I highly doubt any radiation worker would use this in his job just due to the fact that it doesn't have any test source listed. What use is a radiation monitoring device if you can't even tell if its working, particularly a device that measures cumulative dose? It might have an application for a secondary short term radiation monitoring in high radiation areas except that anyone who is going to work in a high radiation area will already have more specialized equipment.
And why would you want a radiation monitoring device on a watch on your wrist? If it were used by any radiation worker, he would probably tie it to his belt instead (to give a more accurate estimate of dose recieved).
This device really doesn't have much practical use. Really, its just a gadget for the geek who has to have everything.
You said: " Too bad thats not how radiation works. If you ever were near a large source of radiation your own clothes would absorb radiation and keep it coming to your body. One of the most important parts of a nuclear fallout shelter is the entrance room where you take off ALL clothing and shower. Your clothes and aything else you wear if you were near a nuclear explosion would continue the damage if not taken off immediatly.
Your description of radiation and contamination is a little hairy, let me clean it up:
Radiation is the propogation of energy over a distance via waves. Some types of radiation are (using the example of a nuclear bomb): neutrons (very hazardous--you need to be in a deep fallout shelter or surrounded by a significant amount of water to protect you), alphas (very hazardous--are shielded by your skin, but if they are emitted inside your lungs you are in trouble), betas (minor hazard--shielded by your clothing, not a real problem unless ingested or inhaled), EM radiation in general (the frequency; therefore, the energy of the photon is of prime concern: a radio wave will probably not hurt you but a high energy gamma will--shielded by being in a fallout shelter as long as its deep enough), and non-interacting (like neutrinos--you don't have to worry about these, they can't hurt you). This watch will detect gammas and maybe some other high energy EM radiation (neutrons require larger detection devices, and alphas and betas would be shielded by the metal of the watch). I doubt it can detect as low energy as x-rays, but it might.
Contamination is getting radioactive material on you. This radioactive material will undergo decays producing radiation. You take your clothes off and shower to remove the contamination so you don't get irradiated.
Radiation (with the exception of neutrons and alphas) does not beget long term radiation (longer than for example a gamma to be absorbed by an atom and re-emit a lower energy gamma). Its just absorbed and thats the end of it. Neutrons and alphas will typically not beget long term radiation because of the specialized conditions required (causing fission of an atom and releasing radioactive products or being absorbed and transmuting an atom into a radioactive isotope). The contamination on your skin and clothes will be due to fallout (i.e. radioactive material) from the nuclear weapon, not the radiation.
I think perhaps the button with the problem isn't the back button, but the forward button. Consider:
1) Go to the Slashdot main page at http://slashdot.org
2) Go to the discussion about the back button.
3) Click your back button and go back to the main page Note: the forward button is active 4) Click on the link to the discussion about Microsoft being its own worst enemy.
5) Now try to use your back button... The forward button is active again.
The problem isn't with the back button. Its that the forward button doesn't give you options. This can be implemented by considering each website a node in a tree structure. As you visit a hyperlink you go up the tree. When you click back, you go down the tree one step. Forward will bring you up the tree again, but will pick a default unless you specify which branch to follow (to be implemented).
The only problem is that the forward button is typically implemented so that it gives you a list of items to pick so that if you hit back 3 times, you would see the 3 web pages you just visited in reverse order in the list. I think it could be adequately implemented with expanding menus (but this is a UI pain-in-the-ass!).
You said "First of all, neutrons are stopped fairly easily by minimal shielding. Most of the irradiated debris would not get bombarded by a single neutron from that neutron bomb.
This isn't exactly true. Neutrons are not easy to shield. They tend to pass through heavier elements like lead due to their neutral charge and the fact that they don't lose much kinetic energy per collision with a heavy nucleus. They can be shielded much easier with something like water where a light nucleus (of a hydrogen atom in water) can transfer more of the neutrons kinetic energy, slowing it down and hence shielding it. But this is still not trivial shielding. Things like the iron, cement, and other plant materials around the Chernobyl site should offer minimal shielding. Only the water that is above the core should affect it (which is undefined).
You said: "We already know how to do that. Evaculate all the people, detonate a neutron bomb at high altitude, move back in and operate normally. The spray of neutrons from such a bomb would make all the radioactive atoms decay on the spot."
This is not true. While some radionuclides would absorb neutrons and transmute (maybe or maybe not to a radioactive nuclide) and some would undergo fission (probably leaving radioactive fission products), there would exist some radionuclides that would not be affected at all. A stream of neutrons doesn't affect how long it takes for any radionuclide to decay, only time does (after all this is a one time stream, not a flux--so you can't do more than one transmutation). This doesn't mean that it wouldn't reduce the radioactivity at the site. It might (I highly doubt it though). But also remember that these neutrons will activate some other nuclides that are not at the site. Overall effect is likely more radionuclides released to the environment.
