Why can't we make small, self-contained nuclear reactors to generate electricity for trains and large trucks, etc?

We have submarines and ships, why not trains and trucks? Little, tiny reactors would produce tons of power without polluting the air, right?

Baron Max

There are at least three problems that have to be addressed. There is a minimum size requirement for the reactor itself - submarine reactors are about as small as possible. Even more problematical for trains and trucks is the shielding requirement. Intrinsically shields are heavy. Furthermore there is a safety problem - what would happen in case a truck or train got into an accident?

Already been done.

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Dr Ray Stantz: You know, it just occurred to me that we really haven't had a successful test of this equipment.

Dr. Egon Spengler: I blame myself.

Dr. Peter Venkman: So do I.

Dr Ray Stantz: Well, no sense in worrying about it now.

Dr. Peter Venkman: Why worry? Each one of us is carrying an unlicensed nuclear accelerator on his back.

Daniels Power Pile

http://www.osti.gov/accomplishments/pdf/DE00836858/120.pdf

small nuclear reactor cooled by gas

Daniels Power Pile .... small nuclear reactor cooled by gas

Nothing at all since 1958??? Doesn't that seem like a long time ago?

If we could have small reactors, say even in basements of big office buildings, it would be major reduction in the electric grids for cities. What's the deal?

Baron Max

Mathman has it. The physics of uranic fission dictate to us that a reactor must have a certain core geometry in order to be able to sustain a criticality. The fuel elements must be set up in such a manner so as to capture neutrons well enough to accelerate the reaction (cross section for collision needs to be high enough) when all control rods are removed. There must also be space for control rods and coolant channels. Finally, shielding (particularly neutron shielding) can easily consume as much, if not more, weight and volume than the core itself. All of these aspects confer a size that is prohibitive for use in vehicles or homes. This doesn't even address the issue of how much it would cost to install and maintain a plant in an average home.

The contaminant concern in case of a containment breach, or whatever, is significant more because people think it is than because of a real world radiological hazard, but significant (for mostly political reasons) none the less. Also, the fuels infrastructure, at least here in the US, is not set up to handle thousands upon thousands of small reactors spread all around the country so trying to implement these solutions would probably be cost prohibitive as well.

A gas or liquid metal cooled reactor (like the one mentioned above) would never pass licensing for utility use by the general public, and for good reason. Reactors with solid moderators and positive void coefficients harken back to the RBMK that caused the explosion at Chernobyl and as such have been eschewed by responsible nuclear states, at LEAST since 1986, although any nuclear engineer worth his or her salt can see the inherent safety flaws of a solid moderator reactor by spending five minutes looking at the design specs. Also, they tend to rely on more fast neutron exchanges than light water reactors, which means you end up with lots of plutonium in your spent rods - a proliferation concern as well.

Mathman has it. The physics of uranic fission dictate to us that a reactor must have a certain core geometry in order to be able to sustain a criticality. The fuel elements must be set up in such a manner so as to capture neutrons well enough to accelerate the reaction (cross section for collision needs to be high enough) when all control rods are removed. There must also be space for control rods and coolant channels. Finally, shielding (particularly neutron shielding) can easily consume as much, if not more, weight and volume than the core itself. All of these aspects confer a size that is prohibitive for use in vehicles or homes. This doesn't even address the issue of how much it would cost to install and maintain a plant in an average home.

The contaminant concern in case of a containment breach, or whatever, is significant more because people think it is than because of a real world radiological hazard, but significant (for mostly political reasons) none the less. Also, the fuels infrastructure, at least here in the US, is not set up to handle thousands upon thousands of small reactors spread all around the country so trying to implement these solutions would probably be cost prohibitive as well.

