To understand the working principle and device of a nuclear reactor, you need to make a small excursion into the past. A nuclear reactor is a centuries – old embodied, though not to the end, the dream of mankind an inexhaustible energy source. The ancient “grandparent” — the fire of dry branches, once brightened the room and the arches of the cave, where he found salvation from the cold, our ancestors. Later on, people mastered the hydrocarbons – coal, shale, oil, and natural gas.
Came rapid, but short-lived era of steam, which was replaced by the even more fantastic era of electricity. The city was filled with light and shop – hum of unseen machines, driven by electric motors. Then it seemed that the progress had reached its climax.
That all changed in the late nineteenth century, when the French chemist Antoine Henri Becquerel accidentally found that uranium salts possess radioactivity. 2 years later, his compatriots Pierre Curie and his wife Maria Sklodowska-Curie received from them radium and polonium, and their level of radioactivity millions of times superior to the performance of thorium and uranium.
The baton was picked up by Ernest Rutherford in detail studied the nature of radioactive rays. So began the atomic age hath brought to light his favorite child – nuclear reactor.
The first nuclear reactor
“Firstborn” comes from the United States. In December, 1942, gave the first current reactor, which inherited the name of its Creator — one of the greatest physicists of the century Enrico Fermi. Three years later, Canada acquired the life of the nuclear installation ZEEP. “Bronze” went to the first Soviet reactor f-1, launched in late 1946. Director of the domestic nuclear project was the Kurchatov. In the world today successfully employs more than 400 nuclear reactors.
Types of nuclear reactors
Their main purpose is to maintain a controlled nuclear reaction that produces electricity. Some reactor produced isotopes. In short, they represent the device in the depths of which some substances are transformed into others with the release of large amounts of thermal energy. This kind of “oven”, where instead of traditional fuels “burn” the isotopes of uranium – U-235, U-238, and plutonium (Pu).
In contrast, for example, from the vehicle, designed for multiple types of gasoline, each type of radioactive fuel requires a specific type of reactor. Two of them – slow (U-235) and fast (c U-238 and Pu) neutrons. Most nuclear power plants are installed reactors on slow neutrons. In addition to the plant, the installation of “work” in research centers, nuclear submarines, and desalination of seawater.
How does the reactor
All reactors approximate one scheme. Its “heart” — active area. It can be roughly compared with the conventional firebox of the stove. Only instead of wood there is nuclear fuel in the form of fuel elements with the moderator – Fuel rods. The active area is within a sort of capsule — reflector of neutrons. The fuel rods of the “washed” by the heat carrier – water. Because the “heart” of a very high level of radioactivity that surrounds it reliable radiation protection.
The operators control the plant using the two major systems control the chain reaction and remote control system. If there is an emergency situation, immediately triggered the emergency protection.
How does the reactor
The nuclear “flame” is invisible, since the processes occur at the level of nuclear fission. During the chain reaction a heavy nucleus breaks into smaller fragments, which, when in an excited state, become the sources of neutrons and other subatomic particles. But the process does not end there. Neutrons continue to “split up”, resulting in releasing a large energy, that is, there is something for which built NPP.
The main task of the staff – maintaining chain reaction with control rods at a constant, regulated level. This is its main difference from the atomic bomb, where a nuclear decay process is unmanaged and occurs rapidly, in the form of a powerful explosion.
What happened at Chernobyl
One of the main causes of the Chernobyl disaster in April 1986 – a gross violation of operational security rules in the process of routine maintenance on a 4-m unit. Then from the active zone was simultaneously withdrawn 203 of the graphite rod instead of the 15 allowed by the rules. In the end, the outbreak of an uncontrolled chain reaction ended with a heat explosion and total destruction of the unit.
The new generation reactors
Over the last decade, Russia has become one of the world leaders in nuclear energy. At the moment Rosatom is building nuclear power plants in 12 countries, where built 34 units. Such high demand is evidence of a high level of modern Russian nuclear technology. The next step — the new reactors of the 4th generation.
One of them – “Brest”, which is being developed in the framework of the project “Breakthrough”. Existing open loop systems operate on low-enriched uranium, leaving a large amount of spent fuel to be disposed of, which requires huge expenses. Brest is a fast neutron reactor is a unique closed cycle.
Spent fuel in it after appropriate processing in the fast reactor again becomes a fuel that can be loaded back into the same setting.
“Brest” features a high level of security. He never “blows” even in the most serious accidents, very economical and environmentally safe because it re-uses his “updated” uranium. It also cannot be used for producing weapons-grade plutonium, which opens up tremendous prospects for its exports.
VVER-1200 is an innovative reactor of generation 3+ with a capacity of 1150 MW. Due to its unique technical capabilities, he has almost absolute operational safety. The reactor in abundance equipped with passive safety systems, which work even in the absence of power supply in automatic mode.
One of them is the system of passive heat removal, which is automatically activated when the full de-energizing of the reactor. In this case provided emergency hydrohematite. The abnormal pressure drop in the primary circuit of the reactor starts the supply of large quantities of water containing boron, which extinguishes the nuclear reaction and absorb the neutrons.
Another know-how is at the bottom of the containment – the trap-melt. If, however, in the accident the active area “will flow”, “trap” will not allow you to break the protective shell and will prevent the migration of radioactive products in the soil.
- The first nuclear reactor
- Types of nuclear reactors
- How does the reactor
- How does the reactor
- What happened at Chernobyl
- The new generation reactors