Chernobyl continues to pose a major risk even four decades after the disaster; what would happen if the NSC failed and the old sarcophagus was breached?
The Chernobyl Nuclear Power Plant has long symbolized the worst nuclear disaster in history, and its fourth reactor—the shattered epicenter of the 1986 explosion—still contains a significant amount of radioactive material. Today, the world’s attention has returned to Chernobyl: according to Ukrainian authorities, a Russian drone struck the protective shell (denied by Russia, which claims it was a Ukrainian provocation) – the so-called New Safe Confinement (NSC) – which covers the remains of Reactor No. 4, causing a fire. Although the fire was quickly extinguished and, according to the International Atomic Energy Agency (IAEA), no increase in radiation levels was detected, the incident was a reminder that this enormous steel structure was never intended to be a military bunker. It raises the question: what could happen in a worst-case scenario—if stronger strikes caused a serious breach? How real is the threat of radioactive release for the local environment and for Europe?
What follows is a deeper look into the risks posed by a possible direct attack on Chernobyl today, how the New Safe Confinement was built, its characteristics, and what the consequences of more severe damage could be. Along the way, it’s worth mentioning the Zaporizhzhia Nuclear Power Plant, which—with its recently active reactors—may be an even more dangerous target. Still, most of this analysis focuses on the “heart of darkness” – Reactor No. 4 at Chernobyl, covered by the NSC.
Understanding the “New” Sarcophagus and Its Vulnerabilities
Thirty-nine years after the Chernobyl disaster, the area around Reactor No. 4 still contains highly radioactive remnants. In 1986, Soviet authorities hastily erected the original “sarcophagus”—a concrete structure designed to prevent further spread of radioactive dust and fuel debris. However, because it was built under extreme pressure and conditions, over time it showed signs of structural failure, risking a re-release of radioactive contamination.
To prevent this, the New Safe Confinement (NSC) was conceived and completed in 2016. This massive steel arch, over 100 meters tall, was gradually moved over the old sarcophagus. Its main purpose: to provide safe and stable conditions for the next 100 years, enabling the step-by-step dismantling of the original structure and removal of the most dangerous molten core material and reactor debris. The structure is indeed impressive—it can withstand extreme weather (strong winds, earthquakes, heavy precipitation) and prevents water intrusion and the dispersal of radioactive dust.
However, despite its robustness, the NSC was not designed as a military fortification capable of withstanding direct attacks. Most nuclear safety models are based on the assumption that nuclear plants won’t be military targets—when the NSC was designed, no one anticipated war in the area of a long-decommissioned facility. Also, even modern reactors, with their reinforced concrete domes, are not built to withstand missile or cruise missile strikes, only industrial accidents, earthquakes, or lighter aircraft crashes. According to some analyses, the NSC can withstand hurricanes and severe storms, but it is significantly more vulnerable to targeted attacks.
This was just confirmed, albeit on a smaller scale: according to Ukrainian reports, a drone—allegedly launched by the Russian military—struck part of the NSC roof, penetrated it, and caused a fire. Metal and plastic insulation materials burned, but luckily the inner layer wasn’t breached, which would have led to direct contact with radioactive debris. The IAEA confirmed there were no signs of increased radiation levels, but photos of the damage show that even a small drone-borne explosive caused serious harm. What would happen if larger munitions, long-range artillery, or cruise missiles were used instead?
Worst-Case Scenario – What If Russia Is Right and Someone in Ukraine Is Trying to Stage a Major Provocation?
