One of the early Russian moves during the invasion of Ukraine was to take control of the Chernobyl Nuclear Power Plant (NPP) in February 2022. Currently, the plant is occupied by Russian troops and over 200 workers are being held hostage the plant. The move may have seemed like an odd one, tactically. However, the plant still poses and incredible risk. The plant lost power days ago, it was restored 2 days ago and in less than 24 hours lost power again after Russian occupiers damaged a power line.
The International Atomic Energy Agency (IAEA) monitors nuclear power and materials worldwide. Active, and inactive, power plants and nuclear facilities report their activities and have monitoring for radioactivity that is governed by the IAEA. A second nuclear power facility in Ukraine, Zaporizhzia, is also monitored by the IAEA and has been overtaken by Russian troops. Both facilities stopped reporting data to the IAEA on March 8th and March 9th respectively. Currently, this means the IAEA cannot confirm nuclear materials at the facilities remain contained and under safe control measures.
What is the Danger?
Spent nuclear fuel rods require a cooling measure in order to keep fission in check and ensure there is not another meltdown. Although the facility has been decommissioned since the 1986 disaster, the nuclear materials and fuel rods still exist in the facility and have to be remediated. They are stored in cooling pools that are decades old. Nuclear fuel rods can still react, even after many years, because of the nature of radioactive elements. It is an extremely powerful source of energy, under safe conditions. However, with the power failing the pools are slowly emptying as the heat is dispersed and the water vaporizes.
According to the IAEA in public announcements, the risk is relatively low.
…[the] heat load of spent fuel storage pool and volume of cooling water at #Chornobyl Nuclear Power Plant sufficient for effective heat removal without need for electrical supply — IAEA tweet March 9, 2022
However, in another tweet on March 9, 2022 they also insisted that the power loss “violates key safety pillar” but they see “no critical impact on safety”. Others in the industry corroborate this opinion. Malcolm Grimston, the Senior Research Fellow at the Imperial Centre for Energy Policy and Technology in London provided some insight on rate of decay and the heat produced in his commentary relating to the IAEA’s General Statement. Grimston states
…there are some 20,000 assemblies at the site, each generating an average of the order of 35 Watts of heat…in the event of a complete and sustained loss of power, the water in the cooling pools would only reach around 60C (over several weeks) before heat loss at the surface was sufficient to reach equilibrium — though the water level would obviously have to be kept topped up — and second that even if all the water escaped the maximum temperature that the most active assemblies would reach would be of the order of 300C, well within the normal operating temperature when it was in the reactor and for which its zirconium cladding was designed
It Is Not Just About Fuel Rods
If you consider the IAEA position and the position of some scientists exclusively, you could assume that the situation is relatively safe, in spite of the fact that a loss of power is a violation of the 7 Nuclear Safety pillars. However, there are other concerns. The New Confinement facility that now contains waste in reactor 4 replaced failing concrete and steel structures that had been there previously. If the power is not restored, several elements of the decommissioning processes and ventilation systems are in danger of failing. Clair Corkhill, Chair in Nuclear Material Degradation at the University of Sheffield, cites the concern is not only heat but radioactive isotopes. The pumps failing with power loss mean that no fresh, cool water is being supplied, consequently this results water evaporation and potentially “contaminating the building [with] low levels of radioactive isotopes”.
She also has a concern that the occupation will derail the decommissioning program whose focus is rendering the site safe. After reactor 4’s violent meltdown in 1986, the site spewed radioactive materials for miles. This material degrades at a such a slow rate, naturally, that it would take millions of years for the area to be safe without decommissioning intervention. The exclusion zone has only recently allowed for limited tourism that is monitored for radioactive exposure. The New Confinement facility shrouds the most fatal areas. Beneath that facility, robots and humans work together to decontaminate the plant in layers, safely.
Ukrainian officials have requested safe passage to repair the power again. The workers remain hostages at the facility that now has no ventilation, fire impairment system or environmental controls. The State Service of Special Communications and Information Protection of Ukraine has been tweeting to convey the risks to the world. The Zaporizhzia facility remains under Russian occupation. Both facilities remain off the radar for data and communication with the IAEA.