The first experimental graphite reactor in the United States, under the leadership of physicist E. Fermi, was completed and criticalized in December 1942, while Germany used a heavy-water reactor to produce plutonium-239, and a small subcritical unit was not completed until early 1945.

In order to produce highly enriched uranium, Germany had focused on the development of high-speed centrifuges, but progress was slow due to air raids and lack of electricity and materials.

Secondly, A. Hitler's persecution of scientists, and the uncooperative attitude of some scientists, are another reason for the slow progress of this work.

What is more important is that the German fascist leaders were overly confident, believing that the war could end quickly, and that there was no need to spend energy to develop a problem that was not sure to be achieved.

After Germany's surrender in May 1945, the United States knew a lot

The insiders of the "Manhattan Project" Fat Man (who threw himself at Nagasaki), including a large number of scientists engaged in this work, led by physicist J. Frank, opposed the bombing of Japanese cities with ***.

At that time, China began to strike back against Japan. The U.S. offensive in the Pacific destroyed almost all of the Japanese navy, and the naval blockade made Japan's domestic supplies extremely scarce.

In World War II, Churchill estimated that he would completely defeat Japan and land on the Japanese mainland, at least 1 million American troops and 500,000 British troops would have to pay for their lives.

The United States cannot afford such a heavy burden. I don't want to memorize it, and using *** is the best way. The United States dropped the only two remaining *** in Hiroshima and Nagasaki in Japan, codenamed respectively

"Little Boy" and

"Fatty". (According to historical records, this catastrophe caused more than 300,000 Japanese civilians to die and more than 80,000 to be injured.)

The unprecedented lethal and destructive power has shocked the world and given people a new understanding of new weapons made by harnessing the enormous explosive power of fission or fusion in atomic nuclei.

Before the Soviet Union was invaded by the Germans in June 1941, it also carried out research and development work.

The spontaneous fission of uranium nuclei was discovered during this period by Soviet physicists N. Frerov and Κ. A. Petzak.

After the outbreak of the Great Patriotic War, development work was interrupted until the beginning of 1943 in the physicist И.

It was gradually restored under the organizational leadership of V. Kurchatov and accelerated after the war. In August 1949, the Soviet Union conducted *** tests.

In January 1950, U.S. President H.S. Truman ordered the acceleration of development**. In November 1952, the United States conducted a test on the principle of using liquid deuterium as thermonuclear fuel, and the experimental device was very cumbersome.

In August 1953, the Soviet Union conducted a test of using the solid lithium deuterate 6 as a thermonuclear fuel, which made the practical use of ** possible.

A similar ** test was conducted in the United States in February 1954. Britain and France also carried out *** and ** experiments in the 50s and 60s respectively.

During the period when China began to build socialism in an all-round way, the basic industry has developed to a certain extent, that is, it has begun to prepare for research and development.

When it started in 1959, the national economy was experiencing serious difficulties. In June of the same year, the Soviet Union tore up the agreement on new technologies for national defense signed between China and the Soviet Union in October 1957, and subsequently withdrew its experts, and China was determined to achieve this task entirely on its own.

China's first test was codenamed "596", which was to encourage the military and civilians across the country to work together to do a good job.

On October 16, 1964, the first *** test was successful. After more than two years, on December 28, 1966, the principle test of small equivalent was successful; Half a year later, on June 17, 1967, a million-ton ** airdrop test was successfully carried out.

China adheres to the principle of independence and self-reliance, and has fulfilled the tasks of the two stages of development of nuclear weapons at the fastest pace in the world.

The two bombs dropped by the United States on Japan were in the form of nuclear bombs with parachutes, using airplanes as delivery vehicles.

Later, with the development of weapons technology, a variety of nuclear weapons systems have been formed, including ballistic nuclear, cruise nuclear, air defense nuclear, anti-nuclear, anti-submarine nuclear rockets, deep-water nuclear, nuclear aerial bombs, nuclear artillery shells, nuclear weapons, and so on.

