Dr. Conca reports says ... No. Nuclear plants are still mostly analog and not connected to the Internet. On purpose. Hackers have been penetrating the computer networks of companies that operate nuclear power stations and other energy facilities, as well as manufacturing plants in the U.S. and other countries. But hackers can not affect a nuclear power plant operations or safety systems. They can hack some business, personnel and other non-essential files, which may be embarrassing and costly, but not dangerous. These reactors are truly operational islands wholly disconnected from the Internet.
The origins of the hackers are not known, although a joint report from the DHS and the FBI suggests many of the hackers are backed by governments like Russia. In a joint statement, the government agencies said, that there is no indication of a threat to public safety, as any potential impact appears to be limited to administrative and business networks. American nuclear plants are one of the best protected of all systems from possible cyber threats. The safety and control systems for our nuclear reactors and other vital plant components are not connected to business networks or the Internet.
We learned a lot from Stuxnet, the malicious computer worm that substantially damaged Iran nuclear program. Unlike other industries, the nuclear power industry conducts regular briefings, and receives quarterly classified briefings on cyber and physical threats, with the FBI and the DHS to discuss threat assessments, to strategize on guarding against them and to maintain situational awareness.