Nuclear Power Stations 
                                                                (PDF 280KB)