Among them, ballistic nuclear weapons equipped with multiple warheads** and cruise nuclear weapons with various launch modes are the main nuclear weapons equipped by the United States and the Soviet Union.

Nuclear weapons are usually divided into two categories according to their operational use, namely, strategic nuclear weapons used to attack the enemy's strategic targets and defend one's own strategic points, and tactical nuclear weapons mainly used to strike at the enemy's combat strength on the battlefield.

The Soviet Union was also divided into

"Campaign-tactical nuclear weapons". The classification of nuclear weapons is not very strict because of geographical conditions and socio-political factors.

Since the late 70s, official U.S. documents have been rarely used

"Tactical nuclear weapons", in place of it, there is

"Theater Nuclear Weapons",

"Non-strategic nuclear weapons", etc., and medium- and long-range and medium-range nuclear weapons are also classified in this category. The nuclear weapons that have been produced and equipped with troops, according to the design of nuclear warheads, mainly belong to two types: *** and ***.

As for the number of nuclear weapons, no accurate figures have been published, and estimates by the relevant research institutions are inconsistent.

According to a comprehensive analysis of data in recent years, by the mid-80s, the United States and the Soviet Union had a total of about 50,000 nuclear warheads, accounting for more than 95 percent of the world's total.

Its equivalent amount, totaling about 12 billion tons. During World War II, the United States dropped a total of about 2 million tons in Germany and Japan, which is only equivalent to the equivalent of 2 ** carried by American B-52 bombers.

This rough comparison illustrates the enormity of the stockpiles of nuclear weapons. Nuclear**[7] Offensive strategic nuclear weapons (including intercontinental nuclear**, ballistic nuclear** launched by submarines**, cruise nuclear**, and strategic bombers) of the United States and the Soviet Union are less than the Soviet Union in terms of total number and yield of projection vehicles (land-based launchers, submarine launch tubes, aircraft), but more than the Soviet Union in the total number of nuclear warheads.

Considering that the damage effect of the target opposite the nuclear explosion is not a simple proportional relationship with the yield size, another estimation method is to measure the destruction capability of the nuclear warhead by the destruction area corresponding to a certain shock wave overpressure, that is, to the power of 2/3 of the nuclear warhead equivalent value (calculated in million tons).

The value of "equivalent megaton equivalent" (there are also cases where less than 2/3 of other orders are selected according to the characteristics of the target and its distribution and the size of the nuclear attack), and then the total value is calculated according to the cumulative number of nuclear warheads of various types.

According to this method, the United States and the Soviet Union compare the destructive capabilities of strategic nuclear weapons, and because the yield is less than one million tons of nuclear warheads, the United States has more than the Soviet Union, and the gap between the two countries is not very large.

But since the 80s, with the development of the Soviet Union in the nuclear weapons of the split-guided multiple warheads, this gap has also widened.

And the ability to destroy point (hard) targets (see point targets), the accuracy of nuclear weapon projection plays a more important role, since the United States has always been ahead in this regard, it is still in an advantage.

After the Cuban crisis in 1962, people began to attach great importance to the consequences of nuclear weapons, and feared that the whole world would be destroyed once a nuclear war broke out, so the nuclear powers of the United States, the Soviet Union and Britain, another country with nuclear weapons at that time, began to actively negotiate and formulate the relevant details of the Nuclear Non-Proliferation Treaty after the Cuban crisis, and in 1968, the United States, the Soviet Union and the United Kingdom signed the Nuclear Non-Proliferation Treaty, when the two superpowers of the United States and the Soviet Union were in a state of hostility and confrontation at the same time China under its leadership did not sign this treaty until 1992, when *** and *** agreed to sign it.

Like China, which successfully conducted its first nuclear test in 1964, France, which had long insisted on maintaining its independence in the face of the confrontation between the United States and the Soviet Union, signed the Nuclear Non-Proliferation Treaty in 1992.

