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#251 2021-07-26 18:08:41

tahanson43206
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Registered: 2018-04-27
Posts: 7,313

Re: Nuclear power is safe

For Calliban (or anyone who might be inspired to pursue the details) .... it sure would be interesting to see more about all these designs, but the tiny one ** might ** be small enough to deliver power for an over-the-road truck or a train or ship/boat. 

(th)

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#252 2021-07-27 04:39:07

Mars_B4_Moon
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Registered: 2006-03-23
Posts: 885

Re: Nuclear power is safe

Calliban wrote:

Interesting news from China.


The Chinese actually build these things.  People in the western world just write about them.

more ideas from the West built by Chinese?

China plans to build the first 'clean' commercial nuclear reactor
https://www.engadget.com/china-molten-s … 10381.html

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#253 2021-07-28 06:55:59

tahanson43206
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Registered: 2018-04-27
Posts: 7,313

Re: Nuclear power is safe

https://www.yahoo.com/news/davis-besse- … 00238.html

"Operators took action to address the equipment issues, and the reactor was shut down safely and placed in a stable condition. After making the necessary repairs, the reactor returned to power," the statement said. "Based on the complications of the [unplanned automatic shutdown of a nuclear reactor], the agency chose to expand the special inspection to better understand equipment performance issues and operator response."

The article at the link above is about the challenges of maintaining a full sized nuclear fission reactor.

The reactor came online in 1978, so has been in operation for over 40 years.

It is rated at 894 Megawatts.

What Calliban has been talking about recently are modular 1 Megawatt reactors that operate without human supervision, and are intended to be swapped out every 10 years.

Thus, the equivalent of the existing reactor would be 894 smaller ones times 4 decades, or 3200 + 360 + 16 or 3576 reactors.

The earnings of the existing reactor have covered construction, loans interest, maintenance including refueling, staff salaries, insurance, taxes and donations of various kinds, including political ones that lead to fines of substantial size.

All that income would have to cover the costs of equivalent nature for 2682 modular reactors, hopefully not including the bribes and fines.

However, a benefit of Calliban's concept (as I understand it) is that the reactors would breed their own next batch of fuel, so fuel costs might end up lower over the same period.

Edit#1: For Calliban ... I'd like to offer a target/goal/vision to serve as a focus for the development of the concept (as I understand it) of a modular reactor that is part of an industry that builds, deploys, supervises, recovers and rebuilds units for customer use world wide.

The population of the Earth is (roughly) 8 billion people ...

Long ago, I attempted to see of solar power might provide sufficient energy for the population of Earth to enjoy a first tier lifestyle, and my recollection is that I could not find a solution that covered more than a fraction of the total before running into diminishing returns.

Is it possible to imagine deploying 8 billion of these reactors?

Are there enough raw materials on Earth to support that number? 

I'd be surprised if there are, but the investigation ** should ** yield a figure for the number of reactors that might realistically be placed into regular service.

As I understand the situation, there are zero such reactors in production at present, but there may be a number of them in research status.

Edit#1:

7,874,965,825
World Population Projections

(th)

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#254 2021-07-28 15:46:07

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

I do not know if mass production of such small nuclear units (1MWe) is really a cost optimum solution.  One is substituting economy of scale for economy of size.  Economy of scale says that for every doubling of production, unit cost drops by 10%.  This would indicate that smaller units will generally enjoy better economy.  However, there are inherent inefficiencies in smaller systems, which tend to mean that larger units produce cheaper power, all else being equal.  Of course, all else is not equal.  Huge monolithic 1000MWe powerplants take several years to build, as huge components are slowly assembled onsite with rigorous quality control.  If smaller units can be shipped to site nominally intact, then build times could be short, which would really reduce the cost of nuclear electricity.  Smaller units can be mechanically simpler as well, relying upon natural heat loss for decay heat removal.  Do we really need to reduce powerplant sizes down to 1MWe to get those advantages?  To give some idea as to why shrinking reactors down may not be cost effective beyond a certain point: the 10MWe SSTAR weighs 200 tonnes.  The 100MWe weighs 500 tonnes.  So capital cost for the 100MWe unit will be ~2.5 times greater, but it will produce 10 times more power.

I do not know.  The original SSTAR lead cooled reactor concept was for 10-100MWe levels of power production, with core life up to 30 years.  That level of power production would be sufficient for a large town or small city, or a very large industrial heat load.  Even smaller 1MWe units, whilst possible, may not be cost optimal as a universal solution, as the high levels of neutron leakage from the core would necessitate a high initial fissile loading.

I don't know at present.  There are a lot of unknowns.  The SSTAR concept is quite close to the original concept that I had in mind.  To power large grids, 100MWe units could be clustered to serve as large powerplants.  For large industrial heat loads and district heating, single 10MWe (25MWth) units may be useful.  The concept could be scaled down further to 1MWe for off grid applications, like mines.  The largest container ships have about 30MW of engine power.  So a single lead cooled SSTAR unit in that size range could power it for 30 years, which is pretty much the fatigue life for a large steel ship.

A 100MWe unit would be a good baseline unit to start with, as it is still small enough to be transportable by rail and is small enough for rapid deployment at a site.  A 100MWe unit is also small enough that it will not overwhelm even small country grids.  For reference, the average electricity demand of the Republic of Ireland (one of the smallest countries in Europe) is just under 3GWe.  So roughly 30x 100MWe reactors would be needed to supply Ireland with electricity and somewhat more to meet heat and transportation energy loads.  This suggests that a 100MWe reactor could still achieve plenty of scale economy.

Last edited by Calliban (2021-07-28 15:52:19)


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#255 2021-07-28 16:21:30

kbd512
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Re: Nuclear power is safe

Why would we deploy thousands of tiny nuclear reactors unless we have severe size and weight constraints?

