On April 26, 1986, at 1: 23 am the world witnessed one of the most critical nuclear disasters in the nuclear age. This was not provoked by a nuclear test or the use of nuclear weapons. This happened at the Chernobyl Nuclear Power Plant in Soviet Ukraine, when Mikhail Gorbachov was the leader of the Soviet Union. It has been 40 years since the accident.
On March 11, 2011 at 14: 46, following a massive 9.0 magnitude earthquake a subsequent tsunami flooded the Fukushima Daiichi nuclear plant, causing the failure of cooling systems, leading to reactor core damage and hydrogen explosions. This happened in Japan when Naoto Kan was prime minister. It has been 15 years since the accident.
Although Chernobyl and Fukushima-Daiichi rate as the only level 7 "Major Accidents" on the International Nuclear Event Scale (INES), in fact INES was created in 1990, meaning it did not exist during the Chernobyl nuclear disaster. It was created by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD/NEA). Initially the scale was applied to classify events at nuclear power plants, then extended and adapted to enable it to be applied to all installations associated with the civil nuclear industry. It has subsequently been extended and adapted further to meet the growing need for communication of the significance of all events associated with the use, storage and transport of radioactive material and radiation sources.
Prior to Chernobyl and Fukushima, other severe incidents occurred, although not as catastrophic. On September 29, 1957 the Kyshtym disaster in the city of Chelyabinsk 40, in Eastern Urals, in Soviet Union, contaminated 20 000 square kilometers affecting 270 000 people. The fallout created a polluted path that required long-term evacuation of dozens of villages. It was provoked by a cooling system failure in a storage tank containing ~80 tons of radioactive waste which caused the temperature to rise, causing a chemical explosion equivalent to about 70–100 tons of TNT. The Soviet authorities did not provide information to the public until decades later. This was level 6 on INES scale.
Then On March 28, 1979 at 4 am, the Three Mile Island partial meltdown near Harrisburg, Pennsylvania, United States caused alarm. The meltdown affected almost half of the uranium fuel and led to uncontrolled releases of radiation into the air and surrounding Susquehanna River. It was the single worst disaster ever to befall the US nuclear power industry and on the INES scale was level 5.
The United Kingdom also experienced a dramatic nuclear accident. On October 8, 1957, the Windscale nuclear reactor in Cumberland, released significant radioactivity due to a fire. The fire left about 10 tons of radioactive fuel melted in the reactor core. The Windscale fire also caused the release of sizable amounts of radioactive iodine into the atmosphere. As a consequence, the government banned for several weeks the sale of milk produced in a 500-square-km (200-square-mile) area around the reactor site. The British Government minimized the accident until the 80’s when a cleanup process began, expected to conclude by 2015. This accident was level 5 on INES scale.
Japan, on September 30, 1999, had the Tokaimura nuclear accident, caused by human error. To speed up production, workers improperly mixed uranium oxide with nitric acid in stainless steel buckets instead of using specialized equipment, violating safety regulations. They poured approximately 16 kg of uranium into a precipitation tank designed to hold a maximum of 2.4 kg. This caused a self-sustaining chain reaction (criticality), emitting a blue flash (Cherenkov radiation) and releasing intense neutron and gamma radiation. Hundreds of people, including workers and nearby residents, were exposed to radiation. Around 310,000 residents within 10 km were initially asked to stay indoors. On INES scale this accident was level 4.
What are the differences between the various INES scale levels? From 1 to 3 on INES scale, anomalies, incidents and serious incidents are included. Starting from level 4, it implies an accident with local consequences. Level 5 is an accident with wider consequences. Level 6 is a serious accident whereas a level 7 is a major accident.
The use of nuclear energy for civilian purposes of course implies enormous benefits for the environment since it is a low carbon industry -although an accident may be very harmful for ecosystems and communities. Also, it helps to control the harm of diseases, such as diabetic foot, by restoring the skin and preventing amputations. It assists doctors in their diagnosis and treatment of patients, including cancers and kidney failure. Nuclear technology improves agriculture by boosting crop yields, ensuring food safety, and enhancing sustainability through mutation breeding, pest control, and efficient resource management. Key applications include developing drought-resistant crops, using sterile insect techniques to control pests, and optimizing fertilizer/water use via isotopes.
The exploration of outer space would not be possible without nuclear fuel. By providing reliable power and high-efficiency propulsion where solar energy is insufficient nuclear energy includes radioisotope thermoelectric generators (RTGs) for long-duration probe electricity, fission reactors for Moon/Mars surface power, and nuclear thermal propulsion to drastically reduce interplanetary transit times. The Voyagers 1 and 2, launched by NASA in August and September 1977 are powered by RTGs, which convert heat from the natural radioactive decay of plutonium-238 into electricity. These "nuclear batteries" have allowed them to operate for over 45 years in deep space. The Voyagers use these power sources to operate far from the sun, where solar arrays are ineffective -in fact they have already abandoned the Solar System. As of April 2026, they continue to operate in interstellar space. They carry proof of the existence of mankind in case some day they reach other civilizations or living forms in distant Galaxies.
