The battle against terrorism has been more complicated since 9.11 suicide attack. Different from international wars, the targets of terrorists are not limited to the army and related facilities. Any areas which are deemed as influential are subjected to bomb.
It is easy to imagine that terrorists will try to destroy a nuclear power plant to do damage to the foe. It is unlikely that the plant explodes when ignited, but if it is crippled, serious problems will occur.
As well as physically destructive activity, cyber-attack is also to be expected. Most of the modern machines are connected to the internet, and it means there is a way for terrorists to intrude. We sometimes hear the news of official websites being hacked temporarily.
Recently, Nuclear Threat Initiative examined several countries to check the vulnerability of their nuclear facilities against cyber-attack. As a result, 24 nations were identified as not being protected properly.
International Business Times: Nuclear power plants in 20 countries 'do not have any protection' against cyberattacks
Fortunately, Japan is said to be strong against cyber-attack, as well as the UK. After Fukushima Daiichi atomic power plant accidents, relevant professionals were keen to strengthen the ability of damage control.
I hope the countries ranked as vulnerable also equip secret resolutions against cyber-attack. These solutions are usually concealed from outsiders. Otherwise terrorists can break the shield according to the information. In the “Star Wars” series, the Empire is repeatedly defeated by the resistance with its weakness penetrated. The real world is different, I believe.