It is highly unlikely that Russia would purposefully target Ukrainian nuclear reactors with the intention of damaging them, both because of the potential resulting public health consequences for Russia and the loss of critical infrastructure that occupying forces would wish to control. However, this does not mean these facilities will avoid danger.
While nuclear power plants always have safety and security measures, these are generally intended to defeat attacking terrorist groups and aircraft strikes, not invading armies and bunker busting missiles. Munitions do go astray from their intended targets, and local commanders may decide that an attack is justified despite their orders.
Furthermore, these plants depend on external factors for their safe operation – even if they are shutdown to prevent an accident, they still need to draw power from electrical grids to maintain nuclear materials in a safe state, which may be compromised. Plant workers may also find it more difficult or dangerous to travel to the site, preventing safety critical operations from being carried out.
Nuclear power has numerous advantages, but plants are not intended for conflict zones – it would be far better for Russian forces to avoid Ukraine’s nuclear plants altogether rather than attempt to take control of them. Russian military planners must ensure these sites are not targeted or hit by mistake in the fog of war. Regardless of the outcome of the fighting, whoever is in control will have a responsibility to ensure that these reactors are safe and secure, and do not endanger the local population, neighbouring countries or the wider world.