1In the context of fuel cycle facilities, the licensing documentation (or safety case) is a collection of arguments and evidence in support of the safety of a facility or activity. This will normally include the findings of a safety assessment and a statement of confidence in these findings. ‘Safety case’ is the same as ‘licensing documentation’ and these titles are used interchangeably in this Safety Guide.

2See paras 6.4–6.9, V.1 and III–10 of NS-R-5 (Rev. 1) [1].

3The mass margin is: the difference between the safety limit (the maximum amount allowed within the operational limits and conditions) and the subcritical limit (effective neutron multiplication factor k_eff < 1, often taken as k_eff < 0.95).

4In this context, acceptability may include regulatory limits and considerations of the optimization of protection.

5Design extension conditions are postulated accident conditions that are not considered for design basis accidents, but that are considered in the design process for the facility in accordance with best estimate methodology, and for which releases of radioactive material are kept within acceptable limits.

6Emergency procedures are part of overall emergency arrangements to be established in accordance with the guidance in paras 4.126–4.128.