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#526 2023-03-01 21:16:24

SpaceNut
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#527 2023-03-10 11:39:12

Mars_B4_Moon
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Posts: 9,769

Re: Nuclear power is safe

I have not seen many news updates on Nuclear powered Space-Tugs but there are already many discussions on this topic on new mars

Small mini reactors for power and Nerva Rocket was discussed again recently

I did see other news on the Nuclear Industry


Germany ‘not opposed’ to nuclear-made hydrogen, says will import from France
https://www.euractiv.com/section/energy … om-france/

'Fusion News' vid
https://www.youtube.com/watch?v=8wC99ND8rkU

Measurements Recent paper open access from TAE in Nature Communications about p11B fusion
https://www.nature.com/articles/s41467-023-36655-1
Peter Norreys, a plasma physicist at the University of Oxford in the UK, says the researchers have done “a fine job” in their experiments. But he argues that proton–boron fusion is still far from rivalling deuterium–tritium reactions. One potential complication, he says, is the need for relativistic descriptions of plasma dynamics at such high temperatures. He also thinks it likely that bremsstrahlung radiation could impair plasma confinement by eroding a reactor’s inner surfaces.

Scientists at the EUROfusion consortium in Garching, Germany, are also guarded. Tony Donné, Hartmut Zohm and Volker Naulin told Physics World that the observed reaction rate in the latest experiments is about ten orders of magnitude too small to be useful for fusion energy (taking into account proton–boron’s low power density).

They have “strong doubts” that it will ever be possible to achieve the gains needed for commercial power generation, and caution that bremsstrahlung radiation could in fact be so strong that it exceeds the power needed to heat and control the plasma – causing the plasma to collapse.


What is Fusion, and Why Is It So Difficult to Achieve?
https://www.iaea.org/bulletin/what-is-f … to-achieve

an old discussion on newmars from many years ago

ColdFusion - Is it real?
https://newmars.com/forums/viewtopic.php?id=2956

Last edited by Mars_B4_Moon (2023-03-10 11:44:22)

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#528 2023-03-17 08:07:44

Mars_B4_Moon
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Re: Nuclear power is safe

Rolls-Royce to build Moon base nuclear reactor in space deal
https://www.derbytelegraph.co.uk/news/d … se-8261628
Rolls-Royce has signed a £2.9m deal to develop a Moon base nuclear reactor to power space missions.


Rolls-Royce secures funds to develop nuclear reactor for moon base
https://www.theguardian.com/business/20 … -moon-base

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#529 2023-03-18 18:45:11

tahanson43206
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Re: Nuclear power is safe

This may be a duplicate of Mars_B4_Moon #528

https://www.yahoo.com/news/rolls-royce- … 00498.html

The Telegraph
Rolls-Royce go-ahead to build a nuclear reactor on Moon

Telegraph reporters
Fri, March 17, 2023 at 3:00 AM EDT

Space Flower Moon Micro Reactor - Rolls-Royce

Rolls-Royce has received funding from the UK Space Agency to develop a nuclear reactor for a Moon base.

The project will look into how nuclear power could be used to support a future base on the Moon for astronauts.

Scientists and engineers at the British company are working on the micro-reactor programme to develop technology that will provide power needed for humans to live and work on Earth's natural satellite.

All space missions depend on a power source to support systems for communications, life-support and science experiments.

Experts suggest nuclear power could potentially dramatically increase the length of lunar missions.

The UK Space Agency has announced £2.9 million of new funding for the project which will deliver an initial demonstration of a UK lunar modular nuclear reactor.

A £249,000 study was funded by the UK Space Agency in 2022.

'The ultimate laboratory'
George Freeman, the Science Minister, said: "Space exploration is the ultimate laboratory for so many of the transformational technologies we need on Earth: from materials to robotics, nutrition, cleantech and much more.

"As we prepare to see humans return to the Moon for the first time in more than 50 years, we are backing exciting research like this lunar modular reactor with Rolls-Royce to pioneer new power sources for a lunar base.

"Partnerships like this, between British industry, the UK Space Agency and Government are helping to create jobs across our £16 billion space tech sector and help ensure the UK continues to be a major force in frontier science."

Rolls-Royce plans to have a reactor ready to send to the Moon by 2029.