A gas or liquid metal cooled reactor (like the one mentioned above) would never pass licensing for utility use by the general public, and for good reason. Reactors with solid moderators and positive void coefficients harken back to the RBMK that caused the explosion at Chernobyl and as such have been eschewed by responsible nuclear states, at LEAST since 1986, although any nuclear engineer worth his or her salt can see the inherent safety flaws of a solid moderator reactor by spending five minutes looking at the design specs. Also, they tend to rely on more fast neutron exchanges than light water reactors, which means you end up with lots of plutonium in your spent rods - a proliferation concern as well.

that's all pretty decent, understandable information ..I think. But should I just take your word for it? I mean, who are you? What's your background in nuclear physics? How long have you studied nuclear physics and nuclear reactor engineering?

I want to believe you, but....?

Baron Max

I'm some random guy, ON THE INTERNET!!

Actually, I have a BS in nuclear engineering from the University of Texas at Austin, although I haven't done anything with it professionally.

I guess you'll have to take my word for it, although you can corrborate all of what I said with a basic understanding of the engineering fundamentals. If there is something specific you'd like clarified, I can try to explicate further.

I'm some random guy, ON THE INTERNET!!
:roflmao:

Small Self-Contained Reactors?
Ever heard of economies of scale? :rolleyes:

Or how about "radioactive waste"?:rolleyes:

The Russians used small amounts of radioactive materials to make a power generator for remote locations. They were very dangerous.

The Russians used small amounts of radioactive materials to make a power generator for remote locations. They were very dangerous.

oh really? weres your proof?

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

In addition to spacecraft, the Soviet Union constructed many unmanned lighthouses and navigation beacons powered by RTGs[1]. Powered by 90Sr, they are very reliable and provide a steady source of power. However, critics argue that they could cause environmental and security problems, as leakage or theft of the radioactive material could pass unnoticed for years (or possibly forever: some of these lighthouses cannot be found because of poor record keeping). There has been even an instance where the radioactive compartments were opened by a thief; it was inferred that the resulting radiation poisoning was fatal[2]. There was also the case of two woodcutters in Siberia who came across one of these units and slept close to it as a heat source during a cold night. They both died of radiation poisoning within a few days afterwards. The unit was eventually recovered and isolated[3].

Not to mention the problem posed by idiots with a religious or poltical agenda that allows them to use terrorism as a way of self expression.

Or the the problem posed by idiots with no agenda at all.

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

In addition to spacecraft, the Soviet Union constructed many unmanned lighthouses and navigation beacons powered by RTGs[1]. Powered by 90Sr, they are very reliable and provide a steady source of power. However, critics argue that they could cause environmental and security problems, as leakage or theft of the radioactive material could pass unnoticed for years (or possibly forever: some of these lighthouses cannot be found because of poor record keeping). There has been even an instance where the radioactive compartments were opened by a thief; it was inferred that the resulting radiation poisoning was fatal[2]. There was also the case of two woodcutters in Siberia who came across one of these units and slept close to it as a heat source during a cold night. They both died of radiation poisoning within a few days afterwards. The unit was eventually recovered and isolated[3].

not all of this is true.

not all of this is true.


Then provide us with a critique. From some reliable source, not your words please, because you always fail to deliver accurate prose.

Anyway, like SpiderGoat said, RTG's have been used to power Spacecraft, they are very simple, a radioactive source decays and provides heat, and a thermocouple uses the differential with the temperature of space to make electricity.

Can be used on Earth too, but that would mean selling fairly large quantities of radio isotopes to individuals, (and there are strict laws about that, you are allowed just enough to run a smoke detector) and while they would not be able to assemble fission bombs from the content, merely detonating them as a 'dirty bomb' would be bad news.

...are very reliable and provide a steady source of power. However, critics argue that they could cause environmental and security problems, ...

"Could" cause? Could, might, maybe,.... Is that just more of the overly cautious liberal scare tactics about nuclear energy generation?

When the oil and coal and gas is all gone, maybe, possibly, we'll have to take a few chances. Or else we can go back to subsistance farming and living in caves! Nuclear energy generation is the only real viable method to date as far as I can see. Windmills? Takes too many, uses too much valuable land. Solar? Uses too much land, low power output.

Trains and farm tractors and distribution trucks and the like are going to have to use some small power source ...small nukes are it as far as I can see.

