China intends to build the world's smallest nuclear reactor. Atomic constructor: reactor on the table The smallest nuclear reactor

Chinese scientists at the Institute of Nuclear Power Safety Technology have begun work on creating nuclear power plant, which will become the smallest in the world. Reported about it.

The nuclear power plant will be a reactor fast neutrons... Scientists themselves called it "portable nuclear battery." This design will allow the reactor to operate without difficult maintenance conditions for 5 years. Molten lead will be used for cooling.

A small power plant will be able to produce up to 10 megawatts of electricity. Moreover, its dimensions will be only 2 meters wide and 6 meters high. According to scientists, it will be able to supply energy to about 50 thousand homes. Despite this, the scientists chose a desalination unit located in the South China Sea as the first point of operation of the new reactor.

The Chinese authorities intend to bring such "portable nuclear batteries" into operation within the next 5 years.

1. Free-piston Stirling engine runs on heating by "atomic steam" 2. An induction generator gives about 2 watts of electricity to power an incandescent lamp 3. A characteristic blue glow is the Cherenkov radiation of electrons knocked out of atoms by gamma quanta. Can serve as a great night light!

For children from 14 years old, the Young Researcher will be able to independently assemble, albeit small, but real nuclear reactor, find out what prompt and delayed neutrons are, and see the dynamics of acceleration and deceleration of a nuclear chain reaction. A few simple experiments with a gamma spectrometer will allow you to understand the production of various fission products and experiment with the reproduction of fuel from the now fashionable thorium (a piece of thorium-232 sulfide is attached). The included book "Fundamentals of Nuclear Physics for the Little Ones" contains a description of more than 300 experiments with the assembled reactor, so the scope for creativity is huge

Historic Prototype The Atomic Energy Lab Kit (1951) empowered schoolchildren to experience the most advanced field of science and technology. An electroscope, a Wilson chamber, and a Geiger-Muller counter made it possible to carry out many interesting experiments. But, of course, not as interesting as the assembly of an operating reactor from the Russian set of "Desktop NPP"!

In the 1950s, with the advent of atomic reactors, it would seem that brilliant prospects for solving all energy problems loomed before mankind. Power engineers designed nuclear power plants, shipbuilders - nuclear electric ships, and even auto designers decided to join the holiday and use the "peaceful atom". A "nuclear boom" arose in society, and the industry began to lack qualified specialists. An influx of new personnel was required, and a serious educational campaign was launched not only among university students, but also among schoolchildren. For example, A.C. The Gilbert Company released the Atomic Energy Lab children's kit in 1951, containing several small radioactive sources, the necessary instrumentation, and samples of uranium ore. This "state-of-the-art science kit," it said on the box, allowed "young researchers to conduct more than 150 exciting scientific experiments."

Cadres are everything

Over the past half century, scientists have learned some bitter lessons and learned how to build reliable and safe reactors. And although there is now a decline in this area, caused by the recent accident at Fukushima, it will soon be replaced by an upswing, and nuclear power plants will continue to be seen as an extremely promising way to obtain clean, reliable and safe energy... But already now in Russia there is a shortage of personnel, as in the 1950s. In order to attract schoolchildren and increase interest in nuclear energy, the Research and Production Enterprise (NPP) "Ecoatomconversion", following the example of A.C. The Gilbert Company has released an educational kit for children from 14 years of age. Of course, science for these half a century has not stood still, therefore, unlike its historical prototype, the modern set allows you to get a much more interesting result, namely, to put together a real model of a nuclear power plant on the table. Of course, the current one.

Literacy from the cradle

“Our company comes from Obninsk, a city where nuclear energy is familiar and familiar to people almost from kindergarten, - explains "PM" scientific director of NPP "Ecoatomconversion" Andrey Vykhadanko. - And everyone understands that there is absolutely no need to be afraid of her. After all, only an unknown danger is truly terrible. Therefore, we decided to release this set for schoolchildren, which will allow them to experiment and study the principles of nuclear reactors to their fullest, without exposing themselves and others to serious risk. As you know, the knowledge gained in childhood is the strongest, so with the release of this kit we hope to significantly reduce the likelihood of a recurrence of Chernobyl or

Fukushima in the future. "

Waste plutonium

Over the years, many nuclear power plants have accumulated tons of so-called reactor plutonium. It consists mainly of weapons grade Pu-239, containing about 20% impurities of other isotopes, primarily Pu-240. This makes reactor plutonium completely unsuitable for making nuclear bombs. The separation of the impurity turns out to be very difficult, since the mass difference between the 239th and 240th isotopes is only 0.4%. The manufacture of nuclear fuel with the addition of reactor plutonium turned out to be technologically difficult and economically unprofitable, so this material was left out of business. It is the "waste" plutonium that was used in the "Young Atomic Engineer Kit" developed by the NPP "Ecoatomconversion".

