2h39m42s16f Fukushima Decay Heat - PWR Dispersion - Salt Chemcial Bonds - TR2016a
Channel: Thorium Remix
Date: 2017-05-09

http://ThoriumRemix.com/ It is actually very easy to turn off the fission reaction. When the reactors at Fukushima Daiichi, there were seismic sensors in the plant that notice the earthquake before any human being ever noticed it. And they noticed that was out of their tolerance their bounds they've been set to, and so before anybody did anything the computers started shutting down the reactor.

The workers stayed calm because they knew Japanese power plants are designed to withstand earthquakes. The reactors automatically shut down within seconds. But nuclear fuel rods generate intense heat even after a shutdown, so backup generators kicked into power the cooling systems and stop the fuel rods from melting.

Kirk Sorensen:
So when you turn a reactor off fission stops, but you have this decay heat. You have to manage that decay heat. The tsunami hit about an hour after the reactors were shut down. So fission was long gone by the time the tsunami came along, but the reactors are still managing decay heat. That decay he continued to build. Heat was not being removed from the reactor. And why weren't they using the power from the reactor in the pumps? Because the reactor been turned off. The reactor was turned off immediately when the seismic sensors sensed the quake. So there was no reactor generated power.

Dr. Per Peterson:
In Light Water Reactors, if you allow fuel to be uncovered and you allow it to heat up the zirconium cladding will react with steam to form hydrogen. As the fuel overheats to temperatures where it begins to lose its physical integrity and have localized melting- in the chemical conditions that you have with water- highly oxidized conditions- cesium and iodine are very volatile. They evaporate out, condense to small particles, and you have intrinsically high pressure. So you therefore how physical mechanisms that can mobilize cesium and iodine. Now we designed the reactors to make that very unlikely through a combination of highly reliable cooling systems. Passive systems are better than active as we learned at Fukushima.

Kirk Sorensen:
But the physical mechanism remains.

Dr. Per Peterson:
The physical mechanism remains.

Kirk Sorensen:
Whereas in a salt reactor-

Dr. Per Peterson:
In a salt reactor, cesium- There's nothing that cesium loves more than fluorine and it will compete with anything else to grab hold of fluorine. And cesium-fluoride is very low volatility and very high solubility in salt.