The most essential material in construction is concrete. It is durable, versatile, and strong. Not only concrete can stay stable for many years, be molded into different shapes and sizes, and withstand harsh weather conditions but it can also withstand vibrations and shocks, is non-combustible, inexpensive, and helps maintain a comfortable temperature inside buildings.
All these amazing properties of concrete make it a valuable construction material that is used to build all kinds of different structures, including roads, bridges, dams, tunnels, foundations, pillars, walls, slabs, driveways, and patios.
Given the importance of concrete in building infrastructure, the concrete market size is projected to surpass $972 billion by the end of this decade.
Rapid urbanization and industrialization along with an increase in government expenditures for development and reconstruction of infrastructures are driving this growth. A rise in the adoption of environment friendly material for building construction and the high initial setup cost of plants, however, acts as restraint to this market.
When it comes to concrete type, the ready-mix concrete segment dominates the market. This mixture, after all, is cost-effective and is manufactured in batches at a central plant instead of being mixed on the job site. Meanwhile, the reinforced concrete segment leads the market in terms of application.
Concrete to Help Achieve Decarbonization
Now, this essential and popular construction material is also playing a role in helping us achieve decarbonization through nuclear power plants. This man-made mixture of cement, water, and aggregates like sand, actually serves as the primary construction material for reactor containment and shielding.
Concrete is an affordable material that offers protection against gamma-rays and neutrons. Its water content and high density are what make it so widely used for radiation shielding.
But while engineers have come up with formulas to decide the optimum thickness of shielding for radioprotection purposes, they do not take into account the effects of radiation damage. And the long-term permanence of concrete is critical to operate these nuclear power plants safely.
The radiation damage process is simply not understood well yet. So, it is crucial that we remedy this issue if we want to take advantage of nuclear power, which can help us achieve a carbon-neutral world.
Nuclear power is a low-carbon energy source that can help combat climate change. It provides us with a reliable source of electricity regardless of weather, something renewable energy sources like wind and solar energy struggle with. Nuclear power is even considered safer than solar and wind power.
Moreover, nuclear fuel has high energy density and a small land footprint, all the while protecting air quality as there are no harmful emissions.
Nuclear power is a key part of total energy generation globally, contributing around 12% of the world’s electricity. In Europe, 30% of its electricity demand is met by nuclear energy while fossil fuels account for 40% and the rest of the share is made up by renewables.
Meanwhile, the US is the largest producer of nuclear power in the world, having a 30% share of global nuclear electricity produced. In 2022, the country’s nuclear reactors generated 772 TWh, 18% of total electrical output.
Despite many benefits, accidents like Chernobyl and Fukushima have created fear. As a result of that, Italy and Germany have permanently closed all of their nuclear power plants.
However, given the need to have clean and sustainable energy and nuclear being a zero-emission clean energy source, it is important to find ways to enhance the cost-effectiveness, reliability, and safety that will reduce people’s fears regarding this technology as well as improve their receptiveness to it. This is where concrete comes into the picture.
Click here to learn what makes concrete a critical material and how we can overcome its shortcomings.
Concrete’s Crucial Role in Nuclear Energy
A nuclear facility uses a nuclear reactor as its primary heat source and utilizes that heat to generate steam, which drives a steam turbine connected to a generator. Due to the inherent radioactivity of nuclear fission, it is critical that the reactor core is encased in a safeguarding shell. This effectively mitigates the dispersion of radiation and prevents the release of radioactive substances into the environment.
These reactor containments are made of concrete, which is also used for structural foundations and primary biological shields for the reactors. So, to operate nuclear facilities long-term, it is necessary that we perform the integrity analysis of concrete structures. After all, in nuclear power plants, concrete has to undergo severe and long-term exposure to γ-ray irradiation, neutron radiation, and extremely high temperatures.
This is something conventional structures do not encounter, which means all the evaluation of reinforced concrete components’ performance in general civil engineering structures and buildings can’t really help here. As such, we need knowledge specific to the nuclear power industry.
On top of that, there’s a big challenge of material alterations that lead to the degradation of concrete structures in nuclear power plants. These alkali-silica reactions, expansion, and delayed ettringite formation are due to the neutron amorphization of rock-forming minerals in aggregates. So, that’s yet another reason to specifically assess concrete in nuclear power plants.
This, however, isn’t anything new. Researchers have been looking into radiation’s impact on the structural integrity of concrete for a long time now. But new research has uncovered the deeper details of the effect of radiation on concrete expansion.
Advanced Concrete Research Focused on Nuclear Plants
Published in Science Direct, the study by researchers at the University of Tokyo, among others, has uncovered details of the effect of radiation on concrete expansion1. They can actually demonstrate just which concrete properties affect its structural attributes when exposed to different neutron radiation levels.
To address the significant concern of concrete aggregate expansion caused by radiation, understanding the sensitivity of rock-forming minerals, quartz in particular, to neutron radiation is very important.
