History of Chоrnobyl

Chornobyl, Fukushima and other radiation accidents around the world

Chornobyl, Fukushima and other radiation accidents around the world

April 26, 1986, was one of the most famous accidents globally, which was accompanied by the release of radioactive substances into the environment. Chornobyl. According to the International scale of nuclear events INES, the catastrophe was assigned the highest - the seventh level.

The story continued on March 11, 2011 - a catastrophic earthquake and tsunami damaged the Fukushima Daiichi nuclear power plant. Despite the different causes and scale of the consequences, experts often compare these accidents. On the one hand, they belong to the same class: radioactive isotopes have caused large-scale pollution. On the other hand, despite the highly negative consequences for the environment, both catastrophes confirmed the resilience and strength of nature.

One worker was killed, and 15 others were injured in the Fukushima bombings. Japanese authorities evacuated up to 200,000 people from the 20-kilometre zone. About 1,000 square kilometres were contaminated with radioactive particles. The radioactivity in the area of ​​340 square kilometres is 50 times higher than the standard limit.

In general, the Exclusion Zone around Fukushima is not the same as the Chernobyl Exclusion Zone. The Chernobyl Zone is being transformed into a protected area, into a natural form. Animals return there, and the former fields are swampy. The central part of the territory becomes a reserve, where biological processes are observed. And in some areas, in a 10-kilometre zone, we have received an "open-air laboratory", there are opportunities to study how radionuclides migrate in the natural environment.

At the beginning of the Japan situation, the Exclusion Zone was divided into three different territories: "green", "orange" and "red". The latter is quite polluted, and they do not expect that it can be used shortly. "Orange" and "green" - were also contaminated, but there was active decontamination. And in 10 years in these territories, in principle, cleanly - evacuation orders are removed, and the official return of people is allowed.

The Japanese set a particular norm for the radiation background of the territories - no more than 20 microsieverts per hour. If it was more prominent, they removed a layer of soil 5 cm and placed it on a particular site. This is a vast area, and a massive amount of land was deducted. Japanese scientists have estimated that if the threshold was, for example, 18 microsieverts, Japan could save more than $ 500 million.

The Chernobyl experience became very valuable for the Japanese. A few months after the accident at the PNPP, they turned to the Ukrainian side for relevant information. Sometime later, Japanese and Ukrainian scientists joined forces in radioecological research.

Other known and silenced radiation accidents around the world
If the world had worked on its mistakes before, the scale of both casualties would probably have been much horrific. We will remind only some of them:

Kyshtym accident
INES level: 6
Where: Russia, USSR
When: September 29, 1957

This catastrophe was the first artificial radiation emergency in the USSR. It happened at the Mayak chemical plant, located in the closed city of Chelyabinsk-40.
Since 1994, the city has been called Ozersk, but its last name in Soviet times was used only in secret correspondence, so the accident was named "Kishtim", after the closest to Ozersk city, which was marked on the maps, Kishtim.

The explosion occurred in a container for radioactive waste due to a failure of the cooling system. The area of ​​several Mayak enterprises, a military town, a fire station, a prison colony, and  ​​23,000 km2 with a population of 270,000 in 217 settlements in three oblasts: Chelyabinsk, Sverdlovsk, and Tyumen were in the area of ​​radiation contamination. Chelyabinsk-40 itself was not damaged.

90% of radiation pollution fell on the territory of the Mayak chemical plant, and the rest dissipated further.

During the liquidation of the consequences of the accident, 23 villages from the most polluted areas with a population of 10 to 12 thousand people were resettled, and buildings, property and livestock were destroyed.

The Soviet authorities classified the information about the accident, although it was impossible to hide it completely, including the extensive pollution area. After the explosion, a column of smoke and dust rose to a kilometre high, flickering with orange-red light. Still, the newspapers of Chelyabinsk then wrote about ... "the phenomenon of the northern lights in the latitudes of the Southern Urals."

In the contaminated area, the Soviet authorities still created a sanitary protection zone with a particular regime. And in 1968 - the Eastern Ural Reserve. Its territory still cannot be visited.

Accident at the Chok River Laboratory
INES level: 5
Where: Canada
When: December 12, 1952

The Chock River Laboratory is a Canadian nuclear research complex on the Choke River, about 180 km from Ottawa's capital. Extensive research and development have been conducted here to support and promote nuclear technology. The accident in this laboratory is the first known radiation accident in the world, during which there was a partial melting of the reactor core. The accident occurred due to energy loss and partial loss of coolant in the reactor, which led to significant damage to the core. Among the reasons are mechanical problems and human errors. Hydrogen explosions severely damaged the reactor and the reactor vessel. As a result of the explosion in the basement of the building were 4,500 tons of radioactive water. It was dumped into ditches about 1,600 meters from the Ottawa River. 

