The New York Times reported today:
In a belated acknowledgment of the severity of Japan’s nuclear disaster, the Tokyo Electric Power Company said Tuesday that three of the stricken Fukushima plant’s reactors likely suffered fuel meltdowns in the early days of the crisis.
The plant’s operator also said that it was possible that the pressure vessels in the three stricken reactors, which house the uranium fuel rods, had been breached as well. But most of the fuel remained inside the vessels, the company said — far from a more severe nuclear meltdown in which molten fuel penetrates the ground, a calamity known as the “China Syndrome.”
If all three units suffered reactor breaches, it may take longer for TEPCO to bring the units to cold shutdown:
Tuesday’s disclosure by Tokyo Electric Power, the operator of the stricken Fukushima Daiichi nuclear power plant, could delay efforts to bring the plant’s reactors under control. Earlier this month, the company released an updated plan to bring all reactors at the plant to a stable state known as a “cold shutdown” in six to nine months. But that goal was based on an understanding that workers could efficiently cool the fuel in the three reactors, a harder task if their inner pressure vessels are breached.