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We have several topics that include "fission" in the title, but there is none appropriate to the announcement that will be offered in post #3.
This topic is offered for NewMars members to report news of developments in the field of fission-only reactors, or to comment.
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This post is reserved for an index to posts that may be contributed by NewMars members over time.
Calliban: ADR Accelerator Driven Reactor
https://newmars.com/forums/viewtopic.ph … 04#p229404
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This post is about what appears to be encouraging news for a small reactor that may eventually qualify for use in populated areas:
https://interestingengineering.com/ener … 23_11_24_3
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The accelerator driven reactor (ADR) is an interesting concept.
https://en.m.wikipedia.org/wiki/Acceler … al_reactor
Carlo Rubio advocates what he calls an Energy Amplifier. This is a spallation driven nuclear reactor. A particle accelerator is used to accelerate a beam of protons to 1GeV. The protons collide with lead nuclei inside a nuclear reactor core. A collision at this energy will almost completely disintegrate a heavy nucleus, releasing a dozen or more neutrons. These neutrons are then absorbed by thorium nuclei in a fuel blanket surrounding the spallation source. The 232Th transmutes into 233U, which is fissile. When spallation neutrons impact 233U, energy is generated by fission. Fission releases even more neutrons, causing more fission and transmuting more 232Th into fissile 233U.
This type of reactor is useful, as in addition to generating power its discharged fuel would contain enough fissile 233U to fuel several downstream nuclear reactors of comparable power. On Mars we could use these devices to breed 239Pu and 233U from native or imported uranium and thorium. One interesting feature of spallation sources is that the number of neutrons produced by disintegration increases as the atomic weight of the target nuclei increases. This means that higher actinides in long-lived nuclear waste are even better targets than lead. Far from being waste, this material provides us with a useful source of neutrons. On Earth, this technology could allow the expansion of light water reactor fleets without concerns over uranium depletion. On Mars, the use of ADRs allows rapid expansion of nuclear power supply. It also allows 100% of the energy content of uranium and thorium to be extracted. This is important if uranium and thorium turn out to be rare on Mars or if we are importing these fuels from Earth.
On Mars, we would load an ADR with uranium or thorium metal fuel, clad with stainless steel. The reactor would be cooled with ducted sodium coolant channels or liquid lead. Fuel would be shuffled inward, with the innermost blankets discharged at perhaps 5% atom burnup. The resulting discharged fuel would be about 75% thorium, 5% fission products and 20% 233U. The metallic fuel would then be dissolved in nitric acid. Fission product nitrates would be extracted and vitrified as waste. The remaining mix of uranium and thorium nitrate would be blended down with additional thorium nitrate. This 5% 233U nitrate liquor is then used as fuel for unity breeding ratio aqueous homogenous reactors. The nitrate liquor from the ADR effectively provides a starter core for new reactors. This allows nuclear capacity to expand quickly to meet the energy needs of a rapidly growing Martian colony.
Last edited by Calliban (2025-01-28 10:05:29)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Additional: The Belgian government started construction of a lead-bismuth cooled spallation driven reactor last year.
https://www.myrrha.be/
Belgium is a country of 10 million people. Their ability to pursue this gives me confidence that it should also be possible for a Mars colony when population reaches a similar level. Early Mars reactors will most likely be modular light water reactors using fuel imported from Earth. But beyond a certain level of development, it makes sense to start using domestic resources and to extract as much energy from uranium and thorium as is physically possible.
An accelerator driven system can work in a number of different ways. A proton beam can directly transfer energy to a heavy nucleus causing it to break up into smaller pieces, including neutrons. These neutrons then cause fission and nuclear transmutation. Alternatively, a high energy proton beam can generate muons or anti-protons. Muons can catalyse fusion in a suitable target, releasing very fast neutrons. Anti-protons are a powerful spallation source. Upon impacting a heavy nucleus, they release almost 2GeV of energy, breaking the nucleus apart and releasing a great many neutrons. I am uncertain as to which neutron source is best. They all require high energy protons to work, so the best neutron source is the one that produces the most neutrons per MJ of energy input to the accelerator.