Breach Possibilities and Radiation Contamination Consequences
Whenever a new “Chernobyl incident” is mentioned, experts typically outline several levels of damage:
a) Minor damage, no direct breach
This is the current scenario: a hole in the NSC’s outer shell, fire quickly brought under control, and radiation readings showing the inner protective layer remained intact. In such a case, no radiation leaks out, and the consequences are more financial and infrastructural than environmental or health-related. Still, repairing the roof requires complex work in a high-radiation zone but does not pose a regional catastrophe.
b) Larger breach, partial penetration
Imagine a scenario where higher-caliber projectiles strike the structure repeatedly, or an explosion inside the NSC causes a major crack in the roof or side panels. Workers (or military personnel in the area) would be exposed to direct radiation, and dispersal of radioactive dust would be inevitable, especially if the original 1986 concrete sarcophagus was also damaged. This could cause local contamination and raise airborne particles, spreading depending on wind. Danger to the surrounding area (within several dozen kilometers) could be significant—though still not on the scale of the original 1986 disaster, when the reactor burned, the graphite core ignited, and massive amounts of radioactive debris were released into the air for weeks.
c) Catastrophic collapse of the NSC and old sarcophagus
The worst-case scenario involves total destruction—e.g., several powerful bombs or missiles fully collapse the NSC along with the decaying structure beneath. This would expose a massive area still containing hundreds of tons of radioactive material. While it wouldn’t trigger a nuclear chain reaction (the reactor was destroyed nearly 40 years ago), it would act as a giant “dirty bomb.”
Estimates suggest up to 95% of the original nuclear fuel remains in the reactor ruins. Breaching it would release isotopes like cesium-137, strontium-90, plutonium-239, and americium-241. It wouldn’t cause a nuclear explosion but rather a mechanical dispersal of radioactive material. The extent would depend on fires (which could carry particles higher into the atmosphere), wind, and rain. Even if this “new” cloud wasn’t as large as in 1986, such destruction would again severely contaminate Eastern Europe—especially northern Ukraine and parts of Belarus.
Short-lived isotopes (like iodine-131) have long decayed, but long-lived cesium-137 (half-life ~30 years) and transuranic elements like plutonium and americium still pose a serious environmental and health risk.
Local and Regional Effects of a New Disaster
While the brunt of radiation exposure would hit the plant site and its 30-kilometer exclusion zone (where few live permanently, though adventurers visit), renewed dispersal of radioactive dust would make access even harder. In the worst case, firefighting and emergency response would take place inside a radioactive cloud. Workers involved in containment would face high radiation doses.
What about the rest of Ukraine and abroad? In 1986, radioactive fallout was recorded across Europe, reaching Scandinavia and the Balkans. A similar spread could happen again: if an explosion lifts particles high into the atmosphere, they could travel hundreds of kilometers. Precautions around milk and vegetable consumption could return, as well as warnings for children to stay indoors during cloud passage.
Of course, this depends on the scale of destruction. With partial damage and limited release, the impact would mostly be local. To repeat the mass contamination of 1986 would require truly massive destruction. Still, history shows that the “unthinkable” can sometimes become real. That’s why the IAEA once again condemned any military attacks on Chernobyl, warning that “everything happening there risks spilling beyond the country’s borders.” One issue with the IAEA is its (not openly declared) policy of rarely naming the party responsible for such incidents, even though they likely know more than anyone. This allows both sides to use “nuclear threats” as tools for possible “false flag” operations.
Expert Views and Official Positions
The International Atomic Energy Agency (IAEA) clearly states that no nuclear plant or contaminated site should ever become a battlefield. Even the mere possibility of damage to the NSC—the largest mobile structure ever built—has prompted the IAEA to maintain observers on-site and continuously monitor radiation levels. In the recent drone attack, experts confirmed no radiation leakage—but they admit that was more due to luck (a relatively small explosion) than to actual NSC resistance to military attacks.
Ukrainian nuclear engineers have long warned that some old waste storage sites and the NSC itself are “soft targets” lacking additional concrete barriers. Western analysts in 2022 and 2023 reported that even a relatively small explosion at a critical point could disperse nuclear material long dormant in these “bunkers.” No one wants to see another 1986-style radioactive cloud, but heavy shelling or bombing could trigger a scenario worrying for the entire continent.
On the other hand, it’s emphasized repeatedly that Reactor 4 is shut down and that there’s no risk of a spontaneous nuclear chain reaction (as would exist with an active reactor). As noted before—it cannot result in a nuclear explosion.