Why can't it simply be something small enough to fit on a truck, with a radiation shielding cask surrounding the reactor vessel?

For example, a 250MWe molten salt or molten metal cooled reactor is the size of a small car and will fit quite comfortably on the bed of a semi-truck, with radiation shielding in place.  A unit that size may be less efficient than much larger units that cost billions of dollars and require 5 years to build, but I can guarantee you it's a whole lot more efficient than 1MWe units.  If we're using Thorium for fuel to forego all the long-lived fission products, then we're not going to run out of that stuff for the next several thousand years.

I'm much less concerned about a small bank of 250MWe reactors than 1MWe units that someone with a pickup truck can move around.

We still need to be smart about site selection and avoid obviously bad locations, but this would be quite unlike the gigantic units and sprawling facilities used today.  Far fewer permanent personnel would be required to maintain smaller reactors, so we could afford to employ more people at fuel reprocessing and separation facilities.  Using a slurry-based or salt-based fuel that doesn't have the cracking problem that fuel rods do would only require reactor shutdowns for periodic maintenance on the pipes and heat exchangers, since neutron poisons can be chemically separated as the fuel is consumed.  More frequent but much shorter duration shutdowns would also be easier to handle.

If we could limit shutdowns to a single shift for exchanging fuel salt / slurry loaded with fission products to fresh fuel devoid of fission products, then scheduled downtime would have far less of an impact on the grid.  If you have 4 250MWe units instead of a single massive 1GWe unit, then you can afford to shut one unit down during the night shift to clean the fuel.

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#256 2021-07-28 18:23:14

tahanson43206
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Re: Nuclear power is safe

For Calliban and kbd512 ...

This is Calliban's topic and I'm delighted to see such robust responses to my inquiry ....

We (three at present - perhaps more in future) seem to be a long way from consensus on something that could be presented to policy makers with any chance of success.

The 1 Megawatt size seems "just about right" to me for a small business. 

The size (as I understand Calliban's description) is NOT something small enough to fit in a pickup truck.  It ** sounds ** more like something that would move around on a large multiwheeled flatbed, and which would be installed in secure bunkers able to withstand a wide range of environmental stesses.

However, more to the point, a system of that size seems (to me at least) comprehensible to an average American (and I assume to citizens of many other first tier countries).

I can imagine managing a small business that is able to sell power to neighbors, while supporting small scale manufacturing operations.

I can imagine being able to recycle water and waste completely, instead of sending it out into the public space to be processed by huge facilities managed by city sized entities.

Having enough power to disassociate molecules completely means the waste can be returned to elemental form for sale or use on premise for new products or maintenance of old ones.

In human evolution, we spent a lot of time learning how to use small fires and small flowing water systems, and lots and lots of mechanical contraptions operated by other humans and by animals of various kinds.

We learned to cooperate to achieve large scale operations supported by hundreds and even thousands of individual humans.  I'm interested in the potential of small power sources on the level of 1 Mw to allow for return of focus to smaller operations and thus reduction of complexity of society, and thus reduction of risk of system failure.

It might be worth a reminder that Terraformer imported me from Dr. Dartnell's Knowledge Forum, which is concerned with the complexity of the society we have built over many centuries, and the significant risk of total collapse that lurks just one more disease away.

I find the (generally) upbeat thinking found in this forum to be inspiring, although at the same time I enjoy and appreciate the hard nosed realism that some members bring to bear on overly optimistic visions.

All that said, I need to study the recent posts by Calliban and kbd512 more carefully.

Todo: Reread 254 and 255

(th)

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#257 2021-07-28 21:16:10

kbd512
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Posts: 4,614

Re: Nuclear power is safe

tahanson43206,

Apart from regulators subsequently holding up paperwork after initially agreeing to move forward, discouraging future investors who have already put money into nuclear plants as part of good faith arrangements with the government, the other major reason reactors built in America are so expensive to construct is the fact that each reactor is effectively a completely custom one-off design with no others exactly like it anywhere in the world.  If we could stop the endless experimentation and simply pick a good solid design to mass manufacture, we could probably have 2.5GWe for the same $5B invested, which could be built in increments of 250MWe.  If we start using shipyards or steel foundries to fabricate reactors, then we stand a better than average chance of reworking our power delivery infrastructure at and affordable price.

We need moderate temperatures and zero pressure above atmospheric to make these reactors as durable as we can, with generous use of Iron, no penny-wise / pound-foolish nonsense trying to save a few pennies on Iron.  Cast ductile iron with nanoparticle Iron Oxide (rust) thoroughly mixed in to reinforce the grain boundaries of the cast iron, a surface nitriding for corrosion protection, and WPC treated to create a very uniform surface that prevents crack propagation, should be the material of choice.  After casting, the reactor vessel should undergo a normalization, followed by nitriding, followed by WPC treatment.  The coolant / thermal power transfer medium should be liquid metal (Lead as Calliban suggested) or molten salt.  We can do high heat or high pressure, but not both at the same time- because that's where most of the maintenance headaches come into play.

We can be clever in our use of aerospace coatings and additives to extend the service lives of major components, such as the reactor vessel and primary heat exchanger.  We will not allow our engineers to prove how "clever" they are by saving a few tons of Iron if that means the service life takes a nosedive.  We can't be clever by resorting to the use of expensive and difficult to machine super grade steels or Titanium alloys.  We want cheap and cheerful, no-frills, plain Jane design that showcases how clever our engineers can be elsewhere in the plant design, such as using really cheap fuels like Thorium and novel refueling strategies.  The engineers can nerd out over the chemical separation processes, but the basic plant design and materials selections for components that need to be durable must be selected with a keen eye towards ease of fabrication and total cost of ownership.  In the photon and electron moving business, it doesn't pay to save money in ways that detract from the robustness or practicality of the design, nor does it help to splurge on extravagant and overly-complex doo-dads that make construction and maintenance costs skyrocket.

