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, to
achieve stabilization of the Reactor, it is necessary to improve the
working environment in the Reactor Building for the workers.
As to the Reactor Building of Unit 2, from the evaluation result of the
figures measured on June 4, the total density of radioactive substances
was 1.6 x 10-1 Bq/cm3 and the humidity was 99.9%. Therefore, we will
install the ambient air filtration system to Unit 2 also and circulate the
air inside the Building in order to reduce the density further.
Subsequently, we will open the airlock of the Reactor Building for the
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 environment is sufficiently low.
As for the humidity inside the Building, the Building will be ventilated
when we open the airlock thus will become lower.
Regarding this matter, on June 8th, TEPCO have received an order* from the
Minister of Economy, Trade and Industry (METI) to submit reports related
to improvements to the work environment, evaluation of the impact of
radioactive substance to the outside environment and radiation management
plan for the workers.
(Previously announced on June 8th and 16th)
Afterward, we have been operating local exhausters and circulating the air
in the reactor building, which should lead to removing radioactive
materials and decrease the density of the radioactive materials inside the
reactor building. With regard to our report to METI on June 15th, METI
informed us on June 17th that the contents of the report are valid.
Considering this notice, we have decided that we are going to begin to
open the airlock in the reactor building gradually, preventing the dust in
the building from stirring up, and finally open it all from 8 pm today to
4 am tomorrow.
We have monitoring posts that monitor the radiation in the air around the
site borders of the plant, but, as a result of evaluation of the influence
of this opening the airlock, we have confirmed that the influence is not
the level that changes the instrument reading (the latest one is
approximately several dozenμSv/h) of the monitoring posts .
Attachment:Influence evaluation on the radiation after operating local
exhausters in the Reactor Building of Unit 2 at Fukushima
Daiichi Nuclear Power Station(PDF 60.6KB)
Order to report to METI
* We have provided a Japanese press release version of the instruction
document received from NISA. However, at this time we have reserved the
right to not provide an English version due to potential misunderstandings
that may arise from an inaccurate rendering of the original Japanese text.
We may provide the English translation that NISA releases in our press
releases. However, in principle we would advise you to visit the NISA
website for timely and accurate information.