Power regardless of location
The company will work with a variety of collaborators including the universities of Oxford, Bangor, Brighton and the University of Sheffield's Advanced Manufacturing Research Centre (AMRC) and Nuclear AMRC.

Compared with other power systems, a relatively small and lightweight nuclear micro-reactor could enable continuous power regardless of location, available sunlight and other environmental conditions.

Abi Clayton, director of future programmes for Rolls-Royce, said: "This funding will bring us further down the road in making the micro-reactor a reality, with the technology bringing immense benefits for both space and Earth.

"The technology will deliver the capability to support commercial and defence uses alongside providing a solution to decarbonise industry and provide clean, safe and reliable energy."

Dr Paul Bate, chief executive of the UK Space Agency, said: "This innovative research by Rolls-Royce could lay the groundwork for powering continuous human presence on the Moon, while enhancing the wider UK space sector, creating jobs and generating further investment."

(th)

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#530 2023-03-20 10:03:23

Calliban
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From: Northern England, UK
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Posts: 3,542

Re: Nuclear power is safe

I wasn't sure where it was best to put this.  But it makes for fascinating reading.

https://www.nextbigfuture.com/2020/05/164531.html

It concerns laser induced proton annihalation.  Brian Wang explains in more detail how intense laser beams can induce the conversion of protons into kions, mesons, muons, photons and neutrinos.  The intense laser beam actually changes the spin of some of the protons, causing them to annihalate other protons.  Some 50% of the mass of the protons is converted into kinetic energy.  This is 109x more efficient than fusion and 1000x more efficient than fission.  If it could be made to work as a space drive or static power source, it really would change everything.  Human beings would have an energy device that could convert regular hydrogen into useful energy with high efficiency.  There is almost no limit to what we could do with an energy device like this.


"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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#531 2023-03-20 10:29:21

Void
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Re: Nuclear power is safe

Very exciting.  Of course I really don't understand it much.

But I saw this:

Thus, it is estimated that 50% of the proton mass is converted to useful kinetic energy by such a rocket drive.

And from what I know, the conversion of mass to energy is the ticket.

But I confess again that it is very above me.

Nice inclusion Callliban

Done.

A bit later I may take a copy of your materials here, for one of my topics.

Done.

Last edited by Void (2023-03-20 10:34:46)


Done.

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#532 2023-03-20 10:47:20

Calliban
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From: Northern England, UK
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Posts: 3,542

Re: Nuclear power is safe

If ordinary hydrogen can be transformed into captured energy with a 50% efficiency, then this affords humanity an effectively infinite source of energy, as hydrogen is the most abundant material in the cosmos.  With this energy source, humanity would no longer need to rely on stars as sources of energy.  We can convert ordinary hydrogen into energy with 100x the efficiency of ordinary fusion.

If this source of energy could be integrated into a Bussard ramjet, then we could accelerate close to the speed of light.  This would allow individual human beings to visit multiple star systems in their lifespan.  It would be almost like Star Trek.


"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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#533 2023-03-20 13:12:12

tahanson43206
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Re: Nuclear power is safe

For Calliban re original article ... I finally took/made the time to read the article at the link you provided.

I came away with the impression the reporter/writer is an enthusiast who does not know quite a bit.  We ** all ** don't know "quite a bit", but this gent is writing an article about space travel and specifically, about how rockets work.

As you have shown in your post 532, you understand that the ultimate speed of a rocket is NOT dependent upon the exhaust velocity of the exhaust relative to the rocket.  Because the author did not understand that particular point, I think there is a decent chance he did not understand other details in the report.

For that reason, I'm hoping ** some ** member of the forum has the time to investigate the original paper(s) on this report.

The idea of flipping the spin of a proton is novel on it's own, and that achievement (if true) seems to have inspired speculation about what it might mean.

(th)

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#534 2023-03-20 14:05:42

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Nuclear power is safe

TH, rather like Fox Mulder, I want to believe.  But you are correct.  Changing such a fundamental nuclear property of a proton would seem far fetched, regardless of how much energy we pump into it.   But I am not a physicist.  I do note that both articles on this topic were written by a Scandanavian chemist, not a physicist.  There is remarkably little reference to laser induced proton annihalation outside of his two publications.  So it could very well be hooey.


