Misplaced Pages

#792207

74-543: The Kyshtym disaster , sometimes referred to as the Mayak disaster or Ozyorsk disaster in newer sources, was a radioactive contamination accident that occurred on 29 September 1957 at Mayak , a plutonium production site for nuclear weapons and nuclear fuel reprocessing plant located in the closed city of Chelyabinsk-40 (now Ozyorsk ) in Chelyabinsk Oblast , Russian SFSR , Soviet Union . The disaster

148-414: A concrete slab weighing 160 tons, and a brick wall was destroyed in a building located 200 meters (660 ft) from the explosion site. A tenth of the radioactive substances were lifted into the air. After the explosion, a column of smoke and dust rose to a kilometre high; the dust flickered with an orange-red light and settled on buildings and people. The rest of the waste discarded from the tank remained at

222-820: A contamination hazard. Access to such areas is controlled by a variety of barrier techniques, sometimes involving changes of clothing and footwear as required. The contamination within a controlled area is normally regularly monitored. Radiological protection instrumentation (RPI) plays a key role in monitoring and detecting any potential contamination spread, and combinations of hand held survey instruments and permanently installed area monitors such as Airborne particulate monitors and area gamma monitors are often installed. Detection and measurement of surface contamination of personnel and plant are normally by Geiger counter , scintillation counter or proportional counter . Proportional counters and dual phosphor scintillation counters can discriminate between alpha and beta contamination, but

296-404: A discussion of environmental contamination by alpha emitters please see actinides in the environment . Nuclear fallout is the distribution of radioactive contamination by the 520 atmospheric nuclear explosions that took place from the 1950s to the 1980s. In nuclear accidents, a measure of the type and amount of radioactivity released, such as from a reactor containment failure, is known as

370-488: A low external risk due to the shielding effect of the top layers of skin. See the article on sievert for more information on how this is calculated. Radioactive contamination can be ingested into the human body if it is airborne or is taken in as contamination of food or drink, and will irradiate the body internally. The art and science of assessing internally generated radiation dose is Internal dosimetry . The biological effects of ingested radionuclides depend greatly on

444-420: A major contamination incident, all potential pathways of internal exposure should be considered. Successfully used on Harold McCluskey , chelation therapy and other treatments exist for internal radionuclide contamination. Cleaning up contamination results in radioactive waste unless the radioactive material can be returned to commercial use by reprocessing . In some cases of large areas of contamination,

518-430: A particular inhalation hazard. Respirators with suitable air filters or completely self-contained suits with their own air supply can mitigate these dangers. Airborne contamination is measured by specialist radiological instruments that continuously pump the sampled air through a filter. Airborne particles accumulate on the filter and can be measured in a number of ways: Commonly a semiconductor radiation detection sensor

592-401: A result of the explosion, however, and the scope and nature of the disaster were covered up both internally and abroad. Even as late as 1982, Los Alamos published a report investigating claims that the release was actually caused by a weapons test gone awry. The disaster is estimated to have released 20  M Ci (800  P Bq ) of radioactivity. Most of this contamination settled out near

666-413: A sharp increase in the background radiation . Many industrial buildings, vehicles, concrete structures, and railways were contaminated. The most polluted were the central city street Lenin, especially when entering the city from the industrial site, and Shkolnaya street, where the management of the plant lived. Subsequently, the city administration imposed measures to stop the spreading of contamination. It

740-580: A short half-life, the best course of action may be to simply allow the material to naturally decay . Longer-lived isotopes should be cleaned up and properly disposed of because even a very low level of radiation can be life-threatening when in long exposure to it. Facilities and physical locations that are deemed to be contaminated may be cordoned off by a health physicist and labeled "Contaminated area." Persons coming near such an area would typically require anti-contamination clothing ("anti-Cs"). High levels of contamination may pose major risks to people and