You really aren't supporting your argument that fusion is cleaner than fission, but I will.
Fission is dirty: you get neutrons and gammas irradiating things while in operation, activated reactor plant components when shut down and spent fuel that is highly radioactive to dispose of when done. Of course its highly radioactive because the fission products are decaying (hence heating it up). Don't let it get too hot even when shut down or bad things can happen (aka Three Mile Island).
Fusion is dirty: you get neutrons and gammas irradiating things while in operation and activated reactor plant components. From what I hear the reactants and products are not radioactive.
Overall fusion is less radioactive, but still is radioactive.
According to this article "in 1957 the world's first nuclear reactor went online at Shippingport, Pa". This is wrong and a conceptual error: the first human-built nuclear reactor was the Chicago Pile. The first reactors were built for the future Manhattan project. While nuclear weapons exist or have existed without using plutonium, ones that do, get their plutonium from a nuclear reactor.
Wrong (unless you define a small city well less than 1000 homes)!
An average house uses about 2 KWe. If you have a large refrigerator it may use up to 1.5 KW when the compressor is running. A small city may use 30 MW for housing, but industry uses far more. One small plant for refining silicon, in rural Montana, uses 60 MW. With the other plants in this small city, it comes well in excess of 100 MW. 2.1 MW is barely anything in terms of power generation. 48 engines are hardly going to counter the GW shortages than California had causing brownouts.
Diesel is inefficient? Thats debatable depending on the context, but as far as power generation its not going to get nearly as much efficiency in a locomotive as it would in a power plant. But hydro really isn't an option. The rivers are pretty much dammed up as much as they can be reasonably (further damming will just cause ecological damage to be greater than the gain from power production) and hydro doesn't really produce a significant amount of power anyways. There are better solutions: gas-powered, but its cost varies often, coal, but it has high transportation costs, nuclear, unlikely in the future in california due to nimby syndrome, wind, but very low power production, or solar with very very low power production and concerns about caustic chemical processes to be used. Actually now that I look at it, there is no solution in california. Bring on the Diesels!
Would you like to have some of that 70-year vintage isotope buried under your backyard near the water you drink?
No? I thought so.
I am an engineer. Whenever I see another engineer telling me that something is "perfectly safe" I know I am being lied to.
I would accept nuclear waste if its safety could be guaranteed 100%. Since no such guarantees can be given, I consider the waste unacceptable. That's where I draw the line. It's like with the death penalty. As long as the justice system cannot guarantee 100% correct sentences, the death penalty should not be applied because innocent may get put to death.
And before you give me crap about cars not being 100% safe for not exploding or bridges not being 100% safe for not breaking down, the nuclear radiation can have a lethal effect on much larger groups of people for generations after generations.
Having the isotope buried under my yard would not worry me. As long as it is properly shielded and contained it would be no threat. And if it broke containment it would be fairly obvious by sampling the water. If contamination was detected I would stop drinking the water. I think you have a misconception to how well highly radioactive material can be leached into ground water. Fuel rods, for example, are specifically designed not to be easily leachable by water.
I wonder if you accept gas-electrical or coal-electrical plants. They are certainly not 100% safe and they certainly emit low level radioactivity due to impurities in the coal and oil/gasoline.
I think I'm not afraid of the word 'nuclear' because I've worked with it and its lost its mysteriousness to me. Its not magic. The radiation is very detectable. Its not like its anthrax where its almost invisible to detection. And low levels are relatively harmless if you know the precautions.
A nuclear rocket is not a risk of radiation exposure until the reactor is started. Due to a well known theory of nuclear physics, an isotope with a longer half-life will emit less energetic radiation overall. IIRC, U-235 has a 0.7 billion year half-life and U-238 has a multi-billion year half-life. The reactor will not become radioactive until it actually fissions uranium making radioactive fission products, activates uranium making transuranics, and activates other parts of the reactor assembly. In fact fuel rods for nuclear reactors are assembled by hand with only gloves as a protection because they are very, very mildly radioactive and no fission products or transuranics exist yet (in detactable quantities). The gloves are to prevent oil and dirt from getting on the fuel rods.
Nuclear rockets would have very low thrust compared to chemical rockets, but very long duration. They would not be able to be used (under normal circumstances) to escape the earths atmosphere and would have to be pushed into orbit with a chemical rocket. For this reason there is no real threat of the nuclear rocket spreading radiation. It will be too far away from the earth before it starts.
There is no threat of assembling the rocket in earth orbit. Education of the public is the key.
