The Office for Nuclear Regulation has published a revised version of its Safety Assessment Principles (SAPs). This revision of the SAPs was prompted by the Chief Inspector’s report on the implications of the Fukushima accident for the UK nuclear industry. Although the Chief Inspector’s report concluded that there were no significant gaps in the 2006 safety assessment principles, it nevertheless recommended a review to ensure that lessons learned were incorporated. That review is now complete and the SAPs revised accordingly. We have also taken the opportunity to ensure compatibility with recent work by the International Atomic Energy Agency (IAEA), and the most recent version of the WENRA reference levels.