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Safety Assessment Principles (SAPs)

Our inspectors use Safety Assessment Principles (SAPs), together with the supporting Technical Assessment Guides (TAGs), to guide regulatory decision making in the nuclear permissioning process. Underpinning such decisions is the legal requirement on nuclear site licensees to reduce risks so far as is reasonably practicable, and the use of these SAPs should be seen in that context.


The SAPs provide ONR's inspectors with a framework for making consistent regulatory judgements on nuclear safety cases. The SAPs also provide dutyholders with information on the regulatory principles against which their safety provisions will be judged. However they are not intended or sufficient to be used as design or operational standards, reflecting the non-prescriptive nature of the UK's nuclear regulatory system. In most cases the SAPs are guidance to inspectors, but where guidance refers to legal requirements they can be mandatory depending on the circumstances.

A formal review of ONR's SAPs in 2011 concluded that while no urgent changes were required, the SAPs should nevertheless be updated to reflect both learning from Fukushima and wider changes in the industry since the SAPs were last revised in 2006.

Following extensive work by our inspectors, as well as from other regulators and government departments such as the Environment Agency, the Scottish Environment Protection Agency and the Defence Nuclear Safety Regulator, proposals for an update have were drafted. Recognising that our safety assessment standards are important to the wider nuclear industry, we offered site licence holders, Non-Governmental Organisations and other interested parties an opportunity to comment on our proposals.

We were specifically interested in views on whether the changes adequately addressed:

  • learning from the Fukushima accident;
  • developments in international nuclear safety standards and relevant good practices since 2006.

We also asked that those responding suggested how the text should be amended to take account of their comment, since this helps to reach a common understanding.