One substantial advantage that an ADR offers is safety. The reactor is subcritical, with additional neutrons provided by the electrically driven accelerator. Rapid reactor shutdown can be achieved by cutting power to the neutron source. This can be done more rapidly than mechanically inserting control rods. This design feature could be especially useful for certain types of nuclear reactor. The gas cooled fast reactor for example, has advantages of being an extremely compact direct cycle CO2 cooled reactor, with a hard neutron spectrum and high breeding ratio. A weakness with this reactor type is that a coolant leak removes moderation from the reactor, hardening the neutron spectrum, causing power to surge. An accelerator driven reactor could solve this problem, by tripping the accelerator if neutron count increases outside a pre-defined range.
Last edited by Calliban (2025-01-28 10:29:01)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Metallic nuclear fuels are now being considered for light water reactors.
https://www.neimagazine.com/advanced-re … -11283875/
This has a number of near term advantages. Metallic fuels have improved thermal conductivity and fissile density. This may ultimately allow higher power density reactors. Conversion ratio will also be slightly improved.
Another advantage that is less frequently discussed, is that metallic fuels are substantially easier to reprocess using pyroprocessing. The sent fuel pellets can be melted within a crucible and mixed with liquid cadmium. Fission products dissolve into the cadmium. The actinides are denser and remain seperate, allowing them to be cast into fresh fuel pellets.
This technology is especially interesting for the thorium fuel cycle. Fuel pellets can be made from uranium thorium zirconium alloy. Pryro fuel processing techniques are far more compact and suitable to automation than classic chemical plant reprocessing. This makes it realistic to consider onsite reprocessing within manual handling of fuel. It means that Martian based nuclear reactors can be based upon conventional light water designs and Martian thorium can be integrated into the fuel cycle relatively easily.
Last edited by Calliban (2025-02-14 07:19:40)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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The article at the link below is about a design for small reactors to power data centers.
This are apparently smaller than SMR's.
https://interestingengineering.com/ener … oup=test_a
US firm unveils powerful nuclear reactor prototype to power data centers, AI
The Aalo Pod is designed to work in a grid-independent, fully dependent, or hybrid mode, giving users much-needed flexibility with nuclear and available grid power.Updated: Apr 09, 2025 06:58 AM EST
Photo of the Author Ameya Paleja
Ameya PalejaUS firm unveils powerful nuclear reactor prototype to power data centers, AI
Representative image of the Aalo X, the first nuclear reactor from Aalo Atomics.Aalo
Aalo Atomics, a Texas-based nuclear energy company, has unveiled the industry’s first fully modular reactor designed to meet the power demands of data centers.
Dubbed the Aalo Pod, the company says that the prototype belongs to the category of XMR, or an extra modular reactor with extra flexibility and modularity, according to a press release.
With the rise of demand for clean energy, nuclear power is poised for a major comeback as an energy source without any carbon emissions. Previous experiences in dealing with nuclear energy have faced issues such as project delays and cost overruns. Attempts are being made to avoid them using small modular reactor (SMR) designs.
According to Aalo Atomics, while SMRs are a feasible solution for nuclear power, they are not compatible with supplying energy for data centers. SMRs can take as long as a conventional nuclear power plant to build, but their power output is relatively small and cannot scale with the increasing demands of a data center.
“We believe that to address today’s massive data center market demand, another category of nuclear reactor is needed, one that blends the benefit of the factory manufacturing of microreactors, the power levels of SMRs, and the economic targets of a large reactor,” said Matt Loszak, the CEO of Aalo Atomics.
Aalo Pod, an XMR
The Aalo Pod is a 50MWe extra modular reactor, where the reactor and the plan are completely modular. The extra modularity of the design enables the reactor to be scaled easily from 10s of MW to 1,000s of MW as the demand for energy grows.