"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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#535 2023-03-20 14:31:23

tahanson43206
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Re: Nuclear power is safe

For Calliban re #534

Thanks for additional detail about the author of the articles.

There is a reason why I am concerned that there might be some hidden defect in a proton, that would allow a lucky photon to cause it to self destruct.

About 86,200,000 results (0.66 seconds)
Image result for how stable is the proton
To the best of our understanding, the proton is a truly stable particle, and has never been observed to decay. Because of the various conservation laws of particle physics, a proton can only decay into lighter particles than itself. It cannot decay into a neutron or any other combination of three quarks.Jan 3, 2020

How Certain Are We That Protons Don't Decay? - Forbes
Forbes
https://www.forbes.com › startswithabang › 2020/01/03

I've read elsewhere that protons can decay, but the time frame is long enough so our part of the Universe will probably hang together as long as we need it.

However, I ** do ** see potential for a way to use anti-matter, or in this case, reverse-spun matter, if the matter can be created and then stored safely until it is needed.  I've already forgotten where I posted about JoshNH4H's idea of (somehow) collecting protons with no electrons (these are quite common in cosmic ray flows) because they would pull a lot of current when released from storage. The kicker is that no ordinary material storage would be up to the job.

Perhaps the trick is to (somehow) match the reverse-spun proton with a suitable electron to make hydrogen .... I have no idea if that is possible. Heck, I didn't even know that the spin on a proton could be reversed until you posted that article.  It is entirely possible that a reverse-spun proton is inherently UN-stable, so that it immediately deteriorates into a zoo of offspring.

Thanks again for a thought provoking glimpse at a part of the Universe we take for granted.

(th)

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#536 2023-03-20 17:32:03

tahanson43206
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Re: Nuclear power is safe

https://www.yahoo.com/finance/news/us-f … 51674.html

The Telegraph
US firm agrees to sell 24 mini nuclear reactors to UK customers
7
Howard Mustoe
Mon, March 20, 2023 at 2:55 PM EDT

Mini Nukes - Last Energy

A US-based developer of small nuclear reactors has signed a deal to sell 24 of its power plants to UK customers, putting pressure on rival makers including Rolls-Royce.

Stay ahead of the market

Last Energy said the £100m modular units, which are two-thirds the size of a football pitch, can output 20MW of electricity, enough to power 40,000 homes. They will be deployed in 2026 with no government funding required.

Several companies are developing small, factory-made nuclear power plants. It is hoped that making smaller units will lead to lower prices through “economies of scale”, by spreading the cost of development over many units.

For heavy energy users with 24-hour operations like steel mills and data centres, nuclear power is attractive because it consistently provides power, compared to wind and solar generation.

Nuclear plants can also provide heat which can be used in many chemical and industrial processes like cement making. Last Energy’s design can output 60MW of thermal energy.

The US company still needs to win UK regulatory approval for its designs and secure suitable sites before the deals are finalised and customers pay up.

But it still expects its first plant to be delivering electricity in about three years.

Last Energy said it has sought no government funding and many of the components will be bought from existing suppliers.

Mike Reynolds, the firm’s UK boss, said: “Our private-sector led approach to delivering new nuclear power supports the wider Government efforts to promote growth and investment in the green industries of the future.”

The plants have been sold via power purchase agreements, which lock buyers into long-term energy contracts and mean that Last Energy can seek more funding for clearing the designs and eventually building them.

SMR Model - Rolls-Royce

Dozens of other firms are vying to bring a large-scale nuclear plant design to market, including Rolls-Royce, GE-Hitachi and several smaller start-ups.

The UK is seen as a key market because of Britain’s long history with nuclear power and its favourable approach to foreign investment.

Last week, Jeremy Hunt unveiled a new government unit, Great British Nuclear, which aims to get nuclear projects off the ground, focusing on the development of small, modular reactors.

Last week the Government dealt a blow to the ambitions of Rolls, which wants to build a fleet of the reactors in the UK, by opening the process up to competition. The British engineer’s £1.8bn models generate 470MW of power.

While Rolls could press on with foreign or private orders, the move left executives at a loss to explain why the Government would part-fund development to the tune of £210m and then raise the prospect of not buying its models themselves.

