NAS Battery Fire (Second Report)
October 7, 2011
NGK INSULATORS, LTD . wishes to provide an update on the fire involving NGK-manufactured NAS (sodium-sulfur) batteries used for storing electricity that occurred on September 21. The batteries are owned by The Tokyo Electric Power Company, Incorporated (Head office: Chiyoda-ku, Tokyo) and installed at the Tsukuba Plant (Joso City, Ibaraki Prefecture) of Mitsubishi Materials Corporation (Head office: Chiyoda-ku, Tokyo).
The fire occurred at around 7:20 a.m. on September 21, and at around 3:55 p.m. that afternoon the fire authorities declared the fire had been brought under control. Thereafter, the temperature of the combustion residue was monitored and at 3:25 p.m. on October 5 the fire authorities confirmed that the fire had been extinguished. While continuing to monitor the batteries and temperature of the combustion residue, an NGK Accident Investigation Committee is leading efforts to identify the cause of the fire and study measures to prevent a reoccurrence, with the cooperation of interested parties.
NGK deeply regrets any worry or inconvenience to customers, local authorities and residents.