This reactor will be the Henry Ford solution to WWII aircraft engines, rather than the Allison or Rolls-Royce solutions.  Ford's GAA series had so few parts that one person could easily assemble an entire engine in an afternoon.  The Rolls-Royce Merlin looked like something concocted by Rube Goldberg.  Allison's V1710 had about half as many parts as the Merlin but double that of the GAA.  There were significantly more fasteners in the Merlin engine than there were total parts count in the Ford GAA series.  If time and money are no object, then nearly anyone can come up with a dizzying complex solution to a simple problem, but that's not what we need.

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#258 2021-07-28 23:04:12

SpaceNut
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#259 2021-07-29 05:04:24

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

These two references suggest that the largest single loads capable of transportation by rail on standard trucks are 130ton (100 metric tonne), with a length of 53' (16.3m).  Width appears to be restricted to <3m.

https://www.rsa.ie/Documents/Vehicle%20 … eaflet.pdf
https://en.m.wikipedia.org/wiki/Rail_fr … cial_cargo

A mass producable reactor system, capable of widespread deployment, should be composed of modular components with mass and dimensions within these parameters.  Each reactor system should be preassembled into modules at the factory level, such that modules can be welded or flanged together on site.  To meet these requirements, lead coolant would need to be transported separately and the reactor vessel filled as part of the commissioning process.

As kbd512 makes clear, low alloy carbon steels are preferable for many system components as they are ductile and crack growth is a gradual process that can be monitored.  Corrosion in reactor coolant is a problem that can be managed by cladding the inside of the vessel with martensitic stainless steel.

The most compact and efficient power generation cycle is S-CO2.  Heat exchangers between the CO2 secondary fluid and lead primary, would be contained within the vessel and would be martensite stainless steel.  At least two loops should be provided, allowing a single power generation loop to be maintained, whilst the other continues to provide power generation and a decay heat removal path.  The circulation of lead coolant within the vessel and into the heat exchangers, should be via natural circulation.  This avoids the need for internal pumps.

Duty decay heat removal would be provided via the cycle non-regenerative coolers.  Alternative standby DHR would be via radiated heat directly out of the reactor vessel.  The reactor module cylinder would sit vertically within a concrete well, containing water pipes within its walls.  At 500°C, a 3m diameter and 10m long reactor module cylinder, will lose about 2MW of heat by radiation to the concrete walls of the well.  The well cooling pipes would transfer heat by boiling assisted convection to a pond sitting above the well.  Decay heat would be lost via evaporation or boiling from the surface of the pond.  This ensures that decay heat can be reliably removed from the reactor, so long as the pond is kept full of water.  At low decay heat levels, thermal conduction to surroundings would obviate the need for active management of the pond.  The water within the pond would not be radioactive and steam can be vented directly up a cooling stack.  Makeup demineralised water can be drained into the pond entirely by gravity.  The pond and surrounding demin tanks can be sized to allow sufficient boiloff until decay levels decline sufficiently that thermal conduction into surroundings is sufficient to keep pond temperature beneath 100°C.  This allows operators to be confident that the core would remain protected in any emergency.

For decommissioning at the end of its 30 year operating life, the reactor is shutdown through control rod insertion.  Natural heat loss into the cooling pond and surroundings will remove decay heat until decay heat levels are down to about 10kW.  This may take up tona decade.  At this point, lead coolant can be drained out of the vessel and the reactor vessel disconnected from the power generation module.  The reactor vessel would then be lifted onto a flat bed rail car for transportation back to the factory.  The core would lose heat during transit via thermal radiation to the reactor vessel and surroundings.

One of the problems with whole life nuclear cores like this, is that they require a large upfront investment of fissile materials.  Fast neutrons also have a much lower fission cross section, necessitating higher enrichment values.
Additionally, between construction and reprocessing, some four decades may elapse.  This reduces the doubling time of fissile material to at least 4 decades, even if the entire cycle is able to double the amount of fissile isotopes within the core.  The problem that this poses is that there may not be enough plutonium and enriched uranium to allow a rapid transition to a nuclear dominated energy system.  As a way of partially mitigating this, I would propose the use of 208Pb as coolant and stainless steel clad, tube-in-duct metallic uranium-Zr-plutonium alloy fuel, with a DU-Zr blanket region.  This offers a number of advantages.

1) The lead coolant and DU blankets provide excellent reflection of neutrons back into the central core at beginning of life.  This reduces critical mass and increases the number of kW/kg of plutonium initial inventory.

2) Critical mass is inversely proportional to the square of fissile atom density.  The dense metallic fuel therefore reduces neutron leakage from the inner core and increases kW/kg-Pu.

3) The combination of metallic uranium-plutonium fuel, steel based cladding and 208Pb coolant, results in a very hard (high energy) neutron spectrum.  This is very advantageous, because it increases the number of neutrons yielded by fission (improving kW/kg-Pu), results in considerable power yield due to direct fast-fission of 238U (this requires neutron energy exceeding 1MeV) and substantially improves breeding ratio in the blankets.

4) As burnup of the inner core proceeds, it will produce steadily less power towards the end of its life.  The high breeding gain in the outer blankets will allow them to generate increasing power as the inner core depletes and to provide increasing neutronic feedback into the inner core as fissile inventory declines and fission product poisons accumulate.

5) Reactivity control will be accomplished via boron steel control rods surrounding the inner core and burnable poisons.  At the beginning of life, most power will be generated by the inner core, but criticality will depend upon reflection from the blanket regions.  Towards end of life, power levels in the inner core will depend upon direct neutronic feedback from the blankets.  Burnable poisons and control rods should be arranged to flatten the flux profile of the reactor as much as possible.  This allows higher overall power density and improved power output per kg of heavy metal.

