1A ‘nuclear security event’ is an event that has potential or actual implications for nuclear security that must be addressed. Such events include criminal or intentional unauthorized acts involving or directed at nuclear material, other radioactive material, associated facilities or associated activities. A nuclear security event, for example sabotage of a nuclear facility or detonation of a radiological dispersal device, may give rise to a nuclear or radiological emergency.

2‘Emergency’ is defined as a non-routine situation or event that necessitates prompt action, primarily to mitigate a hazard or adverse consequences for human life, health, property and the environment [7]. This includes nuclear and radiological emergencies and conventional emergencies such as fires, releases of hazardous chemicals, storms or earthquakes. This includes situations for which prompt action is warranted to mitigate the effects of a perceived hazard. A ‘nuclear or radiological emergency’ is defined as an emergency in which there is, or is perceived to be, a hazard due to: (i) the energy resulting from a nuclear chain reaction or from the decay of the products of a chain reaction; or (ii) radiation exposure. Notwithstanding the definitions of these terms, for reasons of brevity, in this Safety Guide the term ‘emergency’ is intended to mean a nuclear or radiological emergency, unless otherwise specified.

3‘Facilities and activities’ is a general term encompassing nuclear facilities, uses of all sources of ionizing radiation, all radioactive waste management activities, transport of radioactive material and any other practice or circumstances in which people may be subject to exposure to radiation from naturally occurring or artificial sources [7].

4The ‘emergency response phase’ is defined as the period of time from the detection of conditions warranting an emergency response until the completion of all the emergency response actions taken in anticipation of or in response to the radiological conditions expected in the first few months of the emergency [7]. The emergency response phase typically ends when the situation is under control, the off-site radiological conditions have been characterized sufficiently well to identify whether and where food restrictions and temporary relocation are required, and all required food restrictions and temporary relocations have been put into effect (para. 2.9 of GSG-11 [5]).

5A graded approach is defined as: (i) For a system of control, such as a regulatory system or a safety system, a process or method in which the stringency of the control measures and conditions to be applied is commensurate, to the extent practicable, with the likelihood and possible consequences of, and the level of risk associated with, a loss of control. (ii) An application of safety requirements that is commensurate with the characteristics of the facilities and activities or the source and with the magnitude and likelihood of the exposures [7].

6‘Interested party’ is a person, company, etc., with a concern or interest in the activities and performance of an organization, business, system, etc. [7]. The term interested party is used in a broad sense to mean a person or group having an interest in the performance of an organization. Those who can influence events may effectively become interested parties — whether their ‘interest’ is regarded as ‘genuine’ or not — in the sense that their views need to be considered. Interested parties have typically included the following: customers, owners, operators, employees, suppliers, partners and trade unions; the regulated industry or professionals; scientific bodies; governmental agencies or regulatory bodies (national, regional, local) whose responsibilities may cover nuclear energy; the news media; the public (individuals, community groups, interest groups); and other States, especially neighbouring States that have entered into agreements providing for an exchange of information concerning possible transboundary impacts, or States involved in the export or import of certain technologies or materials.

7The term ‘public information officer’ is used in this Safety Guide to denote a staff member of an organization whose primary responsibility is to provide information to and to communicate with the public and the news media. The ‘lead public information officer’ is the public information officer within the unified command and control system who leads the public communication response. Although lead public information officer is used here, the public communication response might not warrant the establishment of a public information section

8An ‘initial statement’ is used in this Safety Guide to denote an official statement by an entity to inform the public and the news media of the occurrence of an event and the key points, and to state that the entity is actively responding to the event. An initial statement may be delivered in writing or orally.

9‘Risk’ in this context means the estimated probability that a specified health effect will occur in a person or group as a result of exposure to radiation [7]. The health effect(s) in question need to be stated, for example risk of fatal cancer, risk of serious hereditary effects or overall radiation detriment. Risk is commonly expressed as the product of the estimated probability that exposure will occur and the estimated probability that the exposure, assuming that it occurs, will cause the specified health effect(s). The latter probability is sometimes termed the ‘conditional risk’. Risks can be estimated by using evidence from epidemiological investigations of disease rates in previously exposed populations (i.e. based on past observations).

