lven

Thanks for taking the time to think about it - very helpful comments. Will check FenBen out and stick some references in as I find them again.

Do you have a better resource or recommendations? I'd be happy to remove this from the internet. I feel that most other articles on the topic would be severely self-censored because of the small amount of research and the risk you mention, or just not interested in low-cost alternative treatments without a "medical" stamp on it. Research and reporting on low-cost treatment methods is probably underfunded.

Webgl + js. same approach as https://ciechanow.ski/

I worked on this and host it on my site as well where it's not parceled up into bits and pieces. Have to thank Bartosz Ciechanowski. Learned a lot from his code and approach.

https://lvenneri.com/nuclear_reactor_explainer

not when it's more expensive than diesel. Must find the balance.

nah you can just create little holes in the sphere to illuminate the planets. negligible power loss. Earth and all the planets live on the sun's crumbs, no the (crumbs of the cumbs)^12

I like the railgun analogy. I think you can stock up on other fusion cost arguments through my article, Engineering and Economic Challenges of Fusion: https://lvenneri.com/blog/ConFusion

My own partisan comments on the pebble bed class of reactors (https://lvenneri.com/blog/pebble-bed-nukegumball) for those interested in a deeper yet still qualitative comparison of pebble beds and prismatic cores - the main types high temperature reactor. Long story short : pebbles offer significant disadvantages compared to prismatic geometries, summarized by this donald duck clip: https://youtu.be/shvwSBGDmE0.

They will have two types of reactors. First, large centralized reactors for DD fusion to make He3. These will be more expensive and challenging because of the neutron bombardment. The other for D-He3 fusion which will be for smaller sites and produces less neutron damage.

They will make the He-3 using D-D fusion reactors (which is not aneutronic) and waiting for collected tritium to decay into He-3 (12 years). In each shot, they have to remove the he3 and T to prevent them from reacting.

In the D-he3 reactors, they cannot fully prevent the side reactions of DD and DT. But they can minimize them by controlling the mixture of he3 and D in each shot and constantly extracting the T byproduct of D-he3. Basically, they will have high ratio of he3 to D ions so that all the D ions are likely to be used in D-he3 reactions. Removing and collecting the T in each shot removes the opportunity for D-T. It will probably work to an extent, but there will still be side reactions. The overall neutronicity will likely be in the 2-5 range in the D-He3 reactors.

Doesn't matter if the heat is coming from burning more fossils or nuclear fuels or intercepting more solar light - the effect on Earth's temeperature is negligible for now. You can do simple heat balance with Stefan Boltzman Law to show that the temperature of the Earth would increase by less than a tenth of a degree even if we burned 10x more fossil or nuclear fuels. The idea is that all the energy received and and generated on Earth must be reraridated at the Earth's blackbody temperature, and it only changes as the power to the 1/4th - so very small compared to the absolute temperature of the Earth ~300K, and the changes (e.g. seasons).

Main problem is the rock melting temperature ~ 1500 to 2000 °C. Even the best performing nuclear fuels can only reach 1600°C in the fuel (TRISO Particle or FCM fuel) for limited periods of time, meaning 1000°C of heat delivered due to major limitations in the steels and heat transfer. They realized this early on in the Subterrene project at Los Alamos, and transitioned to electrically heated electrodes like graphite and tungsten. They even did field tests near Bandelier National Monument, digging a large diameter door sized hole using 100s of small diameter holes to form the perimeter. Even then, there are material degradation problems especially in the presence of air and water, that make rock melting pretty challenging. More recently, an MIT spinoff (Quaize or Quarkz or something like that) is using microwave emitters to vaporize the rock - which reduces material and mechanical challenges. But it's not ideal for large diameter holes - mostly for geothermal, fossil, or utility boring.

It's not clear to me that melting is less energy intensive than digging (and all it's related machinery and material movement).

