Information from TEPCO

March 18, 2013

Status of TEPCO's Nuclear Power Stations after theTohoku-Chihou-Taiheiyou-Oki Earthquake　2013

Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake(Daily Report as of 3:00 PM, March 18)

http://www.tepco.co.jp/en/nu-news/2013/1225660_5484.html

-As for the hole drilled on the ceiling of Unit 6 Reactor Building on March 18, 2011 for the purpose of preventing hydrogen explosion, considering that cold shutdown is being maintained and the plant condition has been stable at Unit 6, work to close the hole has been started on March 8 in order to maintain the air tightness of the building. On March 11, the work has been completed. As a result of air tightness confirmation performed from 1:51 PM to 2:23 PM on March 17, no problem was found.

-At 6:35 AM on March 18, Unit 2 spent fuel pool alternative cooling system was suspended for power supply multiplication work (The pool water temperature when the system was suspended: Approx. 15.0 °C). The pool water temperature increase rate during the cooling suspension is approx. 0.19 °C/h and the amount of pool water temperature increase during suspension is estimated to be approx. 2.3°C. There is no problem with the spent fuel pool water temperature control considering that there is a sufficient margin to the maximum allowed temperature (65°C).

-As a result of putting the desalination system in operation since April 11, 2012 to prevent mid-term corrosion and damage of the structures in Unit 3 spent fuel pool, the chloride concentration of the spent fuel pool was confirmed to have reduced from approx. 1,600ppm (concentration when the desalination system was first put in operation) to approx. 5ppm on March 18, 2013. Thus, desalting at Unit 3 has been completed.