New nuclear reactor technologies

From ScienceForSustainability
Jump to navigation Jump to search

Most current nuclear power stations use Uranium fuel in solid form in rods, with water or heavy water as coolant. Neutrons produced by the nuclear reactions are slowed down to "thermal spectrum" velocities which affects the range of nuclear reactions they produce. Reactors are large in order to produce high power outputs, but are consequently complex in order to ensure safety through multiple redundant control systems, and expensive to build. Major components including the huge pressure and containment vessels are built or assembled on-site. In most cases even reactors of the same nominal design vary from one instance to another.

Many other reactor designs are possible, and a few are being actively developed. Some build on existing water-cooled Uranium-fuelled designs but shrink and simplify the designs to make them cheaper and quicker to build with the aim of building most of the reactor itself in factories where production-line economies can be gained. Physically smaller, lower power designs can more easily be made "walk away safe", averting the risk of the sort of overheating which lead to the melt-downs at Fukushima, using only passive cooling systems. Thus although the smaller designs have lower power output they may achieve lower cost per power output and bigger power stations can simply use multiple Small Modular Reactors to give higher outputs. Because the capital cost of each SMR is much lower than that of conventional reactors, bigger power stations can be built gradually with smaller amounts of finance exposed to risks of delay or even abandonment of the whole project.

Other designs differ more radically from current generation reactors: Helium is used instead of water as a heat transfer medium in High Temperature Gas Reactors, liquid sodium is used in many "breeder" reactors operating in the "fast" neutron spectrum, and Molten Salt Reactors (MSRs) use molten Fluoride or Chloride salts of Sodium or Lithium (and sometimes other elements) as coolants, and as solutions in which fuel is dissolved. There are also reactor designs - particularly MSRs - which use Thorium rather than Uranium as fuel, and some which are designed to burn existing used nuclear fuel (which still contains much of the theoretically burnable Uranium it started with) or Plutonium (such as now-surplus nuclear bomb material).

See also


Advanced Reactor Infromation System (ARIS)

The ARIS database includes technical information about Advanced Reactor Designs that is provided by the responsible design organizations and/or reactor plant vendors. According to the definitions established by the IAEA, an advanced reactor design consists of both Evolutionary and Innovative reactor technologies. Evolutionary reactor designs are reactor designs that improve on existing designs through small or moderate modifications with a strong emphasis on maintaining proven design features to minimize technological risk. While innovative reactor designs incorporate radical changes in the use of materials and/or fuels, operating environments and conditions, and system configurations. Advanced reactors can be classified in terms of coolant, neutron spectrum, temperature or purpose. With regards to purpose, the reactors can be sorted in terms of experimental, demonstration or prototype, and commercial.

Generation III reactor Wikipedia

Generation IV reactor Wikipedia

Generation IV Nuclear Reactors World Nuclear Association ; Jul 2016

  • An international task force is developing six nuclear reactor technologies for deployment between 2020 and 2030. Four are fast neutron reactors.
  • All of these operate at higher temperatures than today's reactors. In particular, four are designated for hydrogen production.
  • All six systems represent advances in sustainability, economics, safety, reliability and proliferation-resistance.
  • Europe is pushing ahead with three of the fast reactor designs.
  • A separate programme set up by regulators aims to develop multinational regulatory standards for Generation IV reactors.

The Advanced Nuclear Industry Samuel Brinton; Third Way; 15 Jun 2015

has comprehensive list of fission & fusion developments, comparison of technology types, and references

Tomorrow’s Nuclear Reactors are Closer Than You Think Laura Scheele, Idaho National Laboratory;; 1 Mar 2016

Advanced Reactor Nuclear Power Resurgence in the U.S.; 29 Jan 2016

White House strikes a blow for advanced nuclear reactors Richard Martin; MIT Technology Review; 20 Nov 2015

U.S. Department of Energy has announced a new program to help facilitate and finance innovation in nuclear power. Called the Gateway for Accelerated Innovation in Nuclear, the program will “provide the nuclear energy community with access to the technical, regulatory, and financial support necessary to move new or advanced nuclear reactor designs toward commercialization.”

