This paper analyses the differences in nuclear safety regulation between the USA and two European countries, France and the UK, using ecological modernisation (EM) as a theoretical framework. The EU aims to apply the precautionary principle to nuclear safety regulation. This may encourage greater public acceptance of nuclear risks which will benefit the nuclear industry economically through allowing continued operation and deployment. This may fit in with EM's discourse favouring environmental regulation that increases economic efficiency. However, this is a weak version of EM since it involves negotiations with the industry rather than a ‘strong’ version of EM involving engagement with leading environmental NGOs who wish to avoid nuclear power altogether in favour of renewables. By contrast, the USA's nuclear safety regulation is constrained by adherence to cost benefit analysis and not the precautionary principle which is associated with EM. The Nuclear Regulatory Commission is dominated by political appointees in its leadership. Attempts to strengthen nuclear safety regulations are often opposed by Republicans who argue from a general position that stricter environmental regulations involve major increases in industry's costs. However, this can lead to increased public argument about the regulations and resulting regulatory uncertainty may, paradoxically, increase regulatory costs.