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| Fig. 1: All six reactors at Zaporizhzhia Nuclear Plant. (Source: Wikimedia Commons) |
The Zaporizhzhia Nuclear Power Plant is the largest nuclear power plant in Europe. [1] The Russo-Ukrainian War has raised grave concerns about the potential for a nuclear catastrophe at the plant. This paper will explore and analyze the causes of dangerous scenarios that can arise from the ongoing conflict.
The Zaporizhzhia Nuclear Power Plant was constructed between 1980 and 1995. It has six Soviet-designed VVER-1000 V-320 water-cooled and water-moderated reactors. [2] A 2017 report to the International Atomic Energy Agency showed that the plant had 3,354 spent fuel assemblies at the dry facility and around 1,984 assemblies in water pools - a total of more than 2,200 tons of nuclear material excluding the reactors. [1] The plant was captured by Russia in March of 2022, with the Ukrainian staff still remaining on site. [1] Both sides have accused each other of shelling buildings and even power lines that are essential to cooling. [3] On September 12, 2022, the last of the six reactors was placed in cold shutdown. [3] A cold shutdown is when the reactors temperatures are below boiling point but electrical pumps moving water through the reactor core are still running in order to cool the fuel.
The containment building, made of thick, heavily reinforced concrete is unlikely to be breached by any artillery or missiles. [4] The greatest concern would be a loss of power to the reactors, with the back-up generators also failing, leading to the fuel melting. Since all six reactors are in cold shutdown, the amount of power needed to cool them is significantly less than before, meaning that should there be a loss of power, the generators should be able to handle it. Each generator currently has a fuel inventory to last 10 days. [5] After these 10 days, the plant must receive new fuel supplies - current conditions may make fuel delivery difficult.
Another point of concern is the spent fuel. If the plant loses its supply of water, the spent fuel in the water pools will no longer be able to be cooled. The loss of water supply could occur due to damaged water pipelines, which need not necessarily be at the plant, but could be in the surrounding region as well. A loss of water cooling would also affect the reactor cores. A loss of cooling would result in rapid heating, a fire, and potentially an explosion that would release radioactive material into the environment, similar to the Chernobyl disaster. [6] The amount of radioactive material that would be released is unclear and would depend on the severity of the explosion. Modeling of VVER-1000 reactors has shown that without active cooling, there are just 20 hours before the heat rises enough to make explosions inevitable. [7] If the loss of water results from a broken pipeline, 20 hours may be too few to locate the broken pipeline and fix it.
The most dangerous concerns to the Zaporizhzhia Nuclear Power Plant are the backup generators failing or the plant losing its water supply. The latter is quite plausible given the amount of artillery and bombs that the area is currently exposed to. Both concerns lend themselves to the loss of cooling at the plant. Unless cooling were to be restored within 20 hours, a tragic accident would likely unfold. There is no precedence for a nuclear facility operating and fueled in an active war zone. [1] If something were to go wrong, contestation over the plant and the region further complicates and likely slows down any response. Ideally, the plant and the area around the plant be made a demilitarized zone, with both sides taking precautions to ensure its safe operation.
© John Finkelman. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "A Disaster Is Looming at a Huge Ukrainian Nuclear Power Plant," Washington Post, 12 Aug 22.
[2] G. Faulconbridge, "Explainer: The Zaporizhzhia Nuclear Power Plant: Who Controls It and Why Is It Important?" Reuters, 21 Nov 22.
[3] F. Murphy, "Explainer: The Zaporizhzhia Nuclear Power Plant's Shutdown," Reuters, 12 Sep 22.
[4] D. Bilefsky et al., "U.N. Experts Head to the Zaporizhzhia Facility on a Risky Mission After Weeks of Ralks," New York Times, 29 Aug 22.
[5] "Nuclear Safety, Security and Safeguards in Ukraine," International Atomic Energy Agency, September 2022.
[6] M. Joshua, "The Chernobyl Disaster," Physics 241, Stanford University, Winter 2018.
[7] P. Tusheva, "Modelling and Analysis of Severe Accidents for VVER-1000 Reactors," Helmholtz Zentrum Dresden Rossendorf, HZDR-025, 2012.