There are nearly 50 companies in North America working on advanced nuclear reactor technologies, backed by more than $1.3 billion in private capital, according to Third Way, a Washington, D.C.-based research organization focused on energy, climate change, and national security (see “Experiments Start on a Meltdown-Proof Nuclear Reactor” and “Advanced Reactor Gets Closer to Reality”). But a lack of support from the DOE and an expensive, time-consuming licensing process under the Nuclear Regulatory Commission have presented hurdles that are all but insurmountable for startups (see “Advanced Nuclear Industry to Regulators: Give Us a Chance”).

The Gateway program, announced at the Summit on Nuclear Energy held last week at the White House, is the clearest signal to date of the Obama administration’s support for new nuclear technology. The DOE also announced it would broaden its $12.5 billion loan guarantee program for innovative nuclear technologies. These initiatives will give advanced nuclear companies access to the national laboratories, a single point of contact for collaboration with DOE experts, and help in “understanding and navigating the regulatory process for licensing new reactor technology.”

A retrospective analysis of funding and focus in US advanced fission innovation A Abdulla, M J Ford, M G Morgan, D G Victor; IOP science; 10 Aug 2017

Deep decarbonization of the global energy system will require large investments in energy innovation and the deployment of new technologies. While many studies have focused on the expenditure that will be needed, here we focus on how government has spent public sector resources on innovation for a key carbon-free technology: advanced nuclear. We focus on nuclear power because it has been contributing almost 20% of total US electric generation, and because the US program in this area has historically been the world's leading effort. Using extensive data acquired through the Freedom of Information Act, we reconstruct the budget history of the Department of Energy's program to develop advanced, non-light water nuclear reactors. Our analysis shows that—despite spending $2 billion since the late 1990s—no advanced design is ready for deployment. Even if the program had been well designed, it still would have been insufficient to demonstrate even one non-light water technology. It has violated much of the wisdom about the effective execution of innovative programs: annual funding varies fourfold, priorities are ephemeral, incumbent technologies and fuels are prized over innovation, and infrastructure spending consumes half the budget. Absent substantial changes, the possibility of US-designed advanced reactors playing a role in decarbonization by mid-century is low.

Analysis highlights failings in US's advanced nuclear program IOP Publishing; AAAS EurekAlert; 9 Aug 2017

Despite repeated promises over the past 18 years, the US Office of Nuclear Energy (NE) is unlikely to deliver on its mission to develop and demonstrate an advanced nuclear reactor by the mid-21st century.

That is the conclusion of a new study from the University of California, San Diego and Carnegie Mellon University, published today in the journal Environmental Research Letters, which used data obtained through the Freedom of Information Act to reconstruct the program's budget history.

Lead researcher Dr Ahmed Abdulla, from UC San Diego, said: "In theory, advanced, non-light water reactors are a promising carbon-free technology, which could complement or replace light water reactors. Some of these reactors would operate at higher temperatures, providing energy services that existing reactors cannot. Others, meanwhile, could reduce future nuclear waste burdens by operating for decades without refuelling, burning up more of their fuel and generating smaller volumes of waste.

"However, despite repeated commitments to non-light water reactors, and substantial investments by NE (more than $2 billion of public money), no such design is remotely ready for deployment today."

The researchers investigated how effectively those resources were allocated, and how NE has performed as a steward of nuclear technology innovation. What they found was an office beset by problems and violating much of the wisdom about how to effectively run an applied energy research program.

Dr Abdulla said: "There were often inconsistencies in the annual budget documents. The budget itself varies significantly over the period of study, which is fine if these variations are part of a coherent vision that is being pursued, but that is not the case. At all levels, NE favours existing technologies and fuels over innovation, and, where it does support truly innovative research, it is prone to changing priorities before any concrete progress has been made.

