An Interview with Henry Preston
In advance of appearing as a panellist in our upcoming Engineering for the Energy Transition event, Henry Preston spoke to Rhys Phillips from Global Engineering Futures, to discuss his work, the state of the nuclear industry and nuclear’s role in the energy transition in the future.
Our thanks to both Henry and Rhys for having this fascinating conversation.
You can find out more about the event and all our speakers here, and you can register online here.
Rhys Phillips: “Thank you for talking to us, please introduce yourself.”
Henry Preston: “I am a physicist, I graduated from Queen Mary University of London in 2016 and since then I have been working for the National Nuclear Laboratory, I am based conveniently in Preston, like my last name, and my job involves evaluating nuclear fuel and graphite that has come from the UK’s fleet of Advanced Gas-cooled Reactors (AGRs). This process is called Post Irradiation Evaluation (PIE), this is to ensure the continued safe operation of those reactors. Primarily from PIE I am focused on underwater fuel inspections of the nuclear fuel that is cooling in the power station cooling ponds, and I have been leading on various innovation projects, implementing digital solutions and new techniques for those underwater fuel inspections.
Some Useful Nuclear Definitions:
PIE - Post-Irradiation Examination
AGR - Advanced Gas-Cooled Reactor
On the extracurricular side of things, I was part of the team that came runner up in the 2018 Spark! Contest, which is a Franco-British writing contest about the energy transition, and we got to present at the world nuclear exhibition in Paris, which was a lot of fun. I was then awarded the national skills academy nuclear scientific graduate of the year in 2019, which was amazing. I’m also a member of the Institute of Physics, trying to become chartered, and I help coordinate outreach for the Nuclear Institute by editing content for the Young Generation Network (YGN). So yeah that’s kind of me in a nutshell!”
Just mildly impressive then! We’ll jump into the first question, what do you think are the big engineering challenges facing the nuclear industry, during the energy transition?
“With nuclear, you have both fission and fusion, and the biggest thing is always material challenges, handling extreme conditions, reactors put materials under irradiation, high temperatures and high pressures. So for example with fusion, you’ve got cooling of superconducting magnets in the fusion tokamaks, but then for fission reactors (my area) there is a lot of research going on in advanced fuel programs, focused on things like accident tolerant fuels, how you ensure consistent quality during the manufacturing process of those fuels. I think what’s really exciting about those fuels is that they are going to power the 4th Generation of advanced reactors that will withstand temperatures above 1000degC, which make them ideal for co-generation - so not just electricity but also looking at heat and hydrogen. Being able to produce those forms of energy from nuclear reactors is really quite exciting, and solving those materials challenges is instrumental in decarbonising all of energy, not just electricity generation.”
“What I would add, in terms of challenges, there is actually a bigger challenge for engineers and scientists in nuclear which is public engagement. I think being able to communicate about nuclear and highlight the potential benefits for the energy transition and achieving net-zero, but also having a dialogue and listening to what the public think, is probably a bigger challenge than some of the engineering aspects.”
Nuclear sometimes gets a bad rep, less so perhaps with the younger generation than the generation that grew up around the time of the Chernobyl disaster. You’re obviously very engaged with nuclear outreach, what is your go-to argument to say that Nuclear is necessary for the energy transition?
“First of all, I will just counter your point that the younger generation being really keen on it, because actually, I read that only 26% between 18-24 actually know that nuclear is low carbon, which is staggering.
But, my go-to points are usually around energy density, a fingertip of Uranium (500g) will give you the same energy as 5000 barrels of oil, and if you care about the environment that means you can take so much less from nature in terms of land and resource use. The other point is about nuclear waste, one person's lifetime nuclear waste would fit in a Coke can. That’s the amount of high-level waste produced for one person’s lifetime energy usage if all energy came from nuclear power, which is a very manageable and very visual way to think about it, compared to telling people how many billion tonnes of CO2 they emit.”
What are the challenges in keeping aging nuclear plants running for as long as possible?
“The Advanced Gas-Cooled Reactors (AGRs) were designed in the 60s and 70s, and the UK is quite unique in that we operate gas-cooled reactors. They are made up of a graphite core, that acts as the structure for the reactor and as the “moderator” (the moderator is to slow down neutrons to sustain fission chain reactions), the fuel is Uranium Dioxide pellets enclosed in stainless steel, and the reactor is cooled by Carbon Dioxide. The coolant transfers the heat to boil water, which produces steam, which turns a turbine to generate electricity. Like a giant kettle.
The lifetime limiting part of AGRs is the graphite core, under irradiation and over time the material properties of the cores are degrading, so the challenge is really all about monitoring that graphite, through post-irradiation evaluation. We take samples from the reactor cores and do various property measurement techniques on those samples to see how they have changed. It’s all about the monitoring process, how do we keep these reactors operating safely? All of that data gets reported back to the operator and regulator. Alongside that, the coolant chemistry plays an important role in protecting the graphite and optimising the fuel performance, which is why we carry out underwater fuel inspections, to see how the fuel is performing in the reactor. And then beyond that there are the non-nuclear aspects, like the condition of the boiler and the turbines and checking the seawater cooling pipe network for corrosion – the sites are fairly old after all!”
What are the interesting solutions that you have worked on?
“I’m working in post-irradiation evaluation, designing lab experiments as well as going to AGR sites and doing underwater inspections. I’ve lead projects on digital solutions for underwater inspections looking at exploring new techniques. Believe it or not, all the inspections were done with pen and paper when I started and have been since the 80s, with the environment you are in you can see why, but we’re in the process of getting tablets for data recording.
Then we’re also considering machine learning to assist with visual inspections, basically training an algorithm to assess images of carbonaceous deposits on the fuel, that forms during operation. That carbon deposit acts like a blanket on the fuel and you want all the heat to go out from the fuel into the coolant so w monitor that through observation with video cameras underwater, but beyond that, we are also looking to sample that deposit from the fuel in situ in the ponds.
