TEPCO: Fukushima meltdown happened 16 hours after earthquake

The Mainichi Daily News
May 16, 2011

Tokyo Electric Power Co. (TEPCO) admitted for the first time on May 15 that most of the fuel in one of its nuclear reactors at the Fukushima No. 1 Nuclear Power Plant had melted only about 16 hours after the March 11 earthquake struck a wide swath of northeastern Japan and triggered a devastating tsunami.

According to TEPCO, the operator of the crippled nuclear power plant, the emergency condenser designed to cool the steam inside the pressure vessel of the No. 1 reactor was working properly shortly after the magnitude-9.0 earthquake, but it lost its functions around 3:30 p.m. on March 11 when tsunami waves hit the reactor.

Based on provisional analysis of data on the reactor, the utility concluded that the water level in the pressure vessel began to drop rapidly immediately after the tsunami, and the top of the fuel began to be exposed above the water around 6 p.m. Around 7:30 p.m., the fuel was fully exposed above the water surface and overheated for more than 10 hours. At about 9 p.m., the temperature in the reactor core rose to 2,800 degrees Celsius, the melting point for fuel. At approximately 7:50 p.m., the upper part of the fuel started melting, and at around 6:50 a.m. on March 12, a meltdown occurred.

On the reason why it took over two months after the earthquake to reveal the information, TEPCO said it had only been able to start obtaining detailed data on the temperature and pressure in the reactor for analysis in early May.

Junichiro Matsumoto, a senior TEPCO official, said, “Because there is similar damage to the fuel rods at the No. 2 and 3 reactors, the bottoms of their pressure vessels could also have been damaged.” He said the utility would carry out similar analysis on the two reactors.

Hiroaki Koide, professor of nuclear safety engineering at Kyoto University, was critical of TEPCO.

“They could have assumed that when the loss of power made it impossible to cool down the reactor, it would soon lead to a meltdown of the core. TEPCO’s persistent explanation that the damage to the fuel had been limited turned out to be wrong,” he said.


U.S. military begins evacuations of families in Japan

March 17, 2011

As officials struggle to contain leaking radiation from the damaged Fukushima nuclear power plant in Japan, the US military has begun to evacuate families from the disaster-stricken island. Efforts to cool the reactors have seen little success since last Friday’s earthquake and tsunami and concerns are growing of a nuclear disaster in the offing.

The Department of Defense announced this morning that the State Department was planning voluntary evacuations of military families and the families of government employees from Japan. It further will work to evacuate civilians that live within a 50 mile radius of the Fukushima plant. The power facility sustained significant damage in the earthquake and tsunami that struck Japan last Friday.

The Navy has moved quickly to start the process at Naval Air Facility Atsugi and Yokuska Naval Base. Those facilities are approximately 200 miles south of the Fukushima Dai-ichi nuclear power plant.

Following suit, the Air Force announced similar measures at Misawa Air Base and the Army began evacuations at a facility near Tokyo. The Marine Corps has not announced any evacuations at their facilities at this time.

Other military facilities in Japan are expected to announce the evacuations to service members and their families today. Underlying the growing danger of a nuclear catastrophe, the State Department warned of “the deteriorating situation at the Fukushima Daiichi Nuclear Power Plant.”

Col. Otto Feather, 374th Airlift Wing commander at Yokota Air Base, told his command in a radio address, “I know there are a lot of people trying to figure out how to get out of here, and I’m not surprised that there are people that want to get on the road.”

Feather provided a strong statement saying that the US military remained focused on continuing relief efforts in Japan. “The rest of us are going to be lockstep here with the Japanese, doing everything we can to take care of the recovery from this terrible tsunami and earthquake,” he said.

The Department of Defense did not provide numbers as to how many people could potentially be evacuated. However the US military has a heavy presence in Japan with tens of thousands of family members and civilian employees.

Experts generally agree that the radioactive plume from the reactors will move over the Pacific Ocean. Earlier this week the Navy said some of its aircrew that had flown through the plume had become contaminated.

A larger scale event that might include an explosion is possible and causing concern across the globe. White House spokesman Jay Carney said, “The situation has deteriorated in the days since the tsunami and earthquake. The situation has grown at times worse with potential greater damage and fallout from the reactor.”