Probably a stupid car question...

[kandrathe]

Once again, you continue to neglect that you must have a certain amount of material between you and the radiation source, this is something you cannot work around.

Well, no. I'm not suggesting we go without shielding. I'm suggesting we find ways to divide atoms in a manner where the reaction is more predictable and controlled, and based on a "safer" reaction we then shield according to what is needed. If it requires 10 feet of lead to shield it, then the reaction is wrong for our purposes. There are some promising idea's... Hybrid fission/fusion seems like a nice compromise for large reactors, but like hybrid cars, you end up with two systems, more complexity, cost, and need more space. But, if you could control a release of neutrons into natural thorium 232, or uranium 238, then you might direct the direction and number of stray ionizing particles into dense capture materials (and actually "breed" more fuel).

What are your thoughts on traveling wave reactors? It's sort of like the Toshiba 4S, but doesn't need a neutron reflector.

Or how about something like the Hyperion Mini Nuclear Reactor?

[Lissa]

Once again, you continue to neglect that you must have a certain amount of material between you and the radiation source, this is something you cannot work around.

Well, no. I'm not suggesting we go without shielding. I'm suggesting we find ways to divide atoms in a manner where the reaction is more predictable and controlled, and based on a "safer" reaction we then shield according to what is needed. If it requires 10 feet of lead to shield it, then the reaction is wrong for our purposes. There are some promising idea's... Hybrid fission/fusion seems like a nice compromise for large reactors, but like hybrid cars, you end up with two systems, more complexity, cost, and need more space. But, if you could control a release of neutrons into natural thorium 232, or uranium 238, then you might direct the direction and number of stray ionizing particles into dense capture materials (and actually "breed" more fuel).

What are your thoughts on traveling wave reactors? It's sort of like the Toshiba 4S, but doesn't need a neutron reflector.

Or how about something like the Hyperion Mini Nuclear Reactor?

Ok, last time I'm going to post on this cause you can't seem to understand that necessity of shielding. You have to have something there to shield a reactor like this, it doesn't matter how compact you make or how low power it's going to be, there has to be shielding. Shielding is bulky and it weighs a lot. While a reactor like the Hyperion could work for powering a neighborhood or the like, it's still bulky.

Also, you keep mentioning technologies, like the Wave reactor that have been around for decades, yet haven't been used. There's a reason why converters (the Wave reactor) and breeders are not used, and it's political, ie Non-Proliferation Treaty. Because of politics, the only reactors that you will see for civilian use are burner style reactors we have now.

Lastly, we can make reactors that will run for 30+ years without refueling, the problem, again has to deal with Non-Proliferation. Naval reactors are designed to run for 30 years without refueling as they use extremely enriched uranium for their fuel (95%+ enrichment, almost pure Uranium 235). The ship is decommisioned when the reactor's fuel finally starts being so poisoned by the fission fragments that it is difficult to produce power. The Enterprise's refueling was actually a rarity amount ships equipped with Naval reactors, the rest typically get turned into razor blades.

[kandrathe]

Ok, last time I'm going to post on this cause you can't seem to understand that necessity of shielding. You have to have something there to shield a reactor like this, it doesn't matter how compact you make or how low power it's going to be, there has to be shielding. Shielding is bulky and it weighs a lot. While a reactor like the Hyperion could work for powering a neighborhood or the like, it's still bulky.

I know you think I'm being dense (like depleted Uranium) or are in some way contridicting you on this, however, it's not true. In all my posts, I've called for the shielding needed to contain the risk. I'm not convinced the current process of having a "hot" steel core containment vessel inside a vast concrete and steel containment dome (thick enough to prevent a fully loaded aircraft from penetrating) is getting toward the miniaturization I'm thinking about.

Yes, yes, yes, I'm also considering having appropriate shielding, so this is not an issue. I'm asking and wondering if we've advanced the field of materials sciences ( e.g. dense composites and compounds, absorption, or deflection), or it we still tend to think about shielding as calculating it as the number of cm of "dense" and "cheap" elemental materials needed.

Also, you keep mentioning technologies, like the Wave reactor that have been around for decades, yet haven't been used. There's a reason why converters (the Wave reactor) and breeders are not used, and it's political, ie Non-Proliferation Treaty. Because of politics, the only reactors that you will see for civilian use are burner style reactors we have now.

