Is It Time to Reconsider Anti-Nuclear Laws?

In summary, the conversation discusses the laws and attitudes towards nuclear power in Sweden and New Zealand. Both countries have strict laws against nuclear power, with Sweden banning research and new reactors, and New Zealand banning not only nuclear power but also any ships carrying nuclear weapons or waste. The discussion also touches on the use of nuclear power in the US Navy and the concerns surrounding it. The conversation concludes with the idea that laws against nuclear power are often based on moral rather than technical reasons.
  • #1
malawi_glenn
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Hi there nuclear lovers!

Myself lives in sweden, and here it is illegal to do research in nuclear power (experimental), and to build new reactors, research in new fissible nuclides and so on.

And also barley no money is invested in the reactors we do have, so they are not in good shape.. So it has become a very bad "spiral" in our country regarding nuclear power.

Do you know if any other countries have this "twisted" law against better and more safe nuclear power?

My self think it is the same as forbidding research in better medicines. Many people get killed every year due to this, that the medicines have bad effects on some etc...but not one single person has been killed due to nuclear power in our country.
 
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  • #2
Check out the N laws of New Zealand. There is a very stong stand in that country against N weapons and many of the same sentiments exist about N power.

I'm not sure if N power is outlawed or just that the compliance costs would be that high its not worth it.

Funny considering Lord Rutherford was from New Zealand.
 
  • #3
engineroom said:
Check out the N laws of New Zealand. There is a very stong stand in that country against N weapons and many of the same sentiments exist about N power.

I'm not sure if N power is outlawed or just that the compliance costs would be that high its not worth it.

Funny considering Lord Rutherford was from New Zealand.
engineroom,

Yes - New Zealand and certain ports in Japan don't allow nuclear reactors in their
jurisdiction. This creates a bit of a problem for the US Navy because the vast majority
of our aircraft carriers are nuclear powered.

Recently, when Admiral Mullens, the current Chief of Naval Operations; was named to
be the next Chairman of the Joint Chiefs of Staff; C-SPAN ran the video of the Senate
confirmation hearings from a year ago when Mullens was named CNO.

There was concern by Sen Nelson of Florida about the aircraft carrier U.SS. John F.
Kenndedy. Evidently the Kennedy was in need of some refurbishment, and it was
stated that the Navy keeps the Kennedy around so that they have a conventionally
powered aircraft carrier in case they need to station a carrier in a port with a "no-nuke"
policy.

Dr. Gregory Greenman
Physicist
 
  • #4
Making laws based on imperfect, incomplete or incorrect information can be very destructive. Good intentions are irrelevant. The Swedish nuclear laws may be a case in point.

The world prohibition against all use of DDT may have been another. DDT is still the most effective means of controlling mosquitos and the malaria they carry. A reasonable program for careful use of DDT might have saved millions of lives. Millions died directly due to the DDT ban. We are only now realizing that and reintroducing DDT in a measured and careful manner.

The bottom line: if you oppose something, you have an obligation to understand it thoroughly. If you do, you will rarely advocate that a complete ban is the best solution. If something is not economic, you don't have to pass a law to ban it.

AM
 
  • #5
I've always been a very enthusiastic supporter of nuclear power, but I have to admit to a certain degree of apprehension regarding naval reactors. Bottom line is, they're classified and I don't know how they work. I read that they are PWR designed, but before I let them into my harbor I'd want to study the details.
 
  • #6
Morbius said:
engineroom,

Yes - New Zealand and certain ports in Japan don't allow nuclear reactors in their
jurisdiction. This creates a bit of a problem for the US Navy because the vast majority
of our aircraft carriers are nuclear powered.

Recently, when Admiral Mullens, the current Chief of Naval Operations; was named to
be the next Chairman of the Joint Chiefs of Staff; C-SPAN ran the video of the Senate
confirmation hearings from a year ago when Mullens was named CNO.

There was concern by Sen Nelson of Florida about the aircraft carrier U.SS. John F.
Kenndedy. Evidently the Kennedy was in need of some refurbishment, and it was
stated that the Navy keeps the Kennedy around so that they have a conventionally
powered aircraft carrier in case they need to station a carrier in a port with a "no-nuke"
policy.

Dr. Gregory Greenman
Physicist

Actually New Zealand banned any ship equipped with N weapons but this has extended to N power and ships carring N waste. As the US navy have a neither confirm or deny policy concerning whether their ships have N weapons on board or not they can't enter New Zealand waters. A conventional powered US navy ship that is declared as not being N weapons capabity is welcome to enter a NZ port.

