There is such a hellish joke circulating on the Internet: "Q: What is the reason for Japan's thin body and aging population?" A: Both the fat man and the little boy exploded."
Nuclear explosion mushroom cloud
Why hell cold joke? Because the first atomic bomb that exploded in Japan was called "Little Boy", and the second was called "Fat Man".
If you know that the half-life of the atomic bomb often starts in 10,000 years, why is there a large number of people living in Hiroshima and Nagasaki now? Are they already immune to nuclear radiation?
The amount of nuclear radiation received by the human body is different, and the consequences are also different
The half-life of an atomic bomb
An atomic bomb is a weapon of war that uses atomic energy to kill, and its half-life refers to the time it takes for the decay activity of the radioactive isotope atomic nucleus to be reduced to half of its original amount.
Simply put, the longer the half-life, the stronger the radioisotope activity and the greater the impact on the biological environment.
One of the main components of an atomic bomb is isotopes of elements such as uranium and plutonium, which produce large amounts of radioactive material after the atomic bomb explodes.
Detailed explanation of the reaction process
These radioactive substances can penetrate into the air, soil, water sources and the human food chain, causing chronic harm to humans and the environment.
Elemental isotopes such as uranium and plutonium used in atomic bombs have specific half-lives.
The two main isotopes of uranium, uranium-238 and uranium-235, have half-lives of 4.45 billion and 700 million years, respectively, and plutonium-239 has a half-life of 24100 years.
Uranium-238 and uranium-235
Therefore, the harm of these elements to the environment will last for a long time and will have an impact on life for a long time.
During the decay of radioactive isotopes, the nucleus loses energy and releases nuclei and particles, which results in a series of gases, solutions and solid waste.
illustrate
Isotopes with long half-lives produce long-lasting radioactive material that irradiates the environment for longer periods of time, causing harm to human health.
The Little Boy atomic bomb was the world's first nuclear weapon to be used, and its power was astounding.
In 1945, the United States dropped the Little Boy atomic bomb on the Japanese city of Hiroshima, which immediately attracted global attention.
The Little Boy atomic bomb was released by using the fission reaction of U-235, producing huge effects such as airbursts, fireballs, shock waves and radiation.
In the fission reaction of uranium-235, the uranium nucleus is fissioned and splits into two medium-sized fragments after being bombarded by neutrons, accompanied by a large amount of energy release.
Nuclear explosion mushroom cloud
This energy is released in the form of rapid neutrons, thermal radiation, shock waves, and radiation, forming short but violent explosions.
The design principle of the Little Boy atomic bomb is extremely simple, it is to divide a cylinder containing uranium-235 into two parts, and then use an explosive to push them towards each other, so that they merge into a sphere above the critical mass, thus triggering the fission reaction of uranium-235.
After the explosion, the Little Boy atomic bomb produced extremely high temperatures, pressures and radiation, causing hundreds of thousands of deaths and injuries.
Scorched earth left a field of rubble, street traffic was disrupted, the city's electricity, water and communications systems were completely paralyzed, resources were scarce throughout the population, and disease and hunger were spreading rapidly.
Cities bombarded by nuclear weapons
In addition to Hiroshima, in August of the same year, the United States used a similar atomic bomb called Fat Man in the Japanese city of Nagasaki.
As mentioned earlier, uranium-235 has a half-life of 700 million years, why is Hiroshima and Nagasaki now habitable?
Small amount and large range
Although uranium-235 has a long half-life, the amount of uranium-235 released at the beginning is small and the spread is large, resulting in relatively less serious nuclear pollution.
You know, the little boy himself weighed 3 tons, but the amount of uranium 235 carried inside was only 64 kilograms.
According to the data, the scope of damage after the atomic bomb explosion of Little Boy mainly includes the following aspects.
The first is the thermal radiation produced by a nuclear explosion, which is the most direct area of impact within a few kilometers of the explosion point.
No one is spared from the effective range of a nuclear explosion
The temperature of the heat radiation is extremely high, reaching 6,000 degrees Celsius, and in an instant, it can melt buildings and metal structures, forming a sea of fire.
