How to choose 

All about radioactive waste. Topic2. Radioactive waste How radioactive waste is disposed of

Radioactive waste (RW) is a by-product of technical activity containing biologically hazardous radionuclides. RAW is formed:

  • at all stages of nuclear energy (from fuel production to the operation of nuclear power plants (NPPs), including nuclear power plants (NPPs);
  • in the production, use and destruction of nuclear weapons in the production and use of radioactive isotopes.

RW is classified according to various criteria (Fig. 1): according to the state of aggregation, according to the composition (type) of radiation, according to the lifetime (half-life T 1/2), by activity (radiation intensity).

Among RW, liquid and solid are considered to be the most common in terms of aggregate state, mainly arising from the operation of nuclear power plants, other nuclear power plants and at radiochemical plants for the production and processing of nuclear fuel. Gaseous radioactive waste is generated mainly during the operation of nuclear power plants, radiochemical plants for fuel regeneration, as well as during fires and other emergencies at nuclear facilities.

Radionuclides contained in radioactive waste undergo spontaneous (spontaneous) decay, during which one (or several in succession) of the types of radiation occurs: a -radiation (flux a -particles - doubly ionized helium atoms), b -radiation (flow of electrons), g -radiation (hard short-wave electromagnetic radiation), neutron radiation.

The processes of radioactive decay are characterized by an exponential law of decrease in time of the number of radioactive nuclei, while the lifetime of radioactive nuclei is characterized by half-lifeT 1/2 - the period of time during which the number of radionuclides will decrease by half on average. The half-lives of some radioisotopes formed during the decay of the main nuclear fuel - uranium-235 - and representing the greatest danger to biological objects, are given in the table.

Table

Half-lives of some radioisotopes

The United States, which at one time was actively testing atomic weapons in the Pacific Ocean, used one of the islands for disposal of radioactive waste. The containers with plutonium stored on the island were covered with powerful reinforced concrete shells with warning inscriptions visible for several miles: stay away from these places for 25 thousand years! (Recall that the age of human civilization is 15 thousand years.) Some containers were destroyed under the influence of incessant radioactive decays, the level of radiation in coastal waters and bottom rocks exceeds permissible limits and is dangerous for all living things.

Radioactive radiation causes the ionization of atoms and molecules of matter, including the matter of living organisms. The mechanism of the biological action of radioactive radiation is complex and not fully understood. Ionization and excitation of atoms and molecules in living tissues, occurring when they absorb radiation, is only the initial stage in a complex chain of subsequent biochemical transformations. It has been established that ionization leads to the breaking of molecular bonds, changes in the structure of chemical compounds and, ultimately, to the destruction of nucleic acids and proteins. Under the action of radiation, cells are affected, primarily their nuclei, the ability of cells to normal division and metabolism in cells are disrupted.

Hematopoietic organs (bone marrow, spleen, lymphatic glands), epithelium of mucous membranes (in particular, intestines), and thyroid gland are most sensitive to radiation exposure. As a result of the action of radioactive radiation on organs, severe diseases occur: radiation sickness, malignant tumors (often fatal). Irradiation has a strong effect on the genetic apparatus, leading to the appearance of offspring with ugly deviations or congenital diseases.

Rice. 2

A specific feature of radioactive radiation is that they are not perceived by the human senses and even at lethal doses do not cause pain in him at the time of exposure.

The degree of biological effects of radiation depends on the type of radiation, its intensity and duration of exposure to the body.

The unit of radioactivity in the SI system of units is becquerel(Bq): 1 Bq corresponds to one act of radioactive decay per second (non-systemic unit - curie (Ci): 1 Ci = 3.7 10 10 decay acts per 1 s).

absorbed dose (or radiation dose) is the energy of any type of radiation absorbed by 1 kg of matter. The unit of dose in the SI system is gray(Gy): at a dose of 1 Gy in 1 kg of a substance, when absorbing radiation, energy of 1 J is released (non-systemic unit - glad: 1 Gy = 100 rad, 1 rad = 1/100 Gy).

The radioactive sensitivity of living organisms and their organs is different: the lethal dose for bacteria is 10 4 Gy, for insects - 10 3 Gy, for humans - 10 Gy. The maximum dose of radiation that does not cause harm to the human body with repeated exposure is 0.003 Gy per week, with a single exposure - 0.025 Gy.

The equivalent dose of radiation is the main dosimetric unit in the field of radiation safety, introduced to assess the possible damage to human health from chronic exposure. The SI unit of equivalent dose is sievert(Sv): 1 Sv is the dose of radiation of any kind that produces the same effect as the reference X-ray radiation in 1 Gy, or in 1 J/kg, 1 Sv = 1 Gy = 1 J/kg (non-systemic unit - rem(biological equivalent of a roentgen), 1 Sv = 100 rem, 1 rem = 1/100 Sv).

The energy of an ionizing radiation source (IRS) is usually measured in electron volts (eV): 1 eV = 1.6 10 -19 J, it is permissible for a person to receive no more than 250 eV from IRS per year (single dose - 50 eV).

unit of measurement x-ray(P) is used to characterize the state of the environment subjected to radioactive contamination: 1 P corresponds to the formation of 2.082 million pairs of ions of both signs in 1 cm 3 of air under normal conditions, or 1 P \u003d 2.58 10 -4 C / kg (C - pendant) .

Natural radioactive background - the permissible equivalent dose rate from natural radiation sources (the Earth's surface, atmosphere, water, etc.) in Russia is 10-20 μR / h (10-20 μrem / h, or 0.1-0.2 µSv/h).

Radioactive contamination has a global character not only in terms of the spatial scale of its influence, but also in terms of the duration of its action, threatening people's lives for many decades (the consequences of the Kyshtym and Chernobyl accidents) and even centuries. Thus, the main "stuffing" of atomic and hydrogen bombs - plutonium-239 (Pu-239) - has a half-life of 24 thousand years. Even micrograms of this isotope, once in the human body, cause cancer in various organs; three "oranges" of plutonium-239 could potentially destroy all of humanity without any nuclear explosions.

In view of the absolute danger of radioactive waste for all living organisms and for the biosphere as a whole, they need to be decontaminated and (or) thoroughly buried, which is still an unresolved problem. The problem of combating radioactive contamination of the environment is brought to the fore among other environmental problems due to its enormous scale and especially dangerous consequences. According to the famous ecologist A.V. Yablokov, "environmental problem number 1 in Russia - its radioactive contamination."

The unfavorable radiological situation in certain regions of the world and Russia is primarily the result of a long-term arms race during the Cold War and the creation of weapons of mass destruction.

For the production of weapons-grade plutonium (Pu-239) in the 1940s. the first nuclear power plants were built - reactors (tens of tons of Pu-239 are required for nuclear weapons; one ton of this "explosive" is produced by a slow-neutron nuclear reactor with a capacity of 1000 MW - one unit of a conventional nuclear power plant of the Chernobyl type has such power). Tests by nuclear powers (the United States, the USSR, and then Russia, France and other countries) of nuclear weapons in the atmosphere and under water, underground nuclear explosions for “peaceful” purposes, which are now moratoriumed, have led to severe pollution of all components of the biosphere.

