1In general, "safety assessment" is the assessment of all aspects of a practice that are relevant to protection and safety. For an authorized facility, this includes siting, design and operation of the facility. Safety assessment is the systematic process that is carried out throughout the lifetime of the facility or activity to ensure that all the relevant safety requirements are met by the proposed (or actual) design. Safety assessment includes, but is not limited to, the formal safety analysis.

2The term ‘radiation risks’ refers to:− Detrimental health effects of exposure to radiation (including the likelihood of such effects occurring).− Any other safety related risks (including those to ecosystems in the environment) that might arise as a direct consequence of:• Exposure to radiation;• The presence of radioactive material (including radioactive waste) or its release to the environment;• A loss of control over a nuclear reactor core, nuclear chain reaction, radioactive source or any other source of radiation.

3The list of facilities and activities given here has been compiled from the lists provided in the Fundamental Safety Principles [1] and in the Safety Requirements publication on the Governmental, Legal and Regulatory Framework for Safety [2].

4Requirements for transport related activities are established in Regulations for the Safe Transport of Radioactive Material [3].

5The standards of the American Society of Mechanical Engineers are examples of industrial standards.

6The term ‘possible radiation risks’ relates to the maximum possible radiological consequences that could occur when radioactive material is released from the facility or in the activity, with no credit being taken for the safety systems or protective measures in place to prevent this.

7Safety functions are functions that are necessary to be performed for the facility or activity to prevent or mitigate radiological consequences of normal operation, anticipated operational occurrences and accident conditions. These functions can include control of reactivity, removal of heat from radioactive material, confinement of radioactive material and shielding, depending on the nature of the facility or activity.

8The ‘site’ is taken to mean the location of the facility or the location where an activity is conducted. [5]

9A ‘cliff edge effect’ is an instance of severely abnormal conditions caused by an abrupt transition from one status of a facility to another following a small deviation in a parameter or a small variation in an input value. [5]

10‘Safety analysis’ is the evaluation of the potential hazards associated with a facility or an activity. The formal safety analysis is part of the overall safety assessment, i.e. it is part of the systematic process that is carried out throughout the design process (and throughout the lifetime of the facility or activity) to ensure that all the relevant safety requirements are met by the proposed (or actual) design [5].

11It should be noted that different terms are used for internal and external events and processes for different types of facility and activity. For example, for nuclear reactors, the term ‘postulated initiating events’ is used, whereas for the safety of radioactive waste, the term usually used is ‘features, events and processes’ [5].

12The term ‘scenario’ means a postulated or assumed set of conditions and/or events [5].

13There are two facets to uncertainty: aleatory (or stochastic) uncertainty and epistemic uncertainty. Aleatory uncertainty has to do with events or phenomena that occur in a random manner, such as random failures of equipment. These aspects of uncertainty are inherent in the logical structure of the probabilistic model. Epistemic uncertainty is associated with the state of knowledge relating to a given problem under consideration.

14The scope and extent of the independent verification carried out by the regulatory body is at the discretion of the State.