This could be one reason Americans should not be afraid of "nuclear explosions". It is said temperature inside a nuclear explosion is higher than inside the Sun, or around 100 million Celsius. It is said temperature at the surface right under the explosion in Hiroshima (explosion occurred at 1800 ft above) was about 7700 K or 7500 C or around 16000 F or hotter than Sun's surface. Steel melts at around 1400-1500 C (depending of type) and vaporizes at 2800 C.
In this diagram it can be seen that temperature at Hiroshima at the so called Atomic Dome which was right under explosion (ground zero) was much above iron melting point for several seconds. But it could have been higher because heat could not evacuate like in areas further from ground zero.
I know it is not temperature but heat that melts metal, which means a heat transfer need to occur from environment to metal and that needs time. However, at 7500 Celsius, or 5 times iron melting point or three times iron vaporizing temperature, much higher pressure and hot fluid surrounding metal structure moving at high speed, like in a blow torch but much faster, heat transfer may occur much faster than near melting in a stationary pool. It also depends how big the piece of iron is. It is true that the roof which might have been ceramic could have shielded that temperature, but blast waves near epicenter traveling much faster than speed of sound would have blown the roof almost instantly. Also blast shock-wave traveling at several times the speed of sound should have blown the metal structure probably before having time to melt.
Here is the image with the dome. One can see there is no signs of melting the iron works on top or signs of melting (vitrifying) of concrete and/or bricks like some say found on the ground after explosion. Event smaller (thinner) pieces survived.
Could had been hundreds or thousands of tones of conventional explosives brought in in a number of wooden Spruce Goose type of planes in close formation and detonated simultaneously producing a much lower temperature and smaller shock wave.
Critical mass (in nuclear physics) is when there is enough mass or density of naturally radioactive materials caused by the natural constant spontaneous random neutron emissions by random atom split (radioactive decay) while each neutron emitted hits and splits another atom, emitting more neutrons, to exceed a certain number of emissions (or atom splits) and initiate a cascade known as
chain reaction. Each atom split releases energy. If not controlled, like by cooling down inside a reactor, chain reaction may lead to an explosion. In some uranium devices critical mass or higher is achieved "simply" by putting
together two smaller pieces. Hiroshima bomb had 3.5 critical masses.
HEU or Highly Enriched Uranium, or weapon grade uranium contains typically 80% uranium 235, or fissile (fissionable) isotope of uranium (I remember the address in Cumpulung, were i lived after birth, was Nr.235 on 7 November or 25 October old style, St, and now that address changed to 235 Transylvania St.) but there are some
reactors that use up to 90%.
Amounts smaller than critical mass can be encountered in small reactors, like those used to power
Voyager space probe.
We now see that it takes some time since chain reaction is initiated until it goes out of control, since in reactors temperature inside rods is hotter than the coolant, and there is a temperature gradient inside rods.
Increased
thermal agitation should also
oppose to an accelerated chain reaction because it may stop neutrons from spreading fast inside the material, pretty much like the case of
moving electrons. When temperature increases, electric resistance of most material increases because of thermal agitation (or agitation of atoms). Faster moving atoms could be more difficult targets for neutrons (i assume a neutron has to hit a fissile atom at a certain angle and speed and/or atom also has to be quite stationary to take the hit and get split).
The devices may heat up the material to the point it boils and vaporizes before chain reaction can consume most of the fuel and heat up to 100 million degrees. Or it can only melt and gather as a pool (of many critical
masses) at the bottom of a reactor, phenomena known to us as a meltdown.
Pretty much like an ordinary explosive which will not do much damage if not encased in a suited shell, having time to build pressure you will have to encase the material in a steel shell in order to reach more efficiency and for such big yields that could be so heavy it would be hard to transport and use as weapon.
The thicker the shell, the bigger the pressure and temperature that can be achieved. Without it, there will be no explosion but a meltdown. Because being so heavy they should be using giant planes, like Spruce Goose, An 224, etc. and mos likely destroy the plane too in the process. Because of this and radiation, the planes should be controlled remotely.
But they could also secretly install it and detonate a device in an already controlled and evacuated area, to scare everybody else on planet into thinking they have delivery capabilities of such devastating weapons.
Maybe this is what they've been doing for decades, with thousands of tests and supercomputer simulations, trying to invent conventional spatial charges or smaller devices that could maintain pressure long enough around the big one in the middle, without a heavy encasing.
Also, another inconvenience, it think nuclear devices do not last long enough to be stored, because of decay of materials, heating up, loosing structural integrity, etc.. At barely sub critical
mass or
density or even critical mass (3.5 critical masses were kept apart but in same enclosure like in case of Hiroshima) due to continuous decay, a device would lower its fissionable mass and/or density changing continuously the ratio enriched of isotopes inside; material it may also heat up, like the reactors on Voyager. The whole steel structure will get damaged soon because of neutron emissions.
This
image show not all rods in a reactor are at the same temperature. Thinking how hot is actually inside the rods themselves and for how long those rods keep their structural
integrity while transferring those tremendous amounts of energy, due to density changes through atom splitting (changing from uranium to thorium), radiation and thermal stress. If rods are made mostly of uranium 235 dioxide (like in naval reactors), will that turn into thorium dioxide after split? If one neutron is splitting an uranium atom, what happens to the oxygen atoms in the molecule?
Ok let's say that due to ratio of atom number of uranium, that is of course 235 to 16 for oxygen, you could have close to 90 percent ratio by using oxide. But what will hold the rod together especially at that temperature after let's say 10% of the uranium turned to thorium, of course, breaking the chemical bond with oxygen in the process, by reason that the uranium does not exist anymore?
Conclusion. I think, like in the case of Hiroshima and Nagasaki in WWII when they only had two devices which could have been of a much bigger size and weight than shown because of heavy cases, or smaller in effective magnitude than told ever since, they might have some, just a few, not the numbers and readiness and deliverability they claim, by at least two orders of magnitude. Enough to keep the whole planet in check though, while they do their job (depopulation,
dumbification, zombification) with their actors in all important positions in all countries, which must have a purpose, which could be sending the gold through a line of accelerated particles in Orion constellation. Trying to cover through specially fabricated or adjusted events, like now Musk's
satellite train.
I also believe that if the temperature in the center of explosion at Hiroshima, at 1800 ft or 600 meters above ground was 100 million degrees, or ten times hotter than inside the Sun as claimed with a total energy release of 50 TJ, or maybe and average 10 TW per second (1J = 1W/S) for 5 seconds and temperature at the surface was 7700 Kelvin, again hotter than 5500 at the surface of the Sun, even for only a few seconds with air turned to plasma blowing at speeds much greater than speed of sound, causing tremendous heat exchange, that dome in the first picture and generally surface of the ground would have looked like
flat a glazed ceramic crater.