Next Steps for Nuclear Innovation in the UK Stephen Tindale, with Katherine Chapman and Suzanna Hinson; Weinberg Next Nuclear; Apr 2016

Nuclear energy makes a major contribution to UK energy security. Existing civil nuclear reactors provide clean, low carbon energy, mitigating the problems of air pollution and climate change. But they have high upfront capital costs, and are not sufficiently flexible to back up wind and solar power. Significant progress on advanced nuclear energy technologies over the next ten years would address these drawbacks and contribute substantially to a more secure and sustainable UK energy system. However, advanced nuclear should be pursued as well as - not instead of - new nuclear facilities using existing nuclear technology. Advanced nuclear is not yet ready to fill the entire gap created as current UK nuclear facilities reach the end of their design life.

Advanced nuclear reactors could deliver energy that is even lower-carbon than energy from existing nuclear designs. They could be inherently and passively safe and have a significantly reduced proliferation risk. They would be cheaper to build than the EPR, and very probably cheaper than any existing nuclear design. They could be a means of re-using spent fuel and reducing the UK’s plutonium stockpile.

Includes summary of some new generation designs
Charles Barton's comments on Weinberg report:

Next Step for Nuclear innovation in the UK is a deeply flawed document prepared for the British Government by the Weinberg Institute as a policy guide intended to assist the Government of the UK on future choices regarding advanced nuclear technology. Unfortunately, the Weinberg Institute lacks the Depth of Alvin Weinberg, the famous Nuclear Scientist for which it is named. Below is a link to this document. I will focus here of the criteria by which this document suggests future nuclear decisions should be based. Next Step places two Safety and proliferation prevention above other categories. But Generation III + reactors are already highly safe, indeed safer than renewable generation technologies, and minimal safety standards for Generation IV reactors are in some cases even safer. Efficiency requirements might well produce generation IV reactors that meet absurdly safe standards. So why make safety more important than other considerations. The second standard is the prevention of nuclear proliferation. Yet we are talking her about Reactors to be built in the UK, the United States and Canada. The first two countries are already nuclear powers, while the third country has possessed the ability to build nuclear weapons since WW II, but has refrained to do so. The reactors built in these three countries are very unlikely to cause nuclear proliferation, and one way to avoid proliferation from Generation IV technology built in any of these countries, is an agreement between the three of them to not sell Generation IV reactors to any State that is likely to embark on nuclear weapons programs. A further consideration is that the Chinese are working on development projects involving 3 different types of Generation IV reactor technology. Unless brought into proliferation prevention arrangements, China could sell Generation IV reactors to countries known to pose proliferation risks. Clearly there are problems with this study.

Conventional large reacors


Atmea is a joint venture between Mitsubishi Heavy Industries (MHI) and EDF Group that develops, markets, licenses and sells the ATMEA1 reactor, a new generation III+, medium-power pressurized water reactor (PWR). See [Wikipedia].

Floating reactors

Are Floating Reactors The Future Of Nuclear Energy? Vanand Meliksetian; OilPrice; 8 Dec 2018

The future of nuclear energy is either gloomy or promising depending on the country or region in question. In the developed world nuclear power is in decline. Especially after the disaster at Fukushima in Japan, the nuclear power industry is fighting an uphill battle. Tokyo became the world’s largest importer of LNG following the closure of several of its nuclear facilities. Germany is planning to decommission all of its 22 plants until 2022. Also, heavyweight France which derives 75 percent of its energy from nuclear, has announced the decommissioning of 14 of its 58 plants. Only the UK intends to construct a new power plant with Chinese and French help.

In other parts of the world, however, nuclear energy is a highly sought-after prize. Russia’s state-owned Rosatom has emerged as the global leader when it comes to constructing nuclear power plants. The company has an international order book worth $300 billion spread over 12 countries in the developing world. Traditional plants take over a decade to build and are definitively fixed to the grid, but Rosatom intends to provide alternative technologies to overcome these liabilities.

