The Green Frontier: Key Considerations for Data Centers Adopting Nuclear SMRs

With recent news announcements linking big players such as Google, Microsoft and Amazon to nuclear power deals. '𝐍𝐮𝐜𝐥𝐞𝐚𝐫' is the new buzz word in the world of power-hungry data centres.

𝐒𝐦𝐚𝐥𝐥 𝐌𝐨𝐝𝐮𝐥𝐚𝐫 𝐑𝐞𝐚𝐜𝐭𝐨𝐫𝐬 (𝐒𝐌𝐑𝐬) generate electricity through nuclear fission and are considered green because they produce virtually no greenhouse gases during their operation albeit with minor emissions associated with the construction, fuel production, and decommissioning phases of the reactor lifecycle. Therefore, they are touted as a reliable, low-carbon energy option for ever increasing data centre power supply requirements.

While SMRs are currently subject to higher costs, ongoing research and development coupled with economies of scale are expected to reduce these costs over time. They also offer power outputs of up to 300MWe which distinguishes them from smaller 'Microreactors' typically used in remote locations and military bases. Meanwhile '𝐀𝐝𝐯𝐚𝐧𝐜𝐞𝐝 𝐌𝐨𝐝𝐮𝐥𝐚𝐫 𝐑𝐞𝐚𝐜𝐭𝐨𝐫𝐬' (𝐀𝐌𝐑𝐬) refer to SMRs that use advanced technologies beyond traditional designs, i.e. featuring innovations that boast higher efficiencies, improved safety systems, hybrid fuel usage, heat reuse in various applications, etc.

Let's take a look at some of the environmental challenges surrounding this technology.

Sustainability of Uranium Use in Small Modular Reactors (SMRs)

Low-enriched uranium (LEU) is currently the primary fuel for SMRs and sourced via underground or open-pit mines - with many advanced reactor designs requiring high assay low enriched uranium fuel (HALEU) allowing for smaller designs, longer operating cycles and increased efficiency. Australia, Kazakhstan, and Canada hold 50% of the World’s Uranium Reserves, whilst continued advances in extraction technologies can extend the lifetime of these substantial reserves, especially if coupled with innovative uranium recycling from spent nuclear fuel plus fuel-efficient SMR design. Hybrid approaches can also be developed including the use of natural gas as a supplementary fuel to enhance the reliability and flexibility of the system.

Alternative fuel sources include 'thorium-based' nuclear reactors, commonly found in igneous rocks and heavy mineral sands, with India boasting the world's largest reserves - the metal is seen as a more abundant and efficient substitute for the current dominate nuclear fuel.

Uranium is also subject to strict regulations relating to its mining, transportation and disposal - including The Nuclear Safeguards (EU Exit) Regulations 2019 (legislation.gov.uk ) in the UK and the EU's Radioactive Waste and Spent Fuel Management Directive (2011/70/Euratom) requiring all member states to have national policies for managing spent fuel and radioactive waste.

Nuclear waste: The Good, the Bad and the Ugly

The common perception is that traditional nuclear reactors generate reliable supplies of clean electricity whilst on the flip side generating radioactive waste that must be isolated from the environment for hundreds of thousands of years. SMRs were then seen as a way to reduce the CapEx of such installations whilst offering a reduction in radioactive byproducts compared to conventional large-scale reactors.

There is however some speculation in the scientific community that due to the differing design features and compact nature of SMRs - the volume of short-lived low and intermediate-level waste (LILW-SL) may actually be higher compared to larger reactors, depending on the specific system design, fuel cycle and waste management practices dealing with materials such as 'contaminated tools and clothing', 'filters and resins' and 'debris from reactor maintenance'.

On a positive note, because of its lower radioactivity and shorter half-life, LILW-SL can be managed and disposed of more easily compared to high-level waste (HLW), which remains hazardous for much longer periods. Examples of the latter include spent nuclear fuel and reactor components.

