Designed to weather the storm

This second article looks at how weather and climate science can help ensure the design and decommissioning of assets is as safe and efficient as possible. 

Contents

• Forward thinking
• Design for low probability/high impact events
• Decommissioning infrastructure assets

Some of the infrastructure in the UK has already withstood decades of weather events and changing climate. The part we play at the Met Office is in helping ensure that infrastructure built today remains just as resilient in the future by working with engineers during the project’s design and development stage.

Forward thinking

When designing new infrastructure it is critical to ensure that it is resilient to withstand future extremes. To do this, engineers make use of Extreme Value Analyses. These are created by climate experts, such as the Met Office, they use statistics to estimate the probability and severity of weather events that the infrastructure must be designed to withstand. Often these events are expressed as return periods such as a 1 in 50, or a 1 in 100-year event. 
 
In the case of safety critical infrastructure – such as nuclear power stations – there is a requirement to design to withstand a 1 in 10,000-year event. This creates problems because even if you have a set of observations (close to the site of interest) that goes back a significant amount of time – for example  60 years - you are very unlikely to have seen the extreme event in the observed record. In addition, these really good sets of observations often simply don’t exist. This creates significant uncertainty in the return period statistics. . 

Design for low probability/high impact events

Nuclear reactors must be designed with sufficient cooling to withstand extreme high temperature conditions. To develop a better understanding of the likely future temperature conditions that one customer’s reactor was likely to experience, we used a simulated weather dataset or “hindcast”. This was created by using our climate model to represent a 35-year period of recent past-climate. For each year, 40 ensemble members (or plausible forecasts) were used, and this created a virtual event set of 1,400 years of daily scenarios.
 
What this really means is the resulting dataset contains many more physically plausible extreme events than existing observed records. Using simulated weather data in this way reduces the uncertainty in the return period calculation and – in this case - significantly reduced the maximum temperature for which the reactor needed to be designed. This data can also be used with climate projections, such as UKCP, to estimate how the extremes will change in the future as a result of climate change. 
 
Now engineers translate return periods into concrete. Our customer in this instance estimated significant savings in the design of the reactor that resulted from applying this scientific method. The same method can also be applied to look at return periods of other parameters – it was developed to analyse flood risk in China and as part of Defra and the Environment Agency’s National Flood Resilience Review. We have also applied the technique to analyse drought conditions for the UK water sector. 

Decommissioning infrastructure assets

When a large asset like a nuclear power station or an offshore oil rig is being turned off or mothballed, the engineers involved must consider resilience to future climate and weather events. Consequently, the challenges involved in decommissioning are the same as when developing an asset and future scenarios need to be considered.

One example would be legacy mines. These can fill up with water, and if that water seeps out into rivers there’s then a high chance that pollutants will enter the nation’s water supply. It is important to manage this risk and stop any pollution entering the water system.  
 
We can provide consultancy to help engineers make sure legacy assets remain safe. We also offer operational weather forecast services for decommissioned assets, helping industries to manage assets on a day-to-day basis.
 
Fundamentally, our task is to understand the risks that are foremost in the mind of someone who is designing a piece of infrastructure, helping them to design it in a way that keeps infrastructure safe, resilient and efficient throughout its lifespan and beyond.