6) The use of 239Pu, which yields substantially more neutrons than 235U in the fast spectrum, reduces the required enrichment and improves kW/kg of fissile materials.

This combination of factors, especially incore breeding, mostly stemming from a hard neutron spectrum and compact inner core, would minimise the fissile starting inventory of the core.  Some breed and burn reactor concepts would completely obviate the need for fuel reprocessing.  DU is introduced at the edge of a core and is gradually shuffled inwards, breeding the plutonium needed to achieve criticality as it does.  Following an initial load of fissile fuel, all subsequent fuel loads into the reactor are DU.  The problems with this however, are that regular fuel shuffling is needed and relatively high fuel burn up is needed to sustain breed & burn.  Fuel cladding becomes brittle with heavy neutron irradiation and shuffling tends to disrupt power production.  The idea developed here is a sort of compromise, where breeding in the outer core compensates for fuel depletion in the inner core, but reprocessing takes place only after decommissioning.

Last edited by Calliban (2021-07-29 06:51:53)


Interested in space science, engineering and technology.

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#260 2021-07-29 06:58:51

tahanson43206
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Posts: 7,313

Re: Nuclear power is safe

For Calliban re #259

Thank you for developing your thoughts on this important subject and adding references for study.

Having just read through the post for the first time, this is intended only as a quick summary of impressions:

SearchTerm:Modular fission reactor concept suitable for rail transport to secure power generation facilities
SearchTerm:Lifecycle for modular fission reactor part of larger industrial scale implementation on global scale

Security is needed at every stage of an economy built upon this high energy distribution concept.  That means that there would be plenty of well paying employment opportunities for persons with the required psychological makeup.  Not everyone is well suited for the role.  The members of the security force must be on the alert 24*7 forever.

However, that level of security concern is the price an advanced civilization must pay for the luxury of abundant power.

In return, an abundance of energy means that the general well being of the population will/can be sufficient to provide rewarding lives for individuals, over the entire arc from birth though demise at a great age.

It is this concept that makes taking the risks of moving in this direction worth while.

A concern I have is that this concept (again, first impression) is far more powerful than the 1 Megawatt family sized reactor I am hoping will appear at some point.  A large reactor may serve a city or a large industrial complex, or a large military base, or a large ship or a good sized building.

Based upon a quick survey posted recently, there would appear to be thousands of opportunities for deployment of reactors at a mid-range scale of performance in the United States, and (I presume) in many other countries.

(th)

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#261 2021-07-29 09:33:19

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

Very small units (1MWe) are by no mean impossible.  It is more a question of whether they provide an efficient use of resources compared to the alternative of grid connection to larger units.  A 1MWe unit will not be 100 times smaller than a 100MWe unit and it will not operate using 100 times less fuel, because a smaller core has to overcome greater neutron leakage per unit volume.  But small units like this have been constructed in the past and could be again.  There may be some value in a compact heat or electricity source in the single MW range, that can ship on a truck as a fully integrated solution.  But my guess is that it would always be more expensive on a kWh basis, than a 100MWe powerplant and will require substantially more fissile material per kW of power.

On the other hand, there are design simplicities that can be exploited in very small nuclear reactors.  If a fully integrated power system can be delivered by a single flat bed truck, then that is an obvious advantage in terms of portability.  A reactor producing just 2.5MW of heat would produce only 150kW of decay heat at shutdown.  A unit this small would not need any special decay heat removal systems, as it can be configured to lose sufficient heat by radiation and conduction to surrounding materials and air.  Such a unit could be very mechanically simple, which may bring down costs and would benefit from passive safety in ways that are difficult to undermine.  The core would be a single uranium-zirconium-plutonium alloy slug-cartridge, with cooling tubes running through it.

There could be quite a lot of benefit for a power system like that in providing power to applications a long way from any feasible grid connection.  But initial capital costs would be high.  Such a unit would obviously be valuable to a Mars mission.  With a total system mass <100 tonnes, it could fit in a single Starship payload.

On both Mars and Earth, waste heat removal could be accomplished using a trailing hose, carrying cooling water or brine, buried a few inches beneath the soil.  This would dump heat into the dirt, which would then radiate heat into space.  We could have the option of using the heat in places that are cold.

It is worth noting that even 1MWe units are not exactly home systems.  The average European home, consumes about 0.5kWe on a time averaged basis.  The average US or Canadian home, about twice that.  So a 1MWe system is more of a small town sized power source.  Obviously, Kilopower units have been scaled down to 1-10kWe, with a total system mass of 1500kg, using 44kg of highly enriched uranium.  Is that the sort of thing that anyone could afford to buy to power their house?  Not a chance.  And the thought of having that much HEU in public hands is scary to say the least.

For a 1MWe system to produce power for $0.1/kWh, i.e. a typical utility rate, would require that the whole system has capital cost not much greater than $10million.  I think that would be a stretch.

Last edited by Calliban (2021-07-29 10:11:20)


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#262 2021-07-29 11:34:20

tahanson43206
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Re: Nuclear power is safe

For Calliban re #261

Thank you for providing a (modest) degree of support for the vision of 1 Mw reactors.

Your argument about cost effectiveness is strong if you are not concerned about the vulnerability of the grid system we have on Earth today.

Before the industrial revolution, we did not suffer from the risks of excessive complexity.

Dr. Dartnell's Knowledge Forum (where i retain a membership) is all (or at least largely) about reducing risks of excessive vulnerability due to complexity caused or brought about by engineers dedicated to wringing every last bit of economic value out of the flow of energy and materials.

In creating the wondrous structures we have on Earth today, our talented and capable engineers have created a structure that could collapse without hope of remedy.

The idea of reducing the scope of power centers seems to be one you have been willing to consider, but I have (so far) failed to convince you that whatever economic benefits there may be to ultra-efficient networks for power production, they pale in comparison to the risks so blithely assumed by the builders.

