The Kyshtym Disaster (or Kyshtym Accident) was the first technogenic radiation emergency in the Soviet Union. It occurred on September 29, 1957, at the Mayak chemical plant located in the closed city of Chelyabinsk-40 (now Ozersk). Since Ozersk (also referred to as Chelyabinsk-40 and Chelyabinsk-65) is not marked on maps, the case was declared a disaster in Kyshtym, the closest known city.
The incident occurred at the Mayak complex, a facility for plutonium production, nuclear weapons, and the processing of nuclear fuel for the USSR. It is classified as a level 6 accident on the International Nuclear and Radiological Event Scale (INES), making it the third most dangerous nuclear incident in history, following the Fukushima nuclear accident and the Chernobyl disaster, both of which are rated at level 7 on the INES scale.
The name of the city was used only in secret correspondence during Soviet times and was absent from publicly available maps. Therefore, the accident was named “Kyshtym” after the nearest city to Ozyorsk, which was marked on the maps.
The disaster had severe environmental consequences. It contaminated the Techa River and Lake Karachay with radioactive materials, making them among the most polluted bodies of water in the world.
Kyshtym Disaster: Before the Accident
On April 9, 1945, the Government of the USSR issued a decree to establish Plant No. 817 for the production of atomic bombs in the Chelyabinsk region. In June 1948, the first industrial nuclear reactor in Eurasia, known as “A-1,” reached its designed capacity. In January 1949, a radiochemical plant for the extraction and processing of plutonium was launched. In February 1949, a chemical and metallurgical plant for the production of nuclear charges was initiated. Over time, the facility also produced sources of ionizing radiation for various purposes and nuclear fuel for atomic power plants.
Since 2003, the plant has been repurposed as the Russian Storage Facility for Divided Materials (RSFDM) for the processing and storage of radioactive waste. Starting in 1949, planned and accidental discharges of medium- and low-level liquid radioactive waste from production were released into open water bodies. For instance, from 1949 to 1951, discharges were made into the Techa River, significantly contaminating it with radioactivity.
As knowledge and experience about the dangers of radiation accumulated, part of the liquid waste began to be diverted not into the river but into the stagnant Karachay Lake, which was later sealed off due to the threat of widespread radiation contamination (the sealing was carried out from 1973 to 2015). Additionally, due to imperfect air purification technology, emissions of gases and aerosols containing iodine-131 and radioactive isotopes of inert gases (such as argon-41) were also released into the atmosphere, detectable up to 70 kilometers from the Mayak Production Association. High-level radioactive waste was stored in special areas of the facility in closed, specially equipped containers.
The explosion occurred in one of these containers for storing high-level radioactive waste, built in the 1950s. Arkadiy Aleksandrovich Kazutov (1914–1994) served as the Chief Mechanic and V. A. Saprykin was the Chief Engineer at the time of the construction of these containers for the Mayak Production Association. The containers themselves are stainless steel cylinders encased in concrete.
The construction technology of this storage was as follows: in an excavation approximately 18–20 meters in diameter and 10–12 meters deep, reinforcement was installed on the bottom and walls at frequent intervals and then filled with concrete. As a result, the thickness of the concrete walls is approximately one meter. Subsequently, the container for waste was assembled inside using stainless steel struts welded together.
A dome was constructed on top, supported by radial metal trusses, which were attached to a metal cylinder with a diameter of up to 1.5 meters in the center. A cover about one meter thick was poured over these trusses using high-grade concrete. A two-meter layer of soil was then piled on top. Then, green turf was laid to camouflage the structure.
In terms of the strength of this structure during construction, there were no doubts, as evidenced by the dialogue between Kazutov and V. A. Saprykin at the construction of the spent fuel storage:
I remember the meeting when Chief Engineer Vasily Saprykin came to inspect the storage facility. It was during the day, and the sun was scorching. He asked me with a smile:
— Will it collapse under its own weight?
I jokingly replied:
— You could even load a locomotive with a full tender on it.