Which is again... from my original discussion. I'm confident we would do more, and would make more progress if it weren't a political hot potato. It seems that using innovations, and better engineering would result in better designs, and it has outside of the USA. We are "brainwashed" into equating nuclear power with imminent death.

Lastly, we can make reactors that will run for 30+ years without refueling, the problem, again has to deal with Non-Proliferation. Naval reactors are designed to run for 30 years without refueling as they use extremely enriched uranium for their fuel (95%+ enrichment, almost pure Uranium 235). The ship is decommissioned when the reactor's fuel finally starts being so poisoned by the fission fragments that it is difficult to produce power. The Enterprise's refueling was actually a rarity amount ships equipped with Naval reactors, the rest typically get turned into razor blades.

Yes, again, which is why I'm asking why we continue to do it the "old fashioned way", where you need to spend time, energy, risk, and money enriching the fuel, and then building a reaction that results in the need for decommissioning. We know that abundant natural uranium is fissionable (as plutonium 239/94 after two beta decays) with the appropriate neutron source . Why do we need to continue to rely on the 1940's era critical mass approach? Because, people (the government) are afraid of allowing general access to something like weapons grade plutonium that would be generated in a breeder reactor of this sort. Of course, any average Joe who cracked open his "sealed" home nuclear core would probably be dead in minutes or hours. Just as surely as if they filled their basement with gasoline and lit it up.

You seem to be saying, "This is the way it is. Accept it." And, I'm saying, "I don't think it has to remain like this forever." We use and live with very dangerous substances daily, like LNG, ammonia, gasoline, or hydrazine, which nobody gives a seconds extra thought about. Heck, over 5000 people die every year by accidental electrocution, not even broaching the insanity of allowing people to drive their own vehicles. I'm not suggesting we increase our risks, only that we use our brains to better engineer the use of the abundance we already have. For the properly informed and motivated fiends, the means of mass destruction are all around us.

Ultimately I fear for some people, they would feel it is better to bankrupt society and allow millions of people to freeze to death, rather than risk trusting people with a little science. The same political mentality that advocates eliminating the instruments used to cause deaths, rather than contain the people who cause (or who are predisposed to cause) deaths. The same mentality that forces all air travelers to submit to intrusive scanning and groping, rather than to devise a way to separate out the bad apples and prevent them alone from unhindered access to airplanes.

[--Pete]

Hi,

I'm asking and wondering if we've advanced the field of materials sciences ( e.g. dense composites and compounds, absorption, or deflection), or it we still tend to think about shielding as calculating it as the number of cm of "dense" and "cheap" elemental materials needed.

It is not a question of material science (which might be subject to improvement). It is a question of elements and interactions. Radiation loses energy either by ionizing the materials it goes through or scattering off of the material (principally the nuclei) it goes through. The effectiveness of either process depends on the type and energy of the radiation and the element it is interacting with.

Now, for any specific type and energy of radiation, there is an element that would make the best shield. But even that element has to be thick enough that either the ionization per unit length slows or stops the radiation, or the areal density of the projected scatterers will give a sufficiently high probability of stopping or reflecting the radiation.

Any shield made of a composite will not be as good as one made only of the best material in that composite. However, some materials cannot be used in pure form, and others are much easier to handle in a composite.

The situation is not a question of better engineering, it is one of basic physics.

--Pete

[Rhydderch Hael]

On a (slightly) unrelated note, just how dense does the shielding have to be to impart Bremsstrahlung from Nitrogen-16 decay? I mean, just how energetic is that beta particle event?

From Wolfram|Alpha... Nitrogen 16. During its decay back to O16, it gives off 5-7 MeV high energy gamma radiation. From Wiki, "Condensate from the condenser is typically retained for 10 minutes to allow for decay of the 16N. This eliminates the need to shield and restrict access to any of the feed water piping or pumps."

Errr...there's no gamma with the decay, just a beta. Given, you have an electron moving at relativistic speeds, but it's just an electron which will be stopped by your skin if the decay happens external to your body. If the N16 decays in your lungs however, there is definite damage potential.

