reply to post by xEphon
And even then, if there was no water and if the debris in the pool caught fire, they are still encased in zirconium cladding, which holds the
fission products within.
From your source. That statement shows that he really has limited understanding of the processes involved or the threat posed by the (S)pent (F)uel
(P)ool or SFP at #4. The threat posed is the same one that occurred at other Spent Fuel Pools. A little different too..
#4 reactor building has been rocked by repeated earthquakes, at least one explosion and the fuel in the SFP of #4 reactor building has already
partially melted. All this damage combined has made the integrity of the pool itself questionable. It is leaking. It is being topped off by seawater.
The problem is they are having a hard time determining how more earthquakes will affect the pool any further.
The idea is to reinstall a working crane so they can remove the fuel bundles from the pool and temporarily store them in the reactor well (which was
shut down at the time of the Quake in Mar. '11). They are in a race against time hampered by on site radiation, further jolts (which send everyone
running), and logistics of demo-ing out the old infrastructure to facilitate the installation of another crane.
The threat to the environment is actually bigger than the other plants at Fukushima and heres why. # 4 reactor was shut down for refueling at the time
of the quake. All the fuel that has ever been used in the reactor over its entire life span is still being stored in the pool. Plus the very "hot"
fuel they just removed from the well. Plus the new fuel they were going to install after cleaning and maintenance. That is more fuel by far than was
in #3 SFP when it went off. Plus some portion of it is MOX which contains Plutonium (the newer fuel rods).
The concern is that if the fuel sustains any more damage from further quakes that it could begin leaking more than it does already. Combine that with
the damage from the explosion therein and the decay produced by the already melted fuel at the bottom of the pool. This could create a situation
whereby the top of the water level lowers to the point that the top of the fuel rod assemblies in the pool become uncovered.
That is all it will take. As the tips of the fuel rods become exposed they begin to heat up. This begins to boil away more of the remaining water in
the form of steam that further lowers the water level that then exposes more of the fuel rods. The "hot" fuel that has recently been removed from
the reactor is the most likely to heat up and begin to compromise the Zircalloy cladding which crumbles away and falls to the bottom of the pool.
Followed by the fuel it self which also falls to the bottom of the pool and begins to reheat to criticality temperatures.
The more the water boils off the more fuel is exposed, heats up, catches fire and falls to the bottom, causing a "Corium" mass that begins to melt
out the bottom of the pool all the while sustaining an uncontrolled fission chain reaction production of isotopes and radionuclides. The only thing
that will stop it will be when the reaction is done or the singularity runs out of fuel. By then up to 50 tons of fuel will have volatilized in an
open air environment, the worst of all possible scenarios for nuclear power.
Since the fuel pool is open to the air instead of inside the reactor well and sealed in a building, there will be no explosion like in #3. Just an
open air Tepco corium smelting process that will produce a nuclear fog bank spreading to the atmosphere and ocean while simultaneously burning its way
into the ground below the building and maybe the ground water table too. This Mass of metal (elephants foot) although no longer burning in a reaction
will remain radioactively hot for... God only knows. Still producing steam whenever it encounters water or rain or salt water spray from a fire
engine. Additional exotic and rare elements are produced by using seawater as well.
This is what happened to the other three reactors already by the way, don't you know that? They are still emitting as well. Since March of last year,
in fact. Each is unique in the events that befell them and as well the measures used in an attempt to control the amount of radioactive contamination
released so far.
SFP #4 is a race against time to get the fuel into the reactor to contain and cool it more reliably before another melt down fission event occurs
there. It is potentially very serious if... But hey, we won't see it if it happens anyway because TEPCO has total control over the situational
awareness they let on to. Any information that comes from there about any of the reactors there has to "leak" to us (like the radiation).
You know where I learned all this? Right here on ATS. The ongoing Fuku thread.