Fukushima Daiichi NPS Prompt Report (Sep 12, 2015)DRAINAGE OVERFLOW FROM TYPHOON FLOODING HAS BEEN HALTED, IMPACT APPEARS MINOR
Monitoring of water quality continues; construction on permanent improvements for drainage in heavy rains began earlier this year
FUKUSHIMA, Sept. 11-Heavy rains from Typhoon Etau caused intermittent drainage overflows at Fukushima Daiichi on Sept. 9, but the water involved appears to have been only slightly tainted and ongoing water quality monitoring indicates that environmental impact is negligible.
The overflow was from channels that drain surface water from various parts of the facility. None of this surface water comes in contact with the more highly contaminated parts of the facility and, past monitoring has shown, is only slightly tainted. Some of the channels lead to the port area of the plant, which is protected from the open ocean. One channel, K Drainage, leads to the open ocean but pumps have been installed to divert water from K Drainage to C Drainage, thereby retaining the water within the port area.
It was known that during periods of exceptionally heavy rainfall, typically associated with typhoons, the flow of water could overwhelm the available pumping capacity, causing some rainwater to flow into the ocean at the mouth of K Drainage. But monitoring after such an event - such as one on July 16 of this year - showed only slight and temporary increases in radioactivity.
Typhoon Etau appears to have been such an event. In the early morning hours of Sept. 9, heavy rains caused K Drainage to exceed the pumping capacity for two periods, ending at 4:24 a.m. Japan Time. In addition, on Sept. 11 at 3:03 a.m., due to the same reason, heavy rains, rainwater overflowed from the same drainage for three periods, ending at 7:07 a.m.
While the total volume of water cannot be measured for both days, sampling data indicates the water is only slightly tainted and unlikely to have any environmental impact. The sampling data has been made public on:
Sept. 9th
http://www.tepco.co.jp/nu/fukushima-np/f1/smp/2015/images/k_drainage_15090901-j.pdf
Sept. 11th
http://www.tepco.co.jp/nu/fukushima-np/f1/smp/2015/images/k_drainage_15091101-j.pdf
Permanent improvements
Even prior to this year's typhoon season, TEPCO began construction of a permanent solution to prevent these occasional overflows. TEPCO is physically reconfiguring Drainage K, essentially replacing it with a covered drainage channel parallel to Drainage C that will lead to the protected port area.
Work on the new Drainage K began in May and is expected to be completed in March 2016. For TEPCO is physically reconfiguring Drainage K, essentially replacing it with a covered drainage channel parallel to Drainage C that will lead to the protected port area.
For more detailed information, including drawings of the current and future drainage systems, go to
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150716_01-e.pdf
About TEPCO
Tokyo Electric Power Company, Inc. (TEPCO) is Japan's largest power company, supplying energy to the greater Kanto area, including Japan's two most populous cities, Tokyo and Yokohama. Its 34,000 employees are committed to providing safe, reliable power to its 29.0 million customers, diversifying energy resources to ensure sustainability, and contributing to economic growth while fully meeting its responsibilities after the Fukushima Daiichi accident.
TEPCO Website:
http://www.tepco.co.jp/en/index-e.html
TEPCO Facebook page:
https://www.facebook.com/OfficialTEPCOen
TEPCO Twitter page:
https://twitter.com/TEPCO_English