The problem isn't NASA's will to do it. It's funding and the laws of physics. The laws of physics make it extremely difficult to protect astronauts from radiation well enough to keep them healthy on such a trip, which would involve several years coasting in interplanetary space
The laws of physics do allow for shielding however. While this will add extra weight (therefore extra fuel), this is completely feasable. There is no physically known reason why people could not survive in space for extended periods with shielding in place.
the only radioactive product fusion created was a short-lived isotope of hydrogen last time I checked
Wrong. Anytime neutrons get released (such as in fusion) things will become activated. Two things in particular: water (though short lived -> not a problem in storage), and the metals in the reactor plant itself (which are not short lived therefore you have to bury them though they will generally be a problem for about 250 years for radiation exposure). Both of these are orders of maginitude less radioactive than a fuel rod and will not require as stringent storage requirements (as in time and temperature).
It seems to me that this might be our second next step in evolution. There was recently an article about how evolution might be halting in humanity since we allow too much intermigling and no isolated populations where mutants may form (and exploit the survival of the fittest). Even if evolution isn't halting, it is unlikely that natural evolution over millions of years will be fast enough to satiate humanity's goal of advancement. Obviously the closest thing that we are going to do is genetic alteration of newborn. Whether this is legal initially is inconsequential. In the long run we won't be able to hold it back, the world is too big. A genetically altered mutant is more likely to advance in society due to greater intelligence, strength, and reduced genetic diseases. And since they'll breed, society will eventually be altered.
But concievably there is a limit to how far we can advance humanity this way. From here we will have to turn to machines. This is really our next big step in evolution. Regardless of whether we like it or not, if we come and visit humanity 10,000 years from now, it is likely humans will be partly machine. Of course the initial gains might be first in military strength since it is the easiest to realize the value of technology. Imagine the power of an infantryman with just a few enhancements! And due to this fact, the countries that embrace cyborgs will have the greatest advantage (not only in military might, but potential other areas such as communications and memory) in the new age of cyborgs. Those who don't will be punished (due to the lack of the inherent advantages) and will either convert or be reduced in power.
As for being unholy integrating humans an machines: I don't think so. Since machines are really just products of our minds, its more like an extension of the mind: making the body able to fully harness the mind's power.
The purpose of your reactor is to deplete the uranium by fission. When this happens its fission products are typically radioactive and it produces transuranics (like plutonium) by neutron absorption than are also radioactive. This is no-shit radiation. Its not bullshit like radioactive water discharges or similar small things. This must be shielded and buried to protect people. Typically it is put in a water pool for about a year or two to reduce the short lived radioactivity (therby reducing most of the radioactivity). It will still be life-threatening without sheilding for your lifetime. 10,000 years is BS. Its not going to kill you in 1,000 years (unless by increasing the 'risk' of cancer).
The uranium itself is the same though. If you want to chemically seperate it and use it again in another reactor or give to your friends you can. No significant 'risk' whatsoever (this isn't true for freshly mined uranium since it has been in the earth for millions of years and has had time for radioactive byproducts to accumulate though the uranium itself is still safe).
It always ticks me off that the Greenpeace people oppose anything that creates greenhouse gasses while at the same time protesting nuclear power which is the only real way to get free of greenhouse gas emmisions. That is unless we decide to go back into the stone age as many of them suggest. If they weren't such jackasses about the nuclear power situation public opinion might be much different and greenhouse emmission might be significantly less.
The alternative power that they keep on trying to push is a myth. When you look at actual output, it is trivial to any real source. You aren't going to run a 60 MWe silicon refining plant in the northwest with solar panels and windmills. It isn't going to happen. Not unless the price is increased 10-fold. Sure you can power your house as they always point out. But your house is 2 KW load. Industry takes up far more power than housing.
The only way to reduce emissions of greenhouse gasses is to stop burning coal and gas. Thats it. And it has to be done now instead of 30 years from now when the alternative power myth becomes useful (probably more like 50).
My point was that Uranium is not radioactive as a fuel until fission begins in the reactor section of the rocket. Until fission begins Uranium is just as dangerous as any other heavy metal. You can spread it around all you want and it will not increase the risk of cancer (unless by some chemical property).
But once you start up the reactor section, the uranium doesn't make it radioactive, its the fission products, the transuranics (typically things like plutonium transmuted from uranium due to neutron absorption and subsequent beta decay if I remember correctly), and the activated metals in the housing of the reactor section. If you chemically seperated the uranium left over afterwards it would still not be radioactive.
And since there is no reason to start the nuclear section of the rocket on the earth (think multiple stages with chemical sections getting it into orbit), the reactor will not be started, hence no radioactivity until its safely in orbit. If it crashes and burns, its no bigger deal than heavy metals contaminating the environment.