As soon as the end of the Cold War, a number of countries, including Belarus, Ukraine, Kazakhstan, and South Africa, voluntarily abandoned their existing nuclear weapons and nuclear weapons development programs, and became non-nuclear states.

Taiwan has twice developed nuclear weapons, including in 1988, which was close to success, and the report shows that it will be able to build *** in another year.

In order to prevent Taiwan from building nuclear weapons, the United States orchestrated the defection of Zhang Xianyi and exposed Taiwan's nuclear weapons program.

Later, under pressure from the United States, Taiwan gave up developing nuclear weapons. On January 18, 1988, the United States forcibly dismantled Taiwan's heavy water reactor worth $1.85 billion, ordered all heavy water to Taiwan to be stopped, and at the same time moved back to Taiwan's nuclear reactor, counted the number of nuclear fuel rods, and shipped all of them away.

At this point, the Taiwan authorities

The "closest to success" nuclear weapons program has gone bankrupt, and Taiwan has theoretically lost the ability to develop nuclear weapons on its own.

Some countries that do not have nuclear weapons are seeking nuclear weapons in every possible way, becoming

"Nuclear threshold" countries. In addition, under pressure from the United States, Libya abandoned its nuclear program and sent relevant materials and centrifuges to the United States.

Apart from

The "nuclear threshold" countries and various terrorist organizations that seek nuclear weapons are also available. After the Nuclear Non-Proliferation Treaty was signed by most countries in the world in the 1990s, the United States, Russia, China and other major powers slowed down the pace of nuclear weapons development and declared moratoriums on all nuclear tests in their countries, but countries such as India, Pakistan, North Korea, and Iran continued to actively develop nuclear weapons.

North Korea withdrew from the Nuclear Non-Proliferation Treaty in 2003 and conducted three successful nuclear tests in 2006, 2009 and 2013.

IAEA Director General ElBaradei said that "30 countries have the ability to rapidly produce nuclear weapons", and he is referring to "rapid development" of nuclear weapons within three months, which is close to one-sixth of the total number of countries in the world.

At the same time, ElBaradei pointed out that the United Nations' annual spending of $150 million to prevent the proliferation of nuclear weapons cannot effectively stop the "trend" of more and more countries to achieve "self-defense" by possessing weapons of mass destruction, and nuclear weapons may also fall into the hands of terrorist organizations.

After the atomic bombing, the main destructive force of the nuclear bomb in Hiroshima, Japan, came from the shock wave effect.

The vast majority of buildings (except, of course, fortifications of specially reinforced and impact-resistant structures) will be mortally destroyed.

The speed of the shock wave will exceed the propagation of hypersound, and the range of his wrath will increase with the increase in the yield of nuclear weapons.

Two similar but different phenomena will occur with the arrival of the shock wave: static overpressure: the pressure brought by the shock wave rises rapidly, and the static overpressure at any given point is proportional to the density of the air in the shock wave; Dynamic pressure: The effect of being pulled by a blast that creates a shock wave that pushes, shakes, and tears surrounding objects.

Most of the damage caused by nuclear weapons air explosions is the result of a combination of static overpressure and dynamic blasts.

The structure was weakened by overpressure for a long time, when the wind then destroyed it in one fell swoop.

Compression, vacuum, and pulling effects last for a total of several seconds, or longer. And the winds here are more ferocious than any hurricane that can occur in the world.

The main mechanisms of the outbreak of nuclear weapons (shock waves and radiation) can be compared with those of traditional **.