After the French government committed an act of international terrorism in a New Zealand port by bombing the Rainbow Warrior vessel the public opinion of New Zealand became entrenched towards a No Nuclear viewpoint.

New Zealand has been very consistant in its approach to Nuclear weapons and consisitly objects and protects anytime a test is (was) conducted. About 5 years ago a shippment of N watse was moved from France to Japan and this shipment was not allowed in New Zealand waters, I think the NZ navy shadowed the ship while it was close to NZ waters to be sure they stayed out.

It is fair to say that the antinuclear laws in New Zealnd are more a philispocial ideal than a technical problem.
 
  • #7
Andrew Mason said:
Making laws based on imperfect, incomplete or incorrect information can be very destructive. Good intentions are irrelevant. The Swedish nuclear laws may be a case in point.
AM


Just because one can should one?? I don't mean the law by that statement.

Swedish & New Zealand nuclear laws are reflecting strongly held opinions of the majority of the population in those counties - demoracy in action. Laws against N power, N waste & N weapons are never going to be bassed on technical reasons but moral reasons. These laws are quite different to laws that place technical paramenters and restictions on the how or where. These laws ask and challenge the fundamental why?
 
  • #8
How can producing electricity be a moral issue?

It seems that the problem is an entire generation whose first word association after the word 'nuclear' is the word 'bomb'.

Maybe the NucE's need a re-branding? Call it plasma-power or something, rather than next-gen nuclear. Seems to be working for NASA... nuclear pulse propulsion is re-branded external pulsed plasma propulsion. No sign of the words 'bomb' or 'nuclear'. o:)
 
  • #9
engineroom said:
Just because one can should one?? I don't mean the law by that statement.

Swedish & New Zealand nuclear laws are reflecting strongly held opinions of the majority of the population in those counties - demoracy in action. Laws against N power, N waste & N weapons are never going to be bassed on technical reasons but moral reasons. These laws are quite different to laws that place technical paramenters and restictions on the how or where. These laws ask and challenge the fundamental why?

Not quite. In sweden the laws came into place after a referendum where you could vote no to nuclear power in three different ways. But there was no wat to vote for more nuclear power.

The options was.

1. Keep it as long as it is needed until it can be replaced by renewables. Finish the reactors currently beeing built, prohibit building new ones.
2. Was basicly the same as 1 except some minor twists.
3. Shut down all reactors withint 10 years.

The results where
1. 18.9%
2. 39.1%
3. 38.7%

Obviously the referendum was a big pile of ****. Atleast a overwhelming majority wanted to keep the existing reactors. But there is no telling how many wanted more nuclear power.

Today 31% wants to build new reactors, 48% wants to keep the existing ones as long as possible and 19% wants to shut it all down.

The reason things haven't changed in sweden is because 2 small parties are keeping the entire energy policy in sweden hostage. The big left wing party(social democrats) are not quite big enough to get there own majority, so they have to cooperate with the communist party and the green party. But the commies and the greens want to get rid of nuclear power. The greens and commies togheter get around 10% of the votes.

On the right side 3 of the parties want to build more nuclear power while the fourth has strong roots in the anti nuclear movement. The fourth party gets around 7-8% of the votes.

So a 18 % minority is keeping sweden stuck on a nuclear phase out that has no public support anymore. Doesnt matter if right or left wins elections, it the same bull**** on both sides.

On the bright side it is no longer illegal to fund research into new reactors(previously only waste management research was legal and that included transmutation). Its also no longer illegal to make a economic comparison betwen nuclear and other energy sources. So all the brainwashing laws are gone.
 
  • #10
Azael:

Indeed, much have been better in our country, but still far away from what many other countries have.

Good post!
 
  • #11
Azael said:
Not quite. In sweden the laws came into place after a referendum where you could vote no to nuclear power in three different ways. But there was no wat to vote for more nuclear power.

The options was.

1. Keep it as long as it is needed until it can be replaced by renewables. Finish the reactors currently beeing built, prohibit building new ones.
2. Was basicly the same as 1 except some minor twists.
3. Shut down all reactors withint 10 years.