This is followed by the range of influence of the shock wave, which is generated within tens of kilometers around the point of explosion.
The energy of the shock wave is so large that it can easily destroy man-made structures and natural obstacles, and can even squeeze air and water molecules, forming so-called "air explosions" and "splash explosions".
According to reports, the shock wave generated by the atomic bomb of Little Boy reached the equivalent of 100,000 tons of TNT, destroying most of the buildings and infrastructure in the center of Hiroshima.
is the area of influence of radiation, which refers to the area of influence around the atomic bomb site.
Nuclear weapons are too terrible
The intense radiation released after the explosion can cause long-term and lasting harm to the surrounding people, animals and the environment, and may make the area uninhabitable for a long time.
The radiation exposure after the atomic bombing of Little Boy reached hundreds of square kilometers, and the impact on people and the environment continues to this day.
Imagine that 64 kilograms of uranium-235 were spread over hundreds of square kilometers, and the impact was very limited, not to mention that only 1 kilogram of uranium-235 was involved in the reaction at that time.
The fission reaction is insufficient
This is because during the manufacture of the Little Boy atomic bomb, the manufacturers employed a method called the "explosive equalization device".
The internal structure of the atomic bomb
The device roughly compresses two uranium-235 half-shells together by the blast's shock wave to bring them close to critical mass, and then places them inside a reflector.
Under this design, fission would only occur within the half shell, and other uranium-235 material would not participate in the reaction, allowing the fabricators to reduce the size of the reactor and ensure the controllability of the reaction.
In addition, the nuclei of uranium-235 are so unstable that they only fission after neutron bombardment.
Therefore, in the Little Boy atomic bomb, in order to ensure the nuclear fission of uranium-235, sufficient neutron bombardment needs to be provided. This is usually achieved by embedding a neutron source.
Illustration as shown
The neutrons released from this source will react with the uranium-235 nucleus and trigger fission.
In addition, the technology of making nuclear weapons in the United States was not mature at that time, resulting in the waste of uranium-235.
At that time, the U.S. uranium-235 could only support them in building three atomic bombs, one of which was used for test explosions, and the other two were dropped on Hiroshima and Nagasaki.
Japan's efforts
After the war, Japan also cleaned up Hiroshima and Nagasaki, and it was reported that the land in both cities had been plucked several layers.
Specifically, the Japanese government removed radioactive soil from streets, parks, and buildings in and around central Hiroshima.
The shock wave flattens the city
This soil was used to build a large radioactive waste treatment facility, which could reduce the amount of radioactive material and the degree of ionic radiation.
The Japanese government has also vigorously demolished contaminated buildings and facilities.
In addition, in the decades since, they have regularly assessed and monitored radioactive contamination to ensure the safety of the city.
Of course, this kind of nuclear contamination is difficult to eradicate permanently, and despite Japan's efforts on various fronts, until 1999, the amount of nuclear radiation in places such as Aioibashi in Hiroshima City exceeded the standard and was classified as a radioactive contaminated area.
, devastated
What nuclear weapons have taught humanity
The atomic bombings of Hiroshima and Nagasaki were one of the most devastating tragic events in human history, and made many countries deeply aware of the dangers of nuclear weapons to mankind.
The atomic bombing caused countless deaths and suffering, which was a direct damage to people's lives and dignity.
It has also prompted reflection on how to prevent human loss of life as a result of war, terrorism and violence, and to pay greater attention to human well-being and the security and stability of society as a whole.
Cherish peace
To date, mankind's stockpile of nuclear weapons is sufficient to destroy civilization several times, and the nuclear threat of various countries has become more prominent in such a tense international situation.
It is hoped that various countries can grasp the bottom line of the game and ensure that the Hiroshima and Nagasaki events will not be repeated.
Resources
Xinhuanet "Revealed: 72 hours when the US military dropped the atomic bomb on Hiroshima and Nagasaki"
China.com "October 16, 1964 The first atomic bomb on the mainland was successfully exploded"
CNKI "Hao Xiaoyong, Fan Panhua, Analysis of radioactive elements in zirconium silicate"