Title: Fukushima panel told some details will take five years to learn
Source: Platts News
Date: 7 Sep 2012
Key details of how the accident at Japan’s Fukushima I nuclear plant played out have yet to be determined and may not be known for five years or more, when important parts of the plant are safer to enter, officials with the Japanese and US nuclear industries told a US National Academies review committee Thursday.
A committee of the National Academies is conducting the study, which is mandated by Congress, on behalf of the US Nuclear Regulatory Commission. The committee held its second data-gathering session Thursday in Washington.
Yasunori Yamanaka, manager of Tepco’s nuclear safety engineering group, said following the meeting that one of the key pieces of information that will be learned in the coming years is the location and condition of the core of nuclear fuel in the three reactors that experienced meltdowns. Tepco believes the uranium fuel of unit 1 at Fukushima I almost entirely melted its way through the bottom of the thick steel reactor vessel and poured to the floor of the containment structure, eating through a portion of the concrete floor of that area.
The company plans to use cameras and other surveillance equipment to determine how much of the core of units 2 and 3 remain in the reactor, Yamanaka said. The company believes almost half of the fuel in those units, which maintained core cooling longer, melted, he said. It may take more than five years before Tepco can determine whether the fuel in those units remains in the bottom of the reactor vessel or also fell to the containment floor, Yamanaka said.
Regarding Yamanaka’s statements:
- Tepco has admitted that their simulation shows the fuel at Reactor 1 not only burned through the pressure vessel, but came within 27 centimeters of leaving the containment vessel. Others have said they believe the fuel is outside containment. (Source: NHK)
- Tepco has admitted that reactors 1,2, and 3 experienced full meltdowns — not “almost half” at Reactors 2 and 3. (Source: CNN)
Published: September 7th, 2012 at 12:31 pm ET