In order to maintain its competitive edge, the company has invested approximately $400 million in developing a unique kind of nuclear power plant, a floating one. The secretive nature of the project in the first years of its development didn’t help assure critics concerning the safety of the facility. In recent years, Rosatom has disclosed some of the construction methods in order to prove to potential customers the value and safety of its technological breakthrough.

Besides Russia, others also intend to develop floating nuclear power plants of their own. Two Chinese state-owned companies are developing the necessary technology to start constructing up to 20 facilities over the coming years. American scientists are also at it, but according to Jacopo Buongiorno, a professor of nuclear engineering at Massachusetts Institute of Technology “the Russians are light-years ahead of us”.


Bohai Shipbuilding Industry to build China’s first offshore nuclear platform Jason Jiang; Splash 24/7; 20 Apr 2016

China Shipbuilding Industry Corporation (CSIC) has confirmed that it will construct the first offshore nuclear platform at its affiliate yard Bohai Shipbuilding Industry. Currently Bohai Shipbuilding Industry is collaborating with China General Nuclear Power Corporation (CGN) for the preliminary works of the project. CSIC-No.719 Research and Development Institute has completed two designs for the platform, one is a floating platform and the other is a submersible platform. CGN has been developing a small modular nuclear reactor called the ACPR50S for maritime use, which would be able to provide power to offshore oil and gas exploration and production. The investment on the project is about RMB3bn ($464m), and the first platform is expected to start a trial in 2019. China also made plans to build 20 offshore nuclear platforms in the near future. Bohai Shipbuilding is one of China’s more secretive yards, tasked with plenty of military contracts as well as commercial vessel construction.

China Plans A Floating Nuclear Power Plant James Conca; Forbes; 18 Jan 2016

A 200MW light water reactor for electrical power, desalination etc.

Lloyd's Register to help Chinese develop floating SMR World Nuclear News; 26 Oct 2015

Lloyd's Register of the UK announced today it has signed a framework agreement with the Nuclear Power Institute of China (NPIC) to support the design and development of a floating nuclear power plant utilizing a small modular reactor (SMR).

Under the framework agreement, Lloyd's Register and NPIC - a subsidiary to China National Nuclear Corporation (CNNC) - will cooperate on the development of the "first-of-a-kind floating nuclear vessel" which will be used in Chinese waters to supply electrical power to offshore installations.

Lloyd's Register said the first contract under the framework agreement is to develop new safety regulations, safety guidelines, and nuclear code and standards for the floating vessel, that are consistent with Offshore and International Marine Regulations and the International Atomic Energy Agency (IAEA) nuclear safety standards.


Russia to Build World's First Floating Nuclear Power Plant Next Year The Moscow Times; 21 Apr 2015

Russia starts work on Arctic dock for 1st-ever floating nuclear power plant RT; 7 Oct 2016

The world’s first floating nuclear power plant is set to start producing power and heat in 2019. While the plant is already being tested, construction of the dock has begun on the Arctic coast in Russia’s Far East. The construction works on the dock, which will host the floating nuclear power plant ‘Akademik Lomonosov’, kicked off Wednesday in the bay of the city of Pevek, Chukotka, RIA Novosti reports.

Russia's Floating Nuclear Power Plant Has Hit the Sea Jennings Brown; Gizmodo; 30 Apr 2018

Russia launched the world’s first floating nuclear power plant on Saturday. The 70-megawatt vessel, christened the Akademik Lomonosov, was towed away from St. Petersburg by two boats. It is currently coasting through the Baltic Sea to the town of Murmansk for fuel, and is then supposed to embark for the Arctic town of Pevek in 2019, according to a release from the state-run firm that built the rig.

Both reactors on Rosatom’s floating nuclear plant now operational Charles Digges; Bellona; 7 Dec 2018

Both reactors on the Akademik Lomonosov, Russia’s controversial floating nuclear power plant, are now operational, and its starboard side reactor has been brought up to 10 percent of its total power, Rosatom, Russia’s state nuclear corporation, said in a release.

