Wasn't said ever-present background radiation only a thing after the nuclear bomb tests? I read a while ago that steel from old ships that sunk deep is highly valuable because it's not irradiated yet.
It is low-backgroud steel([0]), not no-backbround steel. Potassium-40, for example, is a naturally occurring radioisotope. See Banana equivalent dose ([1]). [0]: https://en.wikipedia.org/wiki/Low-background_steel [1]: https://en.wikipedia.org/wiki/Banana_equivalent_dose
To add: C-14, Al-26, Cl-36, Ca-41, Ca-48, V-50 and more in trace quantities can be present.
Try pointing a Geiger counter at a brick or ever better plaster wall and be surprised about the amount of radiation you get during the day.
A system of particles in thermal equilibrium will contain a small fraction whose kinetic energy exceeds the average by a factor of 10. Also, the energy available in the center-of-mass frame of two colliding particles is higher if they happen to be moving in opposite directions. That could give you another factor of up to 2. In any event, I don't think you want your fuel fusing all at once!
Expanding on this, this 10KeV temperature is the average of all particles, and there's a distribution around this average. Some will be higher, and thus more capable of colliding with high energy. In addition to that, whether two nuclei fuse is also dependent on how squarely they collide. A glancing blow intuitively allows both nuclei to push each other away a lot easier than if they experience a head-on collision. A…
How does one control the chain reaction of the fusion process? I understand fission reactors using control rods to absorb some of the neutrons to prevent those neutrons from hitting other fissile particles, but this seems like a harder problem. Those particles fusing at a "low" temperature in the distribution of equilibrium cause additional fusion reactions at higher temperature thresholds in other particles because of the energy released, if my mental model is correct? And assuming the fuel is gaseous, the idea of a control/absorptive retarder seems like a much harder problem. Edit: Oh! Maybe they reduce the strength of the magnetic containment field? Which reduces pressure inside the reaction chamber and thus reducing temperature?
Let me ask a different question to the knowledgeable folk here. It has been noted that producing the temperature is not the hardest part but confining the plasma for long periods of time is.
On this note, do we have any reason to be particularly confident that magnetic confinement will ever break even and produce surplus energy? In nature fusion seems to occur through gravitational compression, so what makes us sure that we can simulate this by other means that will ever amount to more than just demonstrations?
Any idea on how much money we're spending on this? Also, I can imagine it's a joint project only partially because we can share the cost, I imagine another reason to work together is so that no one country gets this technology first.
Initial budget was €5bn. Current budget is four times that and with completion nowhere near estimates of the final cost are as high as $60bn. Go figure. If by "we" you mean US's share, that's 9% of total costs. China, India, Japan, Russia, South Korea, and the US are paying 9% each and EU is paying 46%.
With 'we' I meant every country that's involved, not just my own country.
$60bn is actually surprisingly little for research that could change the future of energy production and possibly society as we know it. To put it into context, the Apollo program cost $200bn in today's money and a high speed train between LA and SF is projected to cost $100bn.
The main challenge in working with these high temperature plasmas is confinement. In order to achieve nuclear fusion matter needs to be heated to immense temperature, so that the kinetic energy of nuclei colliding can overcome the electrostatic force of the protons pushing each other away and "fuse" into larger nuclei (held together by the "strong force"), converting a fraction of the reaction mass into a relatively…
this is what Doctor Octavius was trying to do in Spiderman 2.
Is it just me, or have we converged on 1 reactor design (the tokamak) relatively early on in the process? I appreciate that funds need to be concentrated in order to have an impact, but we have built dozens of this design since the 1950s, yet here we are.
Once we achieve sustainable fusion, will it be possible to "share" the energy with everyone else to create more independent fusions? Kinda like keeping the candle burning so as to light more candles because matches are too costly. Now, I don't expect politics to allow sharing of fusion energy to help other countries.
Isn't fusion reactor basically infinite energy, I mean sure it makes total sense to no share it with other because you can sell your free energy for cash, but considering that a lot of global scientists work on it and most of the findings are published, don't think that such strategy would last long.
Even if the fuel is pretty cheap the cost of fuel isn't a huge factor in the operation of traditional nuclear power plants - a fusion power plant will still have enormous capex and opex - so in no sense will the power be "free".
Let me ask a different question to the knowledgeable folk here. It has been noted that producing the temperature is not the hardest part but confining the plasma for long periods of time is. On this note, do we have any reason to be particularly confident that magnetic confinement will ever break even and produce surplus energy? In nature fusion seems to occur through gravitational compression, so what makes us sure…
Basically we have good enough materials to bear ignition, we need better materials to keep it running long enough for demonstration, we need even better materials to make it approved and viable.
Is it just me, or have we converged on 1 reactor design (the tokamak) relatively early on in the process? I appreciate that funds need to be concentrated in order to have an impact, but we have built dozens of this design since the 1950s, yet here we are.
Okay, did some search: - When two hydrogen nuclei combine, they produce an enormous amount of energy. That process is known as nuclear fusion. - Light nuclei have to be heated to extremely high temperature, it is challenging to create a controlled, safe fusion reactor that offers more energy than it consumes. Once we have such we’d have a near-limitless source of clean energy. - Nuclear fusion does produce radioactiv…
I will add: - While the products of the fusion reaction are short-lived, operating a fusion reactor will active materials in the reactor and create some longer-lived radioisotopes. - Unlike a fission reactor, which is loaded with months to years worth of fuel, a fusion reactor would have fuel constantly injected. So operator action to stop injecting fuel would stop the nuclear reaction.
There is ongoing research about what to use as chamber wall material. The difficulty is that the material needs to be able to withstand high temperatures, minimize the impurities released when hit by a particles from the fusion plasma and ideally produce short lived and/or harmless isotopes when activated by the fusion radiation.
Unfortunately, the metals most used and best known in engineering have the tendency to produce pretty nasty isotopes. The current best candidates are tungsten based alloys.