I'm hoping to enlist your talent and expertise in creating a vision that is achievable and that policy makers (at all levels) will accept as optimum for creating a resilient power distribution system that does NOT add carbon and which IS resistant to all manner of threats.

Efficiency MUST give way to resiliency in the scenario I see ahead for the population of Earth.

Besides, if you create a 1 Mw reactor that is only 1 % efficient in consuming the atomic energy with which it starts operation, so what?

Who cares?

In the scenario I ** think ** we are creating, all unconsumed material goes back to the recycling center.

For the consumer who "rented" the power package, it looks as though 1 Mw arrived, lasted for 10 years, and then quietly disappeared without creating a mess.

(th)

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#263 2021-07-30 10:55:57

tahanson43206
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Registered: 2018-04-27
Posts: 7,313

Re: Nuclear power is safe

For Calliban regarding interesting (recent) post in Climate Change topic ...

In that post you modestly suggested your talents and capabilities are minuscule, compared to the challenge of designing (and selling) a modular fission reactor able to operate at 1 MW for 10 years before swapout for another one.

You also mentioned Bill Gates .... It is possible to have some knowledge of the way that Bill Gates got started in the career that became one of the top tier in recent decades.  The arrival of a small 8 bit microprocessor on the scene inspired many people around the world to understand that the power of computing could be given to the average person.

Bill Gates decided to create a simple early language to run on the microprocessor, and he had the example of DEC (Digital Equipment Corporation) minicomputers to build from. 

What is noteworthy about Bill Gates is that he did not realize his skills (at the time) were minuscule compared to the scale of the problem he was attacking, so he just concentrated on porting from DEC to the 8080.

It ** just ** so happened he did this work when the entire world was thirsting for the power of computers (and for the most part didn't know it).   Fortunately, several large corporations (but IBM in particular) saw the potential and provided funding that Bill Gates was able to tap.

However, since you have laid out a set of predictions, and since I think they are all testable, I'd like to invite anyone with posting priviliges to help Calliban to work out the details of the race we (humans) are in.

The argument in favor of defeat is well documented by Calliban, as a precursor to failure.

The argument in favor of victory is based on nothing more substantial than the sheer magnitude of abundance of energy and material in the Universe, and the track record of the Human Race in discovering and exploiting fossil fuels for all they are worth.

The age of Atomic Energy has been available since the 1940's when the first working pile was constructed by Enrico Fermi and associates under the seats of the Chicago Stadium.   That is a paltry few years, compared to the age of fossil fuels, which is now coming to an end.

Is there anyone in the group who can help Calliban to put substance into the framework of prediction he has created?

Is there anyone ** not ** in the membership who would like to contribute to an initiative to develop and deploy a megawatt per Earth citizen within the next few decades.  If so, read post #2 of Recruiting and join the undertaking.

Edit at 13:34 local time ...

Calliban, you were composing that helpful reply to Louis as I was composing this message.  I appreciated your adding the chart of energy contributions as of 2016. 

In your discussion with Louis, I may have missed your plan to use Atomic Energy to pay (invest energy) building more reactors, securing the fuel for them, and distributing and refurbishing them.  There should be NO fossil fuel needed to continue the mass production of these units after the first round.  Furthermore, fossil fuel use should decline with each unit placed into service.

(th)

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#264 2021-07-30 13:16:45

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

This article details a 770 metric tonne load moved by road in Nevada and then shipped by rail.
https://www.reviewjournal.com/local/dec … s-2036202/

Moving loads this large is possible, though difficult, by road.  This suggests to me that the 500 tonne SSTAR 100MWe reactor module units are plausibly transported by road as a single piece, but will likely require specialised trucks to spread the load sufficiently to avoid damaging the asphalt.  Such units are more easily transportable by rail.

Rather than start from scratch, I would propose a way forward by picking up the now dormant Livermore SSTAR development work.

The operating temperature of the SSTAR (500°C) should allow the use of compact S-CO2 power generation loops, with an efficiency of around 40%.  S-CO2 turbines and heat exchangers have much higher power density and should therefore be much cheaper than steam power plants of equivalent power.  This is an obvious design improvement on the original SSTAR work.  Inline with the Lucid Catalyst plan, these powerplants could also be clustered into rigs that will produce hydrogen and convert it into ammonia liquid fuels.

Using entirely modular, factory built systems, that can be shipped as modular components and flanged together onsite, it should be possible to build powerplants composed of clustered units, with power ranging from 10MWe to 1000MWe, on time frames of months.

Most of the fabrication and metal forming associated with powerplant construction, are electrically powered.  Steel manufacture uses a lot of electrical power in operation of electric furnaces.  But a chemical reducing agent (CO or H2) is needed to reduce iron oxide into metallic iron and some carbon is needed as an alloying element.  Mining can be powered using electric power, waste heat and ammonia as a substitute for diesel fuel.

Last edited by Calliban (2021-07-30 13:49:03)


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#265 2021-07-30 14:26:05

tahanson43206
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Posts: 7,313

Re: Nuclear power is safe

For Calliban re topic ...

I am encouraged by a first reading of Post #264, but must come back later to try to absorb it properly.

This visit is to drop off a reminder that the path this topic is on requires heightened vigilance on the part of everyone will be developing abundant atomic energy for the population of Earth.  The planet has only 70 years (give or take) of experience with atomic energy, and massive mistakes are in the mix along with some decent success stories. 

There will employment opportunities for armies of regulators, inspectors, maintenance workers and many other specializations that I just don't know about, to support the smooth and rapid transition from fossil fuel to all nuclear power.

This is an organizational change.  Humans have accomplished organizational change on a smaller scale in many instances, although what I'm thinking about is the constant reorganization characteristic of capitalist enterprises.

