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 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 buildings, 
sub-drain water at the Centralized Radiation Waste Treatment Facility and 
sea water of offshore of Ibaraki Prefecture collected during the period 
from June 4 to June 17 and report them as final figures.

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 June 18th. We will announce the results of such 
re-evaluation accordingly.

Reference
  [Definite Report]Result of Nuclide Analysis of Radioactive 
  Materials at the Site of Fukushima Nuclear Power Stations (PDF 524KB)