About 10,000 curies or 370 TBq of radioactive materials were released during the accident. However, two years later, the reactor began to be used again. And in 1958, another accident occurred in this laboratory - a rupture of the shell of the fuel element and a fire in the building of the National Research Universal Reactor. Both accidents required significant clean-up efforts, involving much civilian and military personnel. Interestingly, in the group of volunteers who eliminated the consequences of the first accident, the future President of the United States Jimmy Carter, then an officer of the U.S. Navy.

Today, Choc River Laboratories is used for both research and electricity generation to support Canadian power grids.

Windscale accident
INES level: 5
Where: Great Britain
When: October 10, 1957

This accident is the largest in the history of the British nuclear industry. It happened at a nuclear power plant on the Irish coast. The problem arose during the execution of programs for the scheduled annealing of graphic masonry. But due to the lack of measuring instruments and personalization errors, the process got out of control. A visual inspection of the fuel ducts revealed that many fuel rods were hot to 1400 ° C and could not be unloaded due to swelling and jamming in the ducts.

The selfless actions of the operators did not help, and the fire spread to 150 channels with 8 tons of uranium. Attempts to cool the core with carbon dioxide also failed, so the reactor was flooded with water, although they understood the risk of explosion. Eventually, the reactor was cold.

The accident resulted in releasing radioactive iodine of about 20 thousand curies, or 740 TBq and caesium-137 at the level of 800 curies (30 TBq). However, none of the staff received a dose close to the level that would exceed ten times the established limit. As of now, the Windscale site has been decontaminated and is still in use.

The leak of radioactive gases in a research laboratory in Santa Susanna
INES level: 5
Where: USA
When: July 26, 1959

The Santa Susanna Field Laboratory (or Santa Susanna) is a complex of industrial research and development work located on 1,080 hectares in California. It was used primarily to develop and test liquid-fueled rocket engines for the U.S. space program from 1949 to 2006 and nuclear reactors from 1953 to 1980. These laboratories operated about ten atomic reactors, and at least four of them crashed. They were considered experimental and therefore had no protective structures. Not much is known about the episode of the leak of radioactive gases in July 1959, which was included in the list of the most dangerous accidents: the reactor underwent partial melting of 13 of the 43 fuel cells and the release of radioactive gas into the atmosphere. Wikipedia articles say the release was "controlled." And some Russian media write about the incident as "the third-worst nuclear accident after Chernobyl and Fukushima." The reactor was repaired and restarted in September 1960 and operated until 1981. The public living near the laboratory has repeatedly drawn attention to the potential danger of experiments being conducted there. But the U.S. government was in no hurry to disclose the details of its work and the scale of the threat. The laboratory stopped research and development work in 2006. And only in August 2009, 50 years later, did the U.S. Department of Energy hold a workshop to discuss the 1959 incident. And in 2012, the U.S. Environmental Protection Agency found that the area around the laboratory was indeed very radioactively contaminated. Now the environment is being cleaned up there.

Accident at the Three Mile Island NPP
INES level: 5
Where: USA
When: March 28, 1979

Before the Chernobyl disaster, it was considered the largest in its nuclear energy history and is still considered the worst nuclear accident in the United States. The primary cause of the accident was the failure of feed pumps in the second circuit of the reactor cooling system, resulting in which water supply to both steam generators was stopped. Then, due to an error of the operators, the process of emergency cooling of the reactor core came out of control. Nuclear fuel partially melted during the accident but did not burn the reactor vessel, so that the radioactive substances mostly remained inside. According to various estimates, the radioactivity of noble gases emitted into the atmosphere ranged from 2.5 to 13 million curies (92.5 - 481 thousand TBq, (terabecquerel; becquerel - a unit of measurement of the activity of a radioactive source in the International System of Units; curie - a non-systemic team Emissions of unstable nuclides, such as iodine-131, were low, and the station was also contaminated with radioactive water. From August 1979 to December 1993, and cost $ 975 million. 1985.

Release of radioactive iodine at the SL-1 experimental reactor
INES level: 5
Where: USA
When: January 3, 1961

Reactor SL-1 is an experimental nuclear reactor of the United States Army, located in Idaho. Here, the control rod was incorrectly extended, and an uncontrolled chain reaction began. The operating capacity of the reactor was 200 kW electric and 400 kW thermal for space heating. During the accident, the core power level reached almost 20 G.W. in just four milliseconds, causing a steam explosion. As a result of the accident, three reactor operators died on the spot. And this is the only time in U.S. history that an accident has caused immediate death. About 80 curies (3 TBq) of iodine-131 were released into the atmosphere, which was not considered significant due to the reactor's location in the remote high desert of eastern Idaho. Another 1,100 curies (41 TBq) of fission products were released into the atmosphere. After the accident, the laboratory in Idaho was decommissioned.