Vasily Andreevich laughed at the joke, and then thoughtfully and, as it seemed to me, with a slight concern, said:
— Who knows what force is needed to destroy this?
Explosion and Formation of a Radioactive Plume
A 300 m3 container exploded because the cooling system wasn’t working right. The container held about 70–80 tons of highly radioactive waste that had dried out over time (there was originally 256 m3 of liquid waste with isotopes of strontium-90, cesium-137, cerium-144, zirconium-95, niobium-95, and ruthenium-106). The explosion, estimated to be equivalent to tens of tons of TNT, resulted in the following:
- Complete destruction of the stainless steel container located in an 8.2-meter-deep (27 ft) concrete canyon.
- The one-meter-thick concrete covering, weighing 160 tons, was thrown approximately 25 meters (82 ft) away.
- Similar concrete coverings on two neighboring containers were torn off.
- Glass windows in buildings within a 3-kilometer radius were shattered.
- Approximately 20 million curies of radioactive substances were released into the atmosphere from the ruptured container in the form of aerosols, gases, and particulate matter.
For comparison, during the Chernobyl accident, up to 380 million curies were released, roughly 19 times more. However, in the Chernobyl accident, the majority of radionuclides consisted of short-lived iodine-131 with an 8-day half-life. In the Ural incident, long-lived strontium-90 (28.8-year half-life) and cesium-137 (30.2-year half-life) were released, which could accumulate in bones and, consequently, affect red bone marrow.
The explosion propelled about 10% of the radioactive materials to heights of 1-2 km, creating a cloud of liquid and solid aerosols. Over the course of 10–12 hours, radioactive substances were deposited over a distance of 300–350 km (190–220 mi) in a northeastern direction from the explosion site, following the wind direction. The area affected by radioactive contamination from the chemical plant explosion later became known as the Eastern Ural Radioactive Trace (EURT).
The total length of EURT was approximately 300 km, with a width of 5–10 kilometers. Over 10,000 people resided in areas with a radiation density exceeding 2 Ci/km2, and around 2,100 people lived in areas with a density exceeding 100 Ci/km2. In total, about 270,000 people lived in the EURT zone.
The Soviet government kept the Mayak disaster a secret due to the secretive nature of the state and its nuclear activities during the Cold War. Information about the accident was not made public until many years later.
The Chronicle of the EURT Formation
By Tolstikov:
- On September 29, 1957 (Sunday) at 16:22 local time, an explosion occurred in tank No. 14 of the “C-3” complex.
- At 19:20, air masses from the area of the chemical plant moved toward the village of Bagaryak and the city of Kamensk-Uralsky in the Sverdlovsk region.
- At 22:00 or 00:00 on September 30, the radioactive cloud reached the territory of the Tyumen region.
- Around 23:00, a strange glow was observed in the sky, primarily in shades of pink and light blue. The glow initially covered a significant part of the southwestern and northeastern sky, and later it could be observed in the northwest direction.
- On September 30, at 3:00 in the morning, the process of forming the radioactive fallout was completed (excluding subsequent moves).
Versions of the Incident’s Causes
Official Version
On October 11, 1957, a special technical commission was formed to determine the causes of the explosion. The commission consisted of 11 members, primarily scientists and experts in the atomic industry, such as N. A. Bakh, I. F. Zhezheryun, B. P. Nikolsky, and others. V. V. Fomin, a chemist and corresponding member of the USSR Academy of Sciences, served as the commission’s chair. After examining the circumstances of the explosion of tank No. 14 in the “C-3” complex, the commission determined the following cause of the accident:
The complex, which included the ruptured tank, was an underground concrete structure with cells—cavities for stainless steel containers with a volume of 250 m3 each. These containers stored liquid, high-radioactive waste from the Mayak chemical plant. Due to their high radioactivity, their contents generated heat, and the containers were constantly cooled by circulating water. In 1956, cooling pipes in one of the containers began to leak and were disconnected. More than a year passed without attempts to repair the damage, and the waste began to dry out, accumulating highly explosive nitrate and acetate salts on the surface. A detonation of these salts occurred due to a random spark, with the power of the resulting explosion estimated at 70–100 tons of trinitrotoluene, judging from the crater and damage.
