We are exerting our utmost effort in establishing the stable cooling of 
Reactors and Spent Fuel Pools and contain release of radioactive 
substances at Fukushima Daiichi Nuclear Power Station. As for Unit 2, by 
cooling the Spent Fuel Pool by the circulating cooling system, we have 
reduced evaporation from the Spent Fuel Pool and are reducing the density 
of adioactive substances released from the building.
As to the Reactor of Unit 2, we are considering several measures for 
stabilization. As one of the efforts, we are adjusting the volume of 
water injection monitoring the fluctuation of several parameters. In 
order to solidify these efforts, we have to install and calibrate 
Reactor water level gauge, install a circulating cooling system, and 
set up piping for nitrogen charge to the Reactor Containment Vessel. 
To do these, we have to improve the working environment in the Reactor 
Building for workers. 

In preparation for that improvement, we have been measuring the radiation 
dose, the density of radioactive substances, humidity etc. in the Reactor 
Building of Unit 2. The figures we measured on June 4 were, the total 
density of radioactive substances of 1.6×10-1 Bq/cm3 and the humidity 
of 99.9%.
While the density of radioactive substances is of similar level as the 
target for Unit 1 in improving the working environment by the an ambient 
air filtration system (2.4×10-1 Bq/cm3), we will install the ambient 
air filtration system to Unit 2 also, and circulate air inside of the 
building in order to reduce the density further.
After that, we will open the airlock of the Reactor Building in order for 
workers to enter the building and undertake necessary work. In doing so, 
we will measure the density of radioactive substances inside the building 
to confirm that the impact to the outside is sufficiently low.
As for the humidity inside the building, the building will be ventilated 
when we open the airlock thus will become lower.

We will make announcement before we actually open the airlock of the 
Reactor Building. At the same time, we will carefully monitor figures at 
monitoring posts and announce those figures.

Attachment: The improvement plan of working environment by an ambient air 
            filtration system, Unit 2, Fukushima Daiichi Nuclear Power 
            Station (PDF 94.5KB)