814-422: A sign, shielded with bags of lead shot , or cordoned off with warning tape containing the radioactive trefoil symbol . The hazard from contamination is the emission of ionizing radiation. The principal radiations which will be encountered are alpha, beta and gamma, but these have quite different characteristics. They have widely differing penetrating powers and radiation effects, and the accompanying diagram shows

SECTION 10

#1732773404793

888-619: A variety of causes. It may occur due to the release of radioactive gases, liquids or particles. For example, if a radionuclide used in nuclear medicine is spilled (accidentally or, as in the case of the Goiânia accident , through ignorance), the material could be spread by people as they walk around. Radioactive contamination may also be an inevitable result of certain processes, such as the release of radioactive xenon in nuclear fuel reprocessing . In cases that radioactive material cannot be contained, it may be diluted to safe concentrations. For

962-685: Is a useful comparative guide for selecting the correct technology for the contamination type. The UK NPL publishes a guide on the alarm levels to be used with instruments for checking personnel exiting controlled areas in which contamination may be encountered. Surface contamination is usually expressed in units of radioactivity per unit of area for alpha or beta emitters. For SI , this is becquerels per square meter (or Bq/m ). Other units such as picoCuries per 100 cm or disintegrations per minute per square centimeter (1 dpm/cm = 167 Bq/m ) may be used. The air can be contaminated with radioactive isotopes in particulate form, which poses

1036-434: Is encountered with naturally generated radon gas which can affect instruments that are set to detect contamination close to normal background levels and can cause false alarms. Because of this skill is required by the operator of radiological survey equipment to differentiate between background radiation and the radiation which emanates from contamination. Naturally occurring radioactive materials (NORM) can be brought to

1110-540: Is monitored by specialised installed exit control instruments such as frisk probes, hand contamination monitors and whole body exit monitors. These are used to check that persons exiting controlled areas do not carry contamination on their bodies or clothes. In the United Kingdom , HSE has issued a user guidance note on selecting the correct portable radiation measurement instrument for the application concerned. This covers all radiation instrument technologies and

1184-637: Is the second worst nuclear incident by radioactivity released, after the Chernobyl disaster and was regarded as the worst nuclear disaster in history until Chernobyl. It is the only disaster classified as Level 6 on the International Nuclear Event Scale (INES), which ranks by population impact, making it the third-worst after the two Level 7 events: the Chernobyl disaster, which resulted in the evacuation of 335,000 people, and

1258-449: Is used that can also provide spectrographic information on the contamination being collected. A particular problem with airborne contamination monitors designed to detect alpha particles is that naturally occurring radon can be quite prevalent and may appear as contamination when low contamination levels are being sought. Modern instruments consequently have "radon compensation" to overcome this effect. Radioactive contamination can enter

1332-438: Is very often clinically indistinguishable from any other cancer, and its incidence rate can be measured only through epidemiological studies. Recent epidemiological studies suggest that around 49 to 55 cancer deaths among riverside residents can be associated with radiation exposure. This would include the effects of all radioactive releases into the river, 98% of which happened long before the 1957 accident, but it would not include

1406-648: The Fukushima Daiichi disaster , which resulted in the evacuation of 154,000 people. At least 22 villages were exposed to radiation from the Kyshtym disaster, with a total population of around 10,000 people evacuated. Some were evacuated after a week, but it took almost two years for evacuations to occur at other sites. The disaster spread hot particles over more than 52,000 square kilometres (20,000 sq mi), where at least 270,000 people lived. Since Chelyabinsk-40 (later renamed Chelyabinsk-65 until 1994)

1480-528: The Fukushima nuclear accident of March 2011 from as much land as possible so that some of the 110,000 displaced people can return. Stripping out the key radioisotope threatening health ( caesium-137 ) from low-level waste could also dramatically decrease the volume of waste requiring special disposal. A goal is to find techniques that might be able to strip out 80 to 95% of the caesium from contaminated soil and other materials, efficiently and without destroying