I wasn't wondering about the beta event in of itself. I was wondering about the beta particle causing Bremsstrahlung (braking radiation) due to the use of very thin, dense shielding. Basically, the faster you stop a beta particle in its tracks, the higher the frequency of EM radiation it generates in the aftermath. Stop it fast enough, you boost the frequency into the range of gamma rays.

[Taem]

You just gave the most perfect example for why *not* to ever allow this:

Because, people (the government) are afraid of allowing general access to something like weapons grade plutonium that would be generated in a breeder reactor of this sort. Of course, any average Joe who cracked open his "sealed" home nuclear core would probably be dead in minutes or hours. Just as surely as if they filled their basement with gasoline and lit it up.

You seem to be saying, "This is the way it is. Accept it." And, I'm saying, "I don't think it has to remain like this forever." We use and live with very dangerous substances daily, like LNG, ammonia, gasoline, or hydrazine, which nobody gives a seconds extra thought about. Heck, over 5000 people die every year by accidental electrocution...

THIS, after the Russian bombing a few days ago, makes for great theories on possible acts of terrorism that could be utilized with such technology, from dirty bombs to mini-nukes! Something like this will *NEVER* see the light of day in this day and age!

From a practical standpoint, you would need specialty mechanics, perhaps certified by the government, to work on your car as these "nuclear" run mobiles started slowly replacing standard carbon-emitting automobiles, but I'm sure the trade-off would be slow as the initial prices for such cars would be astronomically higher priced than a standard car as the technology lagged behind the science. Also, there would have to be a radiation detection gauge on the car itself in case there was a crack in the hull, so to speak. Crash-testing these cars could be dangerous and would require a complete regulations over-hall, as would the way police and fire departments deal with car accidents. Basically, if this did become a reality, it would change everything as we know it!

[Lissa]

On a (slightly) unrelated note, just how dense does the shielding have to be to impart Bremsstrahlung from Nitrogen-16 decay? I mean, just how energetic is that beta particle event?

From Wolfram|Alpha... Nitrogen 16. During its decay back to O16, it gives off 5-7 MeV high energy gamma radiation. From Wiki, "Condensate from the condenser is typically retained for 10 minutes to allow for decay of the 16N. This eliminates the need to shield and restrict access to any of the feed water piping or pumps."

Errr...there's no gamma with the decay, just a beta. Given, you have an electron moving at relativistic speeds, but it's just an electron which will be stopped by your skin if the decay happens external to your body. If the N16 decays in your lungs however, there is definite damage potential.

I wasn't wondering about the beta event in of itself. I was wondering about the beta particle causing Bremsstrahlung (braking radiation) due to the use of very thin, dense shielding. Basically, the faster you stop a beta particle in its tracks, the higher the frequency of EM radiation it generates in the aftermath. Stop it fast enough, you boost the frequency into the range of gamma rays.

Not completely, the energy of the Bremsstrahlung is dependent on the initial energy of the incident Beta, the higher the energy of the incident Beta, the lower the energy of the Bremsstrahlung (which seems counterintuitive, but that's what's been observed for a hundred years now), so in the case of N16, the incident Beta is 5 MeV or so (which is pretty high for a Beta since the rest mass energy of an electron/positron is 0.511 MeV) so the Bremsstrahlung should be relatively low.

[kandrathe]

You just gave the most perfect example for why *not* to ever allow this:

It's another freedom thing.

If you are off the Feds sensors, insanely socio-pathic and have no conscience, and know enough about chemistry and physics, and are rational and patient enough, you can kill millions. But, you'll only ever get one shot at it.

THIS, after the Russian bombing a few days ago, makes for great theories on possible acts of terrorism that could be utilized with such technology, from dirty bombs to mini-nukes! Something like this will *NEVER* see the light of day in this day and age!

The problem here is that the government controls airports, and they haven't been creative enough to redesign them away from being the perfect target for every extremist. Why are they popular?