This is because quartz is one of the most common minerals that’s found in almost all rock types. Also, experiments in research reactors have demonstrated that quartz can expand by as much as 18% in volume.
Recent studies also show that while cement pastes shrink and gain strength under neutron irradiation, rock-forming minerals expand, leading to crack initiation within the aggregates. This leads to aggregate cracking, concrete expansion, and decline in sturdiness and Young’s modulus, which measures the ability of a material to withstand changes in length under compression.
So, the researchers went on to investigate the neutron irradiation effects on different types of quartz, including sandstone, metachert, granodiorite, and synthetic quartz. The irradiation temperatures here ranged from 45 to 62 degrees Celsius.
According to research findings, quartz crystals in concrete, in particular, can heal themselves. The radiation-induced volume expansion was mitigated by diffusion of silicon (Si) or oxygen (O) within the quartz grain, creating a radiation-induced relaxation. This could potentially allow some reactors to run for longer than initially thought possible.
Click here to learn if 3D printed concrete can help save the environment.
Enhancing Nuclear Safety with Concrete
A composite material, concrete is made of multiple compounds, which can vary depending on various factors such as local geography. The rock aggregate, a major component in concrete, specifically can turn out to be really diverse but still, “rock will often contain quartz.”
Quartz is found in andesite, granodiorite (GR), sandstone (SS), and several other rocks, which means neutron irradiation can cause swelling of aggregate and successive concrete degradation in shielding walls as well as structures that are exposed to high neutron flux.
This means it is important to gain a better understanding of how quartz changes under different radiation loads. In doing so, Professor Ippei Maruyama from the Department of Architecture noted that:
“[It] can help us predict how concrete should also behave in general.”
However, studying neutron radiation-induced degradation is not so easy or cheap. It is actually a costly area of study, which makes extensive research difficult. The research team has been working on this for the last seventeen years, creating strategies that have culminated in recent experiments in which researchers are utilizing X-ray diffraction to explore irradiated quartz crystals.
One of the things the team looked at is the two properties of neutron radiation — the total dose the samples receive and the flux, which is the rate at which the dose is received.
The team found that the rate of expansion in a quartz crystal is in line with the dose rate; if the rate was higher, the expansion amount was also far higher, and vice versa.
“The discovery of the flux effect indicates not only that neutron radiation distorts the crystal structure, causing amorphization and expansion, but that there is also a phenomenon where the distorted crystals recover and the expansion diminishes, hence a lower rate affords more time to heal.”
– Maruyama
This phenomenon was also found to be dependent on mineral crystals’ size within concrete. Bigger crystal grains showed less expansion, which suggests a size-dependent effect.
The degradation of concrete because of neutrons is currently a cause of concern but as the findings show this may see less expansion than formerly believed. As a result, degradation may be less severe than anticipated, hence, “allowing nuclear power plants to operate more safely over longer periods,” Maruyama stated.
With this research, the idea is to contribute to the selection of materials and design of concrete for future nuclear power plants. Moreover, it can provide valuable insights into the stability and durability of inorganic materials used in space-based structures for extraterrestrial construction both in the orbit of Earth and beyond.
In the next step, the team aims to address challenges in understanding the expansion behavior of different rock-forming minerals. This will help further clarify the expansion mechanisms and develop the ability to predict the expansion of aggregates based on their material properties and environmental conditions.
The research team also plans to be able to predict the way cracks form based on mineral expansion.
Advancing Radiation-shielding Concrete
Given the vital role concrete plays in protecting against harmful ionizing radiation across various applications including medical facilities, research laboratories, military, and nuclear power plants, the material has been subject to a lot of research.
In the last quarter of last year, international researchers took a deep dive into radiation-shielding concrete (RSC), which has been found to be essential in ensuring safety and supporting the beneficial use of radiation in various fields.
One such research2 published in November noted that radiation-shielding concrete, made of cement, water, and heavyweight aggregates, has the capability to bear gravity loads, incidental loads such as earthquake forces, and tornado-generated projectiles throughout its lifespan.
The aggregates mainly used in RSC include barite, hematite, magnetite, and colemanite. Incorporating such dense natural aggregates increases the density of the material and enhances the effectiveness of RSC in both medical and nuclear applications.
It is by improving some reinforced concrete properties to weaken radiation that RSC has become a typical choice for radiation shielding and protection.
Another study3 published around that time looked into enhancing the common and barite concrete’s efficiency in shielding radiation by utilizing different types of aggregates.
The study findings, which state that denser concrete offers better protection compared to lower-density variants, underscore the key role of material density in enhancing radiation shielding effectiveness. Here, barite concrete showed greater shielding properties because of its higher linear attenuation coefficient, which measures just how easily a material absorbs or scatters a beam of energy.
To achieve a high density of RSC, researchers replaced ordinary concrete aggregates with quartz, heavy minerals like zircon and fly ash, and artificial aggregates such as hydrous iron ore, iron waste, tin tailing, bauxite, galena, bismuth oxide, and recycled aggregates.
