Risk assessments

The National Risk Register matrix below presents the impact and likelihood of a plausible worst-case scenario manifestation of each risk.

Each number on the matrix corresponds to a risk ID with more information about each risk detailed below. Likelihood is presented as the percentage chance of the reasonable worst-case scenario occurring at least once in the assessment timescale, and impact is assessed across seven broad categories. More information about how risk impact and likelihood are assessed can be found on the 'Risk methodology' page.

Impact	5	Civil nuclear accident 28 Radiation release from overseas nuclear site 29		Larger scale CBRN attacks 9 Failure of the National Electricity Transmission System (NETS) 26A	Pandemic 54
	4	Aviation collision 21	Loss of Positioning, Navigation and Timing (PNT) services 24 Reservoir/dam collapse 38 Animal disease - major outbreak of foot and mouth disease 56A	Failure of gas supply infrastructure 27 High temperatures and heatwaves  49 Coastal flooding 51A Fluvial flooding 51B Surface water flooding 51C Deliberate disruption of UK space systems and space-based services 61	Combined risk - Conventional attacks on infrastructure 10 Severe space weather 47 Low temperatures and snow 50 Outbreak of an emerging infectious disease 55 Nuclear miscalculation not involving the UK 63
	3	Large passenger vessel accident  17 Accidental fire or explosion at an onshore major hazard (COMAH) site 32 Accidental large toxic chemical release from an onshore major hazard (COMAH) site 33 Accidental fire or explosion on an offshore oil or gas installation 34 Accidental fire or explosion at an onshore fuel pipeline 35 Accidental fire or explosion at an onshore major accident hazard pipeline  36 Animal disease - major outbreak of African horse sickness 56C	Disruption to global oil trade routes 12 Malicious drone incident 22 Disruption of space-based services 23 Drought 52	Simultaneous loss of all fixed and mobile forms of communication 25 Regional failure of the electricity network 26B Technological failure at a systemically important retail bank 31A Humanitarian crisis overseas - natural hazard event 45 Poor air quality 53 Animal disease - major outbreak of highly pathogenic avian influenza 56B	Combined risk - Terrorist attacks on transport 4 Medium scale CBRN attacks 8 Combined risk - Cyber attacks on infrastructure 11 Food supply contamination 40 Volcanic eruption  43 Storms 48 Reception and integration of British Nationals arriving from overseas 60	Combined risk - Terrorist attacks in public venues and spaces 3 Technological failure at a UK critical financial market infrastructure 31B Disaster response in the Overseas Territories 46 Attack on a UK ally or partner outside NATO or a mutual security agreement requiring international assistance 62
	2	Major maritime pollution incident 18 Incident (grounding/sinking) of a vessel blocking a major port  19 Radiation exposure from transported, stolen or lost goods 30 Accidental work-related (laboratory) release of a hazardous pathogen 37 Water infrastructure failure or loss of drinking water 39	Strategic hostage taking 5 Rail accident  16 Major fire 41 Wildfire 42	Insolvency of supplier(s) of critical services to the public sector 14 Accident involving high consequence dangerous goods 20 Animal disease - major outbreak of African swine fever 56D Public disorder  58 Industrial action  59	Smaller scale CBRN attacks 7 Major adult social care provider failure 13 Major outbreak of plant pest - Agrilus planipennis 57B	Northern Ireland related terrorism 2 Assassination of a high profile public figure 6
	1	Earthquake 44			Insolvency affecting fuel supply 15	International terrorist attack 1 Major outbreak of plant pest - Xylella fastidiosa 57A
		1	2	3	4	5
	Likelihood

Impact & Likelihood

Impact key

5	Catastrophic
4	Significant
3	Moderate
2	Limited
1	Minor

Likelihood key

5	>25%
4	5-25%
3	1-5%
2	0.2-1%
1	<0.2%

Risk scenarios

ID	Title	Risk Themes	Publishing date
1	International terrorist attack	Terrorism	July 2023
2	Northern Ireland related terrorism	Terrorism	July 2023
3	Terrorist attacks in venues and public spaces - explosive devices	Terrorism	July 2023
3	Terrorist attacks in venues and public spaces - marauding attacks	Terrorism	July 2023
4	Malicious aviation incident	Terrorism	July 2023
4	Malicious maritime incident	Terrorism	July 2023
4	Malicious rail incident	Terrorism	July 2023
5	Strategic hostage taking	Terrorism	July 2023
6	Assassination of a high profile public figure	Terrorism	July 2023
7	Smaller scale CBRN attacks	Terrorism	July 2023
8	Medium scale CBRN attacks	Terrorism	July 2023
9	Larger scale CBRN attacks	Terrorism	July 2023
10	Attack on government	Terrorism	July 2023
10	Conventional attack - civil nuclear	Terrorism	July 2023
10	Conventional attack - electricity infrastructure	Terrorism	July 2023
10	Conventional attack - fuel supply infrastructure	Terrorism	July 2023
10	Conventional attack - gas infrastructure	Terrorism	July 2023
10	Disruption of Russian gas supplies to Europe	Geographic and diplomatic	July 2023
10	Malicious attack on chemicals infrastructure	Terrorism	July 2023
10	Total loss of transatlantic telecommunications cables	State threats	July 2023