Environmental disputes around spent nuclear fuel (SNF) have always been a little perplexing to me. Storage of this type of "waste" requires strict technical measures and precautions, you need to handle it carefully. But this is not a reason to oppose the very fact of the presence of spent nuclear fuel and an increase in their reserves.
Finally, why waste? The SNF composition contains many valuable fissile materials. For example, plutonium. According to various estimates, it forms from 7 to 10 kg per ton of SNF, that is, in the spent nuclear fuel annually formed in Russia, about 100 tons contain from 700 to 1000 kg of plutonium. Reactor plutonium (that is, obtained in an energy reactor, and not in a production reactor) is applicable not only as nuclear fuel, but also to create nuclear charges. On this account, experiments were carried out that showed the technical feasibility of using reactor plutonium as the filling of nuclear charges.
A ton of spent nuclear fuel also contains about 960 kg of uranium. The content of uranium-235 in it is small, about 1,1%, but uranium-238 can be passed through the production reactor and get all the same plutonium, only now of good weapons quality.
Finally, SNF, especially just recovered from the reactor, can act as a radiological weapons, and it is noticeably superior in this quality to cobalt-60. The activity of 1 kg of spent fuel reaches 26 thousand curies (in cobalt-60 - 17 thousand curies). A ton of SNF, just recovered from the reactor, gives a radiation level of up to 1000 sievert per hour, that is, a lethal dose of 5 sievert runs up in just 20 seconds. Fine! If the enemy is sprinkled with fine SNF powder, then serious losses can be inflicted on him.
All these qualities of spent nuclear fuel have long been well known, only they have encountered serious technical difficulties associated with the extraction of fuel from the fuel assembly.
Disassemble the death tube
Nuclear fuel itself is a powder of uranium oxide, compressed or sintered into tablets, small cylinders with a hollow channel inside, which are placed inside a fuel element (TVEL), from which fuel assemblies placed in the reactor channels are assembled.
This is precisely TVEL - this is the stumbling block of spent nuclear fuel reprocessing. Most TVELs look like a very long gun barrel, almost 4 meters long (3837 mm, to be exact). His caliber is almost rifle: the inner diameter of the tube is 7,72 mm. The outer diameter is 9,1 mm and the tube wall thickness is 0,65 mm. The tube is made of either stainless steel or zirconium alloy.
A mock-up of a fuel assembly, on which the design of the unit, fuel elements and the placement of nuclear fuel inside them
Inside the tube, cylinders of uranium oxide are laid, and laid tightly. The tube accommodates from 0,9 to 1,5 kg of uranium. A closed fuel rod is inflated with helium under a pressure of 25 atmospheres. During the campaign, the uranium cylinders heat up and expand, so that in the end they turn out to be tightly stuck in this long tube of a rifle caliber. Anyone who knocked out a bullet stuck in the barrel with a ramrod can well imagine the difficulty of the task. Only here the trunk is almost 4 meters in length, and the uranium "bullets" stuck in it are more than two hundred. The radiation from it is such that it is possible to work with the TVEL just pulled out of the reactor only remotely, using manipulators or some other devices or automatic devices.
How was irradiated fuel recovered from production reactors? There the situation was very simple. TVEL tubes for production reactors were made of aluminum, which is highly soluble in nitric acid, together with uranium and plutonium. The necessary substances were extracted from the nitric acid solution and went into further processing. But energy reactors, designed for a much higher temperature, use refractory and acid-resistant materials of fuel elements. Moreover, cutting such a thin and long stainless steel tube is a very rare task; usually, all the attention of engineers is focused on rolling such a tube. A tube for a fuel rod is a real technological masterpiece. In general, different methods of destroying or cutting the tube were proposed, but this method prevailed: first, the tube is cut in the press (you can cut the entire fuel assembly) into pieces about 4 cm long, and then the stumps are poured into a container where uranium is dissolved with nitric acid. The obtained uranyl nitrate is not so difficult to isolate from the solution.
And this method, with all its simplicity, has a significant drawback. Uranium cylinders in pieces of fuel elements dissolve slowly. The contact area of uranium with acid at the ends of the stump is very small and this slows down the dissolution. Unfavorable reaction conditions.
If we count on spent nuclear fuel as a military material for producing uranium and plutonium, as well as a means of radiological warfare, then we must learn how to cut tubes quickly and dexterously. Chemical methods are not suitable for obtaining a means of radiological warfare: after all, we need to save the whole bunch of radioactive isotopes. There are not so many fission products, 3,5% (or 35 kg per tonne): cesium, strontium, technetium, but it is they that create the high radioactivity of SNF. Therefore, a mechanical method of extracting uranium with all other contents from the tubes is needed.
Upon reflection, I came to the following conclusion. The thickness of the tube is 0,65 mm. Not so much. It can be cut on a lathe. The wall thickness approximately corresponds to the cutting depth of many lathes; if necessary, you can apply special solutions with a large depth of cutting of viscous steels, such as stainless steel, or use a machine with two cutters. An automatic lathe that can grab a workpiece itself, clamp it and grind it is no longer a rarity these days, especially since cutting a tube does not require precision accuracy. It is enough to grind the end of the tube, turning it into shavings.
Uranium cylinders, freed from the steel shell, will fall into the receiver under the machine. In other words, it is quite possible to create a fully automatic complex that will chop fuel assemblies into parts (the length most convenient for turning), fold the cuts into the machine’s drive, then the machine cuts the tube, freeing its uranium filling.
If you master the dismantling of the "death tubes", then you can use spent nuclear fuel both as a semi-finished product for the separation of weapons isotopes and production of reactor fuel, and as a radiological weapon.
