Tokyo Electric Power Co. delayed reporting the emergency at the Fukushima No. 1 nuclear power plant to the central government for about an hour after it started, according to an in-house investigation.
TEPCO’s investigation provided details of the crisis that unfurled after the Great East Japan Earthquake and tsunami struck on March 11, 2011, and confirmed the delay, the utility said March 1.
The lag led to a delay in the government’s declaration of an emergency situation.
“In the chaos immediately after the outbreak of the emergency situation, staff members may have failed to make the report,” a TEPCO official said. “We want to look in detail into whether they have appropriately dealt with the situation.”
Electric power companies are required by law to report emergency situations at nuclear power plants to the government immediately after they occur.
It is a two-stage process involving a preliminary Article 10 report, which is followed with an Article 15 report. An Article 15 report leads directly to the government’s declaration of an emergency situation.
The Great East Japan Earthquake struck at 2:46 p.m. At around 3:35 p.m., waters from the ensuing tsunami began to inundate the compound of the Fukushima plant. From 3:37 p.m. to 3:41 p.m., all electricity sources for alternating current were lost in order for the No. 1, No. 3 and No. 2 reactors.
At 3:42 p.m., TEPCO judged that all electricity sources for alternating current at the three reactors were lost, including all the electric generators for emergency situations, and informed the government through an Article 10 report.
Around the same time, batteries became submerged at the No. 1 and the No. 2 reactors. Because of that, electrical sources for direct current were also lost. Those electricity sources were “lifelines” to monitor water levels in the nuclear reactors and manage cooling systems.
When all of those electricity sources were lost, the utility was required to immediately file an Article 15 report.
However, TEPCO made the Article 15 report at 4:45 p.m., about one hour later, on grounds that it was not able to monitor water levels at the No. 1 and No. 2 reactors.
The fax the utility sent to the government read, “As a precautionary measure, we made a judgment that the current situation corresponds to that described in the Article 15.”
After the in-house investigation TEPCO admitted the possibility that it could have made the Article 15 report immediately after the tsunami struck the nuclear plant instead of delaying it for an hour.
The investigation results were further evidence that TEPCO failed to appropriately deal with the nuclear accident immediately after it unfolded.
Last month, it became known that the utility was unaware for five years of the existence of internal guidelines to assess whether meltdowns have occurred at nuclear reactors.