A strange song and dance continues between TEPCO and Governor of Niigata Hirohiko Izumida.
Mr. Izumida is considered to be one of the champions for people who are against nuclear power plants in Japan for his combative stance against TEPCO with his remarks like "Which is more important, profit or people's lives?" to a president of a (nominally) for-profit enterprise.
He is also insisting that TEPCO NOT use the filtered vent to be installed at Kashiwazaki-Kariwa Nuclear Power Plant unless he gives the express permission to do so in case of a severe accident like the one that hit Fukushima I NPP.
Why? Because the filtered vent cannot eliminate the volatile radioactive materials like noble gas and iodine-131. Izumida doesn't want the vent to take place while the residents in the surrounding areas evacuate.
So TEPCO came up with an assurance that they would do the vent in 18 hours after the start of a severe accident.
To refresh our memory, Reactor 1 at Fukushima I Nuclear Power Plant suffered a core melt by the early morning of March 12, 2011. The earthquake that triggered the scram of the reactor core was 2:46PM on March 11, 2011.
If that's what Izumida wants - wait for 18 hours to do the vent in a severe accident, I guess he is willing to own a severe accident and its consequences at Kashiwazaki-Kariwa NPP.
From Sankei Shinbun (2/12/2014; part):
TEPCO announced the result of simulation that the vent would be done in 18 hours at the earliest using the filtered vent facilities in order to release the steam inside the Containment Vessel in case of a severe accident at Kashiwazaki-Kariwa Nuclear Power Plant (in Kashiwazaki City and Kariwa-mura in Niigata Prefecture).
TEPCO announced the result in the technology committee made up of nuclear experts and organized by the Niigata prefectural government. The simulation was based on the worst case scenario whereby all the reactor cooling mechanisms failed, including water injection into the reactor core using fire engines.
During the press conference on February 12, Governor Hirohiko Izumida commented on the specific timeframe TEPCO indicated. "We need to do the technical evaluation, including whether the vent could really be delayed for 18 hours as assumed by TEPCO."
According to TEPCO, the filtered vent facilities reduce particulate radioactive materials in the steam inside the Containment Vessel to one-thousands, but they cannot remove volatile radioactive materials.
While I do not think much of Governor Izumida's insistence on approving the vent in case of a severe accident, he is probably doing more to help Yamanashi Prefecture to dig itself out of the heavy snow than the national government or other local government.
Niigata is famous for the extremely heavy snow fall it routinely gets during winter, and it is extremely well-equipped to deal with such snow fall. According to Niigata Nippo newspaper, Izumida has already sent four officials to assess the situation in Yamanashi to plan a rescue operation including sending snow-plowing specialists in Niigata.