I know a fair few folk in this space, at least with in UK
Paul Ingram at CSER (https://www.cser.ac.uk/team/paul-ingram/) and other staff at BASIC (https://basicint.org/) know about cyber security and nuclear weapons (see https://basicint.org/publications/stanislav-abaimov-paul-ingram-executive-director/2017/hacking-uk-trident-growing-threat)
Also Caroline Baylon at the Future Generations APPG has expertise on cyber security at nuclear power plants (https://www.appgfuturegenerations.com/secretariat)
I know a fair few folk in this space, at least with in UK
Paul Ingram at CSER (https://www.cser.ac.uk/team/paul-ingram/) and other staff at BASIC (https://basicint.org/) know about cyber security and nuclear weapons (see https://basicint.org/publications/stanislav-abaimov-paul-ingram-executive-director/2017/hacking-uk-trident-growing-threat)
Also Caroline Baylon at the Future Generations APPG has expertise on cyber security at nuclear power plants (https://www.appgfuturegenerations.com/secretariat)