All the alarms went off this Wednesday when the Ukrainian authorities warned about the consequences of the ‘blackout’ suffered at the Chernobyl nuclear power plant; however, the experts send a message of calm and affirm that the situation is not so critical.
Next April will be the 36th anniversary of the Chernobyl nuclear disaster. An old fear that the war between Russia and Ukraine has revived in recent weeks, especially after Vladimir Putin‘s troops invaded the facilities and remained in Russian hands. At that time, the Ukrainian government already warned of the danger of the situation, warning of a new nuclear catastrophe. Yesterday, the Executive launched new alarm messages, reporting the power cut and a possible radioactive leak if the problem is not fixed “immediately”, calling for a ceasefire.
Shortly after, the International Atomic Energy Agency (IAEA) lowered the tension stating that it does not have a “critical impact on the safety” of the plant
, although he was concerned about the consequences that the conflict may have on the 15 reactors of 5 active nuclear facilities that are scattered throughout the Ukrainian territory. But what real danger exists for a nuclear catastrophe to be triggered again in Chernobyl? And for the rest of the plants? Could we be facing a new and dangerous scenario?
Chernobyl: inactive, but not abandoned
Although no longer a working power plant, Chernobyl was never fully abandoned. In fact, even after the disaster, which affected reactor four, reactors one, two, and three continued to function. It was not until the year 2000 when the last one was closed. And today, the facility still requires constant management, with around 2,400 employees working there, including scientists, technicians, cooks, doctors, and other support staff, as well as members of the National Guard.
“Routine activities, maintenance, and repair of systems and equipment of the Chernobyl nuclear power plant facilities, which must be carried out by day staff, have not been carried out since February 24, 2022, due to occupation. In addition, the activities to be carried out with the participation of the contracting organizations are not carried out, ”said the State Inspectorate for Nuclear Regulation of Ukraine (SNRIU) in a statement, who ensures that these operators have not rotated and slept on the premises since the takeover by the Russian army.
The critical point, the fuel used to trigger the fission processes, has not been in the reactors for more than two decades, so the heat, which is what would activate the reaction, is relatively low. Specifically, it is found in cooling pools that have an electrical power system that is mainly connected to the Ukrainian network. With the cut, energy now depends on internal diesel generators that have autonomy of several days, and that feeds the electricity supply in exactly the same way. “In other words, the danger is extremely low, as low as it was a few weeks or a few months ago,” explains Luis Enrique Herranz Puebla ., of the Department of Energy, Nuclear Safety Unit, of the Center for Energy, Environmental and Technological Research (Ciemat).
But what would happen if that diesel fuel ran out? The expert affirms that “the filtering capacity of the water would be lost” and, likewise, “the capacity to cool that water”, but that in such a case, there would still be “a temporary margin of days, perhaps weeks, before a significant increase of radioactivity in the environment of the facility.
“The stress tests carried out after Fukushima showed in 2012 that in the face of loss of cooling, the pool would not exceed 70ºC. The fuel is designed to work at more than 300ºC, so its integrity would not be affected, “explained Alfredo García, reactor operator and supervisor, through his Twitter account, who stated that even so, the loss due to evaporation could compensate with other means, such as the assistance of fire trucks.
If in the worst case, this scenario were to occur, the consequences would be far from the same as in 1986: after two decades of inactivity, the most dangerous radioactive isotopes, such as I-131 (iodine), have almost completely disappeared, while other isotopes, such as Cs-137 (cesium), have reduced their incidence very significantly. “In short, the potential emissions of radiologically hazardous agents will be drastically lower than in the case of freshly extracted fuels from the reactors.”
When asked if these hypothetical emissions would threaten our country, the experts agree: the probability that amounts dangerous to the environment or public health will reach Spain “is extremely low.” “Of course, the ideal would be to recover the external electricity supply through the external lines that reach the facilities, but in the current circumstances in Ukraine, it may be easier to feed the diesel generators,” says Herranz Puebla.
A Chernobyl is another nuclear power plant?
While the risk at Chernobyl is relatively low, eyes now turn to the country’s five other active nuclear power plants. In fact, in the largest of all, Zaporizhzhya -which has six reactors- a fire was recorded last week in one of the adjoining buildings of the facilities as a result of the impact of a missile. «The fire, suffocated by the personnel of the facilities, has not affected its operation. No variations in radiation levels have been observed either,” the Nuclear Safety Council (CSN) said in a statement.
“According to the information provided by the SNRIU, the operation of unit 1 of the plant has been interrupted and units 2 and 3 have been disconnected from the network and the cooling of these nuclear facilities is being carried out. Unit 4 continues to operate with a power of 690 MW, just over 60% of its capacity, to guarantee a safe source of electrical energy for all the security systems on the site. Units 5 and 6 are stopped and in the cooling process. The cooling of nuclear fuel in the power units of the Zaporizhzhya NPP is guaranteed by the electrical supply systems provided for in their design in accordance with the requirements of the procedures for safe operation,” it was reported at the time.
However, the risk of another Chernobyl in one of these plants grew among the world population. Could a similar event occur? “From a safety point of view, the plant’s reactors have characteristics that are very similar to those in the West and very different from those of the Chernobyl graphite-moderated boiling water reactors (RBMKs).», they affirm the CSN. Herranz Puebla agrees: «Many things were learned from that tragedy and the direct consequence was the increase in safety in all the world’s nuclear power plants, although Chernobyl was closely associated with the use of a nuclear power plant of defective design in carrying an experiment ‘out of design’ and without any observance of the established protocols, even for this type of plant. The design of Ukrainian nuclear power plants today is radically different from that of Chernobyl.”
Fortunately, in more than three decades, and despite the consequences that are still palpable today, society is more prepared so that an event like Chernobyl does not happen again. Different experiments have been carried out to find out the limit and the possible mishaps in these installations. «To give an illustrative example, experiments carried out in the North American desert, showed that the collision of a medium-sized aircraft against a containment enclosure at speeds of about 700 km/h would produce negligible effects on the integrity of the containment enclosure» . At the moment, it seems that the threat of a nuclear catastrophe in one of these plants is much more unlikely compared to the human barbarity of war.
