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Chernobyl: 40 Years ago in 2026, What Happened?
- Poudre Press Staff
- 2 hours ago
- 11 min read
The worst nuclear disaster in human history started during a safety test. On April 24, 1986, the RBMK Soviet reactor began a safety test it started at 1:23:04 am Moscow time (World Nuclear Association). Just thirty-six seconds later, at 1:23:40, the emergency stop button, AZ-5, was activated, setting the reactor's fate in stone. Three seconds after AZ-5 was engaged, the power in the reactor was surging (1:23:43am).
As several fuel cells ruptured, the two-thousand biological shield (reactor lid) was dislodged, jamming the emergency control rods (objects that are used to control the speed of nuclear reactions, in this case, to stop the nuclear reactions), in place, only halfway in the reactor core, making them not only useless but an active ingredient in increasing the power of the reactor. Then at 1:23:58, a mere 15 seconds after the emergency stop button was engaged, the first explosion rings out, blowing the 2000-ton biological shield straight off the reactor. A second explosion roars into existence mere seconds later, destroying the containment building and destroying both the reactor and the containment building releasing massive amounts of radiation into the surrounding area (Chernobyl Gallery). This second, more powerful explosion was fueled by the fury of nuclear energy and chemistry; these forces devastated the reactor. The disaster brought with it a shower of radioactive particles as the reactor was set ablaze. This was only the beginning of the horror that the Chernobyl reactor no 4 disaster would unleash. Forcing thousands to move and contaminating the surrounding area for thousands of years, the legacy of Chernobyl will linger far beyond our lives (times and events via atomic archive).
Why did Chernobyl explode?
The true cause of the Chernobyl explosion was shrouded in mystery; we do know that the explosions that occurred were a result of a series of events, all of which compounded on the night of the accident. These events started on the 25th of April 1986. On this day Chernobyl was scheduled to retake a safety test designed to ensure reactor safety during a blackout. The test was testing if the remaining energy in the steam turbine would be enough to power essential coolant pumps to the reactor in the event of an emergency during the 45-second period while backup diesel generators were spinning up (Atomic Archive). In order to conduct the test, the reactor would have to be at low power, and so operators began lowering reactor power at around 1:00 pm on the 25 in order to prepare for the test, which was to coincide with a reactor shutdown for routine maintenance (Atomic Archive). At around 2 pm, the shutdown was delayed until that night in order to meet power requirements for the region. This delay is partially responsible for the Chernobyl disaster because it allowed large amounts of Xenon-135 to build up in the reactor. Xenon-135 is an isotope of Xenon (pronounced Ze-non), which is a naturally occurring unreactive gaseous element, in Nuclear reactors Xenon-135 is a byproduct of the nuclear reactions taking place (Nuclear power for everybody). When Xenon-135 builds up in a reactor, it is called xenon poisoning as it slows reactivity significantly, causing the reactor to drop in power output. Normally, the xenon is removed when the reactor runs at high power, but it can build up when the reactor runs at low power as it was on April 25th.
After running at low power, Xenon poisoning had built up to a point where reactivity was incredibly low, too low to run the test. As a result, almost all control rods were withdrawn from the reactor. These control rods are necessary to modulate reactivity in the reactor and prevent runaway nuclear reactions. The removal of these control rods was dangerous, and the operators knew it. “A minimum of 30 control rods was necessary to retain reactor control, in the test only 6-8 control rods were actually used. Many of the control rods were withdrawn to compensate for the build up of Xenon which acted as an absorber of neutrons and reduced power.” This meant that in the event of an emergency or a power surge, there was going to be at least a 20-second delay from AZ-5 activation and complete shutdown. Despite the inherent known risk and the fact that the reactor was still at power, which was considered too low for the test they proceeded anyway.
During the test, there was an unexpected power surge. As a result of said power surge, the emergency shutdown command AZ-5 was triggered. It is unknown if this was a result of the operators trying to shut down the reactor as a result of the power surge or standard procedure to shut down the reactor after the test (Chernobyl Gallery). But regardless, mere seconds after the activation, reactor number four was completely destroyed. No less than as a direct result of a crucial design flaw with AZ-5.