Under the program "Peaceful atom" (the term was proposed by the American President D. Eisenhower) in the 1950s. NPP construction began first in the USA and the USSR, and then in other countries. At present, the share of nuclear power plants in the production of electrical energy in the world is 17% (in the structure of the Russian electric power industry, the share of nuclear power plants is 12%). There are nine nuclear power plants in Russia, of which eight are located in the European part of the country (all stations were built during the existence of the USSR), including the largest - Kursk - with a capacity of 4000 MW.

In addition to the arsenal of nuclear weapons (bombs, mines, warheads), nuclear power plants that produce explosives, and nuclear power plants, the sources of radioactive contamination of the environment in Russia (and adjacent territories) are:

  • nuclear icebreaker fleet, the most powerful in the world;
  • submarine and surface warships with power nuclear power plants (and carrying nuclear weapons);
  • ship repair and shipyards of such ships;
  • enterprises involved in the processing and disposal of radioactive waste of the military-industrial complex (including decommissioned submarines) and nuclear power plants;
  • sunken nuclear ships;
  • spacecraft with nuclear power plants on board;
  • RW disposal sites.

It should be added to this list that the radiation situation in Russia is still determined by the consequences of accidents that occurred in 1957 at the Mayak Production Association (PO) (Chelyabinsk-65) in Kyshtym (Southern Urals) and in 1986 at the Chernobyl NPP (ChNPP) 1 .

Until now, agricultural land in the Republic of Mordovia and 13 regions of the Russian Federation on an area of ​​3.5 million hectares is still subject to radioactive contamination as a result of the accident at the Chernobyl nuclear power plant. (The consequences of the Kyshtym accident are discussed below.)

The total area of ​​the radiation destabilized territory of Russia exceeds 1 million km 2 with more than 10 million people living on it. At present, the total activity of unburied radioactive waste in Russia is more than 4 billion Ci, which is equivalent in terms of the consequences of eighty Chernobyl disasters.

The most unfavorable radiation environmental situation has developed in the north of the European territory of Russia, in the Ural region, in the south of the West and East Siberian regions, in the places where the Pacific Fleet is based.

The Murmansk Region surpasses all other regions and countries in terms of the number of nuclear facilities per capita. Objects using various nuclear technologies are widespread here. Of the civilian facilities, this is primarily the Kola NPP (KAES), which has four power units (two of them are approaching the end of their resource). About 60 enterprises and institutions use various radioisotope technological control devices. Murmansk Atomflot has seven icebreakers and one lighter carrier with 13 reactors.

The main number of nuclear facilities is associated with the armed forces. The Northern Fleet is armed with 123 nuclear-powered ships with 235 nuclear reactors; coastal batteries include a total of 3-3.5 thousand nuclear warheads.

Extraction and processing of nuclear raw materials is carried out on the Kola Peninsula by two specialized mining and processing plants. Radioactive waste generated during the production of nuclear fuel, during the operation of the KNPP and ships with nuclear power plants, accumulates directly on the territory of the KNPP and at special enterprises, including military bases. Low-level radioactive waste from civilian enterprises is buried near Murmansk; Waste from the KNPP after holding at the station is sent for processing to the Urals; part of the nuclear waste of the navy is temporarily stored on floating bases.

A decision was made to create special RW repositories for the needs of the region, in which already accumulated waste and newly generated waste will be buried, including those that will be generated during the decommissioning of the first stage of the KNPP and ship nuclear power plants.

In the Murmansk and Arkhangelsk regions, up to 1 thousand m 3 of solid and 5 thousand m 3 of liquid RW are formed annually. The indicated level of waste has been maintained for the last 30 years.

Since the late 1950s to 1992, the Soviet Union disposed of solid and liquid radioactive waste with a total activity of 2.5 million Ci in the Barents and Kara Seas, including 15 reactors from nuclear submarines (NPS), three reactors from the Lenin icebreaker (of which 13 were emergency nuclear submarine reactors, including six with unloaded nuclear fuel). Flooding of nuclear reactors and liquid radioactive waste also occurred in the Far East: in the Sea of ​​Japan and the Sea of ​​Okhotsk and off the coast of Kamchatka.

Nuclear submarine accidents create a dangerous radiological situation. Of these, the most famous tragedy of the Komsomolets nuclear submarine (April 7, 1989), which received worldwide resonance, resulted in the death of 42 crew members, and the boat lay on the ground at a depth of 1680 m near Bear Island in the Barents Sea, 300 nautical miles from coast of Norway. The reactor core of the boat contains approximately 42 thousand Ki strontium-90 and 55 thousand Ki cesium-137. In addition, the boat has nuclear weapons with plutonium-239.

The region of the North Atlantic, where the disaster occurred, is one of the most biologically productive in the World Ocean, is of particular economic importance and is in the sphere of interests of Russia, Norway and a number of other countries. The results of the analyzes showed that so far the release of radionuclides from the boat into the external environment is insignificant, but a contamination zone is forming in the area of ​​flooding. This process can be impulsive, especially dangerous is the contamination with plutonium-239 contained in the warheads of the boat. The transfer of radionuclides along the trophic chain seawater–plankton–fish threatens with serious environmental, political and economic consequences.

In the South Urals in Kyshtym, the Mayak Production Association (Chelyabinsk-65) is located, where since the late 1940s. regeneration of spent nuclear fuel. Until 1951, liquid RW arising during processing simply merged into the Techa River. Through the network of rivers: Techa-Iset-Ob, radioactive substances were carried out to the Kara Sea and with sea currents to other seas of the Arctic basin. Although such discharge was subsequently stopped, after more than 40 years, the concentration of radioactive strontium-90 in some sections of the Techa River exceeded the background by 100–1000 times. Since 1952, nuclear waste has been dumped into Lake Karachay (named technical reservoir No. 3) with an area of ​​10 km2. Due to the heat generated by the waste, the lake eventually dried up. Backfilling of the lake with soil and concrete began; for the final backfill, according to calculations, ~800 thousand m of rocky soil will still be required at a cost of 28 billion rubles (in 1997 prices). However, a lens filled with radionuclides was formed under the lake, the total activity of which is 120 million Ci (almost 2.5 times higher than the radiation activity during the explosion of the 4th Chernobyl power unit).

Recently it became known that in 1957 a serious radiation accident occurred at the Mayak Production Association: as a result of the explosion of a container with radioactive waste, a cloud with radioactivity of 2 million Ci was formed, stretching for 105 km in length and 8 km in width. Serious radiation contamination (approximately 1/3 of Chernobyl) was subjected to an area of ​​15 thousand km 2, which was inhabited by more than 200 thousand people. A reserve was created on the radiation-contaminated territory, where observations of the living world were carried out for decades under conditions of increased radiation. Unfortunately, the data of these observations were considered secret, which made it impossible to give the necessary medical and biological recommendations in the liquidation of the Chernobyl accident. Accidents at "Mayak" occurred many times, the last time - in 1994. At the same time, as a result of the partial destruction of the radioactive waste storage near Petropavlovsk-Kamchatsky, a temporary increase in radiation compared to the background by 1000 times occurred.