Everythings got to have a power source. If you use an ion engine you currently have to use solar power, a battery, or a fuel cell to get it to run. In deep space the solar array would produce no power, the battery would discharge and the fuel cell would burn all its fuel. Of course you could use a nuclear source (such as the plutonium sources that Cassini uses), but that is very low power and wouldn't get you far. If you used a nuclear reactor in the conventional sense to make electricity you could power it, but you'd have to find some method to get rid of the heat needed to condense the steam after it operates the turbine. Since space doesn't allow conductive or convective heat transfer, the only way to transfer heat is through radiative heat transfer. While this technology does exist (its on the ISS), its not particularly powerful and you might end up covering the entire ship with your radiator. I think that at the current time it would be more efficient to use direct thrust than to try to use some sort of ion engine due to the disadvantages of trying to find a method of heat transfer (the added weight of the radiator would probably offset the added efficiency of the ion engine) and since no heat transfer process is ever 100% efficient. You are getting most of your energy in the direct type but you would get less energy from the reactor powers turbine type due to the inefficiencies in any turbine, and the requirement to condense steam; therefore, a good portion of your energy is radiated away.
In space you could simply increase the distance from the reactor to the life support areas by use of a metal truss like structure. The radiation from the reactor will be minimized in the same way that light from a flashlight on your face is minimized the further you walk away from it. In this way only minimal shielding would be required. The truss-like structure would hold up to the forces even if it was a weak constuction since the thrust from the rocket will be small.
Thats only assuming that you use the nuclear rocket part to take off. This is unlikely. A more likely case is it will be lifted by manual methods, piece by piece, assembled in orbit and then operated a safe distance from the earth. Even if these parts explode in takeoff it will not have any real radioactivity risk assuming that it uses normal fuel (ie uranium, not plutonium) since the half-life of U-235 is almost a billion years and U-238 is billions of years (longer half-life means less radioactive and billions of years means very, very small radioactivity). In newly built nuclear power plants you can walk around near the reactor without any radiation risk due to this fact. Of course once you start up, it has radioactive daughters and transuranics that make it radioactive.
This was one of Kennedy's four goals during his Special Message to Congress on Urgent National Needs (a.k.a. go to the moon speech). He said that it gives "promise of some day providing a means for even more exciting and ambitious exploration of space, perhaps beyond the moon, perhaps to the very end of the solar system itself".
The nuclear rocket is probably the best choice in large distance exploration that we have right now. Solar power becomes useless pretty much past the Earth and no other power source can pack the mass to power ratio that nuclear power can. If we want to go big, we have no choice but to use a nuclear rocket or take a long, long time. The weight issue in rockets is a big deal, so alternate propellants are out since they will take up to much weight for the same power.
For close distance exploration (i.e. the moon) I don't really see a nuclear rocket taking any part. While obviously it could achieve its goal, its a little overkill for the purpose (and considering the fact that if it were a direct exhuast type it would have a plume of activated radioactive materials, assuming it uses water as a propellant, it probably wouldn't be that popular).
I hope this happens, and I've been hoping for a long time. Its our only real chance to get off the earth permanently at the present time.
We should complete President Kennedy's space legacy first. It was 4 parts (Special Message to the Congress on Urgent National Needs, Part 9):
1. Go to the moon and return [X]
2. Develop a nuclear rocket
3. Advance communication satellites [X]
4. Satellites for weather bureau [X]
We have yet to implement a nuclear rocket. In his own words:
This gives promise of some day providing a means for even more exciting and ambitious exploration of space, perhaps beyond the moon, perhaps to the very end of the solar system itself.
One of the reasons NASA has lost popularity is that they don't continue to do truly ambitous projects. If you read between the lines, obviously Kennedy was thinking of Mars and beyond. It probably would have suprised him that in 2002 we are still only thinking of going there using conventional means.
Does anyone have any ideas about how it will be designed?
As far as I know, when matter and anti-matter anhillate, it produces two gammas going in opposite directions. So this engine will have to have some type of water tank or other shielding in order for those gammas to ionize atoms and create heat, and then some type of engine to transfer that heat to the fuel to be exhausted. It seems to me that it isn't going to be as easy as tossing some antimatter into the engine and holding on for the ride.
It depends on how efficiently you can produce it. Since when anti-matter and matter anhillate, both of their masses convert to energy in the form of gamma radiation; therefore, if you can achieve an efficiency of producing it of greater than 50%, you are producing more energy in the anhillation than it took to create the antimatter.
There were some good points made in the article. But should we be bloating programs like tar with window manager cooperability? Hell no! I don't even think that tar should have the -z option, as it can just be piped to gzip anyways. I see no problem with an alias to do it, but tar should be considered a completed product, it does what *it is supposed to do*. This is a major accomplishment with a program. If you want it to do something else build a script that runs on the UI.
The power of UNIX is that it has all of these 'infrastructure' type programs upon which so much more can be built. There is no reason to build an extra program within a program. This just adds complexity which the UNIX design is against. If you look into the history of UNIX you will see that it has always favored stability over speed, and a small program that does what it is supposed to do rather than one large bloated 'featureful' program. Why should we get rid of the UNIX design philosophy when making a UI? It doesn't seem logical. As UNIX is an bottom up system so should be the UI (and it has been).