The reactor start, which occurred at Atomflot, Russia’s nuclear icebreaker port in Murmansk, passed without incident, according to the release, and will be followed by a number of reactor tests, which are expected to last several months.

After completing these tests, the Akademik Lomonosov – essentially a large barge atop which sit the reactors – will be towed through the Arctic to the far eastern Siberian port of Pevek, a town of 100,000 people in Chukotka, were it is slated to go online in the summer of 2019.

The plant is expected to replace the energy supplied by the Bilibino nuclear power plant – the world’s four northernmost commercial reactors – which Rosatom will begin decommissioning in 2021.

Washington State SMRs

Washington State continues looking into small modular reactors nuScale, mPower

Advanced Boiling Water Reactor

One step closer to building an Advanced Boiling Water Reactor (ABWR) in the UK The Alvin Weinberg Foundation

Pebble Bed Reactors

Pebble bed reactors use small ceramic-clad balls of enriched Uranium fuel. The fuel can operate at very high temperatures and pebble-bed reactors are generally considered to be meltdown-proof. Due to the high temperatures they can run at they are generally gas cooled, although U. C. Berkley's Kairos Power reactor design uses a molten fluoride salt as coolant. Pebble bed reactors' high operating temperatures open up the possibility of using them to provide industrial process heat, as well as giving higher efficiency converting heat to electricity.


HTR-10 Wikipedia

China plans to open 1st ‘meltdown-free’ nuclear power plant by 2017 Chinese High Temperature Pebble Bed Reactor

China Could Have a Meltdown-Proof Nuclear Reactor Next Year Richard Martin; MIT Technology Review; 11 Feb 2016

Two high-temperature, gas-cooled reactors under construction in Shandong will make up the first commercial-scale plant of its type in the world.

In what would be a milestone for advanced nuclear power, China’s Nuclear Engineering Construction Corporation plans to start up a high-temperature, gas-cooled pebble-bed nuclear plant next year in Shandong province, south of Beijing. The twin 105-megawatt reactors—so-called Generation IV reactors that would be immune to meltdown—would be the first of their type built at commercial scale in the world.

Construction of the plant is nearly complete, and the next 18 months will be spent installing the reactor components, running tests, and loading the fuel before the reactors go critical in November 2017, said Zhang Zuoyi, director of the Institute of Nuclear and New Energy Technology, a division of Tsinghua University that has developed the technology over the last decade and a half, in an interview at the institute’s campus 30 miles south of Beijing. If it’s successful, Shandong plant would generate a total of 210 megawatts and will be followed by a 600-megawatt facility in Jiangxi province. Beyond that, China plans to sell these reactors internationally; in January, Chinese president Xi Jinping signed an agreement with King Salman bin Abdulaziz to construct a high-temperature gas-cooled reactor in Saudi Arabia.

China's HTGR fuel production line starts up World Nuclear News; 29 Mar 2016

A pilot production line of fuel elements for China's Shidaowan HTR-PM - a high-temperature gas-cooled reactor (HTGR) demonstration project - has started in Baotou, Inner Mongolia. The first tank of uranium dioxide powder was slowly poured into the dissolution tank on 27 March, marking formal entry into production of the HTGR fuel line, China National Nuclear Corporation announced the following day. Earlier this month, the National Nuclear Security Administration approved an operating licence for the fuel production line. The production line will have an annual capacity of 300,000 spherical fuel elements. The National Nuclear Security Administration issued a permit for its construction in February 2013 and an opening ceremony was held the following month. The installation of equipment was completed in September 2014.

Progress Report on HTGR reactors in China and U.S. 9 Neutron Bytes; Apr 2016

Development of the a high temperature gas cooled reactor (HTGR), a concept with more than three decades of history behind it, in 2016 has had several new breakout milestones in China and the U.S.