Up to now, up to 100 million Ci of liquid radioactive waste are generated annually at the Mayak Production Association, some of which are simply dumped into surface water bodies. Solid radioactive waste is stored in trench-type burial grounds that do not meet safety requirements, as a result of which more than 3 million hectares of land are radioactively contaminated. In the zone of influence of the Mayak Production Association, the levels of radioactive contamination of air, water and soil are 50–100 times higher than the average values ​​for the country; an increase in the number of oncological diseases and childhood leukemia was noted. The enterprise has begun construction of complexes for vitrification of high-level and bituminization of medium-level radioactive waste, as well as trial operation of a metal-concrete container for long-term storage of spent nuclear fuel from RBMK-1000 series reactors (reactors of this type were installed at the Chernobyl nuclear power plant).

The total radioactivity of existing radioactive waste in the Chelyabinsk zone, according to some estimates, reaches a huge figure - 37 billion GBq. This amount is enough to turn the entire territory of the former USSR into an analogue of the Chernobyl resettlement zone.

Another hotbed of "radioactive tension" in the country is the mining and chemical plant (MCC) for the production of weapons-grade plutonium and processing of radioactive waste, located 50 km from Krasnoyarsk. On the surface, it is a city without a definite official name (Sotsgorod, Krasnoyarsk-26, Zheleznogorsk) with a population of 100,000; the plant itself is located deep underground. By the way, there are similar objects (one at a time) in the USA, Great Britain, France; such a facility is under construction in China. Of course, little is known about the Krasnoyarsk Mining and Chemical Combine, except that the processing of RW imported from abroad brings in an income of $500,000 per 1 ton of waste. According to experts, the radiation situation at the mining and chemical complex is measured not in microR/h, but in mR/s! For decades, the plant has been pumping liquid radioactive waste into deep horizons (according to data for 1998, they were pumped ~50 million m The Yenisei can be traced at a distance of over 800 km.

However, burial of highly radioactive waste into underground horizons is also used in other countries: in the USA, for example, radioactive waste is buried in deep salt mines, and in Sweden - in rocks.

Radioactive pollution of the environment by nuclear power plants occurs not only as a result of emergency circumstances, but quite regularly. For example, in May 1997, during technological repairs at the Kursk NPP, a dangerous leak of cesium-137 into the atmosphere occurred.

Nuclear industry enterprises deal with the production, use, storage, transportation and disposal of radioactive substances. In other words, RW generation accompanies all stages of the nuclear power fuel cycle (Fig. 2), which imposes special requirements on ensuring radiation safety.

Uranium ore is mined in mines by underground or open pit mining. Natural uranium is a mixture of isotopes: uranium-238 (99.3%) and uranium-235 (0.7%). Since the main nuclear fuel is uranium-235, after primary processing, the ore enters the enrichment plant, where the content of uranium-235 in the ore is brought to 3-5%. Chemical processing of fuel consists in obtaining enriched uranium hexafluoride 235 UF 6 for the subsequent production of fuel rods (fuel elements).

The development of uranium deposits, like any other branch of the mining industry, worsens the environment: large areas are taken out of economic use, the landscape and hydrological regime change, air, soil, surface and groundwater are polluted with radionuclides. The amount of radioactive waste at the stage of primary processing of natural uranium is very high and amounts to 99.8%. In Russia, mining and primary processing of uranium is carried out only at one enterprise - the Priargunsky Mining and Chemical Association. At all uranium ore mining and processing enterprises that have been operating until recently, 108 m 3 of radioactive waste with an activity of 1.8 10 5 Ci is located in dumps and tailings.

Fuel elements, which are metal rods containing nuclear fuel (3% uranium-235), are placed in the core of a nuclear power plant reactor. Various types of uranium-235 fission chain reactions are possible (difference in the resulting fragments and the number of emitted neutrons), for example, such:

235U+1 n ® 142 Ba + 91 Kr + 31 n,
235U+1 n ® 137 Te + 97 Zr + 21 n,
235U+1 n ® 140 Xe + 94 Sr + 21 n.

The heat released during the fission of uranium heats the water flowing through the core and washing the rods. After about three years, the content of uranium-235 in fuel rods drops to 1%, they become inefficient heat sources and need to be replaced. Each year, a third of the fuel rods are removed from the core and replaced with new ones: for a typical 1000 MW nuclear power plant, this means 36 tons of fuel rods removed annually.

During nuclear reactions, fuel elements are enriched with radionuclides - fission products of uranium-235, and also (through a series of b-decays) plutonium-239:

238U+1 n® 239 U(b ) ® 239 Np(b ) ® 239 Pu.

Spent fuel rods are transported from the core through an underwater channel to storage facilities filled with water, where they are stored in steel canisters for several months, until most of the highly toxic radionuclides (in particular, the most dangerous iodine-131) decay. After that, the fuel rods are sent to fuel regeneration plants, for example, to obtain plutonium cores for fast neutron nuclear reactors or weapons-grade plutonium.

Liquid waste from nuclear reactors (in particular, water from the primary circuit, which must be renewed) after processing (evaporation) is placed in concrete storage facilities located on the territory of the nuclear power plant.

A certain amount of radionuclides during the operation of nuclear power plants is released into the air. Radioactive iodine-135 (one of the main decay products in an operating reactor) does not accumulate in spent nuclear fuel, since its half-life is only 6.7 hours, but as a result of subsequent radioactive decays it turns into xenon-135 radioactive gas, which actively absorbs neutrons and therefore preventing a chain reaction. To prevent "xenon poisoning" of the reactor, xenon is removed from the reactor through tall pipes.

The generation of waste at the stages of processing and storage of spent nuclear fuel has already been discussed. Unfortunately, all existing and used methods of RW neutralization (cementing, vitrification, bituminization, etc.), as well as solid RW incineration in ceramic chambers (as at NPO Radon in the Moscow Region) are ineffective and pose a significant environmental hazard. .

The problem of disposal and disposal of radioactive waste from nuclear power plants is becoming especially acute now, when the time comes for the dismantling of most nuclear power plants in the world (according to the IAEA 2 , these are more than 65 nuclear power plant reactors and 260 reactors used for scientific purposes). It should be noted that during the operation of a nuclear power plant, all elements of the plant become radioactively hazardous, especially the metal structures of the reactor zone. The dismantling of nuclear power plants in terms of cost and time is comparable to their construction, while there is still no acceptable scientific, technical and environmental technology for dismantling. An alternative to dismantling is sealing the station and protecting it for 100 years or more.