𝐈𝐧 𝐬𝐮𝐦𝐦𝐚𝐫𝐲, both types of waste need to be fully assessed and managed carefully to ensure safety and environmental protection. SMRs need to incorporate advanced waste management strategies to handle these different waste streams effectively.

A multi-step process is usually implemented that can include;

Collection and sorting,
Volume reduction using evaporation or solid-phase separation,
Chemical treatment,
Conditioning (immobilisation and packaged in a stable form) - ANDRA stacks waste packages in reinforced concrete cells. When a cell has been filled, the gaps are filled with gravel or mortar and the cell is sealed with a concrete slab and coated with a waterproofing polymer sealant.
Storage and disposal (i.e. long-term solutions include deep geological repositories (DGRs).

Innovative waste management approaches also include Partitioning and Transmutation (P&T) which converts long-lived radioactive elements from spent fuel into short-lived, less hazardous forms. Reusable parts of spent fuel components can also be reprocessed, transmutated and recycled to minimise waste volumes (i.e. Uranium, Plutonium, Minor Actinides and fission products). Whilst advanced reactors should be designed in a way that reduces waste volume generation and radiotoxicity (making it easier to handle) plus promote higher 'burnup' and improved fuel cycles. Another important design challenge is mitigation of radiation leakage ('neutron leakage' -the escape of neutrons from the reactor core without contributing to the fission process) which can alter the amount and composition of waste streams in addition to the environmental, human health and economic impacts. SMR designs typically utilise three strategies to mitigate neutron leakage, including enriched fuel, neutron reflectors, or modified coolant types. Thus, it is vitally important to evaluate the effectiveness of the mitigation methods chosen.

Radiotoxicity and Deep Geological Repositories (DGRs)

When selecting sites for geologic repositories, radiotoxicity is crucial because of:

Long-Term Safety: High radiotoxicity materials pose a long-term hazard and require isolation.
Environmental Health: Ensuring that the site is secure and that there is minimal risk of human exposure to radioactive materials or environmental contamination.
Regulatory Compliance: Meeting stringent regulatory standards for the safe disposal of high-level radioactive waste. The UK's Planning Act 2008 makes direct reference to radioactive waste geological disposal facilities and considers them 'Nationally Significant Infrastructure Projects (NSIPs)'.

Whilst the amount of spent nuclear fuel continues to grow, several countries are leading the development of permanent DGRs and have historically relied on interim wet or dry storage solutions scattered regionally at the surface or near-surface level. Finland appears to be ahead of the curve with their Onkalo spent nuclear fuel repository situated 400m below ground. It began construction in 2015 and recently completed the first stage of a trial run accepting used fuel from interim storage - highlighting the potential timeframes associated with building, commissioning and operating these kinds of facilities. The US's discontinued 'Yucca Mountain Project' also showcases the political, legal and regulatory challenges with establishing such facilities.

Historically, ocean disposal under the seabed was also an option to consider. However, this practice has since been discontinued due to environmental concerns and international regulations prohibiting ocean disposal of radioactive waste. It's interesting though to follow updates on Japan's gradual nuclear wastewater releases into the ocean (following the 2011 Fukushima tsunami incident) with approval from the International Atomic Energy Agency (IAEA) - a process that could take at least 30 years.

The delay in building permanent DGRs in the UK and Europe can be attributed to several factors including technical, operational and regulatory hurdles in addition to achieving the 'holy grail' of 𝐩𝐮𝐛𝐥𝐢𝐜 𝐚𝐜𝐜𝐞𝐩𝐭𝐚𝐧𝐜𝐞 - the combined willingness of a host community (financial incentives included) plus a suitable host geology being critical success factors in the site selection process - a tough ask when faced with the prospect of potentially hot radioactive waste over the course of a 1,000 years, with prolonged radiological hazards in excess of 10,000 years. Requiring a robust storage solution that ultimately removes any likelihood of barrier system degradation, inadvertent intrusion, and contamination via air, soil and water pathways over the lifetime of the decontamination process. Operators also need to be mindful of nuclear liability conventions set up to compensate victims having suffered nuclear damage either at the installation level or during transportation. Another critical design criterion includes security, with measures for redundancy, diversity, and defense-in-depth to protect against potential threats, which includes cyber-attacks.