The flaw in AZ-5 was simple: there were graphite tips. While this may seem fine (as it was in most situations) in the condition that reactor no 4 was in it would prove catastrophic. Normally, control rods absorb neutrons, greatly slowing nuclear reactions, however graphite does not absorb neutrons nearly as well as the rest of the control rod or water causing the reaction rate to accelerate as they displaced water (a great neutron absorber) in the lower part of the reactor. This displacement caused a final burst of reactivity in the reactor just before it was destroyed (Chernobyl Gallery). This final burst of reactivity is when the reactor was put over the edge, converting all water into steam and causing the fuel cells to rupture. Finally, there were the two separate explosions that destroyed reactor no 4, and the surrounding building. The first was a steam explosion launching of the 2000 ton biological shield and the second was the nuclear chemical explosion destroying the rest of the reactor and containment building (Chernobyl gallery). These terrifying events happened because of one oversight. But horrifyingly this design flaw was not only limited to Chernobyl reactor for this design flaw as present in every single RBMK realtor ever built (Chernobyl Gallery) but just because AZ-5 had caused the explosion in the end does not mean it was solely responsible. It is important to remember when AZ-5 was engaged the reactor was already in critical condition and it is impossible to know what would have happened had direct choices been made.
The disaster that was Chernobyl was caused by both design and leadership oversights while it would have been wise to stop at any number of warning signs when the shutdown button was pushed it was already too late. We will never completely know what happened in Chernobyl reactor no 4 that day as most instruments were destroyed while the reactor was about to explode. We do know that it happened no ifs ands or buts. As far as the soviet union was concern they had to deal with the emergency soon but they did so in a rather messy manner.
The response by the USSR (Union of Soviet Socialist Republics) was not good. They knew about the disaster almost immediately but did not inform the public or the international community when they first found out about it. They only told the international community after nuclear workers in Sweden detected higher than average radiation levels coming from the USSR and then demanded an explanation. (Jensen and Lindhé 30). Clarity was never the priority of the USSR and they had different priorities. At Chernobyl it was sealing the reactor and containing the radiation.
Due to the explosion Chernobyl building number two (the building where reactor number four was held) was destroyed, letting massive amounts of radioactive particles escape into the surrounding environment. Radioactive isotopes like Zirconium 95, Niobium 141 and 144, Cesium 154,and 155, as well as many others were released into the environment (Kashparov and Et). Suffice to say this was not ideal so at the reactor site priority number one was stopping the fire that was ignited when the reactor exploded, and that was releasing the radiation into the environment. The fire was stopped after crews dropped roughly 5,000 tons of boron, dolomite, sand, clay and lead into the reactor both stopping the fire and limiting the amount of nuclear particles being released. During the ten days they were trying to stop the fire by dropping materials from helicopters huge amounts of radioactive materials were being released into the environment, on an unprecedented scale for civilian activities (World nuclear association). This resulted in massive contamination reaching all over Europe although most of the material was deposited near the reactor. Irradiating the surrounding area and contributing to the struggles of working around Chernobyl.
A major reason why working around the reactor was so difficult was that the radiation around the reactor was so high. The initial number that the soviet union was telling that the radiation was much lower than it actually was to both to avoid a panic and because the radiation detecting devices (dosimeters) were maxed out and the dosimeters with a larger range of detection were either destroyed or inaccessible. This somewhat shifts the blame to not be entirely on the soviet union. Due to the intensity maxing out the dosimetry devices they could not have known how bad the situation really was. In reality the radiation was much higher than was reported. According to the Chernobyl gallery they were at 300,000 millisieverts per hour which provided a lethal dose in just under a minute. These radiation levels have decreased over time but when the reactor was being sealed they were still quite high, with 28 emergency workers dying from acute radiation poisoning after their part in the cleanup (World nuclear association). But this was not the only effect the radiation had. Due to its high levels thousands of people who were living in Chernobyl were forced to evacuate and leave their homes. Around 350,000 people were forced to flee the poison released from the catastrophe. This was no solution and so something had to be done thus creating the sarcophagus.
