Water proper rotation operation

The symmetry elements of the water molecule are easily detected. There is only one proper axis of symmetry, which is the one that bisects the bond angle and contains the oxygen atom. It is a C2 axis and the associated operation of rotating the molecule about the axis by 180° results in the hydrogen atoms exchanging places with each other. The demonstration of the effectiveness of the operation is sufficient for the diagnosis of the presence of the element. 

The TMI power plant relied on three separate cooling water systems to work properly. Each of those systems had control valves and rotating equipment that had to work properly. None of these loops was inherentiy safe. There were many backup systems, but these were not effective, even though, unlike Fukushima, all of the equipment was available had the operators known what was going on. 

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