Even before the end of the fire at the Chernobyl nuclear power plant, the laying of a tunnel under the reactor began, the creation of a recess under it, which was then filled with a multi-meter layer of concrete. Both the block and the territories adjacent to it were poured with concrete - this is a “miracle of construction” (and an example of heroism without quotes) of the 20th century. called "sarcophagus". The exploding 4th power unit of the Chernobyl nuclear power plant is still the world's largest and most dangerous poorly equipped radioactive waste storage facility!

When using radioactive materials in medical and other research institutions, a significantly smaller amount of radioactive waste is generated than in the nuclear industry and the military-industrial complex - this is several tens of cubic meters of waste per year. However, the use of radioactive materials is expanding, and with it the volume of waste is increasing.

The problem of radioactive waste is an integral part of the “Agenda for the 21st Century”, adopted at the World Summit on Earth Problems in Rio de Janeiro (1992) and the “Action Program for the Further Implementation of the “Agenda for the 21st Century””, adopted by Special Session of the United Nations General Assembly (June 1997). The latter document, in particular, outlines a system of measures to improve methods of radioactive waste management, to expand international cooperation in this area (exchange of information and experience, assistance and transfer of relevant technologies, etc.), to tighten the responsibility of states for ensuring safe storage and removal of radioactive waste.

The Program of Action acknowledges the deterioration of general trends in the sustainable development of the world, but expresses the hope that by the next international environmental forum, scheduled for 2002, tangible progress will be noted in ensuring sustainable development aimed at creating favorable living conditions for future generations.

E.E. Borovsky

________________________________
1 All the data below are taken from materials of open publications in the state reports “On the state of the environment of the Russian Federation” of the State Committee of the Russian Federation for Environmental Protection and in the Russian environmental newspaper “Green World” (1995–1999).
2 International Atomic Energy Agency.

Radioactive waste (RW) is those substances that contain radioactive elements and cannot be reused in the future, as they have no practical value. They are formed during the extraction and processing of radioactive ore, during the operation of equipment that generates heat, and during the disposal of nuclear waste.

Types and classification of radioactive waste

By types of radioactive waste are divided:

  • by state - solid, gaseous, liquid;
  • by specific activity - highly active, medium activity, low activity, very low activity
  • by type - deleted and special;
  • according to the half-life of radionuclides - long- and short-lived;
  • by elements of the nuclear type - with their presence, with their absence;
  • for mining - in the processing of uranium ores, in the extraction of mineral raw materials.

This classification is also relevant for Russia, and is accepted at the international level. In general, the division into classes is not final, it needs to be harmonized with various national systems.

Released from control

There are types of radioactive waste in which there is a very low concentration of radionuclides. They practically do not pose a danger to the environment. Such substances are classified as exempt. The annual amount of exposure from them does not exceed the level of 10 μ3v.

RW management rules

Radioactive substances are divided into classes not only to determine the level of danger, but also to develop rules for handling them:

  • it is necessary to ensure the protection of a person who works with radioactive waste;
  • the protection of the environment from hazardous substances should be increased;
  • control the process of waste disposal;
  • indicate the level of exposure at each repository on the basis of documents;
  • control the accumulation and use of radioactive elements;
  • in case of danger, accidents must be prevented;
  • in emergency cases, all consequences must be eliminated.

What is the danger of RAO

To prevent such an outcome, all enterprises using radioactive elements are obliged to apply filtration systems, control production activities, decontaminate and dispose of waste. This helps prevent an environmental disaster.

The RW hazard level depends on several factors. First of all, this is the amount of waste in the atmosphere, the power of radiation, the area of ​​the contaminated territory, the number of people who live on it. Since these substances are deadly, in the event of an accident, it is necessary to eliminate the disaster and evacuate the population from the territory. It is also important to prevent and stop the transfer of radioactive waste to other territories.

Rules for storage and transportation

An enterprise working with radioactive substances must ensure the safe storage of waste. It involves the collection of radioactive waste, their transfer to disposal. The means and methods necessary for storage are established by documents. For them, special containers are made of rubber, paper and plastic. They are also stored in refrigerators, metal drums. Transportation of radioactive waste is carried out in special sealed containers. In transport, they must be securely fixed. Transportation can only be carried out by companies that have a special license for this.

Recycling

The choice of recycling methods depends on the characteristics of the waste. Some types of waste are shredded and compacted to optimize waste volume. It is customary to burn certain residues in a kiln. RW processing must comply with the following requirements:

  • isolation of substances from water and other products;
  • eliminate radiation;
  • isolate the impact on raw materials and minerals;
  • assess the feasibility of recycling.

Collection and removal

Collection and disposal of radioactive waste should be carried out in places where there are no non-radioactive elements. In this case, it is necessary to take into account the state of aggregation, the category of waste, their properties, materials, the half-life of radionuclides, and the potential threat of the substance. In this regard, it is necessary to develop a strategy for RW management.

For collection and removal, you need to use specialized equipment. Experts say that these operations are possible only with medium and low active substances. During the process, each step must be controlled to prevent an environmental disaster. Even a small mistake can lead to an accident, environmental pollution and the death of a huge number of people. It will take many decades to eliminate the influence of radioactive substances and restore nature.

Removal, processing and disposal of waste from 1 to 5 hazard class

We work with all regions of Russia. Valid license. Full set of closing documents. Individual approach to the client and flexible pricing policy.

Using this form, you can leave a request for the provision of services, request a commercial offer or get a free consultation from our specialists.

Send

Radioactive waste is a substance unsuitable for further activity, containing hazardous elements in large quantities.

Various natural and man-made sources of radiation provoke the appearance of hazardous waste. Such garbage is generated during the following processes:

  • when creating nuclear fuel
  • operation of a nuclear reactor
  • treatment of fuel elements by radiation
  • production and use of natural or artificial radioisotopes

The collection and further handling of radioactive waste is established by the legislation of the Russian Federation.

Classification

In Russia, the classification of radioactive waste is based on Federal Law No. 190 of July 11, 2011, which regulates the collection and management of radioactive waste.

Radioactive waste can be of the following types:

  • Removed. The risk that may arise during the extraction, as well as the further use of hazardous waste. These costs should not be higher than the risk associated with the creation of a repository in the country.
  • Special. A risk that includes possible exposure to hazardous radiation, as well as other risks based on the retrieval and further use of the elements. Should exceed the risks associated with their burial in the territory of location.

The criteria for distribution are established by the Government of Russia.

Classification of radioactive waste is carried out on the basis of:

The half-life of radionuclides, this includes:

  • long-lived
  • short lived

specific activity. So, depending on the degree of activity, radioactive waste is usually divided into:

  • Weakly active, the concentration of beta - emitting radioisotopes reaches 10 - 5 curie / l in such a substance.
  • Medium activity, the concentration of beta - emitting radioisotopes reaches more than 1 curie / l.
  • Low active.
  • Very low activity.

State. There are three types of such garbage:

  • LRW (liquid radioactive waste)
  • Solid

Presence of nuclear type elements:

  • Availability
  • absence

It is also customary to highlight:

  • Materials formed in the process of mining (processing) of uranium ores.
  • Materials formed as a result of the extraction of mineral (organic) raw materials not associated with the use of atomic energy.