Last Energy has shunned this process and gone directly to customers and investors to fund its smaller units, which with a smaller price tag can be afforded by a wider range of customers.

We have several members of the UK who are also members of the forum.  Any chance one (or more?) of you could snag one of these for your community?

(th)

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#537 2023-03-21 01:04:43

Calliban
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From: Northern England, UK
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Posts: 3,542

Re: Nuclear power is safe

TH, it sounds to me as if the Last Energy design is at concept stage.  It will be a while yet before we see them, if they even make it to production.  A 20MWe plant is small.  My initial thoughts are that the cost of creating and managing a licensed site for a 20MWe plant and producing and maintaining a safety case, will balloon total cost.  It wouldn't be so bad if we could cluster 10-100 of them on a single site.  The thing that pushes up the cost of nuclear power is the bureaucracy around it.  There is nothing inherently expensive about splitting atoms.  These machines are glorified boilers.  But the sheer burden of oversight makes them expensive.

Last edited by Calliban (2023-03-21 01:08:36)


"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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#538 2023-04-01 11:29:30

SpaceNut
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#539 2023-04-01 11:48:26

tahanson43206
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Registered: 2018-04-27
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Re: Nuclear power is safe

For SpaceNut re #538

Thanks for the link to the entertaining report on the outlook for Britain's net zero ambitions.

It was/is interesting to discover that the head of the Rolls Royce SMR program was excused from duty.


(th)

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#540 2023-04-01 12:08:05

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,178

Re: Nuclear power is safe

The world has had a 40 year experiment on going The Dogs of Chernobyl Are Experiencing Rapid Evolution, Study Suggests

gilligans-island-Pass-the-Vegetables-Please.jpg?q=50&fit=crop&w=740&h=370

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#541 2023-04-11 06:44:10

tahanson43206
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Registered: 2018-04-27
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Re: Nuclear power is safe

Reported today by Mars_B4_Moon...

The Case for Nukes: How We Can Beat Global Warming and Create a Free, Open, and Magnificent Future Paperback – April 3, 2023
by Robert Zubrin (Author)
4.4 out of 5 stars    8 ratings
#1 New Release in Nuclear Physics
The Case for Nukes is a unique book. In it, world-renowned nuclear and aerospace engineer

Dr. Robert Zubrin explains how nuclear power works and how much it has to offer humanity. He

debunks the toxic falsehoods that have been spread to dissuade us from using it by variously the

ignorant, the fearful, the fanatical, and by cynical political operatives bought and paid for by

competing interests. He tells about revolutionary developments in the field, including new

reactor types that can be cheaply mass produced, that cannot be made to melt down no matter

how hard their operators try, that use a new fuel called thorium far more plentiful than uranium,

and still more advanced systems, employing thermonuclear fusion - the power that lights the sun

- to extract more energy from a gallon of water than can be obtained from 300 gallons of

gasoline. He tells about the bold entrepreneurs - a totally different breed from the government

officials who created the existing types of nuclear reactors - who are leading this revolution in

power technology.

But there are broader issues involved in the nuclear debate than technology alone, and Zubrin

is not shy about addressing them. He makes clear the critical difference between practical

environmentalism, which seeks to improve the environment for the benefit of humanity, and

ideological environmentalism, which seeks to use instances of human insult to natural

environment as evidence for a prosecutorial case against human liberty. He shows how the latter

school of thought is wrong, not only with respect to the catastrophic harm it would do to

humanity, but to nature as well. He also exposes the masters of mercenary environmentalism,

who deploy troops of dupes to shut down companies or whole industries in order to eliminate

competition in return for being suitably rewarded by the beneficiaries of such efforts. He shows

that when it comes to environmental improvement, freedom is not the problem; freedom is the

solution. He makes clear both the possibility and necessity of a nuclear-power-enabled

revolution in the human condition by putting it in a broader historical context of the overall process of development of civilization, whereby new technologies create
new resources and new knowledge, which in turn make possible still more technological advance.

Finally, Zubrin brings all this to bear to address the greatest threat facing humanity today

- which is the possibility that we will turn on each other, as we did in the 20 th century, under the

spell of the false idea that resources are finite.

Only in a world of unlimited resources can all men and women be brothers and sisters.