1554-704: The International Commission on Radiological Protection has published a guide: "Publication 111 – Application of the Commission's Recommendations to the Protection of People Living in Long-term Contaminated Areas after a Nuclear Accident or a Radiation Emergency". The hazards to people and the environment from radioactive contamination depend on the nature of the radioactive contaminant, the level of contamination, and

SECTION 20

#1732773404793

1628-430: The absorbed dose . When radioactive contamination is being measured or mapped in situ , any location that appears to be a point source of radiation is likely to be heavily contaminated. A highly contaminated location is colloquially referred to as a "hot spot." On a map of a contaminated place, hot spots may be labeled with their "on contact" dose rate in mSv/h. In a contaminated facility, hot spots may be marked with

1702-457: The thyroid gland takes up a large percentage of any iodine that enters the body. Large quantities of inhaled or ingested radioactive iodine may impair or destroy the thyroid, while other tissues are affected to a lesser extent. Radioactive iodine-131 is a common fission product ; it was a major component of the radioactivity released from the Chernobyl disaster , leading to nine fatal cases of pediatric thyroid cancer and hypothyroidism . On

1776-503: The 1957 accident, dumping in the Techa River officially ceased, but the waste material was left in convenient shallow lakes near the plant instead, of which 7 have been officially identified. Of particular concern is Lake Karachay , the closest lake to the plant (now notorious as "the most contaminated place on Earth" ) where roughly 4.4 exabecquerels of high-level liquid waste (75–90% of the total radioactivity released by Chernobyl)

1850-622: The Chernobyl disaster, the Soviet government gradually declassified documents pertaining to the incident at Mayak. The level of radiation in Ozyorsk, at about 0.1 mSv a year, is harmless, but a 2002 study showed the Mayak nuclear workers and the Techa riverside population are still affected. Radioactive contamination Such contamination presents a hazard because the radioactive decay of

1924-683: The EURT area by creating the East Ural Nature Reserve , which prohibited any unauthorised access to the affected area. According to Gyorgy, who invoked the Freedom of Information Act to gain access to the relevant Central Intelligence Agency (CIA) files, the CIA had known of the 1957 Mayak accident since 1959, but kept it secret to prevent adverse consequences for the fledgling American nuclear industry. Starting in 1989, several years after

1998-652: The Eastern Ural Radioactive Trace (EURT). The matter was covered up, and few either inside or outside the Soviet Union were aware of the full scope of the disaster until 1980. Before the 1957 accident, much of the waste was dumped into the Techa River , which severely contaminated it and residents of dozens of riverside villages such as Muslyumovo, who relied on the river as their sole source of drinking, washing, and bathing water. After

2072-468: The Geiger counter cannot. Scintillation detectors are generally preferred for hand-held monitoring instruments and are designed with a large detection window to make monitoring of large areas faster. Geiger detectors tend to have small windows, which are more suited to small areas of contamination. The spread of contamination by personnel exiting controlled areas in which nuclear material is used or processed

2146-405: The Techa River, a cumulative dispersal of 2.75  MCi (102  PBq ) of radioactivity. As many as forty villages, with a combined population of about 28,000 residents, lined the river at the time. For 24 of them, the Techa was a major source of water; 23 of them were eventually evacuated. In the past 45 years, about half a million people in the region have been irradiated in one or more of

2220-472: The U.S. Department of Energy (DOE) and the commercial nuclear industry for decades to minimize contamination on radioactive equipment and surfaces and fix contamination in place. "Contamination control products" is a broad term that includes fixatives, strippable coatings, and decontamination gels . A fixative product functions as a permanent coating to stabilize residual loose/transferable radioactive contamination by fixing it in place; this aids in preventing

2294-558: The activity, the biodistribution, and the removal rates of the radionuclide, which in turn depends on its chemical form, the particle size, and route of entry. Effects may also depend on the chemical toxicity of the deposited material, independent of its radioactivity. Some radionuclides may be generally distributed throughout the body and rapidly removed, as is the case with tritiated water . Some organs concentrate certain elements and hence radionuclide variants of those elements. This action may lead to much lower removal rates. For instance,

