The Tokyo Electric Power Company, which is attempting a massive decommissioning project at the crippled Fukushima Daiichi nuclear power plant, said heavy rains from Typhoon Etau caused drainage overflows at the facility on Sept. 9, but monitoring of water showed “negligible” environmental impact from the storm.
“Heavy rains … caused intermittent drainage overflows … but the water involved appears to have been only slightly tainted and ongoing water quality monitoring indicates that environmental impact is negligible,” the company said in a statement.
TEPCO is dealing with a disaster that was caused by a tsumani event that overwhelmed the plant's back up power, which resulted in a triple-reactor meltdown at the facility. Since the March 2011 meltdown events, TEPCO has continued to battle water problems in the form of groundwater that enters the damaged buildings and exits with absorbed radioactivity.
Over the week, Typhoon Etau symbolized yet another water-based threat in the form of heavy rains that forced more than 90,000 people to evacuate their homes and damaged more than 10,000 homes in Joso and 1,000 homes in Osaki City, according to the BBC and others. In total, 140,000 people were told to evacuate their homes due to the storm that meteorologists called a “100-year-event.”
TEPCO said the overflow came 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,” said TEPCO in a statement.
Some of the channels lead to the port area of the plant, which is protected from the open ocean. A channel labeled K Drainage leads to the open ocean, but pumps have been installed to divert water from the channel to C Drainage, which does not flow to the ocean.
TEPCO had anticipated heavy rainfall and had taken steps to manage a deluge event, such as Typhoon Etau, which hit Japan on Wednesday with heavy rain lasting through Friday.
“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., Tepco said.
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.