People who are selling UNIX by saying that our UI is just a good as XX's are morons. We are really forgetting our strengths. A person could build an excellent windowed compression/decompression program that can drag and drop to other programs, without having to know how to write a compression program, how to write a window environment, or how to figure out drag and drop. To them, it is all pipes. I'm not saying that XX's products don't have these characteristics, but to UNIX it is so much easier to do. Lets not ignore this power.
Taking the gecko engine (or whatever they call it now, 'nslayout or something') and making your browsers render with it rather than writing a new engine for yours, using X to render rather that using the framebuffer in different ways (it seems really stupid to me to make a window manager in UNIX that can't be networked), or making a script to run tar and gzip in a friendly graphic way is my opinion on how UNIX GUI's can be a sucess. Adding a completion bar to tar and using a --nodisplay flag is not.
Slashdot Mirror
I highly doubt any radiation worker would use this in his job just due to the fact that it doesn't have any test source listed. What use is a radiation monitoring device if you can't even tell if its working, particularly a device that measures cumulative dose? It might have an application for a secondary short term radiation monitoring in high radiation areas except that anyone who is going to work in a high radiation area will already have more specialized equipment.
And why would you want a radiation monitoring device on a watch on your wrist? If it were used by any radiation worker, he would probably tie it to his belt instead (to give a more accurate estimate of dose recieved).
This device really doesn't have much practical use. Really, its just a gadget for the geek who has to have everything.
You said: " Too bad thats not how radiation works. If you ever were near a large source of radiation your own clothes would absorb radiation and keep it coming to your body. One of the most important parts of a nuclear fallout shelter is the entrance room where you take off ALL clothing and shower. Your clothes and aything else you wear if you were near a nuclear explosion would continue the damage if not taken off immediatly.
Your description of radiation and contamination is a little hairy, let me clean it up:
Radiation is the propogation of energy over a distance via waves. Some types of radiation are (using the example of a nuclear bomb): neutrons (very hazardous--you need to be in a deep fallout shelter or surrounded by a significant amount of water to protect you), alphas (very hazardous--are shielded by your skin, but if they are emitted inside your lungs you are in trouble), betas (minor hazard--shielded by your clothing, not a real problem unless ingested or inhaled), EM radiation in general (the frequency; therefore, the energy of the photon is of prime concern: a radio wave will probably not hurt you but a high energy gamma will--shielded by being in a fallout shelter as long as its deep enough), and non-interacting (like neutrinos--you don't have to worry about these, they can't hurt you). This watch will detect gammas and maybe some other high energy EM radiation (neutrons require larger detection devices, and alphas and betas would be shielded by the metal of the watch). I doubt it can detect as low energy as x-rays, but it might.
Contamination is getting radioactive material on you. This radioactive material will undergo decays producing radiation. You take your clothes off and shower to remove the contamination so you don't get irradiated.
Radiation (with the exception of neutrons and alphas) does not beget long term radiation (longer than for example a gamma to be absorbed by an atom and re-emit a lower energy gamma). Its just absorbed and thats the end of it. Neutrons and alphas will typically not beget long term radiation because of the specialized conditions required (causing fission of an atom and releasing radioactive products or being absorbed and transmuting an atom into a radioactive isotope). The contamination on your skin and clothes will be due to fallout (i.e. radioactive material) from the nuclear weapon, not the radiation.
I think perhaps the button with the problem isn't the back button, but the forward button. Consider:
1) Go to the Slashdot main page at http://slashdot.org
2) Go to the discussion about the back button.
3) Click your back button and go back to the main page
Note: the forward button is active
4) Click on the link to the discussion about Microsoft being its own worst enemy.
5) Now try to use your back button...
The forward button is active again.
The problem isn't with the back button. Its that the forward button doesn't give you options. This can be implemented by considering each website a node in a tree structure. As you visit a hyperlink you go up the tree. When you click back, you go down the tree one step. Forward will bring you up the tree again, but will pick a default unless you specify which branch to follow (to be implemented).
The only problem is that the forward button is typically implemented so that it gives you a list of items to pick so that if you hit back 3 times, you would see the 3 web pages you just visited in reverse order in the list. I think it could be adequately implemented with expanding menus (but this is a UI pain-in-the-ass!).
You said "First of all, neutrons are stopped fairly easily by minimal shielding. Most of the irradiated debris would not get bombarded by a single neutron from that neutron bomb.
This isn't exactly true. Neutrons are not easy to shield. They tend to pass through heavier elements like lead due to their neutral charge and the fact that they don't lose much kinetic energy per collision with a heavy nucleus. They can be shielded much easier with something like water where a light nucleus (of a hydrogen atom in water) can transfer more of the neutrons kinetic energy, slowing it down and hence shielding it. But this is still not trivial shielding. Things like the iron, cement, and other plant materials around the Chernobyl site should offer minimal shielding. Only the water that is above the core should affect it (which is undefined).