The main difference is that the energy release of nuclear weapons is faster and more intense. Therefore, the power of a nuclear weapon is often measured by the mass of yellow** (*****/***) with the same explosive power: Name yield (thousand tons) Remarks David Crowe recoilless gun (variable yield) 0.01-0.02 mass of only 23kg, the lightest nuclear bomb dropped by the United States Hiroshima *** (little boy) 13-gun uranium 235 nuclear fission bomb Nagasaki *** (Fatty) 20-22 implosion type Plutonium 239 nuclear fission bomb W-761008 pieces equipped on the Trident Type 1 missile B-61Mod30.3/1.5/60/170 free fall **, 4 degree variable yield B-61Mod105 free fall ** can be dropped by tactical aircraft, such as F/A-18, A-10W-8730010 W-884758 equipped on Trident II CastleBavo15000 U.S. maximum yield test warhead EC17/MK17EC24/MK24B41/MK4125000 U.S. equipment troops' maximum yield warhead, carried by B-36, free fall**, retired Tsabomb in 1957 50,000 (formerly 100,000) The maximum yield of the test warhead in the former Soviet UnionEnvironmental pollution 1.Radioactive contamination of the atomic nucleus of certain substances can decay and emit rays that we cannot see or feel with the naked eye and can only be detected with special instruments.

This property of the substance is called radioactivity. 2. Sources of radioactive contamination 1) Fallout from nuclear weapons tests (in the case of nuclear tests in the atmosphere, at the moment of the explosion of the nuclear bomb, a large ball (i.e., a mushroom cloud) is formed by hot steam and gas, carrying bullet shells, fragments, ground objects and radioactive smoke clouds to rise, and with the mixing with the air, the radiant heat is gradually lost, and the temperature gradually decreases, so the gaseous matter condenses into particles or attaches to other dust particles, and finally settles to the ground.

2) Nuclear fuel cycle

The central issue of the "three wastes" emission of the atomic energy industry is the generation, use and recovery of nuclear fuel, and the generation of all stages of the nuclear fuel cycle

The "three wastes" can bring a certain degree of pollution to the surrounding environment. 3) Radioactive pollution caused by medical irradiation, due to the wide application of radiation in medicine, has made medical radiation sources the main source of environmental artificial pollution.

4) Radioactive contamination from other sources Other sources of radioactive contamination can be classified into two categories: first, industrial, medical, military, nuclear ships, or radioactive sources used for research, due to transportation accidents, loss, theft, misuse, and waste disposal out of control and cause large doses of radiation to residents or pollute the environment; The second is the irradiation generated by general household consumption products, including products containing natural or artificial radionuclides, such as radioluminescent dials, luminous watches, and color televisions, although the pollution caused to the environment is very low, but there is also a need for research.

3. The harm of radioactivity to the human bodyUnder the exposure of large doses, radioactivity has a certain damaging effect on the human body and animals.

For example, under 400AD exposure, 5% of the irradiated people died; If 650AD is irradiated, 100% of people die.

Doses below 150 AD are associated with zero mortality, but they are not non-harmful, and it often takes 20 years for some symptoms to manifest.

Radioactivity can also damage genetic material, mainly by causing genetic mutations and chromosomal aberrations, which can victimize one generation or even generations.

4. Radioactivity

The "three wastes" deal with the radioactive materials in the radioactive waste, which cannot be eliminated or destroyed by ordinary physical, chemical and biological methods, and only through the decay of the radionuclides themselves can the radioactive attenuation be reduced to a certain level.

However, many radioactive elements have a very long half-life and the products of decay are new radioactive elements, so radioactive waste has many differences in treatment and disposal compared with other wastes.

1). Treatment of radioactive wastewaterThe treatment methods of radioactive wastewater mainly include dilution discharge method, placement decay method, coagulation sedimentation method, ion shift method, evaporation method, asphalt curing method, cement curing method, plastic curing method and glass curing method.

2). Treatment of radioactive waste gas(1) The waste gas and dust generated in the process of uranium mining can generally be solved by improving the operating conditions and ventilation system.

(2) Laboratory exhaust gas is usually pre-filtered, and then discharged after high-efficiency filtration.