SMR Site Selection and the Approval Process

Proper evaluation of the potential environmental impacts and compliance with environmental regulations is critical - in addition to several important geological surveys to validate the feasibility of the prospective site(s). These include a seismic hazard assessment, soil and rock stability assessment, hydrogeological (groundwater condition) survey, slope stability analysis plus infrastructure availability assessments (i.e. access roads and utilities) with a key focus on redundancy to ensure continuous and reliable operation.

In the UK, the construction, installation, operation, and decommissioning of SMRs are governed by several key pieces of legislation and regulatory frameworks:

Nuclear Installations Act 1965: This act provides the legal framework for the licensing and regulation of nuclear installations, including SMRs.
Office for Nuclear Regulation (ONR): The ONR is responsible for regulating nuclear safety and security in the UK. It ensures that SMRs meet stringent safety standards throughout their lifecycle.
Environmental Permitting Regulations: These regulations, enforced by the Environment Agency and Natural Resources Wales, control the environmental impact of nuclear installations, including waste management and emissions.
Control of Major Accident Hazards (COMAH) Regulations: These regulations require operators to take measures to prevent major accidents and limit their consequences. COMAH-registration depends on the specific quantities and types of substances present at a given site.
Nuclear Decommissioning Authority (NDA): The NDA oversees the decommissioning of nuclear facilities, ensuring that it is carried out safely and efficiently.
Generic Design Assessment (GDA): SMR designs must undergo a GDA process, which assesses their safety, security and environmental impact before they can be approved for construction.

One of the benefits of GDA is that it can reduce the overall time for deployment of a design at more than one site by assessing generic aspects only once and before site specific proposals come forward.

Step 1 – usually takes around a year – this is where the project is set up with the design company, defining the scope and forming an agreement on what information is required. The ONR/EA/NRW assessment team also learn about the design and offer advice to help in the preparation of the assessment.

Step 2 – usually takes around a year – here the fundamentals of the design are assessed – are the basics of the design correct, what’s missing? What are the intended functions of key systems? The key focus is on features of the design which protect the environment including how the design can be optimised to reduce the amount of radioactive waste produced and how that waste is managed and disposed of.

More detailed information from the company is scrutinised and should concerns be raised it will be done via a formal process – be it an issue, observation or query.

Step 3 – usually takes around two years. The design is then assessed in greater detail to ensure that it sufficiently meets the key objectives and intended environmental protection functions. The design should use best available techniques to ensure that the radiation exposure of people and the environment are minimised and within statutory limits and guidelines, and that other environmental impacts are also minimised. Rolls Royce's UK SMR design has recently entered this phase.

New Nuclear Power Plants: Generic Design Assessment Guidance to Requesting Parties

Thus, in order to deploy SMRs quickly and efficiently, several strategies need to be implemented.

Parallel Processes

Early Engagement: Engaging with regulatory bodies early in the design process to ensure all requirements are met from the start.
Parallel Development: Developing the reactor design and conducting the GDA process in parallel to save time.

Streamlined Approvals

Regulatory Cooperation: Close cooperation between the Office for Nuclear Regulation (ONR), the EA and NRW to streamline the assessment process.
Pre-Approved Designs: Utilising pre-approved design elements and safety features to expedite the GDA process.

Factory Fabrication

Modular Construction: Building pre-fabricated reactor components in a factory setting, which can significantly reduce on-site construction time.

Government Support

Policy and Funding: Government support through policies, funding, and incentives to accelerate the deployment of SMRs.
Public-Private Partnerships: Collaborating with private companies to share resources and expertise.