You said: "We already know how to do that. Evaculate all the people, detonate a neutron bomb at high altitude, move back in and operate normally. The spray of neutrons from such a bomb would make all the radioactive atoms decay on the spot."
This is not true. While some radionuclides would absorb neutrons and transmute (maybe or maybe not to a radioactive nuclide) and some would undergo fission (probably leaving radioactive fission products), there would exist some radionuclides that would not be affected at all. A stream of neutrons doesn't affect how long it takes for any radionuclide to decay, only time does (after all this is a one time stream, not a flux--so you can't do more than one transmutation). This doesn't mean that it wouldn't reduce the radioactivity at the site. It might (I highly doubt it though). But also remember that these neutrons will activate some other nuclides that are not at the site. Overall effect is likely more radionuclides released to the environment.
You really aren't supporting your argument that fusion is cleaner than fission, but I will.
Fission is dirty: you get neutrons and gammas irradiating things while in operation, activated reactor plant components when shut down and spent fuel that is highly radioactive to dispose of when done. Of course its highly radioactive because the fission products are decaying (hence heating it up). Don't let it get too hot even when shut down or bad things can happen (aka Three Mile Island).
Fusion is dirty: you get neutrons and gammas irradiating things while in operation and activated reactor plant components. From what I hear the reactants and products are not radioactive.
Overall fusion is less radioactive, but still is radioactive.
According to this article "in 1957 the world's first nuclear reactor went online at Shippingport, Pa". This is wrong and a conceptual error: the first human-built nuclear reactor was the Chicago Pile. The first reactors were built for the future Manhattan project. While nuclear weapons exist or have existed without using plutonium, ones that do, get their plutonium from a nuclear reactor.
Wrong (unless you define a small city well less than 1000 homes)!
An average house uses about 2 KWe. If you have a large refrigerator it may use up to 1.5 KW when the compressor is running. A small city may use 30 MW for housing, but industry uses far more. One small plant for refining silicon, in rural Montana, uses 60 MW. With the other plants in this small city, it comes well in excess of 100 MW. 2.1 MW is barely anything in terms of power generation. 48 engines are hardly going to counter the GW shortages than California had causing brownouts.
Diesel is inefficient? Thats debatable depending on the context, but as far as power generation its not going to get nearly as much efficiency in a locomotive as it would in a power plant. But hydro really isn't an option. The rivers are pretty much dammed up as much as they can be reasonably (further damming will just cause ecological damage to be greater than the gain from power production) and hydro doesn't really produce a significant amount of power anyways. There are better solutions: gas-powered, but its cost varies often, coal, but it has high transportation costs, nuclear, unlikely in the future in california due to nimby syndrome, wind, but very low power production, or solar with very very low power production and concerns about caustic chemical processes to be used. Actually now that I look at it, there is no solution in california. Bring on the Diesels!
I think you have a misconception to how well highly radioactive material can be leached into ground water. Fuel rods, for example, are specifically designed not to be easily leachable by water.
I wonder if you accept gas-electrical or coal-electrical plants. They are certainly not 100% safe and they certainly emit low level radioactivity due to impurities in the coal and oil/gasoline.
I think I'm not afraid of the word 'nuclear' because I've worked with it and its lost its mysteriousness to me. Its not magic. The radiation is very detectable. Its not like its anthrax where its almost invisible to detection. And low levels are relatively harmless if you know the precautions.
A nuclear rocket is not a risk of radiation exposure until the reactor is started. Due to a well known theory of nuclear physics, an isotope with a longer half-life will emit less energetic radiation overall. IIRC, U-235 has a 0.7 billion year half-life and U-238 has a multi-billion year half-life. The reactor will not become radioactive until it actually fissions uranium making radioactive fission products, activates uranium making transuranics, and activates other parts of the reactor assembly. In fact fuel rods for nuclear reactors are assembled by hand with only gloves as a protection because they are very, very mildly radioactive and no fission products or transuranics exist yet (in detactable quantities). The gloves are to prevent oil and dirt from getting on the fuel rods.
Nuclear rockets would have very low thrust compared to chemical rockets, but very long duration. They would not be able to be used (under normal circumstances) to escape the earths atmosphere and would have to be pushed into orbit with a chemical rocket. For this reason there is no real threat of the nuclear rocket spreading radiation. It will be too far away from the earth before it starts.
There is no threat of assembling the rocket in earth orbit. Education of the public is the key.
the only radioactive product fusion created was a short-lived isotope of hydrogen last time I checked
Wrong. Anytime neutrons get released (such as in fusion) things will become activated. Two things in particular: water (though short lived -> not a problem in storage), and the metals in the reactor plant itself (which are not short lived therefore you have to bury them though they will generally be a problem for about 250 years for radiation exposure). Both of these are orders of maginitude less radioactive than a fuel rod and will not require as stringent storage requirements (as in time and temperature).
Yeah vi is for losers. Any true geek uses ed.