(3) Most of the exhaust gas in the fuel reprocessing process is radioactive iodine and some inert gases. 3) Treatment and disposal of radioactive solid wasteRadioactive solid waste is mainly a variety of objects that can no longer be used because of the contamination of radioactive materials (1) incineration (2) compression ( 3) Decontamination (4) Packaging 5. Classification of radioactive materials For the safe transportation of radioactive goods, radioactive materials are divided into five categories: a. low-specific activity radioactive materials b. surface contaminant bodies c. fissile substances d. special forms of radioactive materials e. other forms of radioactive materials Explosive effect of nuclear bombs: Taking the detonated nuclear materials in the B-61 nuclear warhead as an example, the energy of a nuclear weapon is mainly emitted through five mechanisms: shock wave 40%-60% thermal radiation 30%-50% Raw particle radiation 4.9%, nuclear electromagnetic pulse 0.1%, residual radioactivity (radioactive fallout) 5%-10% of the form in which the energy is released depends on the design of the weapon and the environment in which it explodes.

The energy release of radioactive fallout is continuous, while the other four are immediate, short-lived bursts.

The amount of energy released by these first four mechanisms varies according to the size of the **. The thermal radiation mechanism decays most slowly relative to distance, so the larger the yield of the nuclear bomb, the more important this mechanism becomes.

Particle radiation is strongly absorbed by the atmosphere, so it is only important in low-power explosions.

The attenuation of the shock wave effect is somewhere in between. At the moment of the explosion, the nuclear charge reaches an equilibrium temperature within a microsecond.

At this moment, about 75% of the energy is in the form of thermal radiation, especially in the form of soft X-rays, while the rest of the residual energy is in the form of kinetic energy from the weapon fragments.

Next, how these soft X-rays and debris interact with the surrounding medium becomes the determining factor in how the energy is distributed between the shock wave and the light and particles.

In general, if there is a dense mass around the blast, then they will absorb energy very effectively, and the intensity of the shock wave will be enhanced.

When the eruption takes place in the atmosphere near sea level, the vast majority of the soft X-rays will be absorbed within a few feet.

Some of the energy turns to radiation in the ultraviolet, visible, and infrared bands, but more is used to heat the air, forming fireballs.

In high-altitude bursts, soft X-rays tend to travel longer distances due to the reduced density of the air, and after they are finally absorbed, less energy is used to propel the shock wave (50% or less of sea level), and the rest is converted into other forms of thermal radiation.

According to the analysis of experts, countries must first pass four hurdles in technology in developing nuclear weapons: nuclear fuel, nuclear testing, and throwing technology.

Nuclear fuel countries that want to develop nuclear weapons have their eyes on nuclear reactor waste from nuclear power plants. For the sake of absolute safety, the international community has taken non-proliferation as a direction for the improvement of nuclear reactors, and strictly proliferates three sensitive technologies, namely: uranium isotope separation technology (also known as uranium enrichment technology), spent fuel reprocessing technology (technology that can extract plutonium-239 from nuclear waste) and heavy water production technology (deuterium and tritium, which can be used to produce ** raw materials).

To make one, you need not only raw materials to be used as fission fuel, but also a trigger device, and a technology that can fission most of the fuel before the bomb explodes (otherwise the bomb will fail).

The biggest technical problem is the rational configuration of high-explosive **. A true nuclear explosion can only be achieved by detonating two conventional types of fast and slow combustion at the same time in the amount of one millionth of a second.

If the timing error exceeds the above requirements, or the ratio of the two ** is incorrect, the compression effect produced by the conventional explosion will be greatly reduced, resulting in the nuclear explosion power halved, or even not a nuclear explosion.

Some countries that are secretly developing *** are at a loss in the face of this hurdle. Nuclear TestingAfter the adoption of the Comprehensive Nuclear-Test-Ban Treaty by an overwhelming majority at the plenary session of the 50th session of the United Nations General Assembly on September 10, 1996, there have been many introductions that the replacement of traditional nuclear explosion tests with computer simulations can achieve the same test effect.