I am hoping that those who contribute to this topic in coming weeks will identify a path forward that delivers employment for everyone currently working in the fossil fuel industry world wide, while at the same time adding new employment to support the industry I am seeing in my mind's eye.

This is NOT a time to be nickel-dime planning.  This IS a time to identify the work that is needed, and provide that information to policy makers who are in position to enlist the human resources needed to accomplish the goal.  How details of compensation are handled are best left to those who are qualified to manage them.  Engineers are NOT qualified to participate in those discussions, except to provide as accurately as possible the requirements for the transition to the desired end state.

https://www.yahoo.com/news/radioactive- … 00858.html

The Detroit News
Radioactive material missing en route to Michigan, NRC says
Mark Hicks, The Detroit News
Thu, July 29, 2021, 2:08 PM
Jul. 29—Radioactive material headed to Michigan from an Ohio company never made it to its destination, according to a filing by the U.S. Nuclear Regulatory Commission reported this week.

Because I am interested in and supportive of a concept to address the needs of the human race for an abundance of energy for every citizen, and because Atomic Energy appears to be a reasonable way to provide that abundance, I am posting this reminder of the need for constant and high level security of all radioactive materials.

The price that a civilization, human or otherwise, must pay for an abundance of atomic energy is the vigilance that is required to safeguard radioactive material at every phase of it's use, from sourcing through disposal.

The article at the link above is about Iridium, which is used for inspection of pipes and welds, as well as for some medical applications.  However, it is NOT to be taken lightly as harmless, as the article makes clear.


Edit later: I just downgraded from a full sized smart phone to a smart flip phone, due to budgetary constraints.  The transition went well, and I am surprised by the capability of this device and the service that comes with it. 

I bring this up as a reminder that a new technology can sweep the planet if it is well conceived and well executed.  While the introduction of personal power (energy supply) is thought by some to be a startling concept, the fact is that in just a few hundred years humans have advanced so that an individual can control hundreds of horsepower in transportation and employment, instead of one horse or one ox.

If we (humans) can get our collective act together, every citizen can (set aside for the moment "should") control a megawatt of power generation service, which can meet their individual requirements but also supply the community and thus earn income for the citizen.

In this scenario every citizen entrusted with this responsibility will be able to contribute to the common good, although for some the responsibility will be managed by an agent, either appointed by the citizen or by a suitable government agency.

(th)

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#266 2021-07-30 16:43:53

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

A few facts and figures to illustrate the sheer scale of what it would take to pull off the planned nuclear renaissance.  Human energy consumption stands at about 150,000TWh per year.  Global electricity consumption is 26,000TWh per year.  The world consumes about 100 million barrels of oil each day.  One barrel of oil is about 1GJ.

To produce all of the world's electricity, some 30,000x 100MWe nuclear power reactors would be needed.  To meet all global liquid fuel needs using ammonia, produced using nuclear electricity at 70% efficiency, some 16,500x 100MWe reactors would be needed.  In total, the world would need 46,500 nuclear reactors in the 100MWe range.  Let's round that up to 50,000 to account for downtime including maintenance.

If we are to complete this energy transition in exactly 30 years, we would need to bring online some 4.5 new nuclear reactors every day for the next 30 years.  That is possible in principle if the world starts building reactors using the same assembly line methods that it uses to build cars.

Plutonium supply may turn out to be a stumbling block.  Fast breeder reactors typically have central core power density in the region of 300MW/m3.  Our 100MWe reactor will produce about 250MW of total heat.  So I am going to assume a total core volume of about 1m3 with about a 50% fuel volume fraction.  That would give the core a total mass of about 10 tonnes.  Plutonium enrichment is usually 15% in oxide fuelled cores.  However, we are opting for a dense metallic core with a hard neutron spectrum.  Critical mass is inversely proportional to the square of fissile density and uranium metal is twice as dense as uranium oxide.  So I am going to conservatively assume that fissile enrichment of 10%-atom is needed.  That means for each new reactor, we need 1 tonne of plutonium.

According to the IAEA, the world produces about 70 tonnes of reactor grade plutonium each year.
https://world-nuclear.org/information-l … onium.aspx

The world's major nuclear powers would only appear to posses about 300 tonnes of separated reactor grade plutonium, although more certainly exists in spent fuel.  So it would appear that plutonium supply is a severe bottleneck in any fast reactor programme.  We could partially mitigate these shortages by blending the plutonium into already enriched uranium.  I need to think about solutions to this problem.

Last edited by Calliban (2021-07-30 17:13:08)


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#267 2021-07-30 17:20:57

tahanson43206
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Posts: 7,313

Re: Nuclear power is safe

For Calliban re #266

Thank you for taking the concept of global replacement of fossil fuel with nuclear power seriously.

I was guardedly hopeful you would continue as you have before, but it is greatly reassuring to see the figures you provided.

The level of discussion in this topic deserves participation by peers of Calliban who can fill in details or (perhaps) offer insights into options that might be available in addition to the ones Calliban is considering.

Since we have need of additional members to support Calliban in this undertaking, read Post #2 of Recruiting, if you think you can help.

In initial response to the (sobering) figure of only 70 tons of material produced by humans in 2021, across the entire planet ...

It seems likely the rate of production would necessarily have to be exponential instead of linear.

I also note that the cycle time for (hypothetical) modular units is 10 years at the low end, and 30 years in the specific vision Calliban is exploring.  It would seem reasonable to consider shorter swapping times during early years, in order to improve production of useful materials.   

Another issue to be addressed is training of workers for this new industry.  Changes to curriculum for students below maturity would help to prepare for exponential growth, but in the mean time, significant investment in adult education would seem needed to help fossil fuel workers to assume new responsibilities.

I would note (with some mild surprise) that Thorium has not shown up in recent posts, although I understand it has some potential for application in this arena.