10In GSR Part 7 [1], assessed hazards are grouped in accordance with five emergency preparedness categories and establish the basis for a graded approach to the application of the requirements in GSR Part 7 [1], and for developing generically justified and optimized arrangements for preparedness and response for a nuclear or radiological emergency (see also table 1 of GSR Part 7 [1]).

11‘Hazard assessment’ is the assessment of hazards associated with facilities, activities or sources within or beyond the borders of a State in order to identify: (i) those events and the associated areas for which protective actions and other response actions may be required within the State; and (ii) actions that would be effective in mitigating the consequences of such events [7].

12The Inter-Agency Committee on Radiological and Nuclear Emergencies is an inter-agency coordination mechanism to ensure that arrangements for emergency preparedness and response at the international level are consistent. The Committee, which comprises relevant international intergovernmental organizations, maintains the Joint Radiation Emergency Management Plan of the International Organizations.

13Mapping products are outputs from geographical data collection, analysis and processing that support decision making by providing visualizations with regard to plume dispersal information or radiological measurements across a geographic region overlaid on a map for rapid visual analysis.

14In the context of thе UNSCEAR 2012 Report[15] and this Safety Guide, ‘attributability’ refers to whether a manifest health effect in an individual or a manifest increase in frequency of health effects in a population is capable of being ascribed as having been induced by radiation exposure.

15In this context and in line with the UNSCEAR 2012 Report [15], ‘inference’ relates to the process of drawing conclusions from scientific observations, evidence and reasoning in the presence of uncertainty, with a focus on prospectively inferring risk.

16Paragraph 1 of article 1 of the Convention on Early Notification of a Nuclear Accident [11] states: “This Convention shall apply in the event of any accident involving facilities or activities of a State Party or of persons or legal entities under its jurisdiction or control, referred to in paragraph 2 below, from which a release of radioactive material occurs or is likely to occur and which has resulted or may result in an international transboundary release that could be of radiological safety significance for another State.” Paragraph 2 [11] states: “The facilities and activities referred to in paragraph 1 are the following: (a) any nuclear reactor wherever located; (b) any nuclear fuel cycle facility; (c) any radioactive waste management facility; (d) the transport and storage of nuclear fuels or radioactive wastes; (e) the manufacture, use, storage, disposal and transport of radioisotopes for agricultural, industrial, medical and related scientific and research purposes; and (f) the use of radioisotopes for power generation in space objects.”

17Organizations may maintain more than one official social media account and may communicate to diverse audiences using varied social media channels that reach specific audiences.

18Urgent protective action planning zone (UPZ): an area around a facility for which emergency arrangements have been made to take urgent protective actions in the event of a nuclear or radiological emergency to avert doses off the site in accordance with international safety standards. Precautionary action zone (PAZ): an area around a facility for which emergency arrangements have been made to take urgent protective actions in the event of a nuclear or radiological emergency to avoid or to minimize severe deterministic effects off the site. Operational intervention level (OIL): a set level of a measurable quantity that corresponds to a generic criterion. Extended planning distance (EPD): the area around a facility within which emergency arrangements are made to conduct monitoring following the declaration of a general emergency and to identify areas warranting emergency response actions to be taken off the site within a period following a significant radioactive release that would allow the risk of stochastic effects among members of the public to be effectively reduced. Ingestion and commodities planning distance (ICPD): the area around a facility for which emergency arrangements are made to take effective emergency response actions following the declaration of a general emergency in order to reduce the risk of stochastic effects among members of the public and to mitigate non-radiological consequences as a result of the distribution, sale and consumption of food, milk and drinking water and the use of commodities other than food that may have contamination from a significant radioactive release [7].

1Unwarranted actions include: actions that interfere with the prompt implementation of protective actions, such as self-evacuation from both within and outside areas from which evacuation is ordered; actions that unnecessarily burden the health care system; actions that shun or otherwise discriminate against people or products from an area affected by a nuclear or radiological emergency; elective terminations of pregnancy that are not radiologically informed; and cancellations of commercial flights that are not radiologically informed.

1A deterministic health effect of radiation is a radiation induced health effect for which generally a threshold level of dose exists above which the severity of the effect is greater for a higher dose [V–3].

2A stochastic health effect of radiation is a radiation induced health effect, the probability of occurrence of which is greater for a higher radiation dose and the severity of which (if it occurs) is independent of dose [V–3].