Danger

These wastes are extremely dangerous for nature, as they increase the level of radioactive background. There is also a danger of harmful substances entering the human body with consumed food and water. The result is mutation, poisoning, or death.

That is why enterprises are advised to use all kinds of filters in order to prevent harmful waste from entering the external environment. At the moment, legislation obliges the installation of special cleaners that collect harmful elements.

The level of radiation hazard depends on:

  • Quantities of radioactive waste in the biosphere.
  • Dose rate of gamma radiation present.
  • Areas of the territory exposed to pollution.
  • Population.

Radioactive waste is dangerous when it enters the human body. Because of this, it is necessary to localize such mining in the territory of their formation. It is very important to prevent the possible migration of these raw materials through the existing animal and human food chains.

Storage and transportation

  • Storage of radioactive waste. Storage involves the collection and subsequent transfer of harmful elements for processing or disposal.
  • Burial is the placement of waste in landfills. Thus, hazardous waste is removed from the scope of human activity and does not pose a danger to the environment.

It should be noted that only solid and solidified wastes can be sent to burial grounds for storage. The period of radioactive hazard of waste should be lower than the "lifetime" of engineering structures in which storage and disposal take place.

Consideration should also be given to the following features associated with the disposal of hazardous waste:

  • Only radioactive waste with a possible threat period of no more than 500 years will be sent for disposal in a remote area.
  • Waste, the period of danger of which is not more than several decades, can be stopped by the enterprise for storage on its territory without being sent for disposal.

The maximum amount of hazardous waste sent for storage is set based on the safety assessment of the repository. Methods and means for determining the permissible content of waste in a special room can be found in regulatory documents.

Containers for these wastes are disposable bags that are made from the following elements:

  • rubber
  • plastic
  • paper

Collection, storage, transportation and further handling of radioactive waste packed using such containers are carried out in specially equipped shipping containers. The premises intended for the storage of these containers should be equipped with protective screens, refrigerators or containers.

There is a large list of storage options for various radioactive waste:

  • Refrigerators. They are designed to contain the corpses of laboratory animals, as well as other organic materials.
  • Metal drums. Pulverized radioactive waste is placed in them and the lids are sealed.
  • Waterproof paint. She covers laboratory equipment for transportation.

Recycling

Treatment of radioactive waste is possible in several ways, the choice of method depends on the type of waste that will be processed.

Disposal of radioactive waste:

  • They are crushed and pressed. This is necessary to optimize the volume of raw materials, as well as to reduce activity.
  • They are burned in furnaces that are used to dispose of combustible residues.

The processing of radioactive waste must necessarily comply with the hygienic requirements:

  1. 100% guaranteed isolation from food and water.
  2. Absence of external exposure exceeding the permissible level.
  3. No negative impact on mineral deposits.
  4. Implementation of cost-effective actions.

Collection and removal

Collection and sorting during the further destruction of these wastes must be carried out at the places of their occurrence separately from non-radioactive substances.

This should take into account:

  • Aggregate state of a harmful substance.
  • Substance category.
  • The amount of material to be collected.
  • Every property of a substance (chemical and physical).
  • Approximate half-life of radionuclides. As a rule, the measurement is presented in days, that is, more than 15 days or less than 15 days.
  • Potential hazard of the substance (fire or explosion hazard).
  • Future management of radioactive waste.

It is worth noting an important point - collection and disposal can only be done with low and medium active types of waste.

NRW - low active are ventilation emissions that can be removed through a pipe and further dissipated. According to the norm of the CST, which was established by the national operator for the management of radioactive waste, there is a parameter for the height and conditions of the release.

The DCS value is calculated as follows: the ratio of the limit of the annual intake of a substance to a specific volume of water (usually taken 800 liters) or air (8 million liters). In this case, the CST parameter is the limit of the annual intake of harmful substances (radionuclides) into the human body through water and air.

Intermediate and liquid waste treatment

The collection and removal of a radioactive substance of medium activity is carried out using special devices:

  • Gas holders. A technology whose task is to receive, store and then release gas. The main feature is that waste with a low half-life (1 - 4 hours) will be enclosed in the device for exactly as long as it takes to completely deactivate the harmful substance.
  • adsorption columns. The device is designed for more complete removal (about 98%) of radioactive gases. The decontamination scheme is as follows: the gas is cooled with the process of moisture separation, followed by deep drying in the columns themselves and the supply of the substance to the adsorber, which contains coal to absorb harmful elements.

Liquid radioactive waste is usually treated by evaporation. It is an ion exchange of two stages with preliminary purification of the substance from harmful impurities.

There is another way - liquid waste, which is dangerous to the environment, can be cleaned using rubber irradiation plants. In most cases, a Co-60 type irradiator is used, which was stored in water.

    The concept of radioactive waste

    Sources of waste

    Classification

    Radioactive waste management

    Main stages of radioactive waste management

    geological burial

    Transmutation

radioactive waste(RAO) - waste containing radioactive isotopes of chemical elements and having no practical value.

According to the Russian "Law on the Use of Atomic Energy" (No. 170-FZ dated November 21, 1995), radioactive waste is nuclear materials and radioactive substances, the further use of which is not foreseen. Under Russian law, the import of radioactive waste into the country is prohibited.

Often confused and considered synonymous with radioactive waste and spent nuclear fuel. These concepts should be distinguished. Radioactive waste is materials that are not intended to be used. Spent nuclear fuel is a fuel element containing nuclear fuel residues and many fission products, mainly 137 Cs and 90 Sr, widely used in industry, agriculture, medicine and science. Therefore, it is a valuable resource, as a result of the processing of which fresh nuclear fuel and isotope sources are obtained.

Sources of waste

Radioactive waste comes in a variety of forms with very different physical and chemical characteristics, such as the concentrations and half-lives of the radionuclides that make it up. These wastes can be generated:

In gaseous form, such as vent emissions from facilities where radioactive materials are processed;

In liquid form, ranging from scintillation counter solutions from research facilities to high-level liquid waste from spent fuel reprocessing;

In solid form (contaminated consumables, glassware from hospitals, medical research facilities and radiopharmaceutical laboratories, vitrified waste from fuel processing or spent fuel from nuclear power plants when it is considered waste).

Examples of sources of radioactive waste in human activities:

PIR (natural sources of radiation). There are substances that are naturally radioactive, known as natural sources of radiation (NIR). Most of these substances contain long-lived nuclides such as potassium-40, rubidium-87 (which are beta emitters), as well as uranium-238, thorium-232 (which emit alpha particles) and their decay products. .

Work with such substances is regulated by the sanitary rules issued by Sanepidnadzor.

Coal. Coal contains a small number of radionuclides, such as uranium or thorium, but the content of these elements in coal is less than their average concentration in the earth's crust.

Their concentration increases in fly ash, as they practically do not burn.