Alternative Version
Another version suggests that a solution of plutonium nitrate was mistakenly added to a tank evaporator with a hot solution of plutonium oxalate. The oxidation of the oxalate by nitrate released a significant amount of energy, leading to overheating and the explosion of the tank containing the radioactive mixture.
The Scale of the Incident
At 4:00 AM on September 30, 1957, the first rough assessment of the level of radiation contamination was conducted on an industrial site. Starting on September 30, an investigation of the radiation situation beyond the plant and the city of Chelyabinsk-40 began. The initial measurements of contamination in nearby populated areas covered by the radioactive cloud revealed the very serious consequences of the radiation accident. For instance, the exposure dose rate in Satlykovo (18 km) reached up to 300 µR/s, in Galikaevo (23 km) up to 170 µR/s, and in Yugo-Konyovo (55 km) up to 6 µR/s (= 21,600 µR/h).
The areas affected by radiation contamination included several facilities of the “Mayak” plant, a military town, a fire brigade, a prison colony, and a territory covering 23,000 km2 with a population of 270,000 people in 217 settlements across three regions: Chelyabinsk, Sverdlovsk, and Tyumen. Chelyabinsk-40 itself was not directly affected by the fallout (it was on the windward side). 90% of the radiation contamination occurred on the territory of the “Mayak” chemical plant, while the remaining portion dispersed further.
Due to the prolonged decay of strontium-90 and its accumulation in bones, the assessment was based on it. The area of general contamination was defined as the territory limited by an isopleth where the β-activity level from strontium-90 exceeded background by a factor of 2, with measurement error considered, and equaled 0.1 Ci/km2, which was equivalent to 4 Ci/km2 for the total β-activity of the fallen isotopes. The officially recognized radiation-contaminated area requiring protection of the population from radiation was established with a level of 2 Ci/km2 for strontium-90, covering an area of 1,000 km2, forming a zone 105 km in length and 4-6 km in width. The contamination at the industrial site ranged from 4,000 to 150,000 Ci/km2 for total β-activity.
On October 2, 1957, the third day after the accident, a commission was dispatched from Moscow, led by Minister E.P. Slavsky, and formed by the Ministry of Medium Machine Building. The commission’s initial task was to determine the cause of the explosion, but upon arrival, the complexity of the contamination situation and the lack of understanding of this problem in an area with developed agriculture required further investigation and decision-making on many other issues. As a result, the 3rd Main Directorate of the USSR Ministry of Health and the USSR Ministry of Agriculture were also involved. The overall coordination was carried out by the Council of Ministers of the USSR.
The executive committees of the Chelyabinsk and Sverdlovsk regions were also engaged. In May 1958, an experimental scientific biogeoecological station was established for the study of agricultural production in the territory of the Mayak Production Association in Metlino village, 12 km from Chelyabinsk-40. A branch of the Leningrad Research Institute of Radiation Hygiene (now St. Petersburg Research Institute of Radiation Hygiene, named after P.V. Ramzaev of Rospotrebnadzor) was organized in Chelyabinsk, along with a comprehensive agricultural research radiological laboratory.
In December 1962, Branch No. 4 of the Institute of Biophysics of the USSR Ministry of Health (now the Federal State Budgetary Scientific Institution, “United Research Center for Radiation Medicine of the Federal Medical and Biological Agency of Russia”) was established in Chelyabinsk. The employees of this closed scientific institution conducted medical examinations of the population in the Techa River area and within the Mayak Production Association territory, conducting research work.
Several research institutes were involved in addressing issues related to radiation contamination, its impact on human health and the natural environment, the development of protective measures, the determination of safe levels of prolonged exposure to ionizing radiation, and the rehabilitation of the territory, including its potential use for agricultural purposes.