What Lies Beneath the Arch? The Evolution of Reactor 4 and Its Remnants
Inside the original sarcophagus (now under the NSC) lie hundreds of tons of molten fuel, which after the 1986 explosion formed solid lava-like masses mixed with graphite, concrete, and other materials. The most famous example is the “Elephant’s Foot”—a semi-spherical mass of molten fuel that was extremely radioactive in the early years. Its activity is now lower, but it still contains transuranic isotopes with half-lives of thousands of years. Occasionally, spikes in neutron radiation are detected in deep crevices, showing that microfission reactions still occur. These are not strong enough to “reactivate” the reactor, but they demonstrate the potential for unforeseen situations.
Because of these hotspots, the NSC was designed to enable dismantling the old sarcophagus from the inside, step by step, to remove the remaining fuel. But this task is extremely complex—requiring sophisticated technology and absolutely safe working conditions. The plan was to begin initial removal phases in the 2020s. After the war broke out, these efforts have been slowed or halted. As a result, the mass of highly radioactive material remains “permanently” under the steel arch until stable conditions allow full decommissioning. While everything remains undisturbed, the danger is mostly contained—but any serious strike could destabilize this fragile balance.
Why Is the Zaporizhzhia Plant Potentially Even More Dangerous?
It is often emphasized that the Zaporizhzhia Nuclear Power Plant, the largest in Europe, is actually a much more dangerous “ticking time bomb.” Unlike Chernobyl, whose reactor melted down in 1986, Zaporizhzhia recently had six active reactors. They are now officially shut down but still contain fresh and spent nuclear fuel that must be cooled. If the cooling system were damaged or a projectile penetrated the reactor vessel or spent fuel pools, it could lead to core meltdown. Unlike Chernobyl’s old reactor, these modern reactors hold even larger amounts of radioactive material and highly radioactive cooling water.
Because of this, many experts believe that a catastrophe at Zaporizhzhia could surpass Chernobyl—due to potential hydrogen explosions like in Fukushima (2011), and the release of short-lived but very dangerous isotopes like iodine-131, which no longer exists in significant amounts at Chernobyl. In short, if Chernobyl is a “repository of old contamination,” Zaporizhzhia is an “active modern system” requiring continuous cooling and structural integrity.
That said, Chernobyl remains dangerous—the threat is just of a different kind. While Zaporizhzhia is a potential meltdown hotspot, Chernobyl is a massive storage of hazardous materials that remain contained unless disturbed by something like military destruction.
What If the Worst Happens?
The history of conflict shows that worst-case scenarios do sometimes come true. In the event of a direct attack on Chernobyl, both local and global consequences must be considered—from the workers who would be the first exposed to radiation, to the international community that would need to organize a response. In case of major release, control points would likely be re-established, exclusion zones set up, and international radiation-monitoring teams mobilized. We might see attempts to “cover” the ruins with sand, combat fires producing radioactive smoke… It would all resemble 1986—except this time in an active war zone.
Conclusion: Chernobyl Remains Dangerous
It is worth mentioning that international rules for the protection of nuclear facilities during wartime are not sufficiently developed or strictly enforced, even though certain conventions exist. Experts and numerous non-governmental organizations believe that stricter regulation is necessary: in principle, attacks on nuclear installations should be as unacceptable as the use of chemical weapons. However, the reality of war often disregards such “rules.”
One proposed solution is the establishment of a “nuclear safety zone” around key power plants, especially Zaporizhzhia, but also Chernobyl. The IAEA has repeatedly proposed a similar cordon sanitaire, yet an agreement between Kyiv and Moscow remains elusive. The logic behind avoiding military operations in the Chernobyl area is simple: the strategic value of such a location is relatively low, while the risk of a radioactive incident is enormous for all parties involved.
The Chernobyl reactor may be “asleep” under steel, but it has never fully disappeared. In a situation where armed conflict reaches such places, there remains a strong reason for concern across Europe—and beyond. Unfortunately, this is the reality of the year 2025, where any sense of safety is merely an illusion as long as explosive devices fly over one of the world’s most notorious nuclear “tombs.”
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