However, the radioactivity of ash is also very low, it is approximately equal to the radioactivity of black shale and less than that of phosphate rocks, but it represents a known danger, since a certain amount of fly ash remains in the atmosphere and is inhaled by humans. At the same time, the total amount of emissions is quite large and is equivalent to 1,000 tons of uranium in Russia and 40,000 tons worldwide.

Oil and gas. By-products of the oil and gas industry often contain radium and its decay products. Sulphate deposits in oil wells can be very rich in radium; water, oil and gas wells often contain radon. As it decays, radon forms solid radioisotopes that form a deposit inside pipelines. In refineries, the propane production area is usually one of the most radioactive areas, since radon and propane have the same boiling point.

Enrichment of minerals. Waste from mineral processing may be naturally radioactive.

Medical RAO. Sources of beta and gamma rays predominate in radioactive medical waste. These wastes are divided into two main classes. Diagnostic nuclear medicine uses short-lived gamma emitters such as technetium-99m (99 Tc m). Most of these substances decompose within a short time, after which they can be disposed of as ordinary waste. Examples of other isotopes used in medicine (half-life indicated in parentheses): Yttrium-90, used in the treatment of lymphomas (2.7 days); Iodine-131, thyroid diagnostics, thyroid cancer treatment (8 days); Strontium-89, treatment of bone cancer, intravenous injections (52 days); Iridium-192, brachytherapy (74 days); Cobalt-60, brachytherapy, external beam therapy (5.3 years); Cesium-137, brachytherapy, external beam therapy (30 years).

Industrial radioactive waste. Industrial radioactive waste may contain sources of alpha, beta, neutron or gamma radiation. Alpha sources can be used in a printing house (to remove static charge); gamma emitters are used in radiography; Neutron radiation sources are used in various industries, for example, in radiometry of oil wells. An example of the use of beta sources: radioisotope thermoelectric generators for autonomous lighthouses and other installations in areas that are difficult for humans to access (for example, in the mountains).

radioactive waste

radioactive waste (RAO) - waste containing radioactive isotopes of chemical elements and having no practical value.

According to the Russian "Law on the use of atomic energy" (November 21, 1995 No. 170-FZ), radioactive waste (RW) is nuclear materials and radioactive substances, the further use of which is not expected. Under Russian law, the import of radioactive waste into the country is prohibited.

Often confused and considered synonymous with radioactive waste and spent nuclear fuel. These concepts should be distinguished. Radioactive waste is materials that are not intended to be used. Spent nuclear fuel is a fuel element containing nuclear fuel residues and many fission products, mainly 137 Cs and 90 Sr, widely used in industry, agriculture, medicine and science. Therefore, it is a valuable resource, as a result of the processing of which fresh nuclear fuel and isotope sources are obtained.

Sources of waste

Radioactive waste comes in a variety of forms with very different physical and chemical characteristics, such as the concentrations and half-lives of the radionuclides that make it up. These wastes can be generated:

  • in gaseous form, such as vent emissions from facilities where radioactive materials are processed;
  • in liquid form, ranging from scintillation counter solutions from research facilities to high-level liquid waste from spent fuel reprocessing;
  • in solid form (contaminated consumables, glassware from hospitals, medical research facilities and radiopharmaceutical laboratories, vitrified waste from fuel processing or spent fuel from nuclear power plants when it is considered waste).

Examples of sources of radioactive waste in human activities:

Work with such substances is regulated by sanitary regulations issued by Sanepidnadzor.

  • Coal . Coal contains a small number of radionuclides, such as uranium or thorium, but the content of these elements in coal is less than their average concentration in the earth's crust.

Their concentration increases in fly ash, as they practically do not burn.

However, the radioactivity of ash is also very low, it is approximately equal to the radioactivity of black shale and less than that of phosphate rocks, but it represents a known danger, since some fly ash remains in the atmosphere and is inhaled by humans. At the same time, the total volume of emissions is quite large and amounts to the equivalent of 1,000 tons of uranium in Russia and 40,000 tons worldwide.

Classification

Conditionally radioactive waste is divided into:

  • low-level (divided into four classes: A, B, C and GTCC (the most dangerous);
  • medium active (US legislation does not classify this type of radioactive waste as a separate class, the term is mainly used in European countries);
  • highly active.

The US legislation also allocates transuranic radioactive waste. This class includes wastes contaminated with alpha-emitting transuranium radionuclides with half-lives of more than 20 years and concentrations of more than 100 nCi/g, regardless of their form or origin, excluding high-level radioactive waste. Due to the long period of decay of transuranic wastes, their disposal is more thorough than the disposal of low-level and intermediate-level wastes. Also, special attention is paid to this class of waste because all transuranium elements are artificial and the behavior in the environment and in the human body of some of them is unique.

Below is the classification of liquid and solid radioactive waste in accordance with the "Basic Sanitary Rules for Ensuring Radiation Safety" (OSPORB 99/2010).

One of the criteria for such a classification is heat dissipation. In low-level radioactive waste, the heat release is extremely low. In medium-active ones, it is significant, but active heat removal is not required. High-level radioactive waste releases heat so much that they require active cooling.

Radioactive waste management

Initially, it was considered that a sufficient measure was the dispersion of radioactive isotopes in the environment, by analogy with production waste in other industries. At the Mayak plant, in the first years of operation, all radioactive waste was dumped into nearby water bodies. As a result, the Techa cascade of reservoirs and the Techa River itself were polluted.

Later it turned out that due to natural and biological processes, radioactive isotopes are concentrated in various subsystems of the biosphere (mainly in animals, in their organs and tissues), which increases the risks of public exposure (due to the movement of large concentrations of radioactive elements and their possible entry with food in the human body). Therefore, the attitude towards radioactive waste was changed.

1) Protection of human health. Radioactive waste is managed in such a way as to provide an acceptable level of protection of human health.

2) Environmental protection. Radioactive waste is managed in such a way as to ensure an acceptable level of environmental protection.

3) Protection beyond national borders. Radioactive waste is managed in such a way that possible consequences for human health and the environment beyond national borders are taken into account.

4) Protection of future generations. Radioactive waste is managed in such a way that the predicted health consequences for future generations do not exceed appropriate levels of consequences that are acceptable today.

5) Burden for future generations. Radioactive waste is managed in such a way as not to impose an undue burden on future generations.

6) National legal structure. Radioactive waste management is carried out within the framework of an appropriate national legal framework that provides for a clear division of responsibilities and the provision of independent regulatory functions.

7) Control over the generation of radioactive waste. The generation of radioactive waste is kept to the minimum practicable level.

8) Interdependence of radioactive waste generation and management. Due account shall be taken of the interdependencies between all stages of radioactive waste generation and management.

9) Installation safety. The safety of radioactive waste management facilities is adequately ensured throughout their lifetime.

Main stages of radioactive waste management

  • At storage radioactive waste should be contained in such a way that:
    • ensured their isolation, protection and monitoring of the environment;
    • if possible, actions at subsequent stages (if they are provided) were facilitated.