• They are a busy choke point in the transportation system
• People are always carrying large bundles, so it's easy to carry in your bomb.
• It's easy to leave your package somewhere, and get away to any number of destinations before the bomb even detonates
• Even if discovered, the publicity and chaos caused is a win

My answer is to decentralize down to airline, or even gate. Eventually, I would do away with the mega-airport idea, and have each airline have it's own building. Moving from building to building would require you to be screened through security again. Once you are at the right airlines area, then you'd be checked through screening, and sent to your gate for boarding. My idea on screening is that you "register" for travel screening at the time you buy your ticket, and a background check is done on you and kept on file tied to biometric data (iris, palm print, finger print, whatever). When you arrive at the airport, you merely need to show your travel documents, and prove bio-metrically that you are indeed you.

From a practical standpoint, you would need specialty mechanics, perhaps certified by the government, to work on your car as these "nuclear" run mobiles started slowly replacing standard carbon-emitting automobiles, but I'm sure the trade-off would be slow as the initial prices for such cars would be astronomically higher priced than a standard car as the technology lagged behind the science.

I spend about $100 per week on gasoline, or say about $50,000 over ten years for fuel. Figuring that 200 HP = 0.00015 gigawatts,

Using: http://www.wise-uranium.org/nfcc.html ...and, assuming I'm reading the results correctly.

It would take about 100 pounds of uranium ore to power the vehicle for ten years, and using fully processed fuel and accounting for disposal costs would cost about $20 for total fuel costs over the ten years.

Also, there would have to be a radiation detection gauge on the car itself in case there was a crack in the hull, so to speak. Crash-testing these cars could be dangerous and would require a complete regulations over-hall, as would the way police and fire departments deal with car accidents. Basically, if this did become a reality, it would change everything as we know it!

When you crash your car, you usually don't crack open your engine. Radiation is easy to detect, so it's easy to avoid. In that way, it's easier to avoid than the hydrazine vapor used in the air bag deployment. Yes, designing a crash safe mobile nuclear reactor is an engineering problem, but it's one of the easier ones to solve.

Another approach would be to have a small reactor be kept in your house or a slightly larger one at local community level, and have the cars run on batteries.

[kandrathe]

The situation is not a question of better engineering, it is one of basic physics.

Yes, for the density and materials for a specific nuclear reaction, I agree. Better engineering is required to shrink the core, and shrink the components outside the core down to minimal size. Whatever the shielding needs are will be dictated by the reaction.

Is it possible to sustain a fission reaction using non-actinides? Perhaps in combination with a neutron ray source?

[Taem]

From a practical standpoint, you would need specialty mechanics, perhaps certified by the government, to work on your car as these "nuclear" run mobiles started slowly replacing standard carbon-emitting automobiles, but I'm sure the trade-off would be slow as the initial prices for such cars would be astronomically higher priced than a standard car as the technology lagged behind the science.

I spend about $100 per week on gasoline, or say about $50,000 over ten years for fuel. Figuring that 200 HP = 0.00015 gigawatts,

Using: http://www.wise-uranium.org/nfcc.html ...and, assuming I'm reading the results correctly.

It would take about 100 pounds of uranium ore to power the vehicle for ten years, and using fully processed fuel and accounting for disposal costs would cost about $20 for total fuel costs over the ten years.

That’s now what I meant! Of course the fuel efficiency would be cheaper, which is how this branch-off topic started. What I'm talking about is incorporating the technology and science into practical use for the everyday car. There are many examples I can think of with technology (such as video game consoles, cell phones, solar panels) where the cost to produce such items was extremely high when it first came out, even though the science behind it was pretty straight forward. Only after years of development did all the ducks line up where the cheapest manufacturers plus raw materials were chosen, where supply beat out demand and mass ordering reduced initial startup fees, etc, etc. I'm sure the initial cars for the first few years would be several thousand dollars more expensive than the standard cars of today, like how electric cars were, although electric cars are slowly inching down in price as their technology becomes more used. There would be many fees, new regulations which would be expensive, and oversight. $50 Smog check? Nah, get your $200 Stability check. And if not enough people could afford these new vehicals, then price would not go down significantly meaning either 1) The market would dry up and this idea would die a quick death, or 2) It would take long time before the prices went down where your everyday Joe could afford one, so the real changes would not take place for over a decade or more until its the projects inception.