Baron Max

Then provide us with a critique. From some reliable source, not your words please, because you always fail to deliver accurate prose.

well the woodmen getting sick...where's proof of that?

Yes they do use small nuclear reactors in space...yes they do use it in lighthouses...they also use it in groundbreaking driller equipment...but that test was halted (explosion)...Gawd why am I saying this, it is impossible to prove it, because there are no sources that can be trusted, I know this. So let it just be a gossip.

The "dirty bomb" threat from reactor fuel or a stolen RTG exists mostly in people's imaginations. Much like the cobalt bomb or neutron bomb, they are weapons that seem to work on paper (and in Hollywood) but are stunningly ineffective in practice.

From the NRC's fact sheet on dirty bombs:


A dirty bomb is in no way similar to a nuclear weapon or nuclear bomb. A nuclear bomb creates an explosion that is millions of times more powerful than that of a dirty bomb. The cloud of radiation from a nuclear bomb could spread tens to hundreds of square miles, whereas a dirty bomb’s radiation could be dispersed within a few blocks or miles of the explosion. A dirty bomb is not a “Weapon of Mass Destruction” but a “Weapon of Mass Disruption,” where contamination and anxiety are the terrorists’ major objectives.

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/dirty-bombs.html

Taking that a step further, we can conclude that for a dirty bomb to do its job, it could be packed with anything that fits the popular concept of "radioactive" and be every bit as effective as if it contained quality fuels. A dirty bomb is a weapon of perception, not impact. Here is why:


Just because a person is near a radioactive source for a short time or gets a small amount of radioactive dust on himself or herself does not mean he or she will get cancer. Any additional risk will likely be extremely small. Doctors specializing in radiation health effects will be able to assess the risks and suggest mitigating medical treatment, once the radioactive source and exposure levels have been determined.

To get enough people covered with enough radiological material to cause widespread lingering health effects, you need an utterly enormous amount of radiation over a significant amount of time. Using Hiroshima as an example, there we had a rather dirty fission weapon that spread roughly 100 pounds of fission fragments over an circle with a five mile radius. How many cases of illness due to secondary exposure were there? None. Same with Nagasaki. Same with Eniwetok and Bikini Atolls. These were all instances where contamination around ground zero was several thousand times more intense than a dirty bomb could produce, for several days. In those instances, the contaminants were lofted into the air by the heat of the nuclear weapons, so they also spread much MUCH further than a high explosive charge tossing them within a few hundred yards, as would be the case in the popular dirty bomb scenarios.

Nobody was affected by the secondary contamination because they didn't bury themselves under the debris for a few days and lie there, they egressed the area, took showers, and changed their clothes. We could expect the same to happen in any scenario in which some ragtag terrorists decided to waste their time and money getting their hands on some nuclear fuel and dispersing it around a crowded area. In a scenario like that, the high explosive used to disperse the fuel and the pandemonium following the attack would present greater threats to personal safety than the radiological material ever could.

"Could" cause? Could, might, maybe,.... Is that just more of the overly cautious liberal scare tactics about nuclear energy generation?

When the oil and coal and gas is all gone, maybe, possibly, we'll have to take a few chances. Or else we can go back to subsistance farming and living in caves! Nuclear energy generation is the only real viable method to date as far as I can see. Windmills? Takes too many, uses too much valuable land. Solar? Uses too much land, low power output.

Trains and farm tractors and distribution trucks and the like are going to have to use some small power source ...small nukes are it as far as I can see.

Baron Max

They aren't nuclear power plants exactly. Much better to build those instead and tie into the existing electrical grid.

Having multiple small containers of potentially deadly radioactive material everywhere will certainly cause environmental and security problems.

Nothing at all since 1958??? Doesn't that seem like a long time ago?

If we could have small reactors, say even in basements of big office buildings, it would be major reduction in the electric grids for cities. What's the deal?

Baron Max

The physical properties of matter and energy are the same today as they were in 1958. There is this fallacy that we can just do anything if we put our minds to it. Actually we can't. We are always limited by the same variables. sometimes we can manipulate them better (technology) but sometimes we can't.

