What you need to know about an (im)possible accident at Zaporizhzhia NPP
A recurrence of Chornobyl doesn't threaten Ukraine. But that's where the good news ends.
The topic of nuclear blackmail and a possible accident at Zaporizhzhia Nuclear Power Plant, briefly overshadowed by the turmoil caused by Wagnerites in russia, has once again come to the fore. As stated by the head of the Defence Intelligence, Kyrylo Budanov, in an interview with The New Statement, today a plan for the sabotage of the station by the russians has been developed and approved.
Next to four of the six power units of the nuclear plant, the occupiers have placed equipment with explosives, in addition, the accident can be provoked remotely – by increasing the voltage on the power supply line to the station. The command for the explosion can be given as the situation worsens for russian troops on the front – in this case, the exclusion zone will serve as a natural obstacle for the advancement of the Armed Forces of Ukraine. Also, the accident may be a preventive measure to freeze the front and halt the offensive operation. "The situation has never been as serious as it is now," General Budanov added.
Almost simultaneously with such a statement, President Volodymyr Zelensky spoke out, lamenting that the world criminally pays little attention to the prospects of a new nuclear disaster. Without worldwide circumstances, the situation looks like this: "The largest nuclear power plant in Europe and the ninth in the world has been captured by a nuclear terrorist who has replaced safety systems and their power sources, taken operational personnel hostage and is blackmailing the world with a nuclear disaster."
In the opinion of representatives of the International Atomic Energy Agency (IAEA), information about the mining of the Zaporizhzhia’s cooling pond is not confirmed, although the station has been mined around the perimeter and in some places inside.
Mind analysed: what you need to know, being half a step away from the second accident at a nuclear power plant in Ukraine's history.
Are discussions about the threat of a provoked accident at ZNPP a negotiating tactic to increase stakes, or a real risk of terrorism? The Zaporizhzhia plant is a potentially vulnerable platform for russian nuclear blackmail, and the russians have all the levers of influence on the situation. The world's tepid response to the attack on Kakhovka Dam in the form of "great concern" has opened up the possibility for further escalation. So yes, nuclear sabotage is a reality.
But weren't such ultra-dangerous facilities built from the outset taking military risks into account? Yes, both nuclear-generating stations and hydroelectric stations are built with a margin of strength. However, as we see in the case of the Kakhovka Dam, it proved insufficient. Also, any "insurance" measures are calculated for external factors, but not for coordinated sabotage from within.
The existing safety format of the Zaporizhzhia NPP's units is designed for normal operating conditions and does not take into account combat operations in close proximity to the station's industrial site.
What are the consequences of an attack for the aggressor itself, and could they be a deterrent? Considering the tepid world reaction to the Kakhovka attack, one can hardly count on decisive punitive measures if something similar is applied to the ZNPP.
On the other hand, a nuclear threat is a risk of a different order than a local Ukrainian hydrological disaster, even considering its large-scale ecological consequences for the Black Sea basin and European rivers.
The world draws parallels – possibly not entirely accurate – with Chornobyl. A minimally unfavourable wind rose can cause panic in the EU, which will require a harsh response from these countries' governments. The West understands this, so a draft resolution has been submitted to the US Senate that equates russia's use of nuclear weapons to an attack on NATO countries. This will also apply to undermining a nuclear power plant.
If an explosion occurs: a possible scenario. Let's suppose an explosion at ZNPP did happen. According to Professor Ivan Kovalts from the Igor Sikorsky Kyiv Polytechnic Institute's Physico-Technical Institute, this accident belongs to the 7th class in terms of emissions volume according to the International Nuclear and Radiological Event Scale (INES). This is the maximum level on the nuclear events scale. The same accident class includes both Chornobyl and the Fukushima-1 atomic station accident. But in the considered scenario, the equivalent volume of emissions is approximately one and a half times less.
However, as the scientist specifies, this is a conservative, i.e., the worst-case scenario. It assumes the maximum distance from the emission site at which the annual effective dose for one-year-old children will exceed 10 mSv, and this distance was 540 km.
So, is it a new Chornobyl if the accident class is the same? No. Even Fukushima-1, which was operational at the time of the accident, did not become a new Chornobyl in terms of the scale of the consequences. And the situation at ZNPP is somewhat more favourable than in Japan in 2011.
The explosion in Chornobyl occurred when the plant was intensively operating. At the same time, a large number of radioactive elements were directly in the water – that's why so many of them were thrown into the atmosphere and caused such damage as a result of the steam explosion.
The Zaporizhzhia station, if it were to be blown up in a shutdown state, would not be able to generate the same effect. Uranium can't be dispersed over a large distance, and it's poorly absorbed by plants – meaning it will stay where it falls, on a relatively small area, and contamination won't spread.
What is the main threat? ZNPP receives the necessary cooling water from the reserve of the discharge channel of the adjacent Zaporizhzhia Thermal Power Plant (ZTPP). It is separated from the reservoir, the water level of which dropped after the serious damage to the dam on 7 June.
Water from this channel is used to supply water to the ZNPP's spray pools, which cool six shutdown reactors and a spent fuel storage. This water also maintains a full separate large cooling pond at the plant, mainly compensating for evaporation.
As these structures and buildings are located around the perimeter of the ZNPP site, they are primarily prone to the influence of destructive factors, both with direct hits and the impact of shock waves from possible explosions.
Therefore, even considering, for example, that the spray pools are physically separated for each channel of the safety system of a specific power unit, the impact of a shock wave from an explosion could lead to the destruction of all cooling structures or buildings related to that power unit.
In addition, ZNPP depends on a single operating 750-kilovolt (kV) power line for external electricity necessary for reactor cooling and other important nuclear safety functions. Before a full-scale invasion, there were four such lines. There is not enough backup power in case the 750 kV mainline is disconnected.
What countermeasures will be taken if the base accident scenario is realised?
Iodine prophylaxis will not be needed.
The maximum length of the shelter zone will be approximately 200 km.
The maximum length of the evacuation area – 20 km.
The maximum size of the zone where the caesium-137 fallout will exceed 400 kBq/m², which corresponds to the lower limit of justifiability for permanent resettlement, will be 170 km.
The author of this model emphasises that the scenario under consideration is conservative in terms of both the volumes of emissions and meteorological conditions. In the event of a real emergency, the consequences could be much less.
In simple terms, will there be a need for a large-scale evacuation of a large part of the country? No.
In the worst schedules, Kyiv, for example, will need neither sheltering, iodine therapy, let alone evacuation.
The annual effective dose for the population of the capital will be less than 1 mSv.
Even Zaporizhzhia falls within safety standards and is not subject to evacuation.
Can these effects multiply? Yes, if the fifth power unit is brought to minimal controlled power. Simply put, it would require a repeat of Chornobyl – start the station and provoke a thermal explosion to maximise the effects. The likelihood of this happening is very low. But not zero.
Even if excesses can be avoided, what global consequences will the nuclear threat lead to? The mere fact of blackmail by undermining ZNPP, the practical implementation of which will most likely be avoided, will lead to colossal changes in the industry in the long term.
Russia’s aggressive actions at the ZNPP site provoke a review of existing countermeasures against military and terrorist threats at similar facilities. The situation has shown that these risks need to be taken into account both at the design stage and at all stages of licensing and operation of new facilities. Moreover, it is necessary to strengthen the protection of critical infrastructure objects and introduce parallel capabilities for remote counteraction to sabotage.
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