However, on the basis of the existing nuclear explosion test, the various parameters are programmed into the super-large computer, and the method of simulating the nuclear process and the nuclear explosion effect with chemical explosions, laboratories, and computers is undoubtedly a more difficult goal to achieve for those countries that are eager to create nuclear weapons today, and the power of nuclear weapons is difficult to simulate with computers, after all, the complexity of natural conditions makes it difficult to replicate all of them in the computer.

From the first United States nuclear test on 16 July 1945 to the adoption of the Comprehensive Nuclear-Test-Ban Treaty in September 1996, a total of 2,047 nuclear tests have been conducted worldwide.

Among them, 1,031 in the United States, 715 in the former Soviet Union, 210 in France, 45 in the United Kingdom, 45 in China, and once in India in 1974.

It can be seen that it is difficult to imagine the complete physical design of nuclear weapons without the support of a strong and rich test database.

Throwing technologyA real nuclear weapon consists of three parts, namely a nuclear warhead, a delivery vehicle, and a command and control system.

With nuclear weapons, it is necessary to have the means to deliver them. After the successful nuclear explosion, the next issue of miniaturization and weaponization is still a hurdle that cannot be bypassed.

Nuclear-weapon-carrying tests are also essential. Generally speaking, strategic aircraft are mainly installed on aviation and aviation, and launch platforms include ballistics of various ranges, cruises, nuclear submarines, strategic bombers, etc.

However, with the rapid development of the ballistic interception system, it is really doubtful how many opportunities the weak country has to throw the hard-won *** on the head of the opponent by virtue of its limited means of delivery.

The deterrence capability of the *** that cannot be thrown out in the actual sense must be greatly reduced. In addition to the production of nuclear materials such as uranium-235 and plutonium-239, the development of the nuclear warhead itself must be coordinated with the development process of the entire nuclear weapons system.

The development process is roughly as follows: from the idea stage; After the preliminary study or feasibility study of key technical topics and components, several design schemes including weight, size, form, power, nuclear materials, nuclear test requirements, development period, and funding are formed; Then, after demonstration, comparison and evaluation, the design scheme is selected, and the tactical and technical indicators are determined. Then carry out model research and design, various simulation tests; Process test and trial production, through nuclear test to test the rationality of the design, and finally to achieve the design finalization, process finalization and approved production.

To carry out this work, it is necessary to have a special scientific and technological team and to be equipped with the necessary test sites, including nuclear test sites.

After the weapons are delivered to the troops, the R&D and production departments also provide services such as maintenance, repair, and replacement of parts, make necessary improvements according to the feedback information, and be responsible for their decommissioning, processing, and renewal.

In order to do a good job in the design of a nuclear warhead, it is necessary to have an in-depth understanding of its reaction process, to understand the conditions and various physical parameters that it must have, and to grasp the internal relations and laws of change of many factors.

To this end, it is necessary to conduct research on a series of scientific and technological issues in multiple disciplines, such as nuclear physics, neutron physics, high-temperature and high-pressure condensed matter physics, supersonic fluid mechanics, detonation, computational mathematics, and materials science.

In the process of development, the following links play an important role: (1) It is necessary to use a fast and large-capacity electronic computer to carry out the theoretical research and calculation of the reaction process, which should be as close as possible to the actual situation, so as to find the optimal solution from a variety of assumptions or design schemes, so as to save costs and reduce the number of nuclear tests.

Since the 40s of the 20 th century, one of the important factors promoting the rapid development of computer technology has been precisely due to the need for the development of nuclear weapons.

(2) In accordance with the requirements of the plan or index, repeated multi-faceted simulation tests, including chemical detonation test, material and strength test, environmental condition test, control, ignition and safety test, etc.

These are indispensable for achieving a high degree of reliability and security for nuclear weapons. (3) Necessary nuclear tests should be conducted.

Neither the large number of calculations on electronic computers nor the corresponding simulation tests can be 100 per cent consistent with the reality of the nuclear weapons programme.

In particular, the high temperature conditions necessary for fusion reactions can only be provided by fission reactions (the inertial confinement techniques of lasers or particle beams were used to create such simulated test conditions, which were still in the research stage until the early 80s).