Kyshtym disaster - Misplaced Pages Continue

2368-567: The affected area started, still without giving an explanation of the reasons for evacuation. Vague reports of a "catastrophic accident" causing "radioactive fallout over the Soviet and many neighboring states" began appearing in the Western press between 13 and 14 April 1958, and the first details emerged in the Viennese paper Die Presse on 17 March 1959. But it was only eighteen years later, in 1976, that Soviet dissident Zhores Medvedev made

2442-411: The area affected is generally referred to as "contaminated". There are a large number of techniques for containing radioactive materials so that it does not spread beyond the containment and become contaminated. In the case of liquids, this is by the use of high integrity tanks or containers, usually with a sump system so that leakage can be detected by radiometric or conventional instrumentation. Where

2516-510: The body by a Reference Person, where t is the integration time in years. This refers specifically to the dose in a specific tissue or organ, in a similar way to external equivalent dose. Techa River The Techa ( Russian : Те́ча , [ˈtʲet͡ɕə] ) is an eastward river on the eastern flank of the southern Ural Mountains noted for its nuclear contamination. It is 243 kilometres (151 mi) long, and its basin covers 7,600 square kilometres (2,900 sq mi). It begins by

2590-402: The body through ingestion , inhalation , absorption , or injection . This will result in a committed dose . For this reason, it is important to use personal protective equipment when working with radioactive materials. Radioactive contamination may also be ingested as the result of eating contaminated plants and animals or drinking contaminated water or milk from exposed animals. Following

2664-492: The case of fixed contamination, the radioactive material cannot by definition be spread, but its radiation is still measurable. In the case of free contamination, there is the hazard of contamination spread to other surfaces such as skin or clothing, or entrainment in the air. A concrete surface contaminated by radioactivity can be shaved to a specific depth, removing the contaminated material for disposal. For occupational workers, controlled areas are established where there may be

2738-402: The contaminants produces ionizing radiation (namely alpha , beta , gamma rays and free neutrons ). The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard, and

2812-407: The contamination may be mitigated by burying and covering the contaminated substances with concrete, soil, or rock to prevent further spread of the contamination to the environment. If a person's body is contaminated by ingestion or by injury and standard cleaning cannot reduce the contamination further, then the person may be permanently contaminated. Contamination control products have been used by

2886-433: The effects of the airborne plume that was carried north-east. The area closest to the accident produced 66 diagnosed cases of chronic radiation syndrome , providing the bulk of the data about this condition. To reduce the spread of radioactive contamination after the accident, contaminated soil was excavated and stockpiled in fenced enclosures that were called "graveyards of the earth". The Soviet government in 1968 disguised

2960-458: The environment. Elements like uranium and thorium , and their decay products , are present in rock and soil. Potassium-40 , a primordial nuclide , makes up a small percentage of all potassium and is present in the human body. Other nuclides, like carbon-14 , which is present in all living organisms, are continuously created by cosmic rays . These levels of radioactivity pose little bit danger but can confuse measurement. A particular problem

3034-475: The environment. People can be exposed to potentially lethal radiation levels, both externally and internally, from the spread of contamination following an accident (or a deliberate initiation ) involving large quantities of radioactive material. The biological effects of external exposure to radioactive contamination are generally the same as those from an external radiation source not involving radioactive materials, such as x-ray machines, and are dependent on

Kyshtym disaster - Misplaced Pages Continue

3108-450: The extent of the spread of contamination. Low levels of radioactive contamination pose little risk, but can still be detected by radiation instrumentation. If a survey or map is made of a contaminated area, random sampling locations may be labeled with their activity in becquerels or curies on contact. Low levels may be reported in counts per minute using a scintillation counter . In the case of low-level contamination by isotopes with

3182-588: The floor and any rags used to wipe up the spill. Cases of widespread radioactive contamination include the Bikini Atoll , the Rocky Flats Plant in Colorado, the area near the Fukushima Daiichi nuclear disaster , the area near the Chernobyl disaster , and the area near the Mayak disaster . The sources of radioactive pollution can be natural or man-made. Radioactive contamination can be due to