Number one is kind of interesting. Exactly what makes a 'renewable'? 5 billion year supply? 600 million? 500,000? From what I understand, there is a nearly limitless (on human life scales) supply of uranium and thorium. :confused:
 
  • #12
StuMyers said:
Number one is kind of interesting. Exactly what makes a 'renewable'? 5 billion year supply? 600 million? 500,000? From what I understand, there is a nearly limitless (on human life scales) supply of uranium and thorium. :confused:

It seems like it is up to the green fanatics to decide what is renewable or not :grumpy: Imo splitting energy production into renewable and non renewable is utterly pointless. Anything lasting more than 200 years should be sufficient. The whole concept of renewable is laughable since it hides what's most important. How much polutants the energy source release into the environment. I hate to se biomass burning counted as renewable energy despite its negative environmental and health consequenses.

Offcourse the greens are trying there best to fool the public that uranium will run out within 50 years. I don't know how many debate articles I have seen in swedish newspapers where the biggest swedish environmental group is pushing that message. Getting a rebuttal printed in same papers are all but easy.
 
  • #13
engineroom said:
It is fair to say that the antinuclear laws in New Zealnd are more a philispocial ideal than a technical problem.
engineroom,

It's neither a "technical problem", or "philosophical ideal"; it's just plain popular
ignorance and stupidity!

Hey, if New Zealand doesn't want to allow a Nimitz carrier into their ports - it's their loss.

The US Navy has tried to be accomodating - that's one of the reasons for keeping the
conventionally powered U.S.S. John F. Kennedy. It is well known that the USA has
nuclear weapons in its inventories that will fit on aircraft that the Kennedy supports.

However, I believe that the US Navy has stated that surface ships no longer routinely
carry nuclear weapons. The only Navy vessels that routinely carry nuclear weapons
are the Trident subs. The Navy ackowledges that the subs have the Trident missiles;
they just decline to confirm whether those missiles actually have nuclear warheads
installed in them. [ Like who doesn't know it - but that's the policy ]

Since the Kennedy could carry nuclear weapons, but routinely doesn't - do you know
if New Zealand would welcome a visit by the Kennedy?

The USA doesn't owe New Zealand anything. Most nations welcome the
US Armed Forces because that puts them under the USA's military "umbrella".

Do you know if the New Zealanders are so ignorant as to also exclude radio-pharmeceuticals?

Dr. Gregory Greenman
Physicist
 
  • #14
engineroom said:
These laws are quite different to laws that place technical paramenters and restictions on the how or where. These laws ask and challenge the fundamental why?
engineroom,

I would bet that if the former USSR had designs on New Zealand; they wouldn't have had
ANY PROBLEM with the USA showing up with nuclear arsenal in hand.

The USA was the only power that could force the then expansionistic USSR to back down,
and stay in line.

The present day Russia retains and maintains the nuclear stockpile of their former
incarnation - the USSR. There are other powers out there with nuclear weapons also.

As a counter to that - there stands the USA - so nuclear armed expansionistic powers
can not use their nuclear arsenals to advantage.

Dr. Gregory Greenman
Physicist
 
  • #15
Azael said:
Obviously the referendum was a big pile of ****.
Azael,

Yes - you can tell that from the way the referendum was constructed - they give the
pro-nukes two options in order to spilt their votes. That way a minority position can
win.

It's no different than having an election with 3 candidates - two of which are of the same
political philosophy. Even if a majority of voters are of one political opinion - they split
their votes between the two choices - and the minority view will win because they have
only one choice.

You can truly tell that that referendum was authored by some political shills that wanted
to foist their view on the populace - so they "rigged" the election in the manner I describe
above.

Some demonstration of Democracy. NOT!

Dr. Gregory Greenman
Physicist
 
  • #16
StuMyers said:
Number one is kind of interesting. Exactly what makes a 'renewable'? 5 billion year supply? 600 million? 500,000? From what I understand, there is a nearly limitless (on human life scales) supply of uranium and thorium. :confused:
StuMyers,

There's enough to last a VERY LONG time.

Long before we run out of fission fuel; scientists will have mastered nuclear fusion.

Then 1 out of every 6,000 or 7,000 atoms of hydrogen in the ocean will be nuclear fusion
fuel. That's an awful lot of energy that could carry the world until the Sun becomes a
red giant star and incinerates the Earth.

That's another thing - solar and wind don't offer our species the ability to escape the
certain destruction when the sun becomes a red giant. Nuclear power would be our
only hope for mankind to survive into the indefinite future.

Dr. Gregory Greenman
Physicist
 
  • #17
Morbius said:
StuMyers,

There's enough to last a VERY LONG time.

Long before we run out of fission fuel; scientists will have mastered nuclear fusion.

