Preventing Nuclear Accidents by Automation -- Part 2

Bela Liptak Discusses the Design and Control Errors at Fukushima, Because They Still Exist in Many American Boiling-Water Reactors (BWR) and Must Be Corrected

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The second important feature is that the released hydrogen is not allowed to accumulate inside the building, but is released into the atmosphere, where it is diluted and the hydrogen quickly rises up, away from the building. In addition, the radioactive particles are filtered out so they do not contaminate the area around the buildings.

Another important feature is that as soon as the excess pressure is released, the pressure safety valve (PSV) recloses. In case of the Fukushima (or any other plant where the vent valve is manually opened), the operator can forget to close it, releasing additional radioactive vapors. It is also important that full backup is provided for the automatic pressure relief system and that the burst rupture disk can be replaced while the plant is in operation.

In the next article of this series, I will describe how to measure the water/steam ratio, the swelled and collapsed water level and the temperature inside the reactor core, in order to eliminate guesswork. As we know, at Fukushima―and at many American plants―the operators do not have this information and are only guessing when answering such critical questions such as, are the fuel rods covered or if melting has started, how far has it progressed?

There has been, as yet, not time for the American nuclear industry to automate its manual systems based on the type of safety advice presented in this series of articles, but they are already becoming more vigilant. For example, during the latest flooding of the Missouri Rive, the Fort Calhoun plant near Omaha, Neb., was placed into "cold shutdown," and plants in Louisiana and Florida were shut down when hurricanes were approaching. 

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