Not exactly. Nuclear reactors have a difficult time following the load because of Xenon poisoning. Xenon generated during the fission reactions absorbs neutrons that could have been used for fissions. Luckily, it decays away over time. If you turn down the reactor power, you have to wait hours or day for for Xenon buildup to decay so that you can turn the reactor back on. Some reactors manage to load follow more easily by adding lots of excess reactivity (more potent control rods) which is less safe overall. Smaller reactors will have the exact same issue. The amount of Xenon poisoning is proportional to the power density. NuScale reactors run at even higher power density than normal light water reactors, so they will have even worse Xenon poisoning. They won't be load following. One exception where this isn't true is micro gas-cooled reactors that have so low a power density that they have negligible xenon poisoning and can follow loads easily if necessary. Even then, it's not a great idea because of thermal cycling issues.

Probably the same or longer. In fact, the NuScale concept has been pursued since 2002, so more like 2 decades from concept to NRC certification. And you can tack on another 10 years for their hardware demonstration according to their published timelines. Size is not the question here. It's the analysis of the neutronics, thermal hydraulics, coupling of various systems, accident sequence prediction, etc. What takes time is credibility, ultimately getting all the parties involved to believe the calculations and understand the engineering decisions, and collectively agree that it's gonna work out. Have to convince the regulators, the advisory boards, the utility customers, the DOE, the suppliers.

Yes interesting. There are also good reasons to build cities in circles/squares.

1. Minimize the perimeter to area ratio. This minimizes the interface with the outside, such as protective walls and access points. On the other hand, in linear city, everyone gets a nice view, albeit basically the same view.

2. Minimize distance between points. Putting everything on a line means increases the distance for point to point trips. In a 2d city, things are closer together. In a 3d city, even more so. This affects travel, networks, etc. Important / highly frequented things will cluster in the middle.

3. Enhance resilience. If there's a roadblock or problem in a linear city, the whole thing gets blocked. In a 2d city, you can usually just reroute around. This applies to travel, sewage, grid, etc blockages. Linear city is just asking for single point failures.

Many of these points fall apart when you consider American cities are built kind of like 1d cities around highways and such. The linear city is just admitting it upfront.

Great idea! US DOD budget: 700B. We only really need nukes to keep the peace and maintain our interests. Nukes cost 20B/yr to maintain (both stockpile and delivery methods). The rest of the military budget is a bunch of garbage whose availability and global deployment makes it more likely USA engages in needless conflicts. A nukes only military is so cheap and effective. USA could do a yearly nuclear readiness demo on July 4th, like detonating a ICBM on the moon or in space for the whole world to see.

This is it: https://usnc.com/mmr/

I work on it.

I think they are talking about me.

Here's two papers about decay heat in ITER: https://www.sciencedirect.com/science/article/abs/pii/092037..., and https://www.sciencedirect.com/science/article/pii/S092037961...

I used their data to find power density and compared it the micro modular fission (MMR) fission reactors.

“MMR has a lower decay heat power density than fusion systems like SPARC or ARC, DEMO, or ITER and orders of magnitude lower than other advanced fission reactors as show in the figure below. UNSC's MMR has the lowest decay heat power density at 0.075 W/cm3, less than DEMO's 0.083 W/cm3 in the blanket and divertor. A lower decay heat is more manageable by passive cooling systems, allowing the reactor to dissipate heat more easily and without damaging the reactor. The other aspect to consider is the maximum temperatures that can be safely maintained in the reactor. Gas-cooled reactors like the MMR have all-ceramic cores that can withstand much higher temperatures than a fusion's reactors metals, molten salts, and magnets. MMR's low power density is a paradigm shift in nuclear safety, more foundational than fusion, for it can be accomplished cost effectively today.”

Fusion is generally touted by many as an energy "Holy Grail." Indeed, it appears to have similar qualities, being both perpetually elusive and miraculous, able to solve all mankind's problems. Media reporting tends to discuss the benefits of fusion with misleading and false statements and no discussion of fusion’s negative attributes. The financial and practical perspective of fusion based power is missing. I've written a post about this here: https://lvenneri.com/blog/ConFusion. I cover fusion's issues compared to fission. In particular: far worse neutron and gamma damage, 10x more demanding heat transfer, parasitic power draws, 50-100x larger radiological waste volume, higher financial and nuclear accident risk compared to new new micro reactors, higher cost by any metric, similar or worse proliferation characteristics, etc. My aim was to add a dissenting perspective on the practicality of near-term fusion energy systems.

