Emergency preparedness and response (EPR) is the planning and the execution that aims to protect people and the environment from the consequences of a nuclear or radiological emergency. It bridges plant-level accident management (operator) and public protective actions (authorities).

Categories of emergency

IAEA GSR Part 7 organises preparedness around five emergency-preparedness categories, broadly:

  • I — large nuclear power reactors and reprocessing.
  • II — smaller reactors, research reactors, fuel cycle facilities with relevant inventory.
  • III — facilities and activities with significant on-site hazard but limited off-site consequence (industrial irradiator, sealed-source large activity).
  • IV — uncontrolled radioactive sources (orphan source, transport accident, illicit trafficking).
  • V — areas in another country that could be affected by an emergency at a Category I or II facility.

Each category has corresponding emergency planning zones, response capabilities, public information arrangements and exercise frequencies.

Protective actions

The standard catalogue of protective actions in the early phase of an emergency:

  • Sheltering in place — remaining indoors, closing windows and ventilation. Effective dose reduction depends on house tightness and material (factor 2-10 for a typical Nordic single-family house).
  • Iodine prophylaxis (KI) — administering stable iodine to block thyroid uptake of radioiodine. Effectiveness depends strongly on timing relative to exposure.
  • Evacuation — short-term removal from a contaminated or potentially contaminated area. Pre-planned routes and reception centres.
  • Relocation — longer-term protective action when projected doses over months exceed reference levels.
  • Food restrictions — controls on consumption and trade of foodstuffs from contaminated areas (CODEX maximum levels in international trade; EU regulations 2016/52 and 1957/2024 within the EU).

Decision criteria

Decisions to recommend or order protective actions are based on:

  • Projected dose to representative individuals (averted dose).
  • Generic intervention levels (e.g. IAEA EPR-OPI-2020 references).
  • Operator declaration of an emergency class and event categorisation.
  • Real-time measurement (dose-rate networks, source-term inversion, atmospheric dispersion modelling).

Reference operational intervention levels (OILs) translate measurable quantities (air dose rate, deposition density) directly into recommended protective actions, allowing fast first-responder decision-making without waiting for detailed dose assessment.

Operator–authority handoff

During the early phase the operator's emergency-response organisation (control-room, technical support centre, on-site emergency response facility) provides plant status, source-term assessment, and an emergency classification. The authority's emergency-response organisation (national radiological monitoring, decision-support tools, public information) takes the operator's plant data and translates it into off-site protective-action decisions. A clear handoff and a robust common operating picture are central to credibility — see the Three Mile Island and Fukushima Daiichi cases in Incident History.

National examples

  • Sweden — SSMFS 2014:2 sets the requirements on emergency preparedness at nuclear facilities. SSM operates the radiological measurement network and issues advice; the County Administrative Boards execute protective actions; MSB coordinates civil contingencies.
  • Finland — STUK runs the national EPR with YVL Guides C-series and the radiological monitoring network.
  • UK — REPPIR 2019 (Radiation Emergency Preparedness and Public Information Regulations); ONR and HSE supervise operators' off-site emergency plans; local authorities lead protective actions.
  • US — 10 CFR 50.47 and 10 CFR 50 Appendix E set NRC requirements; FEMA supports the off-site planning and exercise framework.
  • International — IAEA IEC operates the USIE notification system and RANET for assistance.

Exercises and lessons

Regulators require periodic full-scale exercises (typically every 2-5 years) plus drill programmes. Lessons-learned reports are public in most jurisdictions and feed back into emergency plans and into regulatory rule revisions.