These institutes included the Institute of Biophysics of the USSR Academy of Medical Sciences, the Institute of Biophysics of the USSR Ministry of Health, the Institute of Applied Geophysics, the Timiryazev Academy, Moscow State University, the Agrophysical Institute of the All-Union Academy of Agricultural Sciences, the Soil Institute of the USSR Ministry of Agriculture, the Laboratory of Forestry of the USSR Academy of Sciences, the All-Union Research Institute of Experimental Veterinary Medicine, and others.
The social, ecological, and economic consequences of the accident were extremely severe. Thousands of people were forced to leave their homes, and many others had to continue living in areas contaminated with radionuclides under conditions of long-term restrictions on economic activities.
Casualties
- 270,000 affected. 10,000–12,000 evacuated.
- At least 200 people died of radiation sickness 66 diagnosed cases of chronic radiation syndrome. [Source]
The fact that radioactive contamination had an impact on water bodies, pastures, forests, and arable land further complicated the situation. A total of 106,000 hectares of agricultural land (54% of them) and forest lands were removed from circulation. The light and fishery industries were closed, including those operating on freshwater and saline lakes. Konyshevsky and Boyevsky mines, which had strategic significance, were also shut down.
Additionally, the upper reaches of the river Techa, already contaminated, were further affected by radioactive pollution due to the accident. Significant areas of the drainage basins of the upper reaches of the Sinyara and Pyshma rivers, as well as the middle reaches of the Iset River upstream to the confluence of the Sinyara and Techa rivers, were included in the affected area (all four areas being part of the lower reaches of the Tobol River basin).
A total of 1,007 personnel of the Internal Troops of the USSR Ministry of Internal Affairs, responsible for guarding nuclear industry facilities, were exposed to radiation during the accident. Among them, 12 military personnel who received doses exceeding 50 röntgens were hospitalized, while 63 military personnel who received doses ranging from 10 to 50 röntgens were placed under continuous medical observation.
The Mayak Production Association is still in operation today but under increased scrutiny and with safety improvements. It continues to be involved in nuclear material reprocessing and management.
Received Radiation Doses
As in the case of the Techa River, an extended cohort of 30,417 individuals (in total, along with Techa, the database includes approximately 80,000 people) who were exposed to the consequences of the accident underwent long-term medical observation in the Chelyabinsk-40 (EURT) area. This cohort included residents of evacuated and non-evacuated settlements from 13 adjacent populated areas, closely bordering the contaminated territory with a contamination level of 2 Ci/km2 of strontium-90.
This cohort comprised individuals born before 1988 and their descendants. These included about 18,000 people born before the accident, 9,492 descendants of the first and second generations of evacuees, and about 3,000 non-evacuees. It should be noted that over the 30 years of observation, 19% of these individuals were lost to follow-up due to migration. It was found that the maximum effective radiation dose, equivalent to 1 Sv, was received by children aged 2–7 at the time of the accident who were evacuated within the first 7–14 days, as well as children aged 1-2 who were not evacuated or were evacuated later.
No statistically significant health deviations were observed in the population of the rest of the Chelyabinsk-40 area.
The effective dose from external gamma radiation was substantial only during the first few months after the accident. Major effect came from beta radiation inside the body from strontium-90 (target organs: bones and red bone marrow) and cerium-144 (target organs: the lungs and digestive tract). Over the 30 years, the accumulated effective dose for residents who were not evacuated and lived at the borders of the zone averaged 1.2 Sv (the equivalent dose to the red bone marrow was approximately 2.5 Sv, and to the bones, approximately 8 Sv).”
References
- Rabl, Thomas. “The Nuclear Disaster of Kyshtym 1957 and the Politics of the Cold War.” Environment & Society Portal, Arcadia (2012), no. 20. Rachel Carson Center for Environment and Society. https://doi.org/10.5282/rcc/4967.
- “The Kyshtym Accident, 29th September 1957,” Norwegian Radiation Protection Agency, August 2007.
- F. X. Clines, “Soviets Now Admit ’57 Nuclear Blast,” New York Times, 18 Jun 89.