Tokyo Electric Power Co. has released a 41-page timeline detailing its initial actions in the first days of the Fukushima nuclear plant crisis, and experts said it reveals a lack of preparedness and severe difficulty in coping with the world’s worst atomic accident since the 1986 Chernobyl meltdown.
According to Tepco, plant director Masao Yoshida ordered staff to prepare to lower the pressure in reactor No. 1 by venting steam from its containment vessel at 12:06 a.m. on March 12, more than eight hours after the 9.0-magnitude earthquake and tsunamic knocked out power to the plant and triggered the crisis.
But Tepco’s records, released Saturday, show it did not have crisis-management manuals that detailed the procedure for manually opening the valves in the event of full power loss.
Only after the situation had turned into a full-blown crisis did Tepco send workers into a quake-damaged building at the compound to grab the documents needed to check the design and other specifications of the release valve to see if it could be opened manually.
At that point, Tepco learned that the valve actually had a handle for doing exactly that, the utility said in the report.
“Tepco should have prepared a manual on (manual) venting in advance, but it seems that wasn’t the case,” Keiji Miyazaki, professor emeritus at Osaka University and an expert on reactor accident management, said Sunday.
“Tepco also should have started the venting procedure right after the station blackout occurred,” he said.
The report also revealed that industry minister Banri Kaieda ordered Tecpo to “manually open” the valves to vent steam from reactor 1 at 6:50 a.m. on March 12.
But Tepco didn’t send anyone to open the valves until 9:04 a.m., after confirming that all residents of Okuma, one of the towns that hosts the power plant, had been evacuated from areas at risk of being contaminated by the radioactive steam and other materials that would be released in the process.
To prevent a critical failure, the pressure should have been released from the reactor’s containment vessel, which would have allowed workers to inject more coolant water into the core.
Tepco managed to open the valves and release steam from reactor 1 at 2:30 p.m. But hydrogen generated from the already melting fuel rods exploded and blew up the building at 3:36 p.m.
In the report, Tepco emphasized a number of difficulties that hindered its efforts.
All the lights in the central control rooms of reactors 1 through 3 eventually went dark after tsunami knocked out auxiliary power supplies at 3:42 p.m. on March 11.
At 9:51 p.m. that day, the main building of reactor 1 was declared off-limits because of rapidly rising radiation inside.
At 3:45 a.m. March 12, workers opened a double-entry door to the reactor building to check radiation levels and prepare for venting. But after seeing a “white haze” inside, they immediately closed the door to avoid radiation exposure, the report said.
Meanwhile workers struggled to connect cables from power-generator trucks to the reactors’ facilities to restart their vital coolant systems to prevent the fuel rods from melting down and releasing radioactive materials.
But darkness, debris, puddles and repeated tsunami warnings hindered their work by forcing them to repeatedly evacuate.
The hydrogen explosion at reactor 1 also damaged some of the cables they laid, prompting the workers to evacuate to the radiation-proof main operation center at the plant, Tepco said in the report.
“Workers were quite tough, given the loss of power supply and aftershocks. (The crisis) was an accident that had gone far beyond the assumptions in our accident management (planning),” Junichi Matsumoto, a Tepco executive and spokesman, said during a news conference Saturday.