Only in a world of freedom can resources be unlimited.

That is the world we can, and must, create. In The Case for Nukes, Zubrin shows us how.
Read more

(th)

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#542 2023-04-11 17:56:48

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Nuclear power is safe

TH, I will buy a copy.  The far left Green fringe have done more damage to the environment than the most commited Texas oil baron.  Had the nuclear industry not been vandalised by these people, we would all be richer, fossil fuels would be a much smaller portion of our energy mix and global warming would be a problem that we had solved.  But idealists made damn sure that didn't happen, because they thought it would be cute to get power from natural ambient energy instead.  A nation can survive its fools.  But it cannot survive idiot politicians.


"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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#543 2023-04-11 18:31:59

tahanson43206
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Registered: 2018-04-27
Posts: 17,844

Re: Nuclear power is safe

For Calliban re #542

Thanks for the good news you'll soon have a copy of Dr. Zubrin's latest book ... it is also available in eBook format for those who are impatient, and willing to put up with the phosphor screen (or whatever LED is there now).

I prefer good old fashioned paper, because I interact with printed material.  This ** should ** be a good read, with plenty of facts and references to go with the opinions that are a Zubrin trademark.

This conversation reminds me that I have intentions of reading the article you found!  I have it saved as an active tab, and am reminded it is sitting there every day, when I cycle through the Todo list.

I don't know if the gent was right or left or something else, but as nearly as I can tell, the person who did the most damage to the US nuclear program was a protege of Admiral Rickover.   That information is printed as plain as day in the book you recommended and which I added to my collection.

(th)

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#544 2023-04-14 06:55:04

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Nuclear power is safe

This article examines the S-CO2 power generation cycle for turbine inlet temperatures as low as 350°C.  This has been a missing link in our previous discussions of this technology.
https://www.researchgate.net/publicatio … hodologies

In a nut shell, the cycle will still function at these low temperatures, but it is a less desirable option, because:

1. Efficiency declines to ~20%, which is inferior to what a steam cycle could achieve at the same temperature.
2. As temperature difference between the turbine inlet and coolers declines, the throughput of CO2 through the compressor, turbine and coolers per unit power, increases progressively.  This makes all of these components bulky, which undermines a key advantage that S-CO2 offers over steam in the first place.

None the less, an S-CO2 cycle does afford us some advantages over steam even at relatively low temperatures.  Firstly, in the specific case of a Martian reactor built from native materials.  Natural uranium that is mined on Mars can be burned in graphite moderated, CO2 cooled reactors.  The moderator and coolant both has low neutron absorption cross section across the thermal and epithermal spectrum.  So this moderator-coolant combination is well demonstrated as part of a natural uranium fuel cycle reactor.  We have discussed this already on the thread 'Magnox Reactors for Mars'.

With an S-CO2 power generation cycle at 300-400°C turbine inlet temperature, these can be constructed as direct cycle, pressure tube reactors.  The fuel assemblies would be inserted into zircalloy pressure tubes running through the moderator block.  Zircalloy has already been used in pressure tube reactors in this temperature range and it has a sufficiently low neutron cross section to allow its use in natural uranium fuelled reactors.  The moderator will be seperately cooled and pressurised, but can operate at much lower pressure and temperature than the pressure tubes and can use a non-oxidising coolant gas.  This is important because the graphite moderators must be very large due to the relatively high atomic mass of carbon and the long slowing down length of neutrons within a carbon moderator.  In a pressure tube reactor, the large volume of the moderator raises fewer issues in terms of construction cost, because the pressure vessel surrounding the moderator will be subject to low pressure and will therefore be a much simpler structural component compared to the enormous pre-stressed concrete pressure vessels required for Magnox and AGR reactors.  Cooling the moderator with a seperate non-oxidising coolant like helium or nitrogen, also avoids age related degradation that occurs in hot CO2.  In Magnkx and AGR, this puts a hard limit on the operational life of the plant.