Once the Generic Design Assessment (GDA) process is approved and complete for a Small Modular Reactor (SMR) deployment, there are still additional approvals required before construction and operation can begin. Again, early engagement is critical to expedite the process. These include:

Site-Specific Approvals: The developer must obtain planning permission and other necessary consents from local authorities and regulatory bodies for the specific site where the SMR will be built. For example, almost all SMR proposals would be classified as “Nationally Significant Infrastructure Projects” (NSIPs), as they would have a generation capacity in excess of 50 MW. Any application for an SMR would therefore be subject to the Development Consent Order (DCO) application process under Part 4 of the Planning Act 2008. The timeframe for this process from application submission to decision can take around 12 to 15 months.
Environmental Permits: Separate environmental permits may be required to address site-specific environmental impacts. Early engagement with the Environment Agency is advised to understand the permitting requirements surrounding emissions to air, water, and land, as well as the management of radioactive substances and waste. In many cases, risks can and should be engineered out at an early stage, reducing the permitted activity requirements. This is Biyat Energy & Environment Ltd's bread and butter so to speak. Sewerage undertakers may also have specific requirements and should be consulted regarding the disposal of wastewater and effluents from SMRs i.e. via cooling systems, decontamination processes and routine maintenance activities. Local authorities (councils) also regulate businesses and are responsible for issuing Part A2 and Part B permits in the UK. These permits are part of the pollution control regimes known as LA-IPPC and LAPPC respectively. Part A permits cover activities that have a significant impact on the environment, such as large-scale industrial processes, while Part B permits cover less-intensive activities.
Construction and Operating Licenses: A Nuclear Site Licence (NSL) issued by the Office for Nuclear Regulation (ONR) is crucial for the deployment of SMRs in the UK. The NSL is a legal document that grants permission to use a site for specified nuclear activities, such as constructing and operating an SMR - covering the entire life cycle of the facility.

Established law firms such as Burges Salmon LLP, Castletown Law and Womble Bond Dickinson (UK) LLP have expertise in these requirements and can help navigate developers through the process.

Synergies with other Technological Developments

Small Modular Reactors (SMRs) produce waste heat as a byproduct of their operations. The amount of waste heat produced can vary depending on the specific reactor design and its efficiency. Whilst about 25% of industrial processes in the EU require heat that is above 400 degrees Celsius, which can be produced by SMRs. In the UK, this heat might be used to produce hydrogen, ammonia, and other sustainable synthetic fuels, as well as to directly absorb carbon dioxide from the air. Conversely, district heating systems could employ lower temperature "waste" steam to heat homes. In colder regions, a number of nations now use nuclear cogeneration for district heating; in China, SMRs are being constructed specifically for this purpose.

For hydrogen production, the waste heat can be harnessed via processes such as high-temperature steam electrolysis (HTSE) or sulfur-iodine (SI) cycles. As showcased by developers including NuScale and Rolls Royce.

Credit: NuScale - The Hydrogen Rush: Ushering in a New Era of Energy with Small Modular Reactors

It's Race Time! The SMR 'Semi-Finals'

Last month, it was announced in the UK that four companies (Westinghouse, GE-Hitachi Nuclear Energy (GEH), Holtec Britain, and Rolls-Royce) remain in the running to potentially deliver nuclear technology development contracts aimed at providing operational SMRs by the mid-2030s.

We look forward to following these developments further, whilst key selection criteria Biyat Energy & Environment Ltd would look out for include:

Power output and scalability,
Cooling infrastructure requirements,
Operational experience, proven technology,
CapEx and OpEx,
Robust active and passive safety features,
Modular deployment capability,
and finally, Reliability!

We hope you found this article useful!

If you require assistance developing a decarbonisation approach in your business or industrial facility…we are here to support you every step of the way.

Contact — Biyat Energy & Environment Ltd (biyatenergyenvironment.com )

This article was written by Luay Zayed, founder of Biyat Energy & Environmental Ltd. A global energy and environmental consultancy specializing in turnkey engineering solutions that protect the environment and improve energy efficiency in the manufacturing & industrial sectors.

Luay ZayedOctober 16, 2024