Gundams are not Nuclear Bombs
As a long time mecha fan I have seen many Gundam series over the years including 08th MS Team, which is a classic for showing how giant walking war machines would actually work in real world combat. Another series that I happened to have enjoyed and that helped to start this blog is Gundam Seed. Now what both of these series have in common is that they have nuclear reactors powering the gundams, and they both have or want a gundam explode in a nuclear explosion. However, that is not exactly how it works.
08th MS Team takes place in the Universal Century timeline, which means that the gundams are powered by fusion reactors. Nuclear fusion occurs when two atoms are slammed together at high speed and high heat. The resulting collision causes the two atoms to fuse together creating a new heavier atom. Hydrogen is the element of choice as its small size requires less energy to slam together to create helium.
This reaction requires a large amount of energy to happen, but it releases an even greater amount of energy. It also occurs in nature, as this is what powers the sun and other stars. While it can be used as a type of nuclear weapon, it can also be used to create electricity. Sadly however, scientists have yet to make a fusion reactor that creates more energy than it needs to actually initiate fusion.
The reactor pictured above uses magnets to contain the plasma (extremely hot ionized gas) needed to initiate fusion. Other types use lasers or electric fields to contain and initiate fusion. Right now the most efficient reactor produced 16 megawatts of power, but it needed 23 megawatts to start the reaction, not exactly efficient.
In the Universal Century the small compact fusion reactors that power the Gundams run on a fictional branch of physics called Minovsky Physics, and uses a fictional particle called the Minovsky particle to work. This particle contains and controls the reaction so only one particular type of fusion reaction occurs.
The proton is easily contained in a magnetic field and it can be used to generate electricity, making it a very clean and efficient reaction. Sadly, we cannot control fusion reactions in the real world like that and there are many different reactions depending on the fuel and conditions. However, the real question is what would happen if a fusion reactor, real or imagined was damaged and lost containment of the fusion reaction inside of it.
If a fusion reactor were to lose containment and the plasma were to begin to leak out of it, the result would be catastrophic for the surrounding area as the temperature of the plasma can run into the millions of degrees Celsius depending on the type of reactor. This would cause massive damage to the surrounding area, but it would not lead to a nuclear explosion. The reason for this is that as soon as the plasma begins to leak out it will begin to cool, dropping below the temperature needed for fusion to occur. Don’t get me wrong, it would be a big explosion and a lot of damage would occur from the escaping plasma, and the amount of radiation would vary based on the type of reactor that exploded, but a fusion reactor is not a fusion bomb.
FYI- Gundam 8th MS team actually plays this straight as one of the commanders in episode 10 tries to use a gundam as a fusion bomb but it does not work.
Gundam Seed Destiny
Unlike their Universal Century counterparts, the gundams of the Cosmic Era use nuclear reactors running on nuclear fission. Nuclear fission is the opposite of nuclear fusion in that here the atoms are split apart instead of smashed together. In this case a sub-atomic particle, usually a neutron, is fired at high speed towards a large atom. The resulting collision breaks the larger atom apart and releases more neutrons, which can split more atoms. The best element for this process is uranium as it is the largest of all the naturally occurring elements. The large size of uranium makes it easier to split than smaller atoms.
In the case of nuclear bombs this reaction continues unabated in a rapid and uncontrolled manner until all of the large atoms are broken apart. This releases a large amount of energy, much more than is possible in a similar mass of high explosives. In a nuclear reactor the reaction is controlled through the use of control rods that absorb some of the neutrons released in a fission reaction. FYI- the world’s first nuclear reactor was built in Chicago in 1942.
The control rods are made out of neutron poisons, which are elements that can absorb neutrons without splitting apart themselves. Some of the more common neutron poisons include:
silver, indium and cadmium, boron, cobalt, hafnium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.
These elements can be used on their own or combined into various alloys, and the type used depends on the particular type of reactor.