[--Pete]

Hi,

When I was working at the Georgia Tech library, we had an 'inventor' come in to search the patents (the GTL is one of the regional patent depositories). His idea was to find or make a lake up on a mountain. Then using the water from the lake, spin three turbines at the foot of the mountain. Two of them would be used to generate electricity and the other would pump the water back to the lake.

At first, I thought he was pulling my leg. That someone had set me up. But it soon became obvious that he was serious. And when I tried to explain the conservation of energy, his counter arguments were all about efficiency and flow control, etc.

There are things that are limited by technology. A good example of that is aircraft power. While vast improvements in the technology increased the speed of aircraft, it took a change to jet propulsion to eliminate the propeller whose tip Mach number was a physical limitation. Other things are limited by nature, by science. Faster than light travel relative to the local space. Conservation of mass-energy.

Orthogonal thinking has to be based on the possible (possible in the sense that conservation laws, etc, are not violated). Once a situation has been analyzed and an optimal theoretical solution has been found, it is senseless to push that technology any further. For instance, there is nothing you can do to improve the efficiency of a gas/coal/wood based heating system beyond its chemical and thermodynamic efficiency. But if you change it to a heat pump system, you can get a lot more for your energy input. And if you do it acoustically, you could (at least in theory) do even better. Not by miniaturizing the fire box or by improving the air flow, or other tweaks to existing technology which only get you closer to a poor theoretical maximum, but by changing to a technology that has a better maximum.

Really, the best suggestion in this thread was naquada. In the sense of a totally unknown (at this time) technology. Perhaps from the high energy work done at CERN and elsewhere, perhaps from string theory, perhaps from the mind of a yet unknown genius, we may one day learn how to manipulate the sub-atomic in a non dangerous, non destructive way. But, always keep in mind, we are of and we live in a sub 10eV world (molecular binding energies, a couple of orders lower for thermal energies). Dealing with high energies is the difference between being patted on the head and being hammered on the head.

--Pete

[eppie]

Hi,

When I was working at the Georgia Tech library, we had an 'inventor' come in to search the patents (the GTL is one of the regional patent depositories). His idea was to find or make a lake up on a mountain. Then using the water from the lake, spin three turbines at the foot of the mountain. Two of them would be used to generate electricity and the other would pump the water back to the lake.

They are actually doing this. Of course not going against the laws of thermodynamics but just using the fact that electrical power is cheap at night and expensive at day time. So at night water gets pumped upwards and during the day electricity is generated.

[Lissa]

Hi,

When I was working at the Georgia Tech library, we had an 'inventor' come in to search the patents (the GTL is one of the regional patent depositories). His idea was to find or make a lake up on a mountain. Then using the water from the lake, spin three turbines at the foot of the mountain. Two of them would be used to generate electricity and the other would pump the water back to the lake.

They are actually doing this. Of course not going against the laws of thermodynamics but just using the fact that electrical power is cheap at night and expensive at day time. So at night water gets pumped upwards and during the day electricity is generated.

You'd be better off storing the electricity in batteries than doing this. There's a reason why power companies have specially designed plants called "peakers" for when the power requirements peak. These power plants are typically gas turbines (basically a large scale jet engine designed to make power instead of produce propulsion).

[kandrathe]

You'd be better off storing the electricity in batteries than doing this. There's a reason why power companies have specially designed plants called "peakers" for when the power requirements peak. These power plants are typically gas turbines (basically a large scale jet engine designed to make power instead of produce propulsion).

Batteries, and converters are a pretty substantial capital investment that require replacement and upkeep, while a lake, some pipes, turbine generator, and a pump are lower tech and more resilient. If you do have times where capacity exceeds demand, this is a way to use the excess off-peak power to charge the potential (if nature doesn't help with rain). I could see where this would be useful where you have excess wind, solar, etc. It's hard to compare to the North American grid, since there are so many generation sources and more variability in generation capacity.

[Kevin]

You'd be better off storing the electricity in batteries than doing this. There's a reason why power companies have specially designed plants called "peakers" for when the power requirements peak. These power plants are typically gas turbines (basically a large scale jet engine designed to make power instead of produce propulsion).

