The Anonymous Widower

Centrica, X-energy Advance Nuclear Plans As UK Regulators To Begin Design Review For Xe-100

The title of this post, is the same as that of this press release from Centrica.

This is the sub-heading.

On the one-year anniversary of the Centrica X-energy partnership being signed, the UK Government has directed regulators to accept the X-energy Xe-100 Advanced Modular reactor into the Generic Design Assessment, marking a significant step toward UK commercial licensing.

Under their partnership, the companies intend to deploy up to 6 GW of new nuclear capacity in the UK (10-20 Xe-100 power stations depending on size of each installation)

These first two paragraphs add some details.

Centrica and X‑Energy, Inc., a leading developer of advanced nuclear reactors and fuel technology, today announced that X‑energy’s Xe‑100 Generation IV advanced Small Modular Reactor (“SMR”) has been accepted into the United Kingdom’s Generic Design Assessment (“GDA”) process.

GDA acceptance formally triggers the process of assessing the design’s acceptability for deployment and operation ahead of the technical and environmental evaluations required for site‑specific licensing and permitting. The assessment is expected to take approximately three years and will be administered by the UK Office for Nuclear Regulation (“ONR”), the Environment Agency (EA), and Natural Resources Wales

 

To learn more, I asked Google AI for what it knows on the Xe-100 reactor and I received this.

The Xe-100 is an advanced Generation IV high-temperature gas-cooled pebble-bed small modular nuclear reactor developed by the American company X-energy.

Key Specifications & Design

Power Output: Generates about 80 megawatts of electricity (MWe) or 200 MW thermal per unit, and can be scaled up into a four-pack configuration yielding 320 MW.

Cooling System: Uses inert helium gas instead of water to remove heat from the core, reaching operating temperatures above 750°C.

Fuel Type: Runs on proprietary TRISO-X fuel pebbles, where each billiard-ball-sized pebble contains roughly 18,000 microscopic TRISO fuel particles that act as individual containment vessels.

Note.

1. 320 MW may seem small, but you have to remember Sizewell A was two 210 MW Magnox reactors and it operated for forty years.
2. I like the choice of helium for a coolant. Especially, as the gas is widely used for cooling superconducting magnets, so there must be plenty of expertise.
3. Helium is also present in the atmosphere at 5.2 parts per million.
4. I also like the concept of the fuel pebbles.

These are some of my questions.

Where Was TRISO Fuel Developed?

The Wikipedia entry for TRISO Fuel has a History section, which starts with this paragraph.

Coated-particle ceramic fuels were initially developed in the United Kingdom as part of the Dragon reactor project. During the development of the Dragon reactor, its designers became concerned by the need to purge gaseous fission products from the reactor core and their potential migration to other parts of the reactor This concern led to the choice of coated-particle fuel, where the fuel would be formed from small particles of uranium then coated with pyrolytic carbon. The inclusion of silicon carbide as a diffusion barrier was first suggested by D. T. Livey in 1961, in order to better retain fission products.

Note.

1. The United States and Germany made contributions to the development of TRISO fuel.
2. the first commercial reactor to use TRISO, was the 330 MW_e Fort Saint Vrain Nuclear Power Plant
3. The experimental High Temperature Test Reactor in Japan, constructed in 1998, uses prismatic UO₂ TRISO fuel.
4. Japan has the only TRISO-fueled reactor in commercial operation.
5. Oak Ridge National Laboratory in the United States, developed the process used to make TRISO fuel.

The Wikipedia entry for the Dragon reactor is worth a read.

These are the first two paragraphs of its Wikipedia entry.

Dragon was an experimental high temperature gas-cooled reactor at Winfrith in Dorset, England, operated by the United Kingdom Atomic Energy Authority (UKAEA). Its purpose was to test fuel and materials for the European High Temperature Reactor programme, which was exploring the use of tristructural-isotropic (TRISO) fuel and gas cooling for future high-efficiency reactor designs. The project was built and managed as an Organisation for Economic Co-operation and Development/Nuclear Energy Agency international project. In total, 13 countries were involved in its design and operation during the project lifetime.

Originally conceived as a small research reactor, during the design phase it grew larger. The choice of helium coolant was made after a long debate within the UKAEA between proponents of helium and carbon dioxide, with helium ultimately selected. Groundbreaking occurred in 1960. It operated from 1965 to 1976, and is generally considered extremely successful.