This is not true. Fission reactors have to deal with decay heat, not fission reactions when cooling is lost. This can be managed. Fusion reactors also have decay heat. In new reactors like the Micro Modular Reactor, it's actually less decay heat than a fusion power plant. Please please read my post :https://lvenneri.com/blog/ConFusion#financial-risk-of-powerp...

You're better off donating money to fusion companies directly than paying taxes to the government. Wish musk had donated his taxesto companies last year instead.

One morea article worth reading about the con-fusion https://lvenneri.com/blog/ConFusion

I tried to describe this problem in further detail in a post called con-fusion. Kind of sad to see money burn like this. https://lvenneri.com/blog/ConFusion

New nuclear is decentralizing with micro reactors.

Theres an mit offshoot using microwAve beams to vaporize rock in a pretty neat process that leaves a glassy and structural tunnel wall not unlike the nuclear subterrene concept from 70s. Pretty cool stuff.

In terms of production capacity and industrial capability, it is mostly there. As an example, the recently unopened nord stream pipeline produced 200,000 pipe sections with similar dimensions and mass to the Micro Modular Reactor pressure vessel - in just a few years. Nuclear fuel costs are dirt cheap and production rates can be ramped pretty quickly - it's the magic of nuclear energy density.the reactor tech is more or less fifty years old with some design to build changes. Culturally, the zero-carbon push, volatile and political fossil markets, and perhaps an end in sight to the shale boom - it's completely changed the customer conversation compared to just a few years ago. Ultimately, energy scarcity is going to be the push for full market deployments. And we may be approaching that. All the delays and waddling will dissolve in the face of cold hard necessity.

his got me thinking about the earth's heat flux to the surface. It comes from primordial heat and radioisotope decay of thorium and uranium. Wild that geothermal energy is really just nuclear decay energy, just like the mars RTGs. But disappointing that it ain't all that much at just 47 TW, compared to the sun's 200,000 TW on the Earth's surface. And of those 47 TW, only 14 TW are on land. Not even close to enough to power mankind and our 20-40TW of primary energy today, and hopefully much much more in the future. Cool stuff, but we gotta think bigger.

I work on nuclear micro reactors (specifically this one: www.usnc.com/mmr) and there is big promise here to make many reactors soon and cheap. Their size of 15 MWe is too small to fully power human civilization which requires 20 TW of primary energy. For reactors with a 60 year life, that would require a population of 300,000 reactors sustained by a production cadence of 5000 reactors per year. That's actually comparable to the production rate of wide body aircraft. Even if such production rates are not acheived, these small reactors do not suffer xenon poisoning and can use thermal storage to produce dispatch power. It's like a zero carbon natural gas peaker, and can provide the needed backbone for intermittent renewables. The optimal mixes for many locations around the US are something like 10% dispatch nuke, and there rest wind and solar. It's one of the few energy solutions that looks a lot like a fossil fuel source, by virtue of it's high temperature heat, the fact it can be used on demand, can be located anywhere where it is needed, etc.

This got me thinking about the earth's heat flux to the surface. It comes from primordial heat and radioisotope decay of thorium and uranium. Wild that geothermal energy is really just nuclear decay energy, just like the mars RTGs. But disappointing that it ain't all that much at just 47 TW, compared to the sun's 200,000 TW on the Earth's surface. And of those 47 TW, only 14 TW are on land. Not even close to enough to power mankind and our 20-40TW of primary energy today, and hopefully much much more in the future.

The part about the dynamo being 10x lower 500 m.y.a. compared to today suggests that the background radiation was 10x higher. They point out that lower dynamo leads to more atmospheric loss to space, thus limiting biological activity. Butthe the great reduction in radiation could be similarly impactful, allowing for more manageable genetic mutation.

There is long term advantage to do robotic surgery in the creation of a large learning dataset. All the inputs to the surgeon - video, audio, bio metrics - are digitized, and all the surgeon outputs like movements and actions and even the peripheral actions like dosage changes or orders to nurses, it's all digitized. If all the inputs and outputs can be digitized,we can also expect the creation of outputs to be automated. Why not?