The mortal danger of tank tracks in a nuclear explosion
Source: pinterest.ru
As you know, for more than half a century, one of the ways to increase security tanks is protection against weapons of mass destruction, and in particular against nuclear weapons. Over the years, many tools have been developed that save the crews and internal equipment of combat vehicles from penetrating radiation and radioactive dust. Among them, one can note filter-ventilation installations, anti-neutron flares and flares, measures of a local nature, such as fuel tanks consumed lastly near the driver, and so on. However, not everything can be protected, and tank tracks are an example of this.
From the title of this article, it may seem that we are talking about radioactive dust that settles on the undercarriage when driving through contaminated areas, but this is not so. Their main danger lies in the fact that after being irradiated with neutrons from a nuclear explosion, they begin to “radiate” so that a long stay near them can lead to serious consequences, up to death.
Tactical nuclear weapons are the main threat
It is widely believed that a nuclear war is a mandatory exchange of crushing strikes by intercontinental missiles with the destruction of all major cities and the death of tens of millions of people. And here the question arises: why think about some kind of radioactivity of tanks if they turn into a pile of scrap metal after "megaton" explosions? But this is just one of the scenarios.
In addition to strategic weapons, the arsenals of nuclear powers are full of tactical warheads of relatively low yield, which are installed in cruise and ballistic missiles, aerial bombs, and even fit into barrel artillery calibers. Their use may be local in nature, and will not necessarily be accompanied by a total nuclear Armageddon.
Model of a 3BV3 nuclear projectile, caliber 152 mm, yield 2,5 kilotons. Source: vk.com/traki_i_katki
The purpose of tactical means is not only important logistical points of the enemy, control centers, infrastructure facilities, etc., but also enemy troops in areas of concentration and on marches. It is in this situation that the tank can fall under the influence of a nuclear explosion.
As mentioned earlier, the power of tactical charges is relatively small, so the shock wave they generate, as a damaging factor for armored vehicles, fades into the background, giving way to neutron radiation. In this case, as a rule, the fewer "kilotons" in the warhead, the greater the neutron flux. The situation is aggravated by the fact that ammunition of this type explodes directly at the earth's surface.
Studies show that in a ground-based nuclear explosion, the flux of "thermal" - the most dangerous - neutrons is 5-6 times higher than in an air one. The influence of such a factor as an increased content of hydrogen in the soil in the vicinity of the epicenter is also great: snow or wet soil after a long rain can additionally increase the neutron load up to 50%.
Induced radioactivity
One of the main dangers of neutrons is the ability to cause induced radioactivity. That is, the stable nuclei of chemical elements become unstable under their influence and begin to decay with the release of ionizing radiation of various energies.
Typical steel armor typically contains manganese, nickel, molybdenum, vanadium, and iron. All these chemical elements are subject to neutron activation with the subsequent appearance of their radioactive isotopes, so the hull and turret of the tank can seriously irradiate the crew with gamma radiation. However, experiments on experimental nuclear reactors that modulate the desired neutron flux, corresponding to a nuclear explosion, showed that armor gives only about 25% of the total specific radioactivity of the tank. Where does the other 75% go?
Activation characteristics of typical armor steel elements. Source: L. A. Irdyncheev, V. L. Reitblat et al. “Induced radioactivity as a factor in the radiation damage of personnel of tank troops”
Some part, of course, can be attributed to road wheels, internal equipment and small external structural elements of the combat vehicle, but only a certain part. But the main "supplier" of destructive radiation are caterpillars.
The fact is that the alloy from which these elements of the undercarriage are made, in most cases, has a high manganese content - up to 13–14% versus 1–2% for armor steel. Of course, manganese is extremely important, since it is impossible to create steels with enhanced mechanical characteristics without it, but when “shelled” with neutrons from a nuclear explosion, it literally produces a fierce manganese-56 isotope with a relatively short half-life of 2,58 hours, but with the release of a powerful gamma radiation with an average energy of 1,18 MeV, from which only a thick layer of lead can be fully protected.
Activation characteristics of typical high-manganese caterpillar steel elements. Source: L. A. Irdyncheev, V. L. Reitblat et al. “Induced radioactivity as a factor in radiation damage to tank troops”
Thousands of X-rays and a sump
Here, of course, you need to make a digression. The radiation background from the caterpillars was studied while simulating the detonation of an ultra-low-yield nuclear warhead of 500 tons (0,5 kilotons) in TNT equivalent at distances of 305 and 125 meters from the epicenter, which correspond to zones of weak and medium damage. Minor damage - after the explosion, the tank is capable of performing combat missions, or minor repairs are required. Medium - the tank is very limited in combat capability, repairs are required. Accordingly, for more powerful charges, other distances will be required.
Already the first test results were quite frightening. So, when a nuclear projectile was detonated at a distance of 305 meters, which corresponded to a zone of weak damage, close to the caterpillar of the "fonilo" tank, at about 120 R/h (roentgen per hour). Such powerful radiation could not be found everywhere even in the immediate vicinity of the Chernobyl nuclear power plant that exploded in 1986. But these, in fact, were only flowers, because an explosion at a distance of 125 meters (medium damage zone) activated the caterpillar so much that it already gave out 1 R / h.
Now, of course, such units of measurement as X-rays are practically not used, and they do not reflect the absorbed dose of radiation, but the exposure dose, that is, just the background. But for example, it can be noted that the safe radiation background as a whole should not exceed 30 μR / h (micro-roentgen per hour), and in one roentgen they should be 1. Calculating the excess from caterpillars is easy.
Inside the tank, the situation is slightly better, since the crew is protected by a massive steel armor. However, one cannot hope for complete isolation from gamma radiation. In general, if the machine was in the zone of weak damage, the background inside was at the level of 11–46 R/h. If we are talking about the zone of moderate damage (105 meters to the epicenter), then the radiation load increased to 75–410 R/h.
In general, it can be said that the tank crew, while inside their combat vehicle, is less exposed to the induced radioactivity of the tracks, although even a couple of hours spent in such radiation can lead to moderate to severe radiation sickness.
Another thing is if the tankers or the repair team are outside and are repairing the tank. Here it is no longer possible to avoid the most severe radiation injuries, which can lead to death.
The best way out of the situation, if the tank has been near the epicenter of a nuclear explosion, is to send it to the sump and hold for a day. During this time, the most "evil" radioactive isotopes will almost completely decay, which will save the lives and health of crews and maintenance personnel.
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