Who Are The Technology Partners Of X-energy?

I had to ask Google AI this question and received this reply.

X-energy works with major technology, industrial, and energy partners to develop and deploy its advanced small modular nuclear reactors (SMRs) and TRISO-based fuel technology.

Key Technology and Strategic Partners

Amazon and AWS: A primary investor (through the Climate Pledge Fund) and customer, Amazon collaborates with X-energy on scaling nuclear energy for data centers and AI infrastructure. X-energy, Amazon Web Services (AWS), NVIDIA, and Idaho National Laboratory are founding members of Project Prometheus to apply AI to advanced nuclear deployment.

NVIDIA: A founding partner in Project Prometheus alongside AWS and Idaho National Laboratory, helping integrate AI accelerators and tools into nuclear design and operations.

Doosan Enerbility & Korea Hydro & Nuclear Power (KHNP): South Korean industrial partners collaborating to support multi-gigawatt deployments of Xe-100 reactors and manufacture key components.

Energy Northwest: A utility partner working on X-energy’s first-of-a-kind project development in Washington state.

Dow Inc.: Partnered with X-energy to deploy an initial four-unit Xe-100 plant at Dow’s Seadrift chemical manufacturing site in Texas.

Centrica: Partnered through a Joint Development Agreement to deploy Advanced Modular Reactors and pursue up to 6 gigawatts of new nuclear capacity in the United Kingdom.

IHI Corporation: Partnered to expand U.S.-Japan supply chain collaboration and commercial-scale manufacturing for reactor components.

Oak Ridge National Laboratory: Collaborates with X-energy’s fuel subsidiary, TRISO-X, on advanced nuclear fuel research.

Note.

1. There are companies and organisations here from Korea, Japan, the US and the UK.
2. Do Amazon and Centrica see an Xe-100 reactor as a reliable way of powering a data centre without a grid connection?
3. The Korean and Japanese companies would be ideal to ensure the quality of reactor and other key compoonents.
4. Chemical manufacturing sites use a lot of electricity and Dow’s contribution could define a widespread use of the Xe-100.
5. Oak Ridge have been a client of mine in the past and like AWRE in England, I would trust their nuclear technology.

I also believe that if you put these companies in a joint venture, you’ll get out more ideas than you expect.

Who Are The Financial Partners Of X-energy?

I had to ask Google AI this question and received this reply.

Amazon & Climate Pledge Fund: Led major funding rounds (including a $500 million investment in 2024 and ongoing backing) and holds a significant stake in the company.

Jane Street: Led X-energy’s oversubscribed $700 million Series D financing round.

Ares Management: Provided financial backing and funds across multiple investment rounds alongside special purpose acquisition sponsorships.

Emerson Collective: Participated as a key venture capital backer across multiple funding rounds.

NGP Energy Capital Management: Contributed significant capital through multiple financing stages.

Segra Capital Management: Acted as an ongoing financial participant in major capital raises.

Other Investors: Includes ARK Invest, Point72, Galvanize, Ken Griffin (Citadel founder), XTX Ventures, Reaves Asset Management, and the University of Michigan.

Note that like the technology, the finance comes from a wide variety of sources.

This all sounds like a good positive start.

Will Centrica, X-energy Be Going For A Multi-Country Design Review For Xe-100?

There are four major countries with extensive nuclear power experience, with stakes in the Xe-100; Japan, Korea, the US and the UK.

There is also Oak Ridge in the US, which appears to be supplying the concept of the fuel.

If this group can’t convince the regulators in these four countries, that they have a safe and viable project, then they shouldn’t be in business.

Conclusion

It’s now mainly up to the regulators.

Unfortunately, you get stories with titles like this article on the BBC, which have a title of Green Party Leader Criticises Nuclear Reactor Plan.

 

September 18, 2026 Posted by AnonW | Artificial Intelligence, Energy | Amazon, Amazon Web Services, Centrica, Data Centre, Dow Chemical, Dragon Reactor, Google AI, Helium, Japan, Korea, Nuclear Power, Nvidia, Politics, Small Modular Nuclear Reactor, TRISO Fuel, UKAEA, X-energy, Xe-100 Advanced Modular Reactor(AMR) | 2 Comments