As you know, for the start of a fission chain reaction, nuclear fuel must have a certain critical mass. For a ball made of weapons-grade uranium-235, it is 50 kg, for plutonium-239 - only 10. A shell made of a neutron reflector, for example, beryllium, can reduce the critical mass by several times. And the use of a moderator, as in thermal neutron reactors, will reduce the critical mass by more than ten times, down to several kilograms of highly enriched U-235. The critical mass of Pu-239 will even amount to hundreds of grams, and it is precisely such an ultra-compact reactor that fits on a table that was developed at Ecoatomconversion.

What's in the chest

The packaging of the kit is modestly decorated in black and white, and only the dim three-segment radioactivity icons stand out somewhat against the general background. “There’s really no danger,” says Andrei, pointing to the words “Perfectly safe!” Written on the box. "But these are the requirements of the official authorities." The box is heavy, which is not surprising: it contains a sealed lead shipping container with a fuel assembly (FA) of six plutonium rods with a zirconium sheath. In addition, the set includes an outer reactor vessel made of heat-resistant glass with chemical hardening, a vessel lid with a glass window and pressure seals, a stainless steel core vessel, a support for the reactor, and a boron carbide control rod-absorber. The electrical part of the reactor is represented by a free piston Stirling engine with connecting polymer tubes, a small incandescent lamp and wires. The kit also includes a kilogram bag of boric acid powder, a pair of protective suits with respirators and a gamma spectrometer with a built-in helium neutron detector.

NPP construction

Assembling the operating model of a nuclear power plant according to the attached manual in pictures is very simple and takes less than half an hour. Putting on a stylish protective suit (it is needed only during assembly), we open the sealed packaging with fuel assemblies. Then we insert the assembly into the reactor vessel, cover it with the core vessel. At the end, we snapped the cover with the cable glands on top. In the central one, you need to insert the absorber rod to the end, and through either of the other two, fill the active zone with distilled water to the line on the body. After filling, pipes for steam and condensate are connected to the pressure seals, passing through the heat exchanger of the Stirling engine. The nuclear power plant itself is finished and ready for launch; all that remains is to place it on a special stand in an aquarium filled with a boric acid solution, which perfectly absorbs neutrons and protects the young researcher from neutron irradiation.

Three, two, one - start!

We bring the gamma spectrometer with a neutron sensor close to the wall of the aquarium: a small part of the neutrons, which does not pose a threat to health, still come out. Slowly raise the adjusting rod until the neutron flux begins to rise rapidly, triggering a self-sustaining nuclear reaction. It remains only to wait until the required power is reached and push the rod back by 1 cm along the marks so that the reaction rate stabilizes. As soon as boiling begins, a vapor layer will appear in the upper part of the core vessel (perforation in the vessel prevents this layer from exposing the plutonium rods, which could lead to their overheating). The steam goes up through the tube to the Stirling engine, where it condenses and flows down the outlet tube into the reactor. The temperature difference between the two ends of the engine (one is heated by steam, and the other is cooled by room air) is converted into oscillations of the piston-magnet, which, in turn, induces an alternating current in the winding surrounding the engine, igniting atomic light in the hands of the young researcher and, as they hope developers, atomic interest in his heart.

Editors note: This article was published in the April issue of the magazine and is an April Fool's Day draw.

Unfortunately, a microatomic reactor for domestic needs cannot be created, and here's why. The operation of a nuclear reactor is based on a chain reaction of fission of the nuclei of Uranus-235 (²³⁵U) by a thermal neutron: n + ²³⁵U → ¹⁴¹Ba + ⁹²Kr + γ (202.5 MeV) + 3n. The picture of the chain reaction of cleavage is shown below.

