via ex-SKF / November 24, 2011 /

After 8 and a half months of trying to lower the temperature of the Reactor Pressure Vessels (RPV), which by the way are broken and probably devoid of melted fuel, TEPCO announced they would now try to raise the temperature to avoid hydrogen explosion.

It seems like another non-reason why they do and do not want to reduce the amount of water in the building basements. (If they reduce the water level too much too soon, the ground water will seep in more – something like that. The ground water keeps coming in anyway.)

From Yomiuri Shinbun (11/24/2011):

東京電力は24日、福島第一原子力発電所1~3号機の原子炉への冷却水の注水量を減らし、圧力容器内の温度を上げる作業を始めたと発表した。

TEPCO announced on November 24 that the work had started on reducing the amount of water being injected to Reactors 1 – 3 at Fukushima I Nuclear Power Plant in order to raise the temperature inside the Reactor Pressure Vessels.

圧力容器には水素が存在していると考えられ、容器が冷えすぎると中の水蒸気が水になって乾燥し、水素に着火する危険が増すため。東電は同時に、中の水素を排出するため、圧力容器に窒素を注入する準備も始めた。

The RPVs are thought to contain hydrogen. If the RPVs are cooled too much, the steam inside the RPVs will become water, making the atmosphere inside the RPV too dry and increasing the danger of igniting hydrogen. At the same time, TEPCO has started the preparation for injecting nitrogen into the RPVs to expel hydrogen inside the RPVs.

1号機の注水 量を毎時0・5立方メートル(現在の注水量は毎時5・5立方メートル)、2、3号機は毎時1・5立方メートル(同毎時10立方メートル)ずつ減らす。現 在、1~3号機の圧力容器底部の温度は70度未満に下がっているが、80度を上回るほどに上げて水蒸気量を確保する。窒素が注入でき次第、注水量を元に戻 すという。

The amount of water injected to Reactor 1 will be reduced by 0.5 cubic meter per hour (currently 5.5 cubic meters/hr water is being injected), and the amount of water injected to Reactors 2 and 3 will be reduced by 1.5 cubic meter per hour (current amount is 10 cubic meters/hr). Right now, the temperatures at the bottom of the RPVs of Reactors 1, 2 and 3 are below 70 degrees Celsius. TEPCO wants to raise them to slightly above 80 degrees Celsius to maintain the amount of steam. As soon as nitrogen is injected inside the RPVs, the amounts of water injection will be restored to the existing level, the company says.

So far, nitrogen injection has been to the Containment Vessels.

Well let’s see. According to the latest plant status by TEPCO (11/24/2011), the temperatures at the bottom of the RPVs are:

  • Reactor 1: 40.4 degrees Celsius
  • Reactor 2: 68.3 degrees Celsius
  • Reactor 3: 66.6 degrees Celsius

And here’s TEPCO’s diagram of the effect of the gas management system on Reactor 2’s CV. It doesn’t make sense whatsoever, as it depicts a reactor that was leaking gas from all over the place but now has stopped leaking, thanks to the gas management system that sucks out the gas from the CV. But isn’t it cute that the melted fuel is depicted still nside the RPV?

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