3256-470: The head of the radiochemical plant and the chief engineer of this plant, who committed a gross violation of the technological regulations for the operation of storage of radioactive solutions". In the order for the Ministry of Medium Machine Building , signed by E.P. Slavsky, it was noted that the reason for the explosion was insufficient cooling of the container, which allowed it to increase in temperature to

3330-478: The high level of radioactivity, the waste was heating itself through decay heat (though a chain reaction was not possible). For that reason, a cooler was built around each bank, containing twenty tanks. Facilities for monitoring operation of the coolers and the content of the tanks were inadequate. The accident involved waste from the sodium uranyl acetate process used by the early Soviet nuclear industry to recover plutonium from irradiated fuel. The acetate process

3404-478: The human body from an external or internal origin. This is due to radiation from contamination located outside the human body. The source can be in the vicinity of the body or can be on the skin surface. The level of health risk is dependent on duration and the type and strength of irradiation. Penetrating radiation such as gamma rays, X-rays, neutrons or beta particles pose the greatest risk from an external source. Low penetrating radiation such as alpha particles have

3478-529: The human body irradiate the tissues over time periods determined by their physical half-life and their biological retention within the body. Thus they may give rise to doses to body tissues for many months or years after the intake. The need to regulate exposures to radionuclides and the accumulation of radiation dose over extended periods of time has led to the definition of committed dose quantities". The ICRP further states "For internal exposure, committed effective doses are generally determined from an assessment of

3552-422: The industrial site. The workers at Ozyorsk and the Mayak plant did not immediately notice the contaminated streets, canteens, shops, schools, and kindergartens. In the first hours after the explosion, radioactive substances were brought into the city on the wheels of cars and buses, as well as on the clothes and shoes of industrial workers. After the blast at the facilities of the chemical plant, dosimetrists noted

3626-502: The intakes of radionuclides from bioassay measurements or other quantities (e.g., activity retained in the body or in daily excreta). The radiation dose is determined from the intake using recommended dose coefficients". The ICRP defines two dose quantities for individual committed dose: Committed equivalent dose , H T ( t ) is the time integral of the equivalent dose rate in a particular tissue or organ that will be received by an individual following intake of radioactive material into

3700-593: The interpretation of the results. The methodological and technical details of the design and operation of environmental radiation monitoring programmes and systems for different radionuclides, environmental media and types of facility are given in IAEA Safety Standards Series No. RS–G-1.8 and in IAEA Safety Reports Series No. 64. Radioactive contamination by definition emits ionizing radiation, which can irradiate

3774-409: The lake. When Lake Kyzyltash quickly became contaminated, Lake Karachay was used for open-air storage, keeping the contamination a slight distance from the reactors but soon making Lake Karachay the "most- polluted spot on Earth". A storage facility for liquid nuclear waste was added around 1953. It consisted of steel tanks mounted in a concrete base, 8.2 meters (27 ft) underground. Because of

SECTION 50

#1732773404793

3848-428: The loose/transferable contamination along with the product. The residual radioactive contamination on the surface is significantly reduced once the strippable coating is removed. Modern strippable coatings show high decontamination efficiency and can rival traditional mechanical and chemical decontamination methods. Decontamination gels work in much the same way as other strippable coatings. The results obtained through

3922-439: The material is likely to become airborne, then extensive use is made of the glovebox , which is a common technique in hazardous laboratory and process operations in many industries. The gloveboxes are kept under slight negative pressure and the vent gas is filtered in high-efficiency filters, which are monitored by radiological instrumentation to ensure they are functioning correctly. A variety of radionuclides occur naturally in

