Nuclear fuel has melted through to the reactor's containment vessel(s). Image Source: Nuclear Energy Institute.
Japan Broadcasting Corporation is now reporting that Tokyo Electric Power Company’s (TEPCO) Fukushima Daiichi reactor No. 1 is likely in a meltdown state.
TEPCO announced today that fuel rods within reactor No. 1 have melted through the reactor vessel into the bottom of the reactor’s containment vessel. The report is unclear on whether fuel had breached the reactor’s steel containment vessel into the primary concrete containment. A TEPCO spokesperson said fuel has “fallen to the bottom of the reactor.”
Coolant levels in the reactor are low enough to fully expose the fuel rods under normal operating conditions, TEPCO acknowledged.
The containment layers were designed to prevent the melted fuel from breaching the facility, but nuclear experts have long raised serious doubts about the decades old GE design’s reliability. Some critics have alleged that cost savings trumped safety.
The good news is that the reactor’s surface temperature indicates that the fuel has cooled down, TEPCO says. Molten fuel could possibly burn through the containment vessel, allowing radioactive material to escape into the environment.
TEPCO officials may fill the containment vessel with water by injecting greater volumes into the reactor core as an added precaution. Water will leak through the breached reactor vessel into the containment vessel; however, that plan also risks contaminating the facility around the reactor. Radioactive water from the plant was dispersed into the ocean several times last month.
This news serves as a reminder that conditions at the earthquake-damaged reactors remain hazardous even though the crisis at Fukushima Daiichi no longer makes front page headlines.
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