Edit#1: The addition of production of Ammonia is a nice supplement to the basic theme, and one which should fit well into a developing vision.  I would add that production of Hydrogen and Oxygen is also possible, and these materials would fit well into an overall plan.

Customer (countries) would be able to choose which set of energy carriers they prefer.  Reactors themselves can be located away from the land surface of owning countries, with appropriate agreements with appropriate authorities.

Edit#2: For Calliban specifically ... there are (traditional) reactors in the US (In Illinois, if memory serves) that are threatened with decommissioning if the state of residence fails to provide supplemental income (or easements).  Such reactors would be ideal (from my perspective) for manufacture of the new reactors being considered in this topic. 

(th)

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#268 2021-07-30 18:08:06

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

Those high plutonium requirements are exactly why breeder reactor programmes envisaged in the 1970s and 80s, valued high breeding ratios and short cycle times.  They wanted to reduce the doubling time of fissile materials, to allow for that exponential growth in reactor capacity that would allow breeders to displace fossil fuels quickly enough to avoid energy shortages.  Fast forward forty years and lo and behold, we have reached the same conclusion.

Thorium does not help very much in solving this problem because it is not fissile.  It is a fertile material that must be converted into 233U by absorbing a neutron.  There generally aren't enough spare neutrons in a nuclear reactor to allow this process to occur as quickly as we would like.  The problem we face is that it is difficult to breed enough fissile isotopes quickly enough, whether the fuel cycle is uranium or thorium based.  The uranium cycle is arguably much better in the fast spectrum, because plutonium produces more neutrons when it undergoes fission in a hard neutron spectrum.  In the sort of average energy levels applicable here (~500KeV), the average neutron yield is greater than three per fission.  In thorium, it is more like 2.5, which really limits the achievable doubling time.

One of the reasons I advocate metallic uranium fuel and lead coolant, is that metallic fuel is very dense and therefore results in a higher density of fissile atoms at any given enrichment level.  Also, the very hard neutron spectrum increases the number of neutrons yielded by fission of plutonium and allows considerable fast-fission (without any intermediate breeding) of 238U.  All of these effects tend to reduce the required critical mass needed for criticality, reducing the amount of plutonium needed to produce each unit of power.  Due to the scarcity of plutonium, we really need each kg of Pu added to the core to generate as much power as possible, breeding replacement plutonium as rapidly as possible.

I agree with Tom, that shorter cycles (and larger cores) would be more beneficial to doubling time than long, 30 year cycles that tend to lock up plutonium in lower power density cores for decades at a time.  Early in the programme, we need each kg of Pu to generate as much power and to burn up as quickly as possible, breeding new fuel in blankets.

However, I may in fact have overestimated the amount of plutonium needed by a factor of three.  I want to avoid getting bogged down in detailed criticality calculations at present.  But the Wiki article on critical mass provides some interesting information.
https://en.m.wikipedia.org/wiki/Critical_mass

'The critical mass for lower-grade uranium depends strongly on the grade: with 20% 235U it is over 400 kg; with 15% 235U, it is well over 600 kg.'

It is noteworthy that critical mass values for a bare metallic sphere of 239Pu are only 10kg, versus 52kg for 235U.  So a critical mass of 15% plutonium in uranium metal, would be ~120kg.  If we further assume a 50% volume fraction of fuel metal and a 50% coolant fraction, critical mass increases about four times to 600kg.

However, the surrounding breeder blankets and lead coolant would function as a very efficient neutron reflector early in the life of the core.  In nuclear bomb designs, dense tamper materials can reduce critical mass by a factor of four.  That estimate is for tamper materials under some degree of explosive compression.  But a halving of critical mass due to the reflection provided by the blankets is not unrealistic, especially considering the potential for fast fission in the blankets.  That brings plutonium critical mass down to 300kg.  There are other fissile actinides in spent fuel, things like americium and curium, which can be added to the fuel to reduce the amount of plutonium needed even more.  If we assume some level of 235U is also present in the central core and also some additional reactivity margin to compensate for the effects of burnable poisons, then an initial plutonium mass of just 0.33 tonnes may turn out to be amply sufficient for a 250MWth core.

Under that scenario, an initial 300 tonnes of reactor grade plutonium, would allow construction of 900x 100MWe nuclear reactors, with 210 new ones constructed each year.  That is enough to meet a big chunk of the world's electricity needs, but not enough to displace fossil fuels from our energy system to any appreciable degree within 30 years.  It looks like we may need one generation of large, short cycle breeder reactors, simply to produce the plutonium we will need for small modular reactors.  After 30 years of course, the burned up cores of the first generation of small modular reactors would provide all the plutonium needed for a doubling of reactor capacity.

Last edited by Calliban (2021-07-30 19:09:49)


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#269 2021-07-30 20:33:56

SpaceNut
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Re: Nuclear power is safe

If one could design a unit that would fit down inside a driven well deep to a hundred feet or so filled with a constant level of water you could have lots of these units safely deployed which would be much smaller and could be able to provide a family power none stop at a within reach cost to have that would be in the kilowatt sizing.

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#270 2021-07-30 20:49:05

tahanson43206
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Re: Nuclear power is safe

For SpaceNut re #269

Thank you for your description of a home sized power unit that I was trying to describe earlier.  Your post goes into details of positioning of the unit that seem (to me at least) to greatly increase the safety factor, while at the same time greatly increasing sales prospects for the entire concept.  My idea here is that the population of the United States is more likely to take an interest in a proposal that could directly benefit them. The problem (from that point of view) is that plans for gigantic power stations only interest very wealthy individuals who can potentially make even more money.  Such proposals do not speak to individual citizens.

I understand from Calliban's posts that there are significant engineering advantages to having large systems, but I am looking for a vision that would appeal to so many citizens that they would support policy makers who would offer to implement it.

