Weapon plutonium: application, production, disposal

Mankind has always been in search of new sources of energy that can solve many problems. However, not always they are safe. Thus, in particular, atomic reactors widely used today, although they are capable of producing just an enormous amount of such electric energy, which everyone needs, still carry a mortal danger. But, in addition to using nuclear energy for peaceful purposes, some countries of our planet have learned to use it in the military, in particular, for the creation of nuclear warheads. In this article we will talk about the basis of such a destructive weapon, the name of which is weapons-grade plutonium.

Brief information

This compact form of metal contains a minimum of 93.5% of the isotope 239Pu. Weapon plutonium was named so that it could be distinguished from a "reactor colleague". In principle, plutonium is always formed in absolutely any nuclear reactor, which, in turn, operates on low-enriched or natural uranium containing, for the most part, 238U isotope.

Military Applications

Weapon-grade plutonium 239Pu is the basis of nuclear weapons. In this case, the use of isotopes with mass numbers 240 and 242 is irrelevant, since they create a very high background of neutrons, which ultimately makes it difficult to design and construct highly effective nuclear ammunition. In addition, the plutonium isotopes 240Pu and 241Pu have a significantly shorter half-life than the 239Pu, so that the plutonium parts become very hot. It is in this connection that in the nuclear ammunition engineers are forced to additionally add elements for removing excess heat. By the way, 239Pu in its pure form is warmer than the human body. We can not ignore the fact that the products of the decay of heavy isotopes undergo a harmful change in the crystal lattice of the metal, and this quite naturally changes the configuration of the plutonium parts, which, in the end, can cause complete failure of the nuclear explosive device.

By and large, all of the above difficulties can be overcome. And in practice, several times have already been tested explosive devices based on "reactor" plutonium. But it should be understood that in nuclear weapons, their compactness, their small mass, durability and reliability are not the last. In connection with this, exclusively weapons-grade plutonium is used in them.

Design features of production reactors

Virtually all plutonium in Russia was produced in reactors equipped with a graphite retarder. Each of the reactors is built around cylindrically assembled blocks of graphite.

In the assembled form, the graphite blocks have special gaps between them to ensure a continuous circulation of the cooler, which uses nitrogen as its source. In the assembled structure there are also vertically arranged channels created for passing through them water cooling and fuel. The assembly itself rigidly rests on a structure with holes under the channels used to ship the already irradiated fuel. Each of the channels is in a thin-walled tube, cast from a lightweight and extra-strong aluminum alloy. Most of the channels described have 70 fuel rods. Water for cooling flows directly around the fuel rods, removing excess heat from them.

Increasing the capacity of production reactors

Initially, the first "Mayak" reactor operated with a capacity of 100 thermal MW. However, Igor Kurchatov, the head of the Soviet nuclear weapons development program, proposed that the reactor should operate at 170-190 MW in wintertime and 140-150 MW in summer time. This approach allowed the reactor to produce almost 140 grams of precious plutonium per day.

In 1952, full scientific research was carried out to increase the production capacity of operating reactors by such methods:

• By increasing the flow of water used for cooling and flowing through the active zones of the nuclear installation.
• By increasing the resistance to the phenomenon of corrosion occurring near the liner channels.
• Reducing the rate of oxidation of graphite.
• Increase the temperature inside the fuel cells.

As a result, the throughput of the circulating water increased significantly after the gap between the fuel and the channel walls was increased. Corrosion also managed to get rid of. For this purpose, the most suitable aluminum alloys were chosen and sodium dichromate was actively added, which ultimately increased the softness of the cooling water (pH was about 6.0-6.2). Oxidation of graphite ceased to be an actual problem after nitrogen was used for its cooling (before that, only air was used).

At the end of the 1950s, innovations were fully realized in practice, which made it possible to reduce the extremely unnecessary uranium inflation caused by radiation, significantly reduce the thermal hardening of uranium rods, improve the shell resistance and improve the quality control of production.

Production at Mayak

"Chelyabinsk-65" is one of those secret factories on which the creation of weapons-grade plutonium took place. The plant had several reactors, each of which we will get to know each other.