It seems to me that this might be our second next step in evolution. There was recently an article about how evolution might be halting in humanity since we allow too much intermigling and no isolated populations where mutants may form (and exploit the survival of the fittest). Even if evolution isn't halting, it is unlikely that natural evolution over millions of years will be fast enough to satiate humanity's goal of advancement. Obviously the closest thing that we are going to do is genetic alteration of newborn. Whether this is legal initially is inconsequential. In the long run we won't be able to hold it back, the world is too big. A genetically altered mutant is more likely to advance in society due to greater intelligence, strength, and reduced genetic diseases. And since they'll breed, society will eventually be altered.
But concievably there is a limit to how far we can advance humanity this way. From here we will have to turn to machines. This is really our next big step in evolution. Regardless of whether we like it or not, if we come and visit humanity 10,000 years from now, it is likely humans will be partly machine. Of course the initial gains might be first in military strength since it is the easiest to realize the value of technology. Imagine the power of an infantryman with just a few enhancements! And due to this fact, the countries that embrace cyborgs will have the greatest advantage (not only in military might, but potential other areas such as communications and memory) in the new age of cyborgs. Those who don't will be punished (due to the lack of the inherent advantages) and will either convert or be reduced in power.
As for being unholy integrating humans an machines: I don't think so. Since machines are really just products of our minds, its more like an extension of the mind: making the body able to fully harness the mind's power.
The purpose of your reactor is to deplete the uranium by fission. When this happens its fission products are typically radioactive and it produces transuranics (like plutonium) by neutron absorption than are also radioactive. This is no-shit radiation. Its not bullshit like radioactive water discharges or similar small things. This must be shielded and buried to protect people. Typically it is put in a water pool for about a year or two to reduce the short lived radioactivity (therby reducing most of the radioactivity). It will still be life-threatening without sheilding for your lifetime. 10,000 years is BS. Its not going to kill you in 1,000 years (unless by increasing the 'risk' of cancer).
The uranium itself is the same though. If you want to chemically seperate it and use it again in another reactor or give to your friends you can. No significant 'risk' whatsoever (this isn't true for freshly mined uranium since it has been in the earth for millions of years and has had time for radioactive byproducts to accumulate though the uranium itself is still safe).
It always ticks me off that the Greenpeace people oppose anything that creates greenhouse gasses while at the same time protesting nuclear power which is the only real way to get free of greenhouse gas emmisions. That is unless we decide to go back into the stone age as many of them suggest. If they weren't such jackasses about the nuclear power situation public opinion might be much different and greenhouse emmission might be significantly less.
The alternative power that they keep on trying to push is a myth. When you look at actual output, it is trivial to any real source. You aren't going to run a 60 MWe silicon refining plant in the northwest with solar panels and windmills. It isn't going to happen. Not unless the price is increased 10-fold. Sure you can power your house as they always point out. But your house is 2 KW load. Industry takes up far more power than housing.
The only way to reduce emissions of greenhouse gasses is to stop burning coal and gas. Thats it. And it has to be done now instead of 30 years from now when the alternative power myth becomes useful (probably more like 50).
My point was that Uranium is not radioactive as a fuel until fission begins in the reactor section of the rocket. Until fission begins Uranium is just as dangerous as any other heavy metal. You can spread it around all you want and it will not increase the risk of cancer (unless by some chemical property).
But once you start up the reactor section, the uranium doesn't make it radioactive, its the fission products, the transuranics (typically things like plutonium transmuted from uranium due to neutron absorption and subsequent beta decay if I remember correctly), and the activated metals in the housing of the reactor section. If you chemically seperated the uranium left over afterwards it would still not be radioactive.
And since there is no reason to start the nuclear section of the rocket on the earth (think multiple stages with chemical sections getting it into orbit), the reactor will not be started, hence no radioactivity until its safely in orbit. If it crashes and burns, its no bigger deal than heavy metals contaminating the environment.
Everythings got to have a power source. If you use an ion engine you currently have to use solar power, a battery, or a fuel cell to get it to run. In deep space the solar array would produce no power, the battery would discharge and the fuel cell would burn all its fuel. Of course you could use a nuclear source (such as the plutonium sources that Cassini uses), but that is very low power and wouldn't get you far. If you used a nuclear reactor in the conventional sense to make electricity you could power it, but you'd have to find some method to get rid of the heat needed to condense the steam after it operates the turbine. Since space doesn't allow conductive or convective heat transfer, the only way to transfer heat is through radiative heat transfer. While this technology does exist (its on the ISS), its not particularly powerful and you might end up covering the entire ship with your radiator. I think that at the current time it would be more efficient to use direct thrust than to try to use some sort of ion engine due to the disadvantages of trying to find a method of heat transfer (the added weight of the radiator would probably offset the added efficiency of the ion engine) and since no heat transfer process is ever 100% efficient. You are getting most of your energy in the direct type but you would get less energy from the reactor powers turbine type due to the inefficiencies in any turbine, and the requirement to condense steam; therefore, a good portion of your energy is radiated away.