In some cases, storage may be carried out primarily for technical reasons, such as storing radioactive waste containing primarily short-lived radionuclides for decay and subsequent disposal within authorized limits, or storing high-level radioactive waste prior to disposal in geological formations for the purpose of reduction of heat generation.

  • Preliminary processing waste is the initial stage of waste management. This includes collection, chemistry control and decontamination and may include an interim storage period. This step is very important because in many cases the pre-treatment provides the best opportunity to separate the waste streams.
  • Treatment management of radioactive waste includes operations whose purpose is to improve safety or economy by changing the characteristics of radioactive waste. Basic processing concepts: volume reduction, removal of radionuclides and composition change. Examples:
    • incineration of combustible waste or compaction of dry solid waste;
    • evaporation, filtration or ion exchange of liquid waste streams;
    • precipitation or flocculation of chemicals.

Capsule for radioactive waste

  • Conditioning radioactive waste management consists of those operations in which radioactive waste is formed into a form suitable for movement, transportation, storage and disposal. These operations may include the immobilization of radioactive waste, the placement of waste in containers, and the provision of additional packaging. Common methods of immobilization include solidification of liquid radioactive waste of low and intermediate levels by incorporation into cement (cementing) or bitumen (bituminization), as well as vitrification of liquid radioactive waste. Immobilized waste, in turn, depending on the nature and concentration, can be packed in various containers, ranging from conventional 200-liter steel drums to containers with a complex design with thick walls. In many cases, processing and conditioning are carried out in close connection with each other.
  • burial mainly that radioactive waste is placed in a disposal facility with appropriate security, without the intention of removing it and without providing long-term storage monitoring and maintenance. Safety is mainly achieved through concentration and containment, which involves sequestering suitably concentrated radioactive waste in a disposal facility.

Technology

Intermediate radioactive waste management

Usually in the nuclear industry, intermediate-level radioactive waste is subjected to ion exchange or other methods, the purpose of which is to concentrate radioactivity in a small volume. After processing, a much less radioactive body is completely neutralized. It is possible to use iron hydroxide as a flocculant to remove radioactive metals from aqueous solutions. After absorption of the radioisotopes by iron hydroxide, the resulting precipitate is placed in a metal drum where it is mixed with cement to form a solid mixture. For greater stability and durability, concrete is made from fly ash or furnace slag and Portland cement (as opposed to conventional concrete, which consists of Portland cement, gravel and sand).

Handling of high-level radioactive waste

Removal of low-level radioactive waste

Transportation of flasks with high-level radioactive waste by train, UK

Storage

For temporary storage of high-level radioactive waste, storage tanks for spent nuclear fuel and storage facilities with dry barrels are designed to allow short-lived isotopes to decay before further processing.

Vitrification

Long-term storage of radioactive waste requires conservation of waste in a form that will not react and break down over a long period of time. One way to achieve this state is vitrification (or vitrification). Currently in Sellafield (Great Britain) highly active PAO (purified products of the first stage of the Purex process) are mixed with sugar and then calcined. Calcination involves passing the waste through a heated rotating tube and aims to evaporate water and denitrogenate fission products in order to increase the stability of the resulting vitreous mass.

Crushed glass is constantly added to the resulting substance in the induction furnace. As a result, a new substance is obtained, in which, during hardening, the waste is associated with a glass matrix. This substance in a molten state is poured into alloy steel cylinders. Cooling, the liquid solidifies, turning into glass, which is extremely resistant to water. According to the International Society of Technology, it will take about a million years for 10% of this glass to dissolve in water.

After filling, the cylinder is brewed, then washed. After being examined for external contamination, the steel cylinders are sent to underground storage facilities. This state of waste remains unchanged for many thousands of years.

The glass inside the cylinder has a smooth black surface. In the UK, all work is done using high activity chambers. Sugar is added to prevent the formation of the RuO 4 volatile substance containing radioactive ruthenium. In the West, borosilicate glass, identical in composition to pyrex, is added to the waste; in the countries of the former USSR, phosphate glass is usually used. The amount of fission products in glass must be limited, as some elements (palladium, platinum group metals, and tellurium) tend to form metallic phases separately from glass. One of the vitrification plants is located in Germany, where the waste from the activities of a small demonstration processing plant that has ceased to exist is processed.

In 1997, the 20 countries with most of the world's nuclear potential had 148,000 tons of spent fuel stored inside reactors, 59% of which had been disposed of. There were 78 thousand tons of waste in external storage facilities, of which 44% was recycled. Taking into account the rate of disposal (about 12 thousand tons annually), the final elimination of waste is still quite far away.

geological burial

Searches for suitable deep final disposal sites are currently underway in several countries; it is expected that the first such storage facilities will become operational after 2010. The international research laboratory in Grimsel, Switzerland deals with issues related to radioactive waste disposal. Sweden is talking about its plans for direct disposal of spent fuel using KBS-3 technology, after the Swedish Parliament deemed it safe enough. Discussions are currently underway in Germany about finding a place for permanent storage of radioactive waste, residents of the village of Gorleben in the Wendland region are protesting vigorously. This place until 1990 seemed ideal for the disposal of radioactive waste due to its proximity to the borders of the former German Democratic Republic. Currently, RW is in temporary storage in Gorleben, the decision on the place of their final disposal has not yet been made. The U.S. authorities chose Yucca Mountain, Nevada as the burial site, but this project met with strong opposition and became the topic of heated discussions. There is a project to create an international repository for high-level radioactive waste; Australia and Russia are proposed as possible disposal sites. However, the Australian authorities oppose such a proposal.

There are projects for the disposal of radioactive waste in the oceans, among which are disposal under the abyssal zone of the seabed, disposal in the subduction zone, as a result of which the waste will slowly sink to the earth's mantle, and disposal under a natural or artificial island. These projects have obvious merits and will allow solving the unpleasant problem of radioactive waste disposal at the international level, but, despite this, they are currently frozen due to the prohibition of maritime law. Another reason is that in Europe and North America they are seriously afraid of leakage from such a repository, which will lead to an environmental disaster. The real possibility of such a danger has not been proven; however, the bans were tightened after the dumping of radioactive waste from ships. However, in the future, countries that cannot find other solutions to this problem are seriously able to think about the creation of oceanic storage facilities for radioactive waste.

In the 1990s, several options for conveyor disposal of radioactive waste into the bowels were developed and patented. The technology was assumed to be as follows: a large-diameter starting well up to 1 km deep is drilled, a capsule loaded with radioactive waste concentrate weighing up to 10 tons is lowered inside, the capsule must self-heat and melt the earth rock in the form of a “fireball”. After the first “fireball” is deepened, the second capsule should be lowered into the same well, then the third, etc., creating a kind of conveyor.

Reuse of radioactive waste

Another use of isotopes contained in radioactive waste is their reuse. Already, cesium-137, strontium-90, technetium-99 and some other isotopes are used to irradiate food products and ensure the operation of radioisotope thermoelectric generators.