Reactor A

The installation was designed and created under the guidance of the legendary NA Dollezhal. It worked with a capacity of 100 MW. The reactor had 1149 vertically arranged control and fuel channels in a graphite block. The total weight of the structure was about 1050 tons. Virtually all channels (except 25) were loaded with uranium, the total mass of which was 120-130 tons. 17 channels were used for the control rods, and 8 for the experiments. The maximum indicator of the projected heat release of the fuel cell was 3.45 kW. At first, the reactor produced about 100 grams of plutonium per day. For the first time, metallic plutonium was produced on April 16, 1949.

Technological disadvantages

Almost immediately, quite serious problems were identified, which consisted in corrosion of aluminum liners and coating of fuel cells. Also, the uranium rods swelled and damaged and the cooling water flowed directly into the core of the reactor. After each leak, the reactor had to be stopped for up to 10 hours in order to dry the graphite with air. In January 1949, liners were replaced with canals. After that, the installation was launched on March 26, 1949.

The weapons-grade plutonium, whose production at reactor A was accompanied by various difficulties, was developed in the period 1950-1954, with an average capacity of 180 MW. The subsequent operation of the reactor began to be accompanied by a more intensive use of it, which naturally led to more frequent stops (up to 165 times per month). As a result, in October 1963 the reactor was stopped and resumed its work only in the spring of 1964. His campaign was completely finished in 1987 and for the entire period of many years of operation produced 4.6 tons of plutonium.

Reactors AB

At the Chelyabinsk-65 plant, three AB reactors were decided to be built in the fall of 1948. Their production capacity was 200-250 grams of plutonium per day. The main designer of the project was A. Savin. Each reactor counted 1996 channels, 65 of them were control. In the installations a technical novelty was used - each channel was equipped with a special detector for the leakage of cooling liquid. This move made it possible to change the liners without terminating the operation of the reactor itself.

The first year of operation of the reactors showed that they produced about 260 grams of plutonium per day. However, since the second year of operation, the capacity has been gradually increased, and already in 1963 its figure was 600 MW. After the second overhaul, the problem with the liners was completely solved, and the power already amounted to 1200 MW with an annual production of plutonium of 270 kilograms. These indicators were preserved until the reactors were completely closed.

AI-IR reactor

The Chelyabinsk enterprise used this facility between December 22, 1951 and May 25, 1987. In addition to uranium, the reactor also produced cobalt-60 and polonium-210. Originally, tritium was produced at the facility, but later plutonium was also produced.

Also, the plant for the processing of weapons-grade plutonium had reactors operating on heavy water and a single light-water reactor (its name was Ruslan).

Siberian giant

"Tomsk-7" - this was the name of the plant, which housed five reactors to create plutonium. Each of the aggregates used graphite to slow neutrons and ordinary water to ensure proper cooling.

Reactor I-1 worked with a cooling system, in which the water passed once. However, the remaining four units were equipped with closed primary circuits equipped with heat exchangers. Such a design made it possible to further develop steam, which in turn helped in the production of electricity and heating of various living quarters.

Tomsk-7 also had a reactor called EI-2, which, in turn, had a dual purpose: it produced plutonium and generated 100 MW of electricity through the generated steam, as well as 200 MW of thermal energy.

Important information

On assurances of scientists, the half-decay of weapons-grade plutonium is about 24 360 years. A huge figure! In this connection, the question becomes especially acute: "How to deal with production waste of this element correctly?" The most optimal option is the construction of special enterprises for the subsequent processing of weapons-grade plutonium. This is explained by the fact that in this case the element can no longer be used for military purposes and will be controlled by a person. This is how the weapons-grade plutonium is disposed of in Russia, but the United States of America took a different route, thereby violating its international obligations.

Thus, the US government proposes to destroy highly enriched nuclear fuel not in an industrial way, but by diluting plutonium and storing it in special containers at a depth of 500 meters. It goes without saying that in this case the material can easily be retrieved from the ground at any time and re-launched for military purposes. As the president of the Russian Federation Vladimir Putin asserts, initially the countries agreed to destroy plutonium not by this method, but to conduct recycling at industrial facilities.

The cost of weapons-grade plutonium deserves special attention. According to experts, tens of tons of this element may well cost several billion US dollars. And some experts at all estimated 500 tons of weapons-grade plutonium as much as 8 trillion dollars. The amount is really impressive. To make it clearer how big this money is, let's say that in the last decade of the 20th century, Russia's average annual GDP was $ 400 billion. That is, in fact, the real price of weapons-grade plutonium was equal to the twenty-year GDP of the Russian Federation.