In space you could simply increase the distance from the reactor to the life support areas by use of a metal truss like structure. The radiation from the reactor will be minimized in the same way that light from a flashlight on your face is minimized the further you walk away from it. In this way only minimal shielding would be required. The truss-like structure would hold up to the forces even if it was a weak constuction since the thrust from the rocket will be small.
Thats only assuming that you use the nuclear rocket part to take off. This is unlikely. A more likely case is it will be lifted by manual methods, piece by piece, assembled in orbit and then operated a safe distance from the earth. Even if these parts explode in takeoff it will not have any real radioactivity risk assuming that it uses normal fuel (ie uranium, not plutonium) since the half-life of U-235 is almost a billion years and U-238 is billions of years (longer half-life means less radioactive and billions of years means very, very small radioactivity). In newly built nuclear power plants you can walk around near the reactor without any radiation risk due to this fact. Of course once you start up, it has radioactive daughters and transuranics that make it radioactive.
This was one of Kennedy's four goals during his Special Message to Congress on Urgent National Needs (a.k.a. go to the moon speech). He said that it gives "promise of some day providing a means for even more exciting and ambitious exploration of space, perhaps beyond the moon, perhaps to the very end of the solar system itself".
The nuclear rocket is probably the best choice in large distance exploration that we have right now. Solar power becomes useless pretty much past the Earth and no other power source can pack the mass to power ratio that nuclear power can. If we want to go big, we have no choice but to use a nuclear rocket or take a long, long time. The weight issue in rockets is a big deal, so alternate propellants are out since they will take up to much weight for the same power.
For close distance exploration (i.e. the moon) I don't really see a nuclear rocket taking any part. While obviously it could achieve its goal, its a little overkill for the purpose (and considering the fact that if it were a direct exhuast type it would have a plume of activated radioactive materials, assuming it uses water as a propellant, it probably wouldn't be that popular).
I hope this happens, and I've been hoping for a long time. Its our only real chance to get off the earth permanently at the present time.
1. Go to the moon and return [X]
2. Develop a nuclear rocket
3. Advance communication satellites [X]
4. Satellites for weather bureau [X]
We have yet to implement a nuclear rocket. In his own words:
One of the reasons NASA has lost popularity is that they don't continue to do truly ambitous projects. If you read between the lines, obviously Kennedy was thinking of Mars and beyond. It probably would have suprised him that in 2002 we are still only thinking of going there using conventional means.
Does anyone have any ideas about how it will be designed?
As far as I know, when matter and anti-matter anhillate, it produces two gammas going in opposite directions. So this engine will have to have some type of water tank or other shielding in order for those gammas to ionize atoms and create heat, and then some type of engine to transfer that heat to the fuel to be exhausted. It seems to me that it isn't going to be as easy as tossing some antimatter into the engine and holding on for the ride.
It depends on how efficiently you can produce it. Since when anti-matter and matter anhillate, both of their masses convert to energy in the form of gamma radiation; therefore, if you can achieve an efficiency of producing it of greater than 50%, you are producing more energy in the anhillation than it took to create the antimatter.
There were some good points made in the article. But should we be bloating programs like tar with window manager cooperability? Hell no! I don't even think that tar should have the -z option, as it can just be piped to gzip anyways. I see no problem with an alias to do it, but tar should be considered a completed product, it does what *it is supposed to do*. This is a major accomplishment with a program. If you want it to do something else build a script that runs on the UI.
The power of UNIX is that it has all of these 'infrastructure' type programs upon which so much more can be built. There is no reason to build an extra program within a program. This just adds complexity which the UNIX design is against. If you look into the history of UNIX you will see that it has always favored stability over speed, and a small program that does what it is supposed to do rather than one large bloated 'featureful' program. Why should we get rid of the UNIX design philosophy when making a UI? It doesn't seem logical. As UNIX is an bottom up system so should be the UI (and it has been).
People who are selling UNIX by saying that our UI is just a good as XX's are morons. We are really forgetting our strengths. A person could build an excellent windowed compression/decompression program that can drag and drop to other programs, without having to know how to write a compression program, how to write a window environment, or how to figure out drag and drop. To them, it is all pipes. I'm not saying that XX's products don't have these characteristics, but to UNIX it is so much easier to do. Lets not ignore this power.
Taking the gecko engine (or whatever they call it now, 'nslayout or something') and making your browsers render with it rather than writing a new engine for yours, using X to render rather that using the framebuffer in different ways (it seems really stupid to me to make a window manager in UNIX that can't be networked), or making a script to run tar and gzip in a friendly graphic way is my opinion on how UNIX GUI's can be a sucess. Adding a completion bar to tar and using a --nodisplay flag is not.