  • In March 2016 China installed the first of two reactor pressure vessels for a demonstration high temperature, gas cooled (HTGR) (Pebble Bed) reactor that is under construction at Shidaowan in Shandong province.
  • In January 2016 the U.S. Department of Energy announced that X-energy, located in the Maryland suburbs of Washington, DC, has won a $40 million grant to develop the Xe-100 pebble bed High Temperature Gas-Cooled reactor (HTGR). The development grant includes $6M in FY2016, which will be supplemented with additional investor funding from X-energy.
  • The Next Generation Nuclear Plant alliance (NGNP) continues its work on development of the Areva Antares HTGR, a prismatic block design. The NGNP alliance has published a business plan with the objective of building a prototype at the U.S. site in the 2020s.

Will China convert existing coal plants to nuclear using HTR-PM reactors? Rod Adams; Atomic Insigts; 21 Nov 2016

It would be a huge benefit to the earth’s atmosphere if China, India, Brazil and the US could reduce direct coal burning while still making use of much of the capital that they have invested in building coal fired power plants. It would make an even larger difference in reducing air pollution in the areas downwind of the coal stations.

Converting coal-burning supercritical steam plants to nuclear power plants by replacing the furnaces and boilers with high temperature gas cooled reactors might become a routine power plant improvement in the relatively near future. The High Temperature Reactor – Power Module (HTR-PM) project is aimed at demonstrating the feasibility of this evolutionary concept.

At the recent High Temperature Reactor 2016 (HTR2016), held in Las Vegas, NV, Prof. Zhang Zuoyi, Director of China’s Institute of Nuclear and New Energy Technologies (INET), briefed his colleagues in the international community of high temperature gas reactor enthusiasts on the current status of the HTR-PM. That project is one of the more intriguing clean air projects underway in the world today.

China Advances HTGR Technology Abby L. Harvey; Power; 1 Nov 2017

China’s State Nuclear Power Technology Corp. (SNPTC) has completed the installation of its high-temperature gas-cooled reactor (HTGR) project, the joint venture told the International Atomic Energy Agency (IAEA).

NGNP Alliance




Meet A Startup Making A New Kind Of Safer, Smaller Nuclear Reactor X-energy PBR

Urenco U-battery

Despite the name this design is a reactor, not a nuclear battery.

Miniature nuclear power stations available within decade Tereza Pultarova; E&T Magazine; 7 Oct 2016

uranium enrichment firm URENCO has decided to go even further and develop a miniature nuclear power plant so small and cheap that it could power a single village or a factory

“A single unit would occupy an area the size of two squash courts,” explained Paul Harding of URENCO, overseeing the project called U-Battery. “The footprint of each unit is about the penalty area of a football pitch. Each unit is designed to give 10 megawatts of thermal output of which around 40 per cent can be converted into electricity, so you can get four megawatts of electricity from a single installation.”

Unlike the larger SMRs, U-battery is a high temperature gas cooled reactor akin to currently developed generation IV nuclear reactors. It uses grain-like TRISO fuel that is not designed for reprocessing but spent after one use.

“The U-Battery is designed to operate at about 700℃ and you do not challenge integrity of the fuel to at least 1600℃ so there is a great margin,” Harding said. “TRISO fuel is inherently safe. It consists of grains of uranium oxide that are coated in three layers of ceramic material, which ensures that fission products do not escape from the inner kernel.”

The remotely controlled U-battery was designed with renewable energy generation in mind and the team envisions it could serve as a back-up power generator for solar and wind power plants.

The team is already negotiating with authorities of the Canadian province of Ontario to have U-Batteries tested in some of the remote northern communities that are not connected to the utility grid.


Ultra Safe Nuclear website

Ultra Safe Nuclear is a small company founded in 2011, based in Seattle, USA.

It is developing a "Micro Modular Reactor" which uses fuel based on Triso pebbles and is cooled by Helium gas.