The radiation sarcophagus was the emergency structure made to contain reactor four that needed to happen fast and so construction began in June of that year; it lasted 206 days, finally being completed in late November of that year. Its construction required a cooling slab to be installed in order to contain the radioactive magma that had formed from the reactor exploding, as a result of this need 400 coal miners were called in to dig the tunnel underneath the reactor building, one the necessary excavation was completed the next steps were relatively simple first the area around the reactor needed to be cleared of debris and concrete. Second reinforced concrete walls needed to be put up around the perimeter. Third there was the construction of the walls separating reactor 3 and reactor 4. Fourth The cascade walls were constructed sealing the destroyed northern wall. Fifth the turbine wall was sealed. Sixth the high rise buttress wall was constructed. Seven the supports were installed along with the reactor covering, and finally the ventilation system was installed. All of this contemplated the sarcophagus that would seal the reactor under some 400,000 cubic meters of concrete and 7,300 tons of steel (Chernobyl Gallery). And yet all of this was still not enough.
In 1988 soviet scientists revealed a concerning truth the sarcophagus was only designed to last 20-30 years and that the sarcophagus was never intended to be a permanent solution, to make the situation worse in 2010 it was reveille that water was leaking through the sarcophagus, becoming radioactive and then entering the soil underneath the powerplant (Chernobyl gallery). This resulted in a major push for a more long-term solution ultimately the Chernobyl New Safe Confinement was made the new safe confinement was completed in 2016. The design was proposed during 1992 when Ukraine held a summit comparing designs for new containment of the already decaying sarcophagus. Ultimately the British proposal won. The new safe confinement (NSC) Began construction. Some key details about its construction is that it was assembled roughly 300 meters (roughly 984 feet) away from the reactor building in order to keep radioactive exposure to a minimum. It was assembled and now stands at 53 meters tall ( roughly 173 feet) and weighs 9100 tons (Chernobyl Gallery). This has been effective at preventing any more leaks; it along with the 30 kilometer (18 miles) exclusion zone has been effective at keeping people safe.
While the design is robust and effective, it has but one flaw, it won't survive long enough. According to the institute of civil engineers the new safe containment will last for 100 year the issue is that the reactor core itself will remain to be dangerously radioactive for thousands of years with the exclusion zone only being considered possibly safe for habitation in 3,000 years (Chernobyl History), with the core benign much more radioactive than the surrounding area 100 years will simply not be enough to contain the radioactive material for as long as we need it to be contained.
Chernobyl today:
The Chernobyl disaster happened 40 years ago on April 26 1986. In these 40 years many things have changed and many things have emerged. The USSR no longer exists, the disaster has been contained and the radiation is no longer continent spanning . Despite the great strides we've made the Chernobyl disaster has left a looming legacy with its contamination of the exclusion zone being severe enough to warrant the ousting of humans but this has interestingly led to the creation of a nature preserve. This nature preserve is still radioactive above normal levels but that has interestingly allowed scientist to observe natural selection take place this is outlined by the UN “Researchers have found the land surrounding the plant, which has been largely off limits to humans for three decades, has become a haven for wildlife” this has lead to many interesting scientific opportunities to study how life interacts with radioactive environments (Beresford).but we still know that it contaminated thousands greatly affecting their lives.
The Chernobyl power plant is normally available for people to visit but with the war in Ukraine as a result of the Russian invasion they have been shut down as of 2024 CNN said it was the frontline for a while but the fighting has since moved on now CNN says "for the most part, only official delegations and military personnel currently have access to the exclusion zone,” (Vlasova and Gigova). But of course Chernobyl is still dangerous even when there isn't a war going on with the radiation making permanent habitation impossible. Of course this disaster with its long reaching effects had a course change effect in nuclear energy.
Nuclear energy's reputation was not helped by the Chernobyl disaster but some good came of it as a result of the Chernobyl disaster many actions were taken to prevent such actions these involved training operators what to do in case of an emergency, the Chernobyl disaster also caused International Atomic Energy Agency (IAEA), an autonomous agency affiliated with the United Nations to convene a conference in which the Convention on Nuclear Safety was adopted it isa treaty developed in response to the Chernobyl accident in order to increase the safety of nuclear power reactors globally (US Government Accountability Office).
Chernobyl was a true disaster as a result of many bad decisions, design flaws in the shutdown sequence, choosing to ignore safety regulations, and removing control rods beyond the minimum required to be in the reactor to run safely. All of these factors combined into the worst nuclear disaster in history, contaminating massive amounts of land and ruining lives for generations. It is unlikely to ever happen again but we must always remember what happens when we choose convenience over safety
F.B. Brookings loves to hang out with his cat, read a good book or get involved. He dose many clubs like model UN, FBLA, Deca and more so he is always quite busy.
Works Cited
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