My father-in-law is an electrical engineer and among his work in the air force was obtaining greater efficiencies from batteries. He shakes his head at all the research that has gone into electric battery operated larger vehicles. He claims the limitation is not one of technology but actual physics. 'The wall' is not limited technology but the intrinsic properties of matter and energy. We can tweak things but not alter fundamentals.

Solar? Uses too much land, low power output.

Baron Max

And just what exactly do you think powers the planet?

The physical properties of matter and energy are the same today as they were in 1958. There is this fallacy that we can just do anything if we put our minds to it. Actually we can't. We are always limited by the same variables. sometimes we can manipulate them better (technology) but sometimes we can't.

My father-in-law is an electrical engineer and among his work in the air force was obtaining greater efficiencies from batteries. He shakes his head at all the research that has gone into electric battery operated larger vehicles. He claims the limitation is not one of technology but actual physics. 'The wall' is not limited technology but the intrinsic properties of matter and energy. We can tweak things but not alter fundamentals.

My father is a materials scientist. There may be limitations on existing battery technology due to physics and the properties of materials, but there are always new materials. Carbon nanotubes are very promising.

Russia [during CCCP days] built and orbited lots of small fission reactors for space satellites.

They are essentially barely-sub-critical spheres of fissile material [Pu-239 as I recall, though possibly U-235]. To get the spheres to engage in fission reaction, they are surrounded by graphite 'vanes' in an arrangement similar to Venetian Blinds. When the vanes are in the open position, there is no fission. When the vanes are in the closed position, fission is at a maximum, due to the reflection of neutrons by the closed vanes stimulating fission. Varying positions in between produce varying thermal energy outputs, which are then converted to electrical energy.

They are designed to be in orbit for several centuries, though I do not have the details. One of them fell out of orbit [premature orbital decay, apparently due to improper initial orbit] early, in the early 1980s as I recall, and crashed in Canada. Canada sent Russia a bill for the extensive cleanup of fissile product and fissile material that was generated.

The rest will crash in the 22nd to 23rd centuries, as I recall. Most will fall into the sea, but some will crash on land, repeating Canada's experience. If all of the fissile material were located, it would be enough to make one implosion-type fission bomb.

Anyway, that's about as small as you can make a fission reactor - any smaller nuclear devices are simply radioisotope units, extracting the heat from the decay of radioactive material.

There seems to be some confusion here between nuclear reactors, which are quite big, and (usually small) radioactive power sources, such as 90Sr.

There seems to be some confusion here between nuclear reactors, which are quite big, and (usually small) radioactive power sources, such as 90Sr.

I was just asking about something to generate electricity to power cars, trucks, trains and so forth. Mobile-type generators so we wouldn't have to depend ONLY on batteries, which aren't very powerful or long-lasting.

But also, as a side note, any small-type of generator for an office building or a house or apartments, etc.

It's more of an electricity generator question than a nuke reactor question.

Baron Max

well the woodmen getting sick...where's proof of that?



Where's your proof it never happened? Query the veracity of the initial claim by all means, but don't make a counter claim without evidence.

The "dirty bomb" threat from reactor fuel or a stolen RTG exists mostly in people's imaginations.

Where is will find a hospitable environment to grow and spread.

Just look at the fallout (pun intended) from 9/11 and the London July bombings. War with two countries, repressive legislation, innocents shot and one killed by the Police in the aftermath.

If there was a 'dirty bomb' imagine what the politicians would drive though on the back of that.

I'm not worried about the effects of such a device, but the increased repression we would see afterwards.

V for Vendetta anyone ?

Where it will find a hospitable environment to grow and spread.

Just look at the fallout (pun intended) from 9/11 and the London July bombings. War with two countries, repressive legislation, innocents shot and one killed by the Police in the aftermath.

If there was a 'dirty bomb' imagine what the politicians would drive though on the back of that.

I'm not worried about the effects of such a device, but the increased repression we would see afterwards.

Yes Yes. A little paranoia is good for the soul! (Not sarcasm)