A direct cycle S-CO2 cycle avoids the need for primary heat exchangers, which are a costly and life limiting component in CO2 cooled reactors.  The relatively low efficiency of S-CO2 at <400°C is less of a problem on Mars, because we have abundant economic uses for low grade heat.  Finally, the use of pressure tubes allows reactor plants to be scaled up relatively easily.  Living on Mars, requires large per capita quantities of electric power and heat compared to Earth based living.  A pressure tube reactor can be scaled up relatively easily.  Pressure vessel wall thickness scales proportionally to the pressure and diameter.  This is why it is difficult to build PWRs with power outputs larger than 1000MWe.  With a pressure tube reactor, a higher power output can be achieved by increasing the moderator blick diameter and adding more pressure tubes.  There is in fact no real upper size limit for pressure tube reactors.  Before Chernobyl, the Soviets were planning build individual reactor plants with power output of 2400MWe.  This was far greater than any western LWR and remains greater than any light water reactor even today.  On Mars, where heat and power are needed in enormous abundance, pressure tube reactors that can be scaled up without engineering difficulties should make it possible to add nuclear generating capacity cheaply and quickly.

The assumption here is that graphite moderated pressure tube reactors will allow the use of Martian natural uranium as fuel.  This avoids the difficult issues around launching fuel from Earth.  The discharged fuel from the reactors will contain substantial plutonium.  Reprocessing can produce MOX or metallic alloy fuel which can then support Martian fast neutron, breeder reactors.  This is relatively straight forward with natural uranium fuel, because burnup is low and cooling periods prior to reprocessing are therefore short.  We can therefore anticipate that a first generation programme of natural uranium - graphite reactors, will provide the fuel for a second generation of fast spectrum reactors.  These will provide an energy source that can be expanded relatively quickly as the demands of Martian settlements grow.

The safety strategy for these reactors can be relatively straight forward.  Firstly, the low power density graphite cores have huge heat capacity.  If coolant is lost and the reactor trips, the fuel will lose decay heat to the pressure tubes by thermal radiation.  The tubes will radiate into the moderator block, which will heat up slowly due to its enormous size.  The natural uranium fuel will have low burnup and short cycle time, due to its low 235U enrichment.  This means decay heat will be dominated by short lived fission products and will decline quickly compared to a light water reactor.  The combination of huge heat capacity and rapidly declining decay heat, may in fact allow a decay heat strategy based entirely on passive thermal radiation and conduction from the moderator block to its surroundings.  This would make the reactor very easy to construct and operate, given that the most challenging safety problem with reactors is removal of decay heat.  Control rods can be constructed from carbon steel, which has more than sufficient neutron cross section the dampen the reactivity of natural uranium fuelled core.

Last edited by Calliban (2023-04-14 07:20:53)


"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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#545 2023-04-14 07:18:35

tahanson43206
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Registered: 2018-04-27
Posts: 17,844

Re: Nuclear power is safe

For Calliban re #544

SearchTerm:reactor This post covers S-CO2 reactors operating with inlet temperatures on the order of 300-400 degrees Celsius.

The post shows that this design might work well on Mars, assuming natural Uranium is available there.

An intriguing possibility is that spent fuel from this reactor type might feed into a second generation series of plants able to breed more fuel.

(th)

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#546 2023-04-14 07:37:33

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,542

Re: Nuclear power is safe

This paper was written by Zubrin 30 years ago this year.
http://www.marspapers.org/paper/Zubrin_1993_3.pdf

Table 1 shows the production rate of CFCs required to achieve different levels of planetary warming.  To achieve a warming of 5K, some 1300MWe would need to be provided for CFC manufacturing.  But average surface temperature on Mars is -60°C.  If we want the planet's surface to be habitable in a reasonable investment window, we should aim to raise temperature by at least 40K, which would still make it much colder than Earth.  The faster this can be achieved, the more rapidly the habitability benefits can be realised.

To achieve a 40K temperature rise, we would need to generate roughly 90GWe.  That is a lot of power.  On Earth, light water reactors generating that much power would cost half a trillion dollars.  If we want to terraform quickly at a price we can afford, we need powerful reactors that can be built quickly and cheaply, using parts and machinery that are built on Mars.  Maybe pressure tube reactors are a better bet than LWRs for this application.  The powerplants must be constructed close to the CFC synthesis plant and it would be ideal to be close to a source of flourite mineral as well.  Reactors in this size range pose a waste heat problem on Mars.  We may need to construct them close to an ice filled crater to provide a source of cooling water.

