Map of the East Urals Radioactive Trace (EURT): area contaminated by the Kyshtym disaster.
| |
| Date | 29 September 1957 |
|---|---|
| Location | Mayak, Ozyorsk, Chelyabinsk Oblast,  Soviet Union |
| Coordinates | 55°42′45″N 60°50′53″ECoordinates: 55°42′45″N 60°50′53″E |
| Type | Nuclear Accident |
| Outcome | INES Level 6 (serious accident) |
| Casualties | |
| 66 diagnosed cases of chronic radiation syndrome | |
| Estimated 200 additional cases of cancer | |
| 10,000 evacuated | |
The Kyshtym disaster was a radioactive contamination accident that occurred on 29 September 1957 at Mayak, a plutonium production site in Russia for nuclear weapons and nuclear fuel reprocessing plant of the Soviet Union.
The event occurred in Ozyorsk, Chelyabinsk Oblast, a closed city built around the Mayak plant. It measured as a Level 6 disaster on the International Nuclear Event Scale (INES), making it the third-most serious nuclear accident ever recorded, behind the Fukushima Daiichi nuclear disaster and the Chernobyl disaster (both Level 7 on the INES). At least 22 villages were exposed to radiation from the disaster, with a total population of around 10,000 people evacuated. Some were evacuated after a week, but it took almost 2 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 Ozyorsk/Mayak (named Chelyabinsk-40, then Chelyabinsk-65, until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.
Background
After World War II, the Soviet Union lagged behind the U.S. in development of nuclear weapons, so it 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 the time made it
difficult to judge the safety
of many decisions. Environmental concerns were not taken seriously
during the early development stage. Initially Mayak was dumping
high-level radioactive waste into a nearby river, which flowed to the
river Ob, flowing farther down to the Arctic Ocean. All six reactors were on Lake Kyzyltash and used an open-cycle cooling system, discharging contaminated water directly back into 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 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 20 tanks. Facilities for monitoring operation of the
coolers and the content of the tanks were inadequate.
The accident involved waste which was from the sodium uranyl acetate
process used by the early Soviet nuclear industry to recover plutonium
from irradiated fuel; this is discussed by Foreman in his review on
nuclear accidents.
The acetate process is a special process which was 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 converts the uranium and plutonium into a solid acetate salt.
Explosion
In
1957 the cooling system in one of the tanks 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 (see ammonium nitrate–fuel oil bomb). The explosion, on 29 September 1957, estimated to have had a force of about 70–100 tons of TNT, threw the 160-ton concrete lid into the air. There were no immediate casualties as a result of the explosion, but it released an estimated 20 MCi (800 PBq) of radioactivity. Most of this contamination settled out near the site of the accident and contributed to the pollution of the Techa River, but a plume containing 2 MCi (80 PBq) 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 the next 10 to 11 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 a long-term contamination of an area of
more than 800 to 20,000 km2 (310 to 7,720 sq mi), depending on what contamination level is considered significant, primarily with caesium-137 and strontium-90. This area is usually referred to as the East-Ural Radioactive Trace (EURT).
Evacuations
| Village | Population | Evacuation time (days) | Mean effective dose equivalent (mSv) |
|---|---|---|---|
| Berdyanish | 421 | 7–17 | 520 |
| Satlykovo | 219 | 7–14 | 520 |
| Galikayevo | 329 | 7–14 | 520 |
| Rus. Karabolka | 458 | 250 | 440 |
| Alabuga | 486 | 255 | 120 |
| Yugo-Konevo | 2,045 | 250 | 120 |
| Gorny | 472 | 250 | 120 |
| Igish | 223 | 250 | 120 |
| Troshkovo | 81 | 250 | 120 |
| Boyovka | 573 | 330 | 40 |
| Melnikovo | 183 | 330 | 40 |
| Fadino | 266 | 330 | 40 |
| Gusevo | 331 | 330 | 40 |
| Mal. Shaburovo | 75 | 330 | 40 |
| Skorinovo | 170 | 330 | 40 |
| Bryukhanovo | 89 | 330 | 40 |
| Krivosheino | 372 | 670 | 40 |
| Metlino | 631 | 670 | 40 |
| Tygish | 441 | 670 | 40 |
| Chetyrkino | 278 | 670 | 42 |
| Klyukino | 346 | 670 | 40 |
| Kirpichiki | 160 | 7–14 | 5 |
Aftermath
Kyshtym Memorial
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 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 in 1976 (18 years after) that Soviet dissident Zhores Medvedev made the nature and extent of the disaster known to the world.
In the absence of verifiable information, exaggerated accounts of the
disaster were given. People "grew hysterical with fear with the
incidence of unknown 'mysterious' diseases breaking out. Victims were
seen with skin 'sloughing off' their faces, hands, and other exposed
parts of their bodies". 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 Leo 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
is clinically indistinguishable from any other cancer, and its
incidence rate can be measured only through epidemiological studies. One
book claims that "in 1992, a study conducted by the Institute of
Biophysics at the former Soviet Health Ministry in Chelyabinsk found
that 8,015 people had died within the preceding 32 years as a result of
the accident".
By contrast, only 6,000 death certificates have been found for
residents of the Techa riverside between 1950 and 1982 from all causes
of death,
though perhaps the Soviet study considered a larger geographic area
affected by the airborne plume. More recent epidemiological studies
suggest that around 49 to 55 cancer deaths among riverside residents can
be associated to 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 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.
Ozyorsk in 2008.
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 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 the Soviet government gradually declassified documents pertaining to the disaster.
Current situation
The level of radiation in Ozyorsk, at about 0.1 mSv a year, is harmless, but the area of the EURT is still heavily contaminated with radioactivity.
