TEPCO Halts Flooding Of Reactor No. 1 After Causing Drop In Pressure That Could ‘Spark A Hydrogen-Oxygen Explosion’

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Japan Nuclear Operator Postpones Plan To Flood Reactor Vessel

TOKYO (Dow Jones)–A plan to flood the containment vessel of one of the reactors at the stricken Fukushima Daiichi nuclear complex to better cool off its nuclear core was postponed Thursday, as concerns about possible leakage in the vessel made workers cautious about filling it with tens of thousands of tons of water.

Meanwhile, Japanese Trade and Industry Minister Banri Kaieda announced a plan to establish an expert panel to draw up the government’s new energy policy, as the continued shut-down of two nuclear plants operated by Tokyo Electric Power Co. (9501) has caused power shortages across eastern Japan, with crippling effects on the manufacturing industry. The panel is expected to hold the first meeting in early May.

A test run for an operation to flood Reactor No.1’s containment vessel began Wednesday morning in a strategy designed to cool down the pressure vessel, the thick steel cylinder housing nuclear fuel.

The move follows the failure by workers to cool down the fuel effectively, as water leaks out of the vessel apparently through damaged parts. Tepco believes that the fuel, which needs to be submerged in water, is actually partially exposed and estimates that 55% of it could be damaged and is releasing radioactive materials into the water.

The flooding operation is aimed at submerging the entire pressure vessel, instead of just the fuel, by injecting a large amount of water into the pressure vessel, allowing water to overflow into the containment vessel, the beaker-shaped metal container that surrounds the pressure vessel.

The trial run saw a more-than-anticipated drop in the temperature and the pressure inside the reactor, raising the possibility that adding water could deflate the containment vessel too much, allow the atmosphere to enter, and spark a hydrogen-oxygen explosion similar to ones that hit the plant in the first week of the crisis in March.

Officials also had lingering concerns about possible (???) leakage in the containment vessel. “The possibility of leakage cannot be ruled out,” said Hidehiko Nishiyama, spokesman of the government’s Nuclear and Industrial Safety Agency said in a news briefing Thursday.

No visible leakage has been found in the containment vessel so far, however.

Tepco officials said that any leaks in the vessel should be plugged as they are found before proceeding with a full-scale flooding operation. Leaks could grow bigger if they are left unplugged, as water pressure rises with the injection of water, causing serious contamination, they said. Tepco plans to inject 7,800 tons of water into the containment vessel in the flooding operation.

At his briefing Kaieda also demanded deeper pay cuts to the top executives of Tepco.

“I heard that the amounts of remuneration differ greatly among the senior executives,” he said in response to the company’s announcement of a uniform 50% pay cut for the 20 board members, including Chairman Tsunehisa Katsumata and President Masataka Shimizu.

Kaieda said that the decision on the remuneration should take into account “public feelings” toward the company and implied that Katsumata and Shimizu should give up their entire pay to take responsibility for the widespread radiation contamination caused by the troubled plant.

Thursday, April 28, 2011

Source: Dow Jones

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