The discovery and application of nuclear energy has brought immeasurable impact to the whole world, both good and bad, first of all, it ensures the stability of the whole world in the long term, after all, the nuclear deterrent in which to put it. No one wants to be attacked by a nuclear bomb, so they are more restrained when things go wrong.
The bad side of it, in fact, we all know, the nuclear reaction released by the energy beyond our imagination, good use can bring us light and heat, if used to do bad things, nuclear energy can also destroy the entire human civilization.
Nuclear weapons have been invented, although only two thrown for war, resulting in a large number of casualties, a look at this weapon must limit the use. But we have also conducted many nuclear tests in no man's land throughout history.
At first scientists didn't think so much about it, believing that nuclear tests on the ground wouldn't have a global impact. But the truth is that on a micro level, each of us and our lives have become more y connected to every nuclear bomb that has ever exploded.
You see, the explosion of a nuclear bomb produces a large amount of lighter radioactive elements, such as carbon-14, cobalt-60, radon and so on, and these elements, including particles of dust on the ground, are carried hundreds of kilometers into the air by the shock wave of the explosion.
Then they are carried to every corner of the earth following the global atmospheric circulation, so that since the first U.S. nuclear test on July 16, 1945, there has been a surge in background radiation levels in the atmosphere and soil around the globe.
Life on our planet is all carbon-based organisms with a carbon-based framework and hydrogen, oxygen, and nitrogen as the main materials, and we are cycling carbon with nature all the time, so carbon-14 levels in all organisms have increased since the last century.
This directly affects radiocarbon dating, which is based on the ratio of the presence of the radioactive isotope carbon 14, so that if a number of years from now, future archaeologists will be puzzled by the fact that the carbon-14 in organisms of our generation is higher than the average, and that they will not be able to estimate our exact age.
Besides the effect on the organisms, it also had an effect on the production of steel, which was not affected by carbon-14 or radon, but by cobalt-60.
That is to say, after the nuclear test, the steel produced all over the world had a much higher reflectivity than before, and these radioactive elements were not cobalt-60. The radioactive element cobalt-60 does not come from iron ore, but from the atmosphere.
Because when we were producing steel around 1850, we needed to oxidize the impurities in the pig iron, and some of those impurities were oxidized into gases that escaped, and some of them were turned into solid oxides that were separated from the iron so that we could remove the impurities.
Whether we press in air before, or pure oxygen later, it will bring in the excess cobalt-60 in the atmosphere, and cobalt-60 also blends perfectly with the molten iron. Any steel produced in this way has a higher level of radioactivity than before.
I'm sure you're now wondering if all this radiation has any effect on the human body, as global radioactivity elevation due to man-made factors peaked at 0.15 mSv/year in 1963.
This value is far below the limit of the human body to withstand, do a chest low-dose CT human body will be in a short period of time to withstand 0.5 ~ 1.0mSv radiation skills, and a one-time acceptance of 4,000mSv will be fatal.
So the human body harmless radiation, why the steel will have an impact? In fact, in life, daily construction, application of radiation high does not matter, and will not affect the physical properties of steel.
But in specific areas of science, such as counters, medical equipment, space exploration launch vehicles and some other places that need to measure tiny radiation, these steels will produce background noise that interferes with the experiment.
The laboratories that detect neutrinos are built deep underground to prevent interference from cosmic rays and to repel background radiation from the Earth's environment.
Because neutrinos, which are ghost particles that react with pure water, emit an extremely weak signal, the construction materials we use need to have very low background radiation.
The main source of this low background radiation steel is currently the salvage of warships that sank in the ocean before the end of World War II. Prior to nuclear testing, these steels were largely uncontaminated with radioactivity. It has also never been recycled, and has not been put back into the furnace to be contaminated by new steel.
Actually, any steel from before the nuclear tests would be fine, like rails or whatever, but the shipwrecks were larger and more concentrated, and a one-time salvage could yield tens of thousands of tons of good steel.
Another solution is to change the source of oxygen, which has always been extracted from the atmosphere and therefore contains radioactive elements. It is possible to switch to electrolyzing ultrapure water to get pure oxygen to make steel. The downside is that the process is too costly.
But fortunately, this problem would soon be a thing of the past: after 1975, scientists recognized the problem of nuclear contamination and all testing was moved underground.
Since various treaties ended nuclear weapons testing, and with the short half-lives of some radioisotopes, background radiation in the air has been decreasing.
Cobalt-60 has a half-life of 5.26 years, which means that the steel itself becomes less and less radioactive, and cobalt-60, which has been around since 1945, is now down to 0.008 percent of its initial level of radioactivity.
In a few decades, the effects of this radioactivity on steel will have disappeared completely.