Its fuel is designed to last 20 years and then be disposed of.

The reactor has a heat output of 15MW and is designed to produce heat and up to 5MW of electricity.

UCB Fluoride Salt Cooled High Temperature Reactor

Pebble Bed / Molten Salt / Brayton cycle

Mk1 PB-FHR Technology Berkeley Nuclear Engineering

The Mark 1 Pebble-Bed FHR (Mk1 PB-FHR) pre-conceptual design is the latest in a series of studies to explore potential designs for fluoride salt cooled, high temperature reactors. The Mk1 design effort established four major goals, aimed at exploring further the potential benefits provided by FHR technology:

1) To evaluate how FHRs might be coupled to air Brayton combined-cycle power conversion, currently the dominant technology for new fossil power plants;

2) To provide a detailed design for a passive decay heat removal system, to enable improved safety studies for FHRs;

3) To develop a credible design for an annular FHR pebble-bed core, based upon earlier UCB work on the use of pebble fuels in FHRs, and

4) To evaluate how modular construction methods could be applied to FHRs, keeping all components inside the size range that is rail-shippable and utilizing the same steel-plate composite modular construction methods applied in the Westinghouse AP1000 reactor design.

The new Mk1 design, completed in September 2014, builds upon earlier pre-conceptual design studies. This design further increases confidence that FHRs can be designed to have high intrinsic safety, and that with their higher temperatures FHRs can provide more flexible and valuable services than current reactor technologies.

The result of the Mk1 pre-conceptual design study is a 236-MWth Mk1 PB-FHR that uses a General Electric (GE) 7FB gas turbine, modified to introduce external heating and one stage of reheat, in a combined-cycle configuration to produce 100 MWe under base-load operation, and with natural-gas co-firing to rapidly boost the net power output to 242 MWe to provide peaking power. As with previous FHR pre-conceptual designs cited above, the Mk1 design is also documented in a new UCBTH report (Report UCBTH-14-002), published at the end of September, 2014.

The UCB Mk1 design has been spun-off into a company - Kairos Power


Kairos Power’s reactor technology uses a novel combination of existing technologies to achieve new levels of economy, safety, flexibility, modularity and security for nuclear power production. These technology choices were driven by a desire for the Kairos Power design to be economically competitive, safe, and optimized to interface with an increasingly intermittent and unpredictable grid. Kairos Power builds upon major strategic investments that the U.S. Department of Energy has made to support development of advanced reactors.

  • High temperature fuels for helium reactors
  • Chemically inert and transparent coolants for molten salt reactors
  • Flexible power conversion technology for natural gas combined cycle plants
  • Passive safety systems for advanced light water reactors
  • Low pressure structural materials for sodium reactors


Kairos Power’s reactor uses fully ceramic fuel, which maintains structural integrity even at extremely high temperatures. This fuel will be undamaged to well above the melting temperatures of conventional metallic reactor fuels. Proven methods for fabricating and testing these fuels have been demonstrated at U.S. National Laboratories. By using pebble-type fuel, Kairos Power reactors can refuel on line, enabling exceptional reliability and availability.


Kairos Power’s reactor uses molten fluoride salt coolant. Molten fluoride salts have outstanding capability to transfer heat at high temperature, excellent chemical stability, and the ability to retain radioactive fission products that might be released from fuel. Extensive experience and design information exists from the early U.S. reactor development program that studied and tested liquid-fueled molten salt reactors. These studies confirmed the compatibility of these salts with Kairos Power’s high-temperature structural materials, enabling commercially attractive reliability and service life.


Kairos Power’s reactor uses a nuclear air combined cycle (NACC) to enable highly flexible and responsive electricity generation. Kairos Power’s NACC technology benefits from the large supply chain that exists for natural gas combined cycle plants with unique capabilities afforded by the nuclear heat source. By co-firing with natural gas or hydrogen, Kairos Power’s NACC technology can deliver high-ramp-rate and efficient peaking power to enable high-renewable-energy (thus high-intermittence) grid operation while simultaneously providing clean baseload generation. No existing generating technology can match the combination of efficiency and flexibility that can be achieved with NACC.