Batteries, and converters are a pretty substantial capital investment that require replacement and upkeep, while a lake, some pipes, turbine generator, and a pump are lower tech and more resilient. If you do have times where capacity exceeds demand, this is a way to use the excess off-peak power to charge the potential (if nature doesn't help with rain). I could see where this would be useful where you have excess wind, solar, etc. It's hard to compare to the North American grid, since there are so many generation sources and more variability in generation capacity.

It also reduces the environmental impact with the recycling of the water. It may actually have more to do with that, than efficiency in power generation.

[Lissa]

You'd be better off storing the electricity in batteries than doing this. There's a reason why power companies have specially designed plants called "peakers" for when the power requirements peak. These power plants are typically gas turbines (basically a large scale jet engine designed to make power instead of produce propulsion).

Batteries, and converters are a pretty substantial capital investment that require replacement and upkeep, while a lake, some pipes, turbine generator, and a pump are lower tech and more resilient. If you do have times where capacity exceeds demand, this is a way to use the excess off-peak power to charge the potential (if nature doesn't help with rain). I could see where this would be useful where you have excess wind, solar, etc. It's hard to compare to the North American grid, since there are so many generation sources and more variability in generation capacity.

It also reduces the environmental impact with the recycling of the water. It may actually have more to do with that, than efficiency in power generation.

Except you're probably doing more environmental harm by doing this because it takes power being produced somewhere else that is probably polluting the environment more than if you stored it in a battery system.

[--Pete]

Hi,

They are actually doing this. Of course not going against the laws of thermodynamics but just using the fact that electrical power is cheap at night and expensive at day time. So at night water gets pumped upwards and during the day electricity is generated.

I read this and went on. Then I thought about it and it makes no sense.

If the electricity is being generated by hydro pressure, then generating electricity at night to pump the water back up wouldn't be as efficient as just not using that water and generating that electricity in the first place. Just shut down the unneeded generators when the load is low and close the water valves.

If the electricity is not being generated by hydro pressure, then the same principal applies unless the water needs to be pumped up for some other purpose (such as irrigation or for a municipal supply). Then, yes, it makes sense to use the nighttime surplus capacity to perform the task (just as most aluminum is processed at night), but it is not a conservation measure, it simply reduces the daytime peak demand.

--Pete

[kandrathe]

Except you're probably doing more environmental harm by doing this because it takes power being produced somewhere else that is probably polluting the environment more than if you stored it in a battery system.

Yeah, that is true. Wrapping that into what Pete last wrote above, unless you use local "Green" sources, or "wasted" energy to drive the pumps at night then the value of re-establishing the potential is dubious.

If you think about huge solar power arrays being proposed, it makes more sense for huge solar arrays to store excess power as heat in huge hyper-insulated vats of molten salt.

Generally, anytime you consume a fuel to generate unneeded power, and then attempt to store it for use later you are introducing another layer of inefficiency, and capital expense. Even with "backup power" for computer rooms, battery storage is so expensive that we only have minutes of capacity (10 minutes in our case). In most cases, battery power acts as a buffer for intermittent power dips and spikes, and it gives the backup generator enough time to automatically fire up, alert someone in case of error, and for a local operator to manually intervene to get power restored.

The more SciFy approach I would propose would be to look into the work of Chunlei Guo, and his femtolaser technology. He has developed a laser etching technique where he can cause the surfaces of metals to exhibit capillary action. It should be possible to create mass produce structures of nanotubes that would "pump" the water uphill without need for powered pumps. Although, a side effect would be (the need for) extreme filtration.

[Zenda]

nanotubes that would "pump" the water uphill without need for powered pumps.

Unfortunately, that won't work. You'd still need the powered pumps to draw the water out of the 'uphill' end of the capillaries, and that would cost more energy then simply pumping the water up.

[kandrathe]

Unfortunately, that won't work. You'd still need the powered pumps to draw the water out of the 'uphill' end of the capillaries, and that would cost more energy then simply pumping the water up.

There is no perpetual motion here, so yes, you'd probably still need some smaller "pump" to over come the positive flow velocity dictated by Hagen-Poiseuille. Nature accomplishes its "pump" by using solar energy to evaporate the water in leaves.

I also believe you could achieve some flow effect by transforming the shape of the pipes at the top. Have you ever heard of a Hydraulic Ram?