Volcanic Ash Hazard to UK Nuclear Generating Facilities

Lead Research Organisation: University of Bristol
Department Name: Earth Sciences

Abstract

Volcanic ash is the most widespread and frequent hazardous volcanic phenomenon, being produced in over 90% of all eruptions. The 2010 eruption of Eyjafjallajökull in Iceland and the resulting closure of Northern European airspace has focused attention on the international reach of ash even from relatively small volcanic eruptions. It is now important to rigorously assess potential impacts on nuclear power facilities in the UK from volcanoes in neighbouring regions. Thick volcanic ash accumulation might render a site temporarily inoperable but even minimal (a few mm) ash deposition in the vicinity of a nuclear facility has the potential to disrupt normal operations.

This proposal will result in a robust, transparent and broadly-applicable methodology for evaluating the likelihood of volcanic ash threatening UK nuclear facilities. This will be based on state-of-the-art probabilistic hazard assessment methodologies developed through NERC-funded science at the University of Bristol, with new knowledge exchange mechanisms and collaborative research strands to adapt to the special circumstances of low probability events relevant to the UK nuclear industry. The hazard assessment will be directly linked to a case study of site management changes to mitigate this hazard, and the methodology will be intentionally transparent and generic to allow application to other volcanic regions hosting nuclear or other sensitive high-tech sites. This project has been developed through ongoing discussions with EDF Energy, and the skills, tools and outputs acquired through the project will be transferable to, and of benefit for, a wider range of the volcanic hazard assessment stakeholder community.

The project builds on NERC science outputs from the consortium projects STREVA,CREDIBLE and VANAHEIM and also the Global Volcano Model (GVM) network, and consists of five components:
1. characterisation of eruption source parameters at regional volcanoes with potential to disperse ash over he UK, and the meteorological conditions affecting ash transport from eruption source to specific location;
2. a workshop with experts from EDF Energy and from academia to create the essential framework for relating volcanic activity probabilities and likelihood of site impacts to nuclear industry procedures, standards and regulatory requirements;
3. a probabilistic framework for modelling airborne and ground-based regional ash hazard arising from multiple volcanoes, and visualisation of ash hazard at UK nuclear facilities;
4. a new set of protocols for nuclear site preparedness and management in the event of volcanic activity; preliminary estimation of implementation costs, business disruption and supply chain issues;
5. generation and dissemination of reports and a scientific paper presenting the hazard assessment methodology for low probability volcanic activity.

The project will provide a quantified volcanic ash hazard assessment for UK sites. The main benefit is improved understanding of credible, though extreme (1 in 10,000 year), volcanic ash hazard on the operation of nuclear power plants in the UK. The far-reaching impacts of volcanic ash means that preparedness and mitigation strategies developed on the basis of findings from this project will protect against unforeseen nuclear safety consequences and help ensure the reliability of electricity supply to the population of the UK. The impact of the exchanged knowledge will range from the development of new informed decision-making concerning the volcanic ash hazard management to the potential design of mitigation measures and procedures if required.

EDF Energy Generation is committed to characterising the hazard due to volcanic ash for its nuclear sites. This project forms the first part of understanding this problem and may identify further research and Knowledge Exchange needs.

Publications

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Description Volcanic ash was transported to the UK from moderate-sized Icelandic volcanic eruptions in 2010 and 2011, resulting in deposits of trace amounts of ash and changes in air quality. This project has produced a comprehensive probabilistic assessment of volcanic ash hazard to UK nuclear generating facilities (as representative of critical infrastructure), and created a database of predicted volcanic ash airborne concentration and thickness for the UK under credible future eruption scenarios.

The ash impact assessment includes determination of the frequency of eruptions of all credible magnitudes for volcanoes within 3000 km of the UK, clustered into nine groups by geographical location, including Iceland, Italy, the Azores and the Aegean. A new efficient ash transport modelling approach was developed using synoptic weather patterns for Europe. The combination of eruption probability, weather pattern occurrence and modelled ash transport results in predictions of probability of exceeding a given ash concentration or deposit thickness at a given UK location. This work has produced a database that can be mined for airborne or ground level ash concentration or deposit thickness for any UK location and for up to four days after the eruption. This database could be used to rapidly assess potential ash impacts in the event of an eruption, or as part of the evaluation of the impact of air-borne volcanic particulates for a particular infrastructure in a specific UK location.