While there are different types of nuclear reactors, they all share some similarities in how they function. The controlled nuclear fission reaction generates a lot of heat, and that heat is used to turn water into steam. The steam is then used to turn a turbine which is connected to a generator, creating electricity.
The green water that flows through the reactor is contained in its own loop to prevent radiation from leaking out of the reactor. The hot pressurized water (green) in the reactor is run through a vat of cool water (blue), turning the blue water into steam (red), and the green water is cooled back down before heading back to the reactor. The steam (red) flows into a turbine causing it to turn and run the connected generator. After leaving the turbine the steam runs over cold-water pipes turning it back into cold water (blue) before returning to the reactor.
The next question is how small can we make a nuclear reactor? It is hard to get accurate numbers, or any numbers at all, but there are nuclear powered submarines, so it is possible to make a reactor small enough to fit inside a ship.
I also found an article discussing how China is working on a nuclear reactor the size of a truck. The article is from Reuters June 2017, and it mentions the reactors being released soon. I was unable to find any follow up articles about it.
While there is a Wikipedia page about small nuclear reactors, there is very little information on the actual size, and if they are actually being used yet. So I have to assume that they are still in a planning or theoretical stage at this point. Either way a reactor that is the size of a truck is still too large to fit inside a gundam.
I just don’t see a gundam sized nuclear reactor to be possible at this point in time, but that might be changing in the near future as new technologies come online.
Nuclear Reactor Meltdown
When a nuclear reactor runs out of control it is typically called a meltdown, due to how the fuel overheats, melting the fuel rods, control rods, and the reactor housing. This has happened more than once, most famously in Chernobyl, and Fukishima. However in Gundam Seed Destiny, Kira Yamato’s Freedom Gundam doesn’t have a reactor meltdown when destroyed; it explodes in what is alluded to be a nuclear explosion.
Leaving Kira’s miraculous survival, and the fuzzy neutron jammer physics, aside, let’s take a closer look at whether or not it could explode in a nuclear explosion.
First off, the nuclear material in a fission bomb is not the same as the material in a fission reactor. Nuclear fission weapons are typically 90% Uranium 235. Uranium 235 is an isotope meaning that is has a different number of neutrons (143) than the much more common Uranium 238 (146 neutrons). This is important because Uranium 235 is fissile, meaning that it can be broken apart in a fission reaction, while Uranium 238 cannot undergo fission. The fuel rods in nuclear reactors have significantly less Uranium 235: 3-5% in civilian reactors, 20% in military reactors. The reduction in the amount of Uranium 235 and the presence of control rods prevents a runaway fission reaction.
When a reactor is damaged, specifically when the control and cooling systems are damaged, the fission reaction begins to run faster and hotter, but not completely out of control. This increased heat causes the fuel and control rods to melt and destroys the containment vessel around the reactor. The result is that radioactive material will leak into the surrounding environment, as was the case in Fukishima and Chernobyl.
In Chernobyl’s case, the water inside the reactor was superheated to such a degree that the steam actually blew off the top of the reactor, spewing radioactive material high into the atmosphere. In either case the small amount of Uranium 235 and the presence of control rods prevents nuclear reactors from being nuclear bombs. I do realize that there is some new evidence that might suggest that there was a small nuclear explosion during the Chernobyl disaster, but that has yet to be confirmed. Additionally, it suggests that the possible explosion during the Chernobyl disaster is only possible in the reactor design used at the Chernobyl reactors.
What all of this means for the Freedom Gundam is that there is no way that its nuclear reactor could have exploded in a nuclear explosion. A large steam explosion spewing nuclear material is potentially possible, but unlikely since outside forces (Shin’s sword) would have destroyed the reactor casing, causing material to leak out, but not explode. Additionally, I think the scientists of the Cosmic Era are probably smart enough not to use an old Russian reactor design should the recent Chernobyl research prove correct. Thus, I do not see any way how the Freedom Gundam’s destruction could have triggered a nuclear explosion. Meltdown yes, explosion no.