Black deadly dust
Radiological weapons, in my opinion, are most applicable in a protracted nuclear war, and mainly to damage the military and economic potential of the enemy.
Under a protracted nuclear war, I am raising a war in which nuclear weapons are used at all stages of a prolonged armed conflict. I don’t think that the large-scale conflict that came or even started with the exchange of massive nuclear missile strikes will end on them. Firstly, even after significant damage, there will still be opportunities for warfare (stocks of weapons and ammunition allow enough intense hostilities for another 3-4 months without replenishing production). Secondly, even after the exhaustion of nuclear warheads on combat duty, large nuclear countries will still have in warehouses which, most likely, will not suffer, a very large number of different warheads, nuclear charges, and nuclear explosive devices. They can be used, and their importance for warfare is becoming very great. It is advisable to save them, and use either for a radical change in the course of important operations, or in the most critical situation. This will not be a salvo application, but a long one, that is, a nuclear war becomes protracted. Thirdly, in the military-economic issues of a large-scale war, in which conventional weapons are used along with nuclear weapons, the production of weapons-grade isotopes and new charges, replenishment of nuclear weapons arsenals, will clearly be among the most important and priority tasks. Including, of course, the speedy creation of production reactors, radiochemical and radio metallurgical industries, enterprises for the manufacture of components and the assembly of nuclear munitions.
It is precisely in the context of a large-scale and protracted armed conflict that it is important to prevent the enemy from taking advantage of his economic potential. Such objects can be destroyed, which will require either a decent-sized nuclear weapon, or a large expenditure of conventional bombs or missiles. For example, during the Second World War, in order to guarantee the decommissioning of a large plant, it was necessary to drop 20 to 50 thousand tons of aerial bombs on it in several stages. The first attack halted production and damaged equipment, and subsequent ones interrupted restoration work and exacerbated the damage. Say, the Leuna Werke synthetic fuel plant was attacked six times from May to October 1944 before production fell to 15% of normal productivity.
In other words, destruction per se does not guarantee anything. A destroyed plant can be restored, and from a heavily destroyed facility you can remove the remains of equipment suitable for creating a new production in another place. It would be good to develop a method that would not allow the enemy to use, restore, or take apart an important military-economic object for spare parts. It seems that radiological weapons are suitable for this.
It is worth recalling that during the accident at the Chernobyl nuclear power plant, in which all attention was usually focused on the 4th power unit, the remaining three power units were also stopped on April 26, 1986. Not surprisingly, they turned out to be contaminated and the radiation level at the 3rd power unit, located next to the detonated one, that day was 5,6 x-rays / hour and a half-fatal dose of 350 x-rays was incurred in 2,6 days or in just seven work shifts. It is clear that working there was dangerous. The decision to restart the reactors was made on May 27, 1986, and after intensive decontamination, the 1st and 2nd power units were launched in October 1986, and the third power unit in December 1987. A 4000 MW nuclear power plant was completely disabled for five months simply because the intact power units were radioactively contaminated.
So, if you sprinkle an enemy military-economic facility: a power station, a military plant, a port, and so on, with spent nuclear fuel powder, with a whole bunch of strongly fading isotopes, then the enemy will lose the opportunity to use it. He will have to spend many months for decontamination, introduce rapid rotation of workers, build radio shelters, incur sanitary losses from re-irradiation of personnel; production will cease altogether or very much decrease.
The delivery and contamination method is also quite simple: the finely ground uranium oxide powder - black deadly dust - is equipped with explosive cartridges, which in turn are equipped with a ballistic missile warhead. 400-500 kg of radioactive powder can freely enter it. Over the target, the cassettes are ejected from the warhead, the cassettes are destroyed by subversive charges, and fine highly radioactive dust covers the target. Depending on the height of the missile warhead’s deployment, it is possible to obtain severe pollution of a relatively small area, or to obtain an extensive and extended radioactive trail with a lower level of radioactive contamination. Although, as they say, Pripyat was evicted, because the radiation level was 0,5 X-ray / hour, that is, a half-fatal dose ran over 28 days and it became dangerous to live permanently in this city.
In my opinion, radiological weapons were in vain called weapons of mass destruction. It can only hit someone in very favorable conditions. Rather, it is a barrier that creates barriers to access to the contaminated area. Fuel from the reactor, which can give an activity of 15-20 thousand X-rays / hour, as indicated in the Chernobyl Notebooks, will create a very effective obstacle to the use of the infected object. Attempts to ignore radiation will result in high irretrievable and sanitary losses. With the help of this obstacle, the enemy can be deprived of the most important economic facilities, key nodes of the transport infrastructure, as well as the most important agricultural land.
Depending on the wind, a pretty decent spot of radioactive contamination can result
Satellite image with the designation of the most important objects: the Chernobyl nuclear power plant and the exploding power unit, the city of Pripyat, the railway station of Yanov, the port. Unlike air bombs, radioactive contamination makes it impossible to use the entire infrastructure of a military-significant facility
Such a radiological weapon is much simpler and cheaper than a nuclear charge, since it is much simpler in design. True, due to the very high radioactivity, special automatic equipment will be required to grind the uranium oxide extracted from the fuel elements, to equip it into cassettes and into a missile warhead. The warhead itself should be stored in a special protective container and mounted on the missile with a special automatic device immediately before launch. Otherwise, the calculation will receive a lethal dose of radiation before launch. It is best to base missiles for the delivery of radiological warheads in mines, since it is easier to solve the problem of the safe storage of highly radioactive warheads before launch.