The annual probability of ash from a volcanic eruption exceeding a ground level concentration of 0.5 mg/m3 at a UK location has been estimated at about 1 in 300, and the duration of ashfall is between 20 and 45 hours for this event probability. The vast majority of ash particles will be smaller than 10 microns (the respirable range, termed PM10), and the most likely source is a moderate size Icelandic eruption. The principle uncertainty on these predictions arises from variable duration of the eruptions and persistence of weather patterns, which is the subject of ongoing analysis. This ash ground level concentration will potentially impact filtration systems on a wide range of infrastructure, and human health (World Health Organisation daily guideline threshold for good air quality is 0.05 mg/m3) leading to increased maintenance and possible workforce disruption. Higher ash concentrations (1 in 1000 annual probability) may disrupt air transportation and affect supply chains. Impacts on water supplies and telecommunications are uncertain.

An expert judgement exercise conducted in collaboration with EDF energy showed that under these credible ash impacts, individual key infrastructure elements installed with filters - including essential systems - could potentially become clogged and functionality could be threatened. This can be effectively mitigated by increased maintenance, and improved understanding of the physical impacts, size and density of these air-borne particulate hazards, although consumables replenishment of filters may be vulnerable to supply chain disruption.

The results of this research have been presented at two international conferences and there are three journal papers in preparation. The socio-economic impact of this research is associated with protecting UK competitive advantage through resilience of nuclear power generation facilities. Impact achieved to date includes, exploring and reviewing plant filter stocks held by a typical EDF Energy nuclear power station and providing initial air-borne particulate data to support relevant claims in safety cases from potential volcanic ash hazard. The database of ash ground-level concentration and thickness will be provided to UK Cabinet Office Civil Contingencies/National Risk Register as information for rapid assessment in the event of a volcanic eruption (via EDF Energy and University of Bristol). The EDF Energy R&D UK Centre co-funded this project and provided expert technical review of the project results.
Exploitation Route The database of ash ground-level concentration and thickness will be provided to UK Cabinet Office Civil Contingencies/National Risk Register as information for rapid assessment in the event of a volcanic eruption (via EDF Energy and University of Bristol).

Further research based on expert judgement with stakeholders using the database of ash ground-level concentration and thickness could be used to improve preparedness planning for UK infrastructure.
Sectors Aerospace, Defence and Marine,Energy,Transport

 
Description The research findings have highlighted potential impacts of relatively low concentrations of volcanic ash to nuclear site infrastructure that could require increased equipment maintenance. EDF have used these results as the basis to make an inventory of filter stocks across their UK sites.
First Year Of Impact 2015
Sector Energy
Impact Types Economic

 
Description EDF UK R&D Research contract
Amount £98,000 (GBP)
Organisation EDF Energy 
Sector Private
Country United Kingdom
Start 03/2016 
End 11/2016
 
Title UK Ash Hazard Assessment 
Description This is a database of advection-diffusion model simulations that can be used to visualise ground level and airborne ash concentrations from eruptions from volcanoes that could impact the UK. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? No  
Impact This database has been used as the basis of a probabilistic ash hazard assessment for UK infrastructure. 
 
Description EDF Nuclear Generation 
Organisation EDF Energy
Country United Kingdom 
Sector Private 
PI Contribution My team conducted the research funded by the ERIIP project 'Volcanic Ash Impact on Nuclear Generating Facilities' (NE/M008878/1).
Collaborator Contribution EDF Energy Nuclear Generation and EDF Energy R&D UK Centre were partners for this project and provided contribution through participation of experienced operators, expert technical review and facilities for the expert elicitation exercise to be held.
Impact The NERC-funded work included an expert elicitation assessment of critical site plant for volcanic ash exposure - August 2015, Hinckley B (11 EDF Energy staff participants), and the immediate impact was a review within EDF Energy of essential filter stocks including replenishment arrangements and maintenance strategy for critical site plant for a typical operating nuclear power plant. The outcomes of this exercise are currently being reviewed and considered by EDF Energy and it is likely that some recommendations will be presented from which changes to working patterns may result. The NERC-funded work included a report on the ash hazard assessment for the UK that EDF Energy are using as part of formal consideration of volcanic ash impacts from regional volcanic eruptions.
Start Year 2015
 
Description ERIIP Webinar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Project results were disseminated by a webinar managed by Construction Industry Research & Innovation Association. Questions relevant to their activity were asked by stakeholders from utilities supply. Follow up discussions are in progress
Year(s) Of Engagement Activity 2016