Removal of radioactive waste into space

Sending radioactive waste into space is a tempting idea, since radioactive waste is permanently removed from the environment. However, such projects have significant drawbacks, one of the most important is the possibility of a launch vehicle failure. In addition, the significant number of launches and their high cost make this proposal impractical. The matter is also complicated by the fact that international agreements on this problem have not yet been reached.

Nuclear fuel cycle

Cycle start

Waste from the front end of the nuclear fuel cycle – usually alpha-emitting waste rock from the extraction of uranium. It usually contains radium and its decay products.

The main by-product of enrichment is depleted uranium, consisting mainly of uranium-238 with less than 0.3% uranium-235. It is stored as UF 6 (waste uranium hexafluoride) and can also be converted to U 3 O 8 . In small quantities, depleted uranium finds use in applications where its extremely high density is valued, such as in the manufacture of keels of yachts and anti-tank shells. Meanwhile, several million tons of waste uranium hexafluoride have accumulated in Russia and abroad, and there are no plans for its further use in the foreseeable future. Waste uranium hexafluoride can be used (along with recycled plutonium) to create mixed oxide nuclear fuel (which may be in demand if the country builds significant quantities of fast neutron reactors) and to dilute highly enriched uranium, which was previously part of nuclear weapons. This dilution, also called depletion, means that any country or group that gets its hands on nuclear fuel will have to repeat a very expensive and complex enrichment process before it can create a weapon.

End of cycle

Substances in which the nuclear fuel cycle has come to an end (mostly spent fuel rods) contain fission products that emit beta and gamma rays. They may also contain actinides that emit alpha particles, which include uranium-234 (234 U), neptunium-237 (237 Np), plutonium-238 (238 Pu) and americium-241 (241 Am), and sometimes even sources neutrons such as californium-252 (252 Cf). These isotopes are produced in nuclear reactors.

It is important to distinguish between the processing of uranium to produce fuel and the processing of used uranium. The used fuel contains highly radioactive fission products. Many of them are neutron absorbers, thus getting the name "neutron poisons". Ultimately, their numbers increase to such an extent that, by trapping neutrons, they stop the chain reaction even when the neutron absorber rods are completely removed.

The fuel that has reached this state must be replaced with fresh, despite the still sufficient amount of uranium-235 and plutonium. Currently, in the US, used fuel is sent to storage. In other countries (in particular, in Russia, Great Britain, France and Japan), this fuel is reprocessed to remove fission products, then, after re-enrichment, it can be reused. In Russia, such fuel is called regenerated. The reprocessing process involves working with highly radioactive substances, and the fission products removed from the fuel are a concentrated form of highly radioactive waste, just like the chemicals used in reprocessing.

To close the nuclear fuel cycle, it is supposed to use fast neutron reactors, which allows processing fuel, which is a waste product of thermal neutron reactors.

On the issue of nuclear proliferation

When working with uranium and plutonium, the possibility of their use in the creation of nuclear weapons is often considered. Active nuclear reactors and stockpiles of nuclear weapons are carefully guarded. However, highly radioactive waste from nuclear reactors may contain plutonium. It is identical to the plutonium used in reactors and consists of 239 Pu (ideal for building nuclear weapons) and 240 Pu (unwanted component, highly radioactive); these two isotopes are very difficult to separate. Moreover, highly radioactive waste from reactors is full of highly radioactive fission products; however, most of them are short-lived isotopes. This means that waste disposal is possible, and after many years the fission products will decay, reducing the radioactivity of the waste and facilitating work with plutonium. Moreover, the unwanted isotope 240 Pu decays faster than 239 Pu, so the quality of weapons raw materials increases over time (despite the decrease in quantity). This causes controversy that, over time, waste storage facilities can turn into a kind of "plutonium mines", from which it will be relatively easy to extract raw materials for weapons. Against these assumptions is the fact that the half-life of 240 Pu is 6560 years, and the half-life of 239 Pu is 24110 years; Pu in a multi-isotope material will halve on its own - a typical conversion of reactor-grade plutonium to weapons-grade plutonium). Therefore, "weapon-grade plutonium mines" will become a problem, if at all, only in the very distant future.

One solution to this problem is to reuse reprocessed plutonium as fuel, such as in fast nuclear reactors. However, the very existence of nuclear fuel reprocessing plants, necessary to separate plutonium from other elements, creates an opportunity for the proliferation of nuclear weapons. In pyrometallurgical fast reactors, the resulting waste has an actinoid structure, which does not allow it to be used to create weapons.

Recycling of nuclear weapons

Waste from the processing of nuclear weapons (unlike their manufacture, which requires raw materials from reactor fuel), does not contain sources of beta and gamma rays, with the exception of tritium and americium. They contain a much larger number of actinides that emit alpha rays, such as plutonium-239, which undergoes a nuclear reaction in bombs, as well as some substances with a high specific radioactivity, such as plutonium-238 or polonium.

In the past, beryllium and highly active alpha emitters such as polonium have been proposed as nuclear weapons in bombs. Now an alternative to polonium is plutonium-238. For reasons of national security, the detailed designs of modern bombs are not covered in the literature available to the general public.

Some models also contain (RTGs), which use plutonium-238 as a durable source of electrical power to operate the bomb's electronics.

It is possible that the fissile material of the old bomb to be replaced will contain decay products of plutonium isotopes. These include alpha emitting neptunium-236, formed from inclusions of plutonium-240, as well as some uranium-235, obtained from plutonium-239. The amount of this waste from the radioactive decay of the bomb core will be very small, and in any case they are much less dangerous (even in terms of radioactivity as such) than plutonium-239 itself.

As a result of the beta decay of plutonium-241, americium-241 is formed, an increase in the amount of americium is a bigger problem than the decay of plutonium-239 and plutonium-240, since americium is a gamma emitter (its external effect on workers increases) and an alpha emitter, capable of generating heat. Plutonium can be separated from americium in a variety of ways, including pyrometric treatment and extraction with an aqueous/organic solvent. A modified technology for the extraction of plutonium from irradiated uranium (PUREX) is also one of the possible separation methods.

In popular culture

In reality, the impact of radioactive waste is described by the effect of ionizing radiation on a substance and depends on their composition (which radioactive elements are included in the composition). Radioactive waste does not acquire any new properties, does not become more dangerous because they are waste. Their greater danger is due only to the fact that their composition is often very diverse (both qualitatively and quantitatively) and sometimes unknown, which complicates the assessment of the degree of their danger, in particular, the doses received as a result of an accident.

see also

Notes

Links

  • Safety in handling radioactive waste. General provisions. NP-058-04
  • Key Radionuclides and Generation Processes (unavailable link)
  • Belgian Nuclear Research Center - Activities (unavailable link)
  • Belgian Nuclear Research Center - Scientific Reports (unavailable link)
  • International Atomic Energy Agency - Nuclear Fuel Cycle and Waste Technology Program (unavailable link)
  • (unavailable link)
  • Nuclear Regulatory Commission - Spent Fuel Heat Generation Calculation (unavailable link)
Have questions?

Report a typo

Text to be sent to our editors:

Send