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lven

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Cancer Treatment on a Budget

lvenneri.com
4 points·by lven·2 lata temu·4 comments

Fourth Power Law

en.wikipedia.org
6 points·by lven·2 lata temu·0 comments

How do nuclear reactors work?

lvenneri.com
4 points·by lven·2 lata temu·0 comments

Silicon Carbide Sic Mug Using Additive Manufacturing

lvenneri.com
3 points·by lven·3 lata temu·0 comments

Additive Manufacturing of SiC and other ceramics

3dcarbide.com
23 points·by lven·3 lata temu·8 comments

Reduced Distortion Eye-Ware

lvenneri.com
5 points·by lven·3 lata temu·1 comments

comments

lven
·2 lata temu·discuss
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.
lven
·2 lata temu·discuss
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.
lven
·2 lata temu·discuss
Webgl + js. same approach as https://ciechanow.ski/
lven
·2 lata temu·discuss
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
lven
·2 lata temu·discuss
not when it's more expensive than diesel. Must find the balance.
lven
·2 lata temu·discuss
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
lven
·2 lata temu·discuss
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
lven
·3 lata temu·discuss
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.
lven
·3 lata temu·discuss
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.
lven
·4 lata temu·discuss
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).
lven
·4 lata temu·discuss
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).
lven
·4 lata temu·discuss
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.
lven
·4 lata temu·discuss
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.