In fig. it can be seen how a neutron entering the nucleus (²³⁵U) excites it and the nucleus splits into two fragments (¹⁴¹Ba, ⁹²Kr), a γ-quantum with an energy of 202.5 MeV and 3 free neutrons (on average), which in turn can split the next 3 uranium nuclei caught in their path. So, in the process of each fission act, about 200 MeV of energy or ~ 3 × 10⁻¹¹ J is released, which corresponds to ~ 80 TerraJ / kg or 2.5 million times more than would be released in the same amount of burning coal. But as Murphy instructs us: "if a trouble should happen, then it must happen," and some of the neutrons produced during fission are lost in the chain reaction. Neutrons can escape (jump out) from the active volume or be absorbed by impurities (for example, Krypton). The ratio of the number of neutrons of the next generation to the number of neutrons in the previous generation in the entire volume of the multiplying neutron medium (the active zone of a nuclear reactor) is called the neutron multiplication factor, k. For k<1 цепная реакция затухает, т.к. число поглощенных нейтронов больше числа вновь образовавшихся. При k>1, an explosion occurs almost instantaneously. When k is equal to 1, a controlled stationary chain reaction occurs. The neutron multiplication factor (k) is most sensitive to the mass and purity of nuclear fuel (²³⁵U). In nuclear physics, the minimum mass of fissile matter required to start a self-sustaining fission chain reaction (k≥1) is called the critical mass. For Uranus-235, it is 50 kg. This is certainly not a micro-size, but also a little. To avoid a nuclear explosion and create the possibility of controlling a chain reaction (multiplication factor), the fuel mass in the reactor must be increased and, accordingly, neutron absorbers (moderators) must be put into operation. It is precisely this engineering and technical equipment of the reactor, in order to sustainably control the chain reaction, the cooling system and additional structures for the radiation safety of personnel, and require large volumes.

Californian-232 with a critical mass of about 2.7 kg can also be used as fuel. In the limit, it is quite possible to bring the reactor to the size of a sphere with a diameter of several meters. Most likely, this is probably done on nuclear submarines. I think it should be very dangerous to approach such reactors ☠ because of the inevitable neutron background, but more details should be asked from the warriors.

Californium is not suitable as a nuclear fuel due to its enormous cost. 1 gram of California-252 costs about $ 27 million. Only uranium is widely used as a nuclear fuel. Fuel cells on the basis of thorium and plutonium have not yet received widespread use, but are being actively developed.

The relatively high compactness of submarine reactors is provided by the difference in design (usually pressurized water reactors, VVER / PWR are used), different requirements for them (other requirements for safety and emergency shutdown; on board usually does not need a lot of electricity, unlike reactors on land-based power plants , which were created only for the sake of electricity) and the use of different degrees of fuel enrichment (concentration of uranium-235 in relation to the concentration of uranium-238). Typically, uranium with a much higher degree of enrichment (20% to 96% for American boats) is used in fuel for marine reactors. Also, unlike land-based power plants, where the use of fuel in the form of ceramics (uranium dioxide) is common, in offshore reactors, alloys of uranium with zirconium and other metals are most often used as fuel.

Devices that generate electric current as a result of using the energy of nuclear fission are well studied (since 1913) and have long been mastered in production. They are mainly used where relative compactness and high autonomy are needed - in space exploration, underwater vehicles, sparsely populated and deserted technologies. The prospects for their use in domestic conditions are rather modest; in addition to the radiation hazard, most types of nuclear fuel are highly toxic and, in principle, are extremely unsafe in contact with the environment. Despite the fact that in the English-language literature these devices are called atomic batteries, and it is not customary to call them reactors, they can be considered as such, because a decay reaction is taking place in them. If desired, such devices can be adapted for domestic needs, this may be relevant for conditions, for example, in Antarctica.

Radioisotope thermoelectric generators have existed for a long time and fully satisfy your request - they are compact and powerful enough. They work due to the Seebeck effect, they have no moving parts. If this did not contradict common sense, safety precautions and the criminal code, such a generator could be buried somewhere under the garage in the country and even powered by a couple of bulbs and a laptop from it. To sacrifice, so to speak, the health of descendants and neighbors for the sake of a hundred or two watts of electricity. In total, more than 1000 such generators were produced in Russia and the USSR.

As other participants have already answered, the prospects for miniaturization of "classical" nuclear power reactors using steam turbines for generating electricity are strongly limited by the laws of physics, and the main restrictions are imposed not so much by the size of the reactor as by the size of other equipment: boilers, pipelines, turbines, cooling towers. Most likely there will be no "household" models. Nevertheless, rather compact devices are now being actively developed, for example, NuScale's promising reactor with a power of 50 MWe has dimensions of only 76 by 15 inches, i.e. about two meters by 40 centimeters.

With the energy of nuclear fusion, everything is much more complicated and ambiguous. On the one hand, we can only talk about long-term perspective. So far, even large nuclear fusion reactors do not provide energy, and there is simply no talk of their practical miniaturization. Nevertheless, a number of serious and even more serious organizations are developing compact energy sources based on a fusion reaction. And if in the case of Lockheed Martin, the word "compact" means "the size of a van", then, for example, in the case of the American agency DARPA, which allocated in 2009 fiscal year