But nuclear energy involves the potential of accidents. Chernobyl, for instance, occurred due to an unfortunate chain of events: first, the lack of a safety nuclear culture, with inadequate communication between designers and operators, leaving the staff unaware of the reactor's risks. Second, the violation of safety procedures by operators, including turning off automatic shutdown systems and conducting the test at a low-power, unstable state. Third, the reactor had a positive void coefficient, meaning that as steam increased, reactivity increased, creating a positive feedback loop. Furthermore, the control rods had graphite tips, which briefly increased reactivity when inserted, causing a surge rather than a shutdown.
Thus, during a planned electrical test on reactor 4, a rapid, uncontrollable power surge occurred, causing a massive explosion that blew the 1000-ton lid off the reactor, destroying the building. The resulting steam explosion and fires released at least 5 percent of the radioactive reactor core into the environment, with the deposition of radioactive materials in many parts of Europe.
Those in favor of nuclear energy -such as nuclear energy companies- may argue that accidents like Chernobyl, Fukushima and others are exceptions rather than the rule. The world hosts 440 nuclear reactors, responsible of the production of 9 percent of the electricity of the planet. The fact that some experienced malfunctions should not lead societies to reject nuclear energy they claim. This narrative is also shared by the head of the IAEA, Argentina’s Rafael Grossi, today one of the candidates to succeed Antonio Guterres as United Nations’ secretary general. He has been quoted by saying that no one died from radiation at Fukushima. Well, not directly, but the way to measure nuclear disasters needs to consider additional consequences.
Beyond the initial fatalities, there are other consequences for the people, such as the psychosocial impact on the affected population. The sense of loss and broken social networks has been accompanied with the social stigma of being an “exposed person.” Remember the Hibakusha?
Maixime Polleri from the K disputes Grossi’s argument that no one died after the Fukushima level 7 nuclear accident. This analyst explains that “the nuclear accident caused numerous indirect deaths, which are deaths resulting from secondary health effects (not radiation per se). For instance, after the reactors’ meltdown, many people had to be evacuated to avoid harmful radiation exposure. During this evacuation, numerous ill and elderly individuals succumbed. Furthermore, the sheer trauma of going through a disaster of such scale also led to suicides, with 99 cases determined to be disaster-related suicides. The catastrophe also caused miscarriages, abortions and stillbirths, which further increased the number of deaths. Labeling these deaths as “indirect” is slightly misleading (in fact the Japanese prefer the phrase saigai kanrenshi, which means catastrophe-related death). Such deaths have perhaps not resulted from radiation exposure, but they are a direct consequence of the nature of nuclear accidents, which requires evacuation to avoid potential hazards to radiation. This specific form of emergency contingency is not found within other technological disasters; when wind turbines stop working, they do not lead to meltdowns requiring full-scale evacuations.” True.
Something similar happened due to the Chernobyl nuclear disaster. Initially the Soviet Government made relocations of 116 000 people. Even some physicians in Europe recommended pregnant women to undergo abortions on account of radiation exposure, due to potential effects on the fetus and the babies. Indeed, there are many sad stories around Chernobyl, including children exposed to radiation -the so-called children of Chernobyl. Even Mikhail Gorbachov has been quoted by saying that the Chernobyl accident was a more important factor in the fall of the Soviet Union than Perestroika and Glasnost.
Believe it or not, after the Chernobyl disaster a lot of knowledge about nuclear accidents and peaceful uses of nuclear energy has been learned and cooperation between the Soviet Union and the West on nuclear safety developed.
Progressive closure of the Chernobyl nuclear plant has been under way, and some interesting events have followed the catastrophe. To start with, in 2011, Chernobyl was declared a tourist attraction (not kidding) and around 100 000 visitors peaked in 2019, although tourism was suspended due to the Russian invasion of Ukraine in February 2022. The Russian invasion has led to accusations by Ukraine of Russian sabotage and a similar narrative by Moscow points to Kiev. The IAEA claims no great damage has been caused to the area due to attacks to the facilities and surrounding area.
Las year, in October 2025, some stray dogs with blue fur were spotted around Chernobyl, leading to speculation that coloring might be the result of radiation exposure. Yet veterinarians believe that dogs most likely encountered chemical dye from an overturned portable toilet, ruling out any connection to radiation.
15 years after Fukushima and 40 after Chernobyl, there are still many unsolved questions. The nuclear energy sector must continue investing in safety instead of denying the adversary effects of the accidents of the past. Disasters are avoidable, not by denying the past but by learning from experiences.
Editor’s Note: The above guest column was penned by María Cristina Rosas, a professor and researcher in the faculty of political and social sciences at the National Autonomous University of Mexico in Mexico City. The column appears in The Rio Grande Guardian International News Service with the permission of the author. Rosas can be reached via email at: mcrosas@prodigy.net.mx