Therefore, whether the design requirements can be met must also be tested by the explosion test of the nuclear device itself.

Of course, the role of nuclear testing is not limited to that. It is precisely because nuclear testing plays a key role in the development of nuclear weapons that the United States and the Soviet Union, in order to restrict the development of nuclear weapons by other countries, signed a "Treaty Banning Nuclear Weapon Tests in the Atmosphere, Outer Space and Underwater" in 1963, which does not prohibit underground nuclear tests, and in 1974 signed a treaty limiting the yield of underground nuclear tests that still suits their needs.

According to the environment of the explosion, it can be divided into: atmospheric explosion, that is, a nuclear explosion test is carried out in a bare atmospheric environment, and this explosion is the most destructive (reflected in the impact on people).

In the absence of good shelter facilities, people within a dozen square kilometers can be severely traumatized or even killed.

Underwater nuclear explosion testsUnderground nuclear explosion experiments are generally scientific experiments, and some military experts believe that underground nuclear explosions can be used to artificially cause earthquakes and tsunamis to enemy countries

"Natural Disaster". However, this kind of damage is difficult to control, so it is not recognized by many military experts.

Underwater nuclear explosions are mainly tested in the sea. In the 50s, the United States carried out a nuclear bomb after the explosion, and all the ships failed to resist the huge explosion power of the nuclear bomb, of course, the nuclear explosion test also caused extremely bad damage to the local natural ecological environment.

Development trend editDue to the improvement of the accuracy of nuclear weapon delivery tools, since the 60s, the development of nuclear weapons, first of all, the weight and size of nuclear warheads have been greatly reduced, but still maintaining a certain power, that is, the specific power (the ratio of power to weight) has increased significantly.

For example, the *** dropped by the United States in Nagasaki, weighing about 4.5 tons and powerful about 20,000 tons;

"Trident" I. submersible **, with a total weight of about 1.32 tons, a total of 8 sub-guided bullets, each with a power of 100,000 tons, its specific power is about 135 times higher than that of the *** dropped in Nagasaki.

Thermonuclear weapons, which are more powerful, are more powerful than they are more powerful. However, it is generally believed that this area of development may be close to the limits of objective reality.

Since the 70s, the development of nuclear weapons systems has focused more on increasing the survivability and accuracy of hits of weapons, as in the case of the American ones

"Peacekeeper/MX" Intercontinental**,

"Gnome" small intercontinental**,

"Trident" II. Submarine **, Soviet SS-24, SS-25 Intercontinental **, have been greatly improved and improved in these aspects.

Second, the reliability of the nuclear warhead and its detonation control safety subsystem, as well as its ability to adapt to various use and combat environments, have also been improved and enhanced.

The United States and the Soviet Union have also developed various types of nuclear weapons suitable for battlefield use, such as nuclear warheads with variable yields, nuclear warheads that are common to various means of delivery, and even envisage the development of miniature nuclear weapons with a yield of only a few tons.

In particular, in the environment of nuclear war, how to improve the anti-nuclear reinforcement capability of nuclear weapons to prevent the destruction of the enemy has received more attention.

In addition, due to the mass production and deployment of nuclear weapons, their safety has also attracted the attention of the countries concerned.

Another development trend of nuclear weapons is to adjust their performance by design, and to enhance or weaken some of the lethal and destructive factors in them according to different needs.

"Enhanced radiation weapons" with

"Reduction of surplus radiological weapons" falls into this category. The former maximizes the share of high-energy neutron radiation as much as possible, making it the main cause of damage and is often called a neutron bomb; The latter minimizes residual radioactivity and highlights the effects of shock waves and optical radiation, but this type of weapon still falls under the category of thermonuclear weapons.

As for the so-called, which caused widespread discussion in the early 60s

Although a lot of research work has been done on "pure fusion weapons" for more than 20 years, such as the research on high-power laser-ignited fusion reactions, which was still going on in the 80s, there is still no real possibility of making such weapons.