3996-698: The nature and extent of the disaster known to the world. Medvedev's description of the disaster in the New Scientist was initially derided by Western nuclear industry sources, but the core of his story was soon confirmed by Professor Lev Tumerman, former head of the Biophysics Laboratory at the Engelhardt Institute of Molecular Biology in Moscow . The true number of fatalities remains uncertain because radiation-induced cancer

4070-445: The next ten to eleven hours, the radioactive cloud moved towards the north-east, reaching 300–350 km (190–220 mi) from the accident. The fallout of the cloud resulted in long-term contamination of an area of 800 to 20,000 km (300 to 8,000 sq mi), depending on what contamination level is considered significant, primarily with caesium-137 and strontium-90 . The land area thus exposed to radioactive contamination

4144-695: The once-secret nuclear processing town of Ozyorsk about 80 kilometres (50 mi) northwest of Chelyabinsk and flows east then northeast to the small town of Dalmatovo to flow into the mid-part of the Iset , a tributary of the Tobol . Its basin is close to and north of the Miass , longer than these rivers apart from the Tobol. From 1949 to 1956 the Mayak complex dumped an estimated 76 million cubic metres (2.7 × 10  cu ft) of radioactive waste water into

4218-724: The organic content in the soil. One being investigated is termed hydrothermal blasting. The caesium is broken away from soil particles and then precipitated with ferric ferricyanide ( Prussian blue ). It would be the only component of the waste requiring special burial sites. The aim is to get annual exposure from the contaminated environment down to one millisievert (mSv) above background. The most contaminated area where radiation doses are greater than 50 mSv/year must remain off-limits, but some areas that are currently less than 5 mSv/year may be decontaminated allowing 22,000 residents to return. To help protect people living in geographical areas which have been radioactively contaminated,

4292-489: The other hand, radioactive iodine is used in the diagnosis and treatment of many diseases of the thyroid precisely because of the thyroid's selective uptake of iodine. The radiation risk proposed by the International Commission on Radiological Protection (ICRP) predicts that an effective dose of one sievert (100 rem) carries a 5.5% chance of developing cancer. Such a risk is the sum of both internal and external radiation doses. The ICRP states "Radionuclides incorporated in

4366-401: The penetration of these radiations in simple terms. For an understanding of the different ionising effects of these radiations and the weighting factors applied, see the article on absorbed dose . Radiation monitoring involves the measurement of radiation dose or radionuclide contamination for reasons related to the assessment or control of exposure to radiation or radioactive substances, and

4440-571: The point its contents reacted with each other and exploded. This was later confirmed in experiments carried out by the Central Factory Laboratory (CPL). The director of the plant M. A. Demyanovich took all the blame for the accident, for which he was relieved of his duties as director. Because of the secrecy surrounding Mayak, the populations of affected areas were not initially informed of the accident. A week later, on 6 October 1957, an operation for evacuating 10,000 people from

4514-433: The site of the accident and contributed to the pollution of the Techa River , but a plume containing 2 MCi (80  P Bq ) of radionuclides spread out over hundreds of kilometers. Previously contaminated areas within the affected area include the Techa river, which had previously received 2.75 MCi (100 PBq) of deliberately dumped waste, and Lake Karachay, which had received 120 MCi (4,000 PBq). In

SECTION 60

#1732773404793

4588-442: The source term. The United States Nuclear Regulatory Commission defines this as "Types and amounts of radioactive or hazardous material released to the environment following an accident." Contamination does not include residual radioactive material remaining at a site after the completion of decommissioning . Therefore, radioactive material in sealed and designated containers is not properly referred to as contamination, although

4662-454: The spread of contamination and reduces the possibility of the contamination becoming airborne, reducing workforce exposure and facilitating future deactivation and decommissioning (D&D) activities. Strippable coating products are loosely adhered to paint-like films and are used for their decontamination abilities. They are applied to surfaces with loose/transferable radioactive contamination and then, once dried, are peeled off, which removes