Can you provide an estimate of the amount of power you would like to see coming from a family sized unit?

I've been hoping for a 1 Megawatt system because it would offer an opportunity to earn income for the family.  My concern with a smaller unit is that it would be like a furnace ... it would require investment to install, it would provide power for the family for 10 years, and then it would have to be swapped out, just like a furnace does today after (about) ten years.

I am attempting to address the problem of poverty in human society by conceiving of a way-of-doing-things that gives every citizen ownership/management of a source of useful product (electricity and heat) that can sustain the family and contribute to society as a whole.

The present capitalist system does allow for distribution of ownership of productive enterprise through stock, but I am talking about something more elemental.  If a person is born into the society I am imagining, they they would be eligible to receive the keys to a 1 Megawatt reactor at maturity.  They would have the option of allowing a paid manager to handle the asset, or they might decide to personally learn enough to be able to take direct charge of the asset.

In any case, in either scenario, the asset has to earn enough to be able to pay for it's own replacement.

(th)

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#271 2021-07-31 09:04:08

tahanson43206
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Registered: 2018-04-27
Posts: 7,313

Re: Nuclear power is safe

For Calliban re topic ...

As you've been advancing the topic, I've noted your mention of anticipating radioactive byproducts that must be dealt with...

The early years of development of atomic power on Earth yielded great quantities of radioactive material, much of which will last for thousands of years unless treated.   There should be a business opportunity for treatment of all those wastes.  Because of reluctance of populations (I'm most familiar with American but no doubt there are others) it might be best to treat such waste on site.  The famous planned underground repository in Nevada is unused because of objections to the site itself, and to transport of radioactive material.

In any case, I am noting your thinking about consuming wastes in new designs.  That would be done at the refurbishment centers, I presume.

Sophisticated means of separating atoms safely would seem necessary.

Many of the historic atomic sites are disaster zones (at least in the United States) so new facilities need to be designed to NOT add to the mess already created.

(th)

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#272 2021-07-31 17:11:16

tahanson43206
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Re: Nuclear power is safe

For all re topic ....

https://www.yahoo.com/news/federal-stud … 03131.html

Sammy Fretwell
Sat, July 31, 2021 5:31 AM
A study by federal nuclear regulators recommends a new 40-year operating license for an atomic fuel factory near Columbia that is considered vital to electric utilities but unwanted by neighbors worried about pollution from the aging facility.

The article at the link above provides a pro and con view of the result of a study that recommends a new license for this facility.

The facility makes fuel rods for reactors.

Facilities like this would be needed to support conversion of the energy economy 100% from fossil fuel.

While the nuclear industry only has 70 years of history building and operating facilities like this, and that history is studded with massive failures of all kinds, I am hoping that enough lessons have been learned so that a new facility for construction and refurbishment of modular reactors might be imagined, constructed and operated safely for many decades.

On the other hand, the arguments of those who oppose facilities like this one are based upon unfortunate reality.

There may well be facilities that have operated safely for decades without creating invisible liabilities that will come to light in future.

It would be good to know if such facilities exist, because they would surely be models for what is needed in great numbers if the global infrastructure is to be converted from fossil fuels in a reasonable number of years.

(th)

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#273 2021-08-01 17:24:53

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

https://www.yahoo.com/finance/news/nucl … 58851.html

Bloomberg
Nuclear Power Could Get Lifeline in Senate Infrastructure Bill

Jon Morgan and Ari Natter
Sun, August 1, 2021, 6:34 PM
(Bloomberg) -- Struggling nuclear power reactors could be given a $6 billion lifeline in the bipartisan infrastructure bill being written in the U.S. Senate, according to a draft obtained by Bloomberg News.

A program to evaluate nuclear reactors that are in jeopardy of closing and provide them with aid would be created within the Energy Department under terms of the $550 billion, bipartisan infrastructure package. The text of the infrastructure bill hasn’t been released and changes could still be made before its release.

(th)

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#274 2021-08-01 17:44:30

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 23,084

Re: Nuclear power is safe

https://beyondnerva.com/radioisotope-po … icium-241/

https://en.wikipedia.org/wiki/Americium-241
possible for use in an RTG.

https://thefutureofthings.com/3015-amer … er-source/

article supporting its use for electricity
UK generates usable electricity from americium

The achievement is seen as a step towards potential use of americium in so-called space batteries, which may mean future space missions can be powered for up to 400 years.

https://inldigitallibrary.inl.gov/sites … rt_877.pdf
Considerations for Use of Am-241 for Heat Source Material for Radioisotope Power Systems

https://3.14.by/en/read/building-nuclea … or-at-home

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#275 2021-08-02 13:44:06

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Nuclear power is safe

One of the most prescient articles that I have read in many years.
https://consciousnessofsheep.co.uk/2021 … -collapse/

The author alludes to a point that should not be taken lightly.  Using the surplus energy stored in fossil fuels, human beings have increased their numbers by an order of magnitude, achieved living standards that exceed those of the Kings of old, and have ruined the ecosystems of planet Earth.  Nuclear fuels contain one million times as much energy per unit mass as fossil fuels.  Imagine how much damage we would do to the Earth if we had that much surplus energy?  Would there be a single wild river or natural forest left after a century of nuclear fuelled growth?

It should give pause for thought.  But one thing that is noticeable about the author's thought process is that he subconsciously assumes that the Earth will remain a closed system.  If we did have access to an abundant, high-EROI energy source, how likely is that?  Here on Planet Earth, opportunities are more and more limited.  Even societies that once pretended to be free, are becoming oppressive and totalitarian.  Given the opportunity, I think a lot of people would leave.  And they can do something that no other species has ever had the power to do, take life out into the solar system.

Last edited by Calliban (2021-08-02 13:54:45)


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