Oh boy. The reason for the teleconferencing system at the Prime Minister's Official Residence not being used (see my previous post) when the Fukushima I Nuclear Power Plant accident happened was that people in charge of maintaining the system didn't even think about turning it on. From what Sankei Shinbun describes, they didn't even seem to remember there was such a thing as the teleconferencing system.
Much like Goshi Hosono (then the assistant to PM Kan) saying "We just didn't feel like telling about the meltdown".
What were they using instead? Good old telephones and fax machines.
From Sankei Shinbun (part; 4/4/2012):
The system is installed in a conference room on the 4th floor, not in the crisis response center in the basement. Japan Nuclear Energy Safety Organization (JNES) and the Cabinet Secretariat are responsible for plugging the system. The person in charge at JNES says, "I didn't even think of turning the system on [I totally forgot about the system], as I was very busy supporting the Off-Site Center. There was no request from the Prime Minister's Residence or Nuclear and Industrial Safety Agency either." The Cabinet Secretariat says, "NISA's officials were at the Prime Minister's Residence, communicating with telephones and faxes. Whether there was no need [for the teleconferencing system] or we didn't think about it, we don't know the answer." They say they will make sure the system is connected at all time, from now on.
I think the answer is that they forgot. The system, as far as they knew, was there to be turned on when they conducted the annual nuclear emergency drills and to be turned off once the drills were over. It was not something that they associated with a real event, like a nuclear power plant having multiple explosions and meltdowns.
Then-Prime Minister Kan hopped on a helicopter in the early morning of March 12, 2011 to bark orders at TEPCO's Fukushima plant management, ostensibly because he couldn't get the first-hand information about the situation. In addition to his inability to ask the bureaucrats in front of him for information and the bureaucrats' pettiness of not doing what was not asked for, maybe the lack of teleconferencing capability had something to do with the lack of fresh information about the situation in Fukushima.