Comments by "Eric Astier" (@ericastier1646) on "DW News"
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@philliplamoureux9489 I am an engineer, not a nuclear engineer, it's reasonably easy for me to understand nuclear power plants design and operation especially on the electrical side.
What i am telling you is publicly available information on the Fukushima disaster which you apparently did not read.
The issue again was that the cooling systems stopped operating when power was lost after being submerged. In that situation the active fuel inside the reactors are the most active and will overheat first (not the spent fuel pools) in a matter of hours and cause a meltdown. If you had read carefully, the hydrogen gas produced by the zirconium tubes from lack of cooling was vented out of the reactor pressure vessel (valve) where it mixed with the ambient air to an upper chamber where steel plates are designed to blow off. This is the lesser evil because you do not want the reactor vessel itself containing the radioactive fuel to explode into million of pieces and spread over kilometers.
The reactor did not "self breech" and it is not "designed to self breech". Less than a day after the hydrogen explosion the reactor cores melted down and almost pierced the bottom concrete walls.
Imagine that without venting out the gas you would have melted radioactive fuel and steam pressure so high the concrete walls would have cracked and be blown away from steam pressure alone in a much bigger explosion than the hydrogen explosion with molten radioactive cesium being in the explosion.
Instead the molten fuel simply cooled down into a solid lump. The venting of Hydrogen did release radioactive steam into the atmosphere so here is the answer to "Is water in a nuclear reactor radioactive?" from Quora :
"Elements dissolved in the water may (depending on what the element is) become activated by the free neutrons produced by fission. This could result in very high radiation levels if the water isn't extremely pure. With that said, the water in a nuclear reactor is extremely pure, with only a few chemicals (that won't become activated) used to control corrosion.
Then of course, there is Nitrogen-16, which is produced when the Oxygen in the water becomes activated. This is incredibly radioactive, but has a half-life of just over 7 seconds - so a couple minutes after the reactor is shutdown it is back to being mostly harmless.
Then there is the water itself. The Hydrogen in water exposed to neutrons will absorb some of the Neutrons and become deuterium, or even tritium. Tritium is radioactive, and the water in a reactor may have many times as much tritium as naturally occurring water.
So clean, pure water from a reactor that has been shut down for more than a few minutes is going to be somewhat more radioactive than the water you drink - which you probably didn't realize was radioactive in the first place."
The much bigger concern from the Fukushima disaster is that the crew released tons of nuclear byproduct waste into the sea. People tend to be mislead by the word explosion but in that case the hydrogen explosion was the least significant part of this catastrophy.
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