Currently, you have to take fuel out of the ponds into another facility and dismantle them entirely before you can take samples of that deposit and measure it under a microscope. So taking samples in situ and then directly to the lab, cuts out a whole load of extra steps. Which is pretty exciting. There is a lot of engineering in terms of deploying tools and equipment in those harsh environments with radiation, underwater and very dark. In fact, you can find out all about this challenge online through Gamechangers here.”
What are the plans for new nuclear stations, are there enough being built or planned?
“Currently nuclear provides about 20% of the UK’s electricity supply, with 7 AGR stations of two reactors each. They are scheduled to come offline by 2030, in addition, you have Sizewell B (a Pressurised Water Reactor (PWR)) which is scheduled to go offline by 2035, but I suspect there will be an extension of that station. In terms of new stations, there is Hinkley Point C, which is due to come online around 2025. Plus there is potential for a new station, Sizewell C, which looks promising, which will provide another 7%. So with those two and an extension at Sizewell B, you just about cover the 20% of electricity generation that Nuclear currently produces. That is impressive in terms of energy density, and you can see that the PWRs have a greater output than the AGRs.
One thing to say on this, although that plan replaces the electricity generation it also leaves gaping holes around the country in terms of the geographic location of those other stations. There are a lot of high-skill high-paid jobs that are provided by those stations around the country. So its not just about replacing the electricity generation its also a question of how do you replace those hubs for high skilled jobs as well?”
That is analogous to the coal mining closures of the 1980s, all of a sudden you are centralising power and taking high skilled, well paid often unionised jobs away from traditional manufacturing hubs.
“Exactly, and if you speak to people close to the stations they are overwhelmingly supportive of the sector because it has provided such good jobs over its history.
It’s worth noting that those nuclear power plants helped us avoid emitting 17.8M tonnes of CO2 in 2019 according to EDF, so If we take those off the grid we need a load more renewables in so if you don’t replace them it is really detrimental to achieving Net-Zero. We are also looking to decarbonise the whole of the grid in the UK, which is not just electricity generation but industrial processes, heating, transport and it’s likely we are going to get an increased demand on the electricity grid as we go to electric cars and electric heating.”
What role will Small Modular Reactors (SMRs) have in the future?
“When they say small, they are ¾ the size of a PWR, like the one being built at Hinkley Point C. The power output is actually comparable to an AGR (roughly 1GW) or 2% of the UK’s electricity demand, so small by name but not in its contribution. The attractiveness of SMRs is around the investment and financing, because they are smaller than traditional builds they should, in theory, take less time to build with reduced capital costs and associated financial risk compared to large new-build nuclear projects. The modular aspect means you are manufacturing components off-site and effectively repeating the build process, which brings the supply chain in line to build multiple units and getting all that experience in the process, reducing the cost and the time for all the SMRs that come online. If we can do all of that then they can really bolster large nuclear projects in achieving Net-Zero and provide more confidence to investors and the public.”
There are some really interesting plans in co-generation and developing hydrogen power and district heating at the same time as well…
“It’s being thought of now in terms of bedding in co-generation in SMRs, obviously that was never thought of when they built the AGRs, they did some demonstrations at Heysham looking at whether they could produce Hydrogen through electrolysis. It would be great if they can put it in the design of the SMRs - why waste all that heat. For those interested in hydrogen, I would highly recommend reading the Lucid Catalyst report here.”
There is definitely an opportunity there. When are the SMRs currently scheduled to come online?
“They are hopeful for the 2030s but it’s hard to say until the first concrete is poured, there is a lot of work going in to consolidating their designs and getting them checked by the regulators, winning the financial backing and government and community support. So there are a few hurdles to get past first.”
How does their construction schedule compare to HPC?
“In theory, its smaller, and its modular so many components will be built in factories offsite. Once you have built one you want to take your workforce to the next one with all that experience of working on the first SMR to the next project and build it in a shorter time, then repeat that process again and again until you have a really experienced team of people that are getting good at building SMRs.”
Finally, what would you say to students interested in getting into nuclear engineering?
“We often forget that nuclear energy is the newest form of energy that humans have tried to harness, so that alone brings a lot of engineering challenges, and we are now entering a renaissance around nuclear which is going to depend on a lot of innovation, so that should excite any engineering student. Personally, I got into nuclear because of its energy density and I consider myself firstly an environmentalist, I want to make the world more sustainable, and that led me to nuclear energy. When you think about those far-reaching benefits of decarbonising the whole of the energy wheel there are great things to be involved in nuclear.
I would also say that there is a really exciting and vibrant community especially for young people, the Nuclear Institute has a Young Generation Network (YGN) which is extremely welcoming, they are always doing events and giving young people like myself a platform, we have the Nuclear Future Journal as well as many webinars and events. There is always a desire to promote young people – which is why I got put forward (by the YGN) for this event! Beyond that there is an incredible international network as well which is growing, I’ve been fortunate myself to travel around the UK, France and South Korea, there are a lot of brilliant opportunities for young people coming into the sector.
The YGN will be attending COP26 in Glasgow, and they want to drive that narrative of Nuclear for the Energy Transition to work alongside renewables to bring about a low carbon future for everyone, so look out for the hashtag #NetZeroNeedsNuclear. There’s a lot of young people in the industry that are really passionate about the possibilities of this technology and we are consciously striving to be a more open and engaging industry.”
Find out more about the YGN here:
https://www.nuclearinst.com/Communities/NI-Young-Generation-Network
Find out more about the Net Zero needs nuclear campaign and read the position paper here:
https://www.netzeroneedsnuclear.com