Although the actual combat application of nuclear weapons is still limited to the two nuclear weapons when they came out, due to the development of nuclear weapons themselves over the past 40 years, as well as the development and application of various projection or delivery vehicles related to them, especially the knowledge accumulated through thousands of nuclear tests, people have a deeper understanding of their unique lethal and destructive effects, and have explored possible ways of practical combat application.

Both the United States and the Soviet Union have formulated and repeatedly revised various strategies emphasizing the important role of nuclear weapons. Where there is a spear, there must be a shield.

While constantly improving and enhancing the performance of offensive strategic nuclear weapons, the United States and the Soviet Union have also been seeking means and technologies that can effectively defend against nuclear attacks.

In addition to improving the anti-nuclear reinforcement capability of nuclear weapons systems and taking measures to reduce losses, such as extensively constructing basement bunkers and civil defense projects, the development and research of defense technology for more effective reconnaissance, tracking, identification, and interception of the enemy's nuclear weapons has never stopped.

In the 60s, the United States and the Soviet Union deployed anti-nuclear anti-** systems. In May 1972, the United States and the Soviet Union signed the Treaty on the Limitation of the Anti-Ballistic System.

Soon the United States stopped

Deployment of the "Guard" anti-** system. At the beginning of 1984, the United States announced that it had developed a multi-layer interception system that included nuclear-excited directed energy weapons, high-energy lasers, neutral particle beams, non-nuclear interceptor missiles, and electromagnetic guns

"Strategic Defense Initiative". Although there is still controversy about the effectiveness of such a defense system, it is certain that the competition between the United States and the Soviet Union for nuclear superiority will continue.

Because of the enormous destructive power and unique role of nuclear weapons, the explosion of nuclear bombs is not so much that it may change the course of future global wars, but that it has had and is constantly having an impact on the actual international political struggle.

At the end of the 70s, the United States announced that it had successfully developed a neutron bomb, which is most suitable for battlefield use and should belong to the category of tactical nuclear weapons, but it was strongly opposed almost worldwide.

This example also illustrates the complexity of the struggle involved in nuclear weapons. At the time of the explosion of the first nuclear weapon, China issued a statement: China's development of nuclear weapons is not due to its belief in the omnipotence of nuclear weapons and its desire to use nuclear weapons.

On the contrary, China's development of nuclear weapons was compelled to do so for the sake of defense, to break the nuclear monopoly and nuclear blackmail of the nuclear powers, and to prevent nuclear war and eliminate nuclear weapons.

Since then, China has solemnly declared on many occasions that it will not be the first to use nuclear weapons at any time and under any circumstances, and has repeatedly put forward suggestions on how to prevent nuclear war.

These propositions of China have gradually won the approval and support of more and more countries and peoples. On August 6, 2014, Japanese Prime Minister Shinzo Abe said in a speech at a ceremony to commemorate the victims of the Hiroshima bombing that Japan has been entrusted with the mission of destroying the world's nuclear weapons.

He also reaffirmed Japan's three non-nuclear principles: not to possess, not to manufacture, and not to import nuclear weapons. At the ceremony, Hiroshima Mayor Kazumi Matsui read out a peace declaration calling for complete nuclear disarmament.

He also called on the leaders of the nuclear powers,

"The first is that Obama personally visits the bombed areas and sees it all with his own eyes."

According to reports, Japan sent condolences to the victims of the bombing of Hiroshima on August 6, 1945, on the 6th.

According to tradition, the commemorative ceremony was held in the Peace Park in the city center. About 45,000 people gathered at the ceremony, which was also attended by diplomats from 65 countries.

[8] According to an article published on the website of Japan's "The Diplomat" on January 7, many countries are quietly looking for helium-3 materials for fourth-generation nuclear weapons, and obtaining this material without radioactive fallout will become the world's new hegemon, and China has won in this competition.