Last edited by Calliban (2023-04-14 07:41:25)


"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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#547 2023-04-14 10:04:22

kbd512
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Registered: 2015-01-02
Posts: 7,548

Re: Nuclear power is safe

Calliban,

For a given cycle pressure ratio,a higher turbine inlet temperature leads to a lower amount of CO2mass flow rate in the supercritical loop. On the other hand, for a given turbine inlet temperature, a higher cycle pressure ratio leads to a lower turbine outlet temperature and, in turn, to a lower potential for regeneration. Therefore, at the sCO2heater, more thermal power is exchanged using a higher CO2mass flow rate. For a given cycle configuration, the net power output depends on the specific net work and the amount of working fluid mass flow rate. This fact explains the net electrical power trend that is shown in the top left chart of Figure 2: even though cycle pressure ratio and turbine inlet temperature both enhance the cycle efficiency and its net specific work, because of a lower amount of working fluid that is needed to balance the heat loads at the heater, the net power output decreases at high values of turbine inlet temperature. For instance, with a pressure ratio of 2 and a turbine inlet temperature equal to 400 °C, theoretical electrical power output would be over 87.4 kW with a 1st law efficiency of 24%. At 500 °C the cycle efficiency would  rise to 28% but the net power output would drop to 75.7 kWe.

Mass flow rate resulting from the energy balance at the heater and cycle pressure ratio affect revolution speed and diameter of the turbomachinery according to Eqns. 8and 9. In particular, for a given flow rate, the compressor and turbine will rotate faster and be smaller with increasing pressure ratio. On the other hand, for a given enthalpy rise/drop, smaller flow rates will reduce the size of the machine increasing its revolution speed. Furthermore, in small machines useful flow passages tend to have the same dimensions as leakage paths. Therefore, efficiency values largely accepted and achievable for MW-scale machines can be hardly assumed in kW-scale ones. In particular, for a given revolution speed of the CGT, due to the high density of the CO2, it is the compressor the most limiting machine in terms of size. Figure  2 provides some figures related to compressor wheel size and speed showing that cycle configurations with high efficiency demand small and fast machines whose specifics exceed the operational constraints mentioned above. Reasonable thresholds for cost effective turbomachinery are a revolution speed lower than 100,000 RPM and wheel diameter greater than 40 mm. Hence, the application of turbomachinery constraints on the thermodynamic design, limit the design configuration to a maximum cycle efficiency of 23% and a net output power range between 50 and 85 kW.

I could be wrong, but what the modeling from this research paper seems to state or suggest about sCO2 efficiency is that the turbo's overall efficiency is terrible as you try to scale it down to the 100kW level or lower.  The applications where such turbines would realistically be used are multiple MWs of output (10MW+), though.

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#548 2023-04-14 10:07:57

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,548

Re: Nuclear power is safe

I can't seem to post the rest of what I intended to post, but it relates back to the Reynolds numbers associated with small gas turbines.  GW has repeatedly related this back to the Reynolds numbers associated with small turbines.  I don't know how much of that paper applies specifically to sCO2 versus very small gas turbines, in general terms.

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#549 2023-04-14 12:02:05

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 9,769

Re: Nuclear power is safe

Almost 7 mins

China's 'artificial sun' sets new world record by running for 403 seconds
https://interestingengineering.com/inno … -new-world

Fusion's future in the US could come down to dollars and cents
https://techxplore.com/news/2023-03-fus … cents.html
This research doesn't claim to know when fusion will come online

Nuclear fusion can help Europe achieve net-zero goal, EU official says
https://www.euractiv.com/section/energy … cial-says/

‘Artificial Sun’ breaks record, marking latest milestone in quest for efficient thermonuclear fusion reactors

http://www.chinaview.cn/20230413/f0463d … eb9/c.html

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#550 2023-04-18 22:12:58

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,178

Re: Nuclear power is safe

Germany has shut down its last three nuclear power plants, and some climate scientists are aghast

"This is hugely disappointing, when a secure low carbon 24/7 source of energy such as nuclear was available and could have continued operation for another 40 years," Henry Preston, spokesperson for the World Nuclear Association, told CNBC. "Germany's nuclear industry has been world class. All three of those reactors shut down at the weekend performed extremely well."

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