Passive safety means that Kairos Power reactors do not require electricity to remove heat from the core after shutting down. Kairos Power reactors have uniquely large safety margins based on the selected combination of fuel and coolant, which allows emergency cooling to be driven by fundamental physics rather than engineered systems. In Kairos Power’s reactor, there is no need to provide for make-up coolant (since the coolant cannot boil away), and the fuel tolerance for extremely high temperatures allows orders of magnitude more cooling capability under accident scenarios compared to water-cooled reactors. High-temperature fuel and coolant dramatically simplifies emergency cooling under all conceivable accidents.


The intrinsic low pressure in Kairos Power reactors enhances safety and eliminates the need for bulky and expensive high-pressure containment structures. Kairos Power technology leverages key U.S. federal investments in design, structural materials, and components for low-pressure pool-type reactors, including critical updates to the ASME Boiler and Pressure Vessel Code for design at our service conditions.


No. While the use of thorium in a breeding reactor provides potentially attractive benefits, the current challenges with baseload generation do not stem from the price or availability of uranium. Using high-temperature fuels and fluoride salt coolants simplifies licensing, operation, and corrosion control of Kairos Power reactors, while maintaining all relevant safety aspects of molten-salt-fueled reactors.

Swimming Pool / District Heating reactors

CNNC completes design of district heating reactor World Nuclear News; 7 Sep 2018

The preliminary design of the Yanlong swimming pool-type low-temperature reactor for district heating has been completed, China National Nuclear Corporation (CNNC) announced yesterday.

CNNC launched its independently researched and developed Yanlong reactor (referred to as the DHR-400) for district heating in November 2017. The move came shortly after the "49-2" pool-type light-water reactor developed by the China Institute of Atomic Energy continuously supplied heat for 168 hours.

CNNC said the Yanlong reactor - which an output of 400 MWt - has been developed based upon the company's safe and stable operation of pool-type experimental reactors over the past 50 years. It said the Yanlong is a "safe, economical and green reactor product targeting the demand for heating in northern cities". The reactor can be operated under low temperatures and normal pressures. It can be constructed near urban areas due to the zero risk of a meltdown and lack of emissions. In addition, the reactor is easy to decommission. The Yanlong "represents a relatively modest investment", according to CNNC.

"It's an effective way to improve China's energy resource structure by utilising nuclear energy for district heating, and to ease the increasing pressures on energy supplies," CNNC said. "Nuclear energy heating could also reduce emissions, especially as a key technological measure to combat haze during winter in northern China. Thus, it can benefit the environment and people's health in the long run."

The company added, "It can be constructed either inner land or on the coast, making it an especially good fit for northern inland areas, and it has an expected lifespan of around 60 years. In terms of costs, the thermal price is far superior to gas, and is comparably economical with coal and combined heat and power (CHP)."

Heavy Nitrogen Gas Cooled Reactors

Heavy nitrogen - the isotope N15, which is found as 0.36% of atmospheric nitrogen - could be used instead of helium as a heat transfer medium in high temperature gas cooled reactors. With density similar to air it is well suited for use with Brayton cycle turbines and unlike its more common N14 isotope it doesn't strongly absorb neutrons or produce C14. Will heavy nitrogen become a widely used fission reactor coolant? Rod Adams; Atomic Insights; 176 Nov 2020


Carbon nanotubes shown to protect metals against radiation damage David Szondy; Gizmag; 5 Mar 2016

An international team of scientists led by MIT has discovered that adding small amounts of carbon nanotubes to metals makes them much more resistant to radiation damage. Though currently only proven in low-temperature metals like aluminum, the team says that the ability of the nanotubes to slow the breakdown process could improve the operating lifetimes of research and commercial reactors.