To suffer loss of coolant in spent fuel pools at a seaside nuclear reactor (Fukushima Dai Ichi) is, at first glance, a bit silly, with the ocean available to provide nearly infinite emergency coolant.
Create a passive system where, if the fresh water level in the pool drops below an emergency level, seawater flows in. I'm imagining a channel to the sea, and a pressure valve which stays closed if there is water on both sides, but opens if the freshwater side completely loses pressure.
Loss of power causes loss of circulation of fresh water coolant. All other backup systems having failed, the water boils, causing a drop in water level, popping the valve.
Even though it is a completely passive emergency system, "circulation" happens, in a sense. The new seawater eventually boils, and is replaced by more seawater. (The radioactive water vapor condenses as death raining from the sky and then... that's a problem for another day.) The cute design feature is that the circulation is powered by the spent fuel itself, which is the only power source you can truly count on in catastrophic power failure. If the spent fuel isn't providing enough heat, then it doesn't need cooling!
How do you prevent the incoming seawater from overflowing the pool (sea level changes with tides)? How do you prevent sea creatures from clogging the channel to the sea? How do you prevent storm surges, tsunamis, etc., from popping the pressure valve? Nothing is ever so easy.
1 comment :
Nuclear plants already have this. There is a pipe connecting the RWST (which has several hundred thousand gallons of clean, borated water) to the SFP, isolated by two manual valves in series. The RWST is located a grade level, while the SFP is below grade, at least at the tops of the fuel assemblies. So opening the valves allows water to flow by gravity.
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