Compared to conventional nuclear power plants or modern-day renewable energy sources, the Aalo Pod has a small footprint of five acres for a 100 MW capacity. Each Aalo Pod consists of five Aalo-1 reactors that have been paired with a single power-generating turbine.
Unlike conventional nuclear power plants that need to go offline for refueling, a reactor in an Aalo Pod can be refueled anytime, while others contribute to energy production.
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This post is about NuScale having won approval for a second reactor design:
This first item is from the financial perspective.
https://www.msn.com/en-us/money/markets … elemetry=1
NuScale Power Corporation (NYSE:SMR) touched a new all-time high of $41.88 at intraday trading before slightly pulling back to end the day at $41.60.
The rally was likely boosted by the US Air Force’s milestone deal with another small modular reactor (SMR) provider, in line with the United States’ plan to ramp up the adoption of nuclear reactor technologies in the country.
It can be learned that President Donald Trump signed two executive orders last month to ramp up the development of nuclear technologies in the country. One of the orders includes the deployment of advanced nuclear reactor technologies for national security and to support the energy needs of Artificial Intelligence infrastructures such as data centers.
This next item is specifically about winning a second approval for their SMR design...
https://www.msn.com/en-us/money/savinga … ngNewsSerp
News about NuScale Power Doubles Number Of Approved
NuScale Power Doubles Number of Approved Small Modular Reactor DesignsThe Motley Fool
NuScale Power Doubles Number of Approved Small Modular Reactor Designs
"The uprate approval by the U.S. regulatory authority increases the power output per …NuScale Power Attracts Data Center Giants With Deployable SMR Technology
Seeking AlphaNuScale Power Attracts Data Center Giants With Deployable SMR Technology
NuScale Power: Tailwinds Are Here, But Elevated Costs Weigh
Seeking AlphaNuScale Power: Tailwinds Are Here, But Elevated Costs Weigh
NuScale’s SMR design approved
Nuclear Engineering InternationalNuScale’s SMR design approved
NuScale Power (SMR) Stock Surges 20% Following Second NRC Design ApprovalNuScale has received NRC design approval for an uprated 250 MWt NuScale Power Module that can put out more than 50% more power, the equivalent of 77 megawatts. This marks NuScale's second design approved by the United States' nuclear regulator12.
Learn more:
MWt vs MWe >>
The key difference between 250 MWt and 77 MWe lies in the type of power they represent:
MWt (Megawatts thermal): This refers to the thermal power generated by a system, representing the energy input. In the case of power plants, it measures the rate at which heat is produced from the energy source (e.g., nuclear fuel in a nuclear reactor or burning coal in a thermal plant).MWe (Megawatts electric): This refers to the electrical power output, representing the useful electricity generated and available for use.
Why the difference?Power plants, especially those that convert heat into electricity (like nuclear or thermal power plants), cannot convert 100% of the input thermal energy into electrical energy. This is due to inefficiencies inherent in the conversion process (e.g., steam cycle losses). The difference between the MWt and MWe values represents the amount of waste heat produced during electricity generation.
In the context of 250 MWt (77 MWe):
This indicates that a system is generating 250 MW of thermal power, but only 77 MW of that thermal power is being converted into useful electrical power. The remaining energy is lost as heat.This example highlights the efficiency of the power plant, which can be calculated by dividing the electrical output by the thermal input: 77 MWe / 250 MWt = 0.308 or 30.8% efficiency.
Megawatts thermal - Energy Education
Because of this, there are two values assigned to a powerplant: megawatts electric (MWe), and megawatts thermal (MWt). The former refers to the electricity outp...favicon
Energy EducationThermal power - Energy Education
In other contexts, it can be a measure of the output—such as the radiant heat given off by the Sun. For power plants, the thermal power input is measured in meg...favicon
Energy EducationMegawatts electric - Energy Education
The power input in a heat engine is measured as MWt, and the output power obtained as electricity is measured as MWe. Megawatts electric or MWe is one of the tw...
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