4736-506: The surface or concentrated by human activities such as mining, oil and gas extraction, and coal consumption. Radioactive contamination may exist on surfaces or in volumes of material or air, and specialized techniques are used to measure the levels of contamination by detection of the emitted radiation. Contamination monitoring depends entirely upon the correct and appropriate deployment and utilisation of radiation monitoring instruments. Surface contamination may either be fixed or "free". In

4810-462: The terms "radiation" and "contamination" are not interchangeable. The sources of radioactive pollution can be classified into two groups: natural and man-made. Following an atmospheric nuclear weapon discharge or a nuclear reactor containment breach, the air, soil, people, plants, and animals in the vicinity will become contaminated by nuclear fuel and fission products . A spilled vial of radioactive material like uranyl nitrate may contaminate

4884-491: The time made it difficult to judge the safety of many decisions. Environmental concerns were secondary during the early development stage. Initially Mayak dumped high-level radioactive waste into a nearby river, which flowed to the river Ob , flowing farther downstream to the Arctic Ocean . All six reactors were on Lake Kyzyltash and used an open-cycle cooling system, discharging contaminated water directly back into

4958-403: The units of measurement might be the same. Containment is the primary way of preventing contamination from being released into the environment or coming into contact with or being ingested by humans. Being within the intended Containment differentiates radioactive material from radioactive contamination . When radioactive materials are concentrated to a detectable level outside a containment,

5032-477: The use of contamination control products are variable and depend on the type of substrate, the selected contamination control product, the contaminants, and the environmental conditions (e.g., temperature, humidity, etc.). [2] Some of the largest areas committed to be decontaminated are in the Fukushima Prefecture , Japan. The national government is under pressure to clean up radioactivity due to

5106-619: Was a special process never used in the West; the idea is to dissolve the fuel in nitric acid , alter the oxidation state of the plutonium, and then add acetic acid and base. This would convert the uranium and plutonium into a solid acetate salt. In 1957, the Mayak plant was the site of a major disaster, one of many other such accidents , releasing more radioactive contamination than the Chernobyl disaster. An improperly stored underground tank of high-level liquid nuclear waste exploded, contaminating thousands of square kilometers of land, now known as

5180-417: Was caused because the cooling system in one of the tanks at Mayak, containing about 70–80 tons of liquid radioactive waste , failed and was not repaired. The temperature in it started to rise, resulting in evaporation and a chemical explosion of the dried waste, consisting mainly of ammonium nitrate and acetates. The explosion was estimated to have had a force of at least 70 tons of TNT . The explosion lifted

5254-415: Was dumped and concentrated in the shallow 45- hectare (0.45 km; 110-acre) lake over several decades. On 29 September 1957, Sunday, 4:22 pm, an explosion occurred within stainless steel containers located in a concrete canyon 8.2 m (27 feet) deep used to store high-level waste. The explosion completely destroyed one of the containers, out of 14 total containers ("cans") in the canyon. The explosion

5328-502: Was forbidden to enter the city from industrial sites in cars and buses. Site workers at the checkpoint got off the buses and passed the checkpoint. This requirement extended to everyone, regardless of rank and official position. Shoes were washed on flowing trays. The city was intentionally constructed to be upwind from the Mayak plant given the prevailing winds , so most of the radioactive material drifted away from, rather than towards, Ozyorsk. There were no immediate reported casualties as

5402-515: Was not marked on maps, the disaster was named after Kyshtym , the nearest known town. After World War II , the Soviet Union lagged behind the United States in the development of nuclear weapons, so its government started a rapid research and development program to produce a sufficient amount of weapons-grade uranium and plutonium. The Mayak plant was built in haste between 1945 and 1948. Gaps in physicists’ knowledge about nuclear physics at

5476-546: Was termed the "East Ural Radioactive Trace" (EURT). About 270,000 people inhabited this area. Fields, pastures, reservoirs, and forests in the area were polluted and rendered unsuitable for further use. In a memo addressed to the Central Committee of the CPSU , Industry Minister E.P. Slavsky wrote: "Investigating the causes of the accident on the spot, the commission believes that the main culprits of this incident are

#792207