Using high-density concrete as radiation shielding can reduce the thickness of RSC by almost 40% compared to ordinary concrete while still maintaining load-carrying capacity.
The studies call for further research on the long-term durability of concrete under continuous radiation exposure, including assessing potential cumulative damage over extended periods for better insight into how the materials hold up over time.
Effects of environmental factors like temperature, humidity, and chemical exposure on concrete’s radiation shielding properties also need to be investigated in order to simulate real-world conditions and understand their impact on concrete’s effectiveness as a shielding material.
Relevant Companies
Now, let’s take a look at prominent names in the concrete and nuclear power space:
1. Vulcan Materials Company (VMC +0.83%)
This one is the producer of aggregates-based construction materials and a major supplier of ready-mix concrete and asphalt. Vulcan Materials’ segments include aggregates, asphalt, concrete, and calcium, which produce calcium products for the animal feed and water treatment industries.
Vulcan Materials Company (VMC +0.83%)
It has a market cap of $35.8 billion with VMC shares trading at $270.16, up 5.42% YTD. The company’s EPS (TTM) is 6.40, its P/E (TTM) ratio is 42.36, and its dividend yield is 0.68%.
For the quarter ended September 30, 2024, the company’s revenue came in at $2 billion, which was down 8.3% from 3Q23. Net income was $208.9 million while profit margin was 10% and EPS was $1.58. The company delivered $61 million to its shareholders through dividends. During this period, Vulcan Materials acquired Wake Stone Corporation to expand its reach in high-growth geographies in the Carolinas.
“While significant weather disruptions have impacted construction activity through the first nine months of the year, overall demand fundamentals continue to underpin long-term growth.”
– CEO Tom Hill
2. Constellation Energy (CEG +2.45%)
This one focuses on clean energy solutions through its nuclear, hydro, wind, and solar generation facilities, which have the capacity to power about 16 million homes. Constellation Energy produces about 10% of the carbon-free energy in the US.
Constellation Energy Corporation (CEG +2.45%)
It has a market cap of $95.8 billion with CEG shares trading at $307.83, up almost 37% YTD. The company’s EPS (TTM) is 9.06, its P/E (TTM) ratio is 33.81, and the dividend yield is 0.46%.
In Q3 of 2024, the company saw its earnings coming in at $1.2 billion, up from $731 million in 3Q23. Revenue also rose 7.2% to $6.55 billion. Its GAAP net income for the quarter was $3.82 per share and adjusted operating earnings were $2.74 per share. Notably, Constellation Energy signed a 20-year power purchase agreement with Microsoft to support its Crane Clean Energy Center.
The company’s nuclear fleet produced 45,510 GWhs during this quarter — increasing from 44,125 GWhs YoY. With that, it achieved a 95% capacity factor, which declined from 97.2% YoY. Constellation Energy’s planned refueling outage days meanwhile increased to 37 and non-refueling outage days doubled to 20.
Conclusion
Nuclear energy is a powerful and clean source of energy that offers high reliability and a small footprint. But serious nuclear power plant accidents have created fear among people. A critical aspect of nuclear power stations’ safety and longevity lies in the materials used in their construction, which is concrete used throughout the buildings.
Concrete is a relatively cheap, robust, and durable material that can be easily cast into various structures and comes with good shielding properties against radiation, making it a popular choice for radiation shielding applications.
While studies have explored radiation’s impact on the structural integrity of concrete, the latest research verifies the radiation effects and provides even more clarity into this material’s protection ability.
For instance, the observation of a clear flux dependency, with higher neutron flux resulting in a higher rate of expansion, and grain size dependence, particularly in the higher neutron fluence range implies the existence of a healing mechanism underlying radiation-induced volume expansion.
With insights like these, research can help develop more resilient structures to enhance the safety of existing reactors as well as build next-generation nuclear plants, in turn, shaping a viable and safe future.
Click here for a list of top nuclear stocks.
Study Reference:
1. Maruyama, I., Murakami, K., Ohkubo, T., Sawada, S., Kontani, O., Igari, T., Kawai, M., & Etoh, J. (2025). Neutron flux impact on rate of expansion of quartz. Journal of Nuclear Materials. Available online 13 January 2025, 155631. https://doi.org/10.1016/j.jnucmat.2025.155631
2. Onaizi, A. M., Amran, M., Tang, W., Betoush, N., Alhassan, M., Rashid, R. S. M., Yasin, M. F., Bayagoob, K. H., & Onaizi, S. A. (2024). Radiation-shielding concrete: A review of materials, performance, and the impact of radiation on concrete properties. Journal of Building Engineering, 97, 110800. https://doi.org/10.1016/j.jobe.2024.110800
3. Ahmad, N., Idris, M.I., Hussin, A. et al. Enhancing shielding efficiency of ordinary and barite concrete in radiation shielding utilizations. Sci Rep 14, 26029 (2024). https://doi.org/10.1038/s41598-024-76402-0