Then 1 out of every 6,000 or 7,000 atoms of hydrogen in the ocean will be nuclear fusion
fuel. That's an awful lot of energy that could carry the world until the Sun becomes a
red giant star and incinerates the Earth.

That's another thing - solar and wind don't offer our species the ability to escape the
certain destruction when the sun becomes a red giant. Nuclear power would be our
only hope for mankind to survive into the indefinite future.

Dr. Gregory Greenman
Physicist

And nuclear bombs will protect us from asteriods :) [from Bruce Willis - Armageddon]
 
  • #18
engineroom said:
Laws against N power, N waste & N weapons are never going to be bassed on technical reasons but moral reasons. These laws are quite different to laws that place technical paramenters and restictions on the how or where. These laws ask and challenge the fundamental why?
StuMyers said:
How can producing electricity be a moral issue?
This is the engineering forum, but I would say it is quite clearly morally wrong to subject your populace to pollution, war, and even higher prices based on an irrational fear of the unknown. Killing people because you don't understand the alternatives should not be morally acceptable.
 
  • #19
malawi_glenn said:
And nuclear bombs will protect us from asteriods [from Bruce Willis - Armageddon]
malawi_glenn,

Yes - actually if the orbit of the asteroid is eccentric enough so that we won't have
a large lead time - a nuclear bomb is the ONLY thing that might save us.

If the orbit of the asteroid is such that it is near by and we determine that it is going to
hit many, many orbits in the future - and hence many years in the future; then there are
a number of technologies that can be employed; because we have many, many years
to give the asteroid a gentle push.

However, if an asteroid comes screaming out of the Ort Cloud beyond the orbit of Pluto;
and this is the first we see it, and it is going to impact the Earth on THIS orbit - then
we don't have many years to give it a gentle push. We have to give it a BIG push NOW!

We have to provide the ENERGY that is needed to put this asteroid into a different orbit.

If it is a big asteroid, what is the one thing that can carry a LOT of energy in a package
that is light enough for us to send into space? A nuclear bomb!

You also have to understand HOW a nuclear bomb is used. Don't listen to the idiots
in the media that say "Oh - nuclear bomb - you're going to blow it up and that's going
to make matters worse". Those people are IDIOTS!

The idea with a nuclear bomb is you want to PUSH the asteroid into a new orbit; just like
the rockets and gravity tractors. You explode the bomb NEAR the asteroid. The
radiation from the bomb ablates the surface and pushes the asteroid. The push will
work even if the asteroid is a "rubble pile" because all the pieces are irradiated. [ You
can't push on a "rubble pile" with a rocket that "docks" with the asteroid.]

So YES - nuclear weapons may be our only hope!

Let's just hope that the asteroid is not too big for a nuke to push!

Dr. Gregory Greenman
Physicist
 
  • #20
Morbius said:
However, if an asteroid comes screaming out of the Ort Cloud beyond the orbit of Pluto; and this is the first we see it, and it is going to impact the Earth on THIS orbit - then we don't have many years to give it a gentle push. We have to give it a BIG push NOW!

We have to provide the ENERGY that is needed to put this asteroid into a different orbit.

If it is a big asteroid, what is the one thing that can carry a LOT of energy in a package that is light enough for us to send into space? A nuclear bomb!

You also have to understand HOW a nuclear bomb is used. Don't listen to the idiots in the media that say "Oh - nuclear bomb - you're going to blow it up and that's going to make matters worse". Those people are IDIOTS!

The idea with a nuclear bomb is you want to PUSH the asteroid into a new orbit; just like the rockets and gravity tractors. You explode the bomb NEAR the asteroid. The radiation from the bomb ablates the surface and pushes the asteroid. The push will work even if the asteroid is a "rubble pile" because all the pieces are irradiated. [ You can't push on a "rubble pile" with a rocket that "docks" with the asteroid.]

So YES - nuclear weapons may be our only hope!

Let's just hope that the asteroid is not too big for a nuke to push!
Interesting possibility.

Here is a quick calculation to see if it is possible:

Let's assume that an asteroid is about 1 km in radius and has the density of iron. I calculate that it would have a mass of about 3x10^13 kg. (4x10^9 m^3 at 8000 kg/m^3).

Let's also suppose that it is moving toward the Earth at a speed of 25 km/sec (2.5x10^6 m/sec)

In order to move it an Earth radius (6x10^6 m) from a path heading for the centre of the earth, at a distance from the Earth of 2.5 lunar orbits (10^12 m), you would have to move it that far in 10^12/2.5x10^6 seconds = 4x10^5 seconds. So you would have to make it move at an average speed (perpendicular to its path) of 6x10^6/4x10^5 = 15 m/sec.

That means imparting an energy of .5mv^2 = .5*3x10^13*(15)^2 = 3*10^15 Joules.

Now, assuming that a nuclear explosion is 1% efficient in converting nuclear energy into actual kinetic energy of the asterioid, you would need a bomb that produced on the order of 3x10^17 Joules of energy. Considering that the bomb dropped on Hiroshima released about 5.2 x 10^13 Joules of energy, you would need a bomb roughly 10,000 times as powerful to move the asteroid.

I hope my calculation is wrong, but I am afraid that even nuclear bombs might not do the trick.

AM
 
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  • #21
Andrew Mason said:
.
Now, assuming that a nuclear explosion is 1% efficient in converting nuclear energy into actual kinetic energy of the asterioid, you would need a bomb that produced on the order of 3x10^17 Joules of energy. Considering that the bomb dropped on Hiroshima released about 5.2 x 10^13 Joules of energy, you would need a bomb roughly 10,000 times as powerful to move the asteroid.

I hope my calculation is wrong, but I am afraid that even nuclear bombs might not do the trick.
Andrew,

A 1 Megaton H-bomb puts out an energy of 4.186 x 10^15 Joules.

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

You are low on your estimate of the energy conversion. The asteroid is going to
subtend a certain solid angle with respect to the bomb - and any radiation from the
bomb that is in that solid angle is going to be absorbed by the asteriod. That energy
is going to end up as "blow-off".

In any case, if a nuclear weapon doesn't have enough energy to deflect the asteroid;
nothing else is going to have enough energy.

Dr. Gregory Greenman
Physicist
 
  • #22
Morbius said:
Andrew,

A 1 Megaton H-bomb puts out an energy of 4.186 x 10^15 Joules.

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

You are low on your estimate of the energy conversion.
Actually, I think I am high. Most of the energy will be in the form of heat. Assuming that it is reasonably efficient in converting heat into kinetic energy of the bomb mass - 50%, and half the bomb mass strikes the asteroid (the other half has to blast off into space), that means that 1/4 of the energy of the bomb is converted into kinetic energy of matter striking the asteroid.

If the bomb weighs 4 tonnes, then 1 tonne of matter containing 10^15 joules of kinetic energy strikes the asteroid. This means the asteroid received an impluse of:

[tex]mv = m\sqrt{\frac{2KE}{m}} = M\Delta V[/tex] (M = mass of asteroid; V = speed of asteroid)

[tex]\Delta V = \frac{m}{M}\sqrt{\frac{2KE}{m}} = \frac{10^3}{3x10^{13}}\sqrt{\frac{2x10^{15}}{{10^3}}} = 3x10^{-10}*1.4x10^6 =4.2\times 10^{-4} \text{m/sec.}[/tex]

It will barely move the asteroid at all.

AM
 
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  • #23
Andrew Mason said:
Actually, I think I am high. Most of the energy will be in the form of heat.
Andrew,

You have to be careful which formulas you use. A lot of the formulas from the
weapons effects handbooks tell you how much heat is put out by a bomb exploding
here on Earth.

However, a lot of that heat actually started life as radiation. It was transformed into
heat as a result of interactions with the air.

However, in space; there is no air - so the radiation component will be higher than
what is usually quoted.

Dr. Gregory Greenman
Physicist
 
  • #24
Andrew Mason said:
If the bomb weighs 4 tonnes, then 1 tonne of matter containing 10^15 joules of kinetic energy strikes the asteroid. This means the asteroid received an impluse of:...
Andrew,

The mechanism is not the bomb mass hitting the asteroid.

The mechanism is that the radiation from the bomb ablates the material of the
asteroid itself, and the blowoff of that material is what gives the asteroid the
impulse.

Dr. Gregory Greenman
Physicist
 
  • #25
Andrew Mason said:
It will barely move the asteroid at all.
Andrew,

Depending on when and where you alter the asteroids orbit; even a very small change
in velocity can alter the orbit enough to miss the Earth.

Dr. Gregory Greenman
Physicist
 
  • #26
Morbius said:
Andrew,

The mechanism is not the bomb mass hitting the asteroid.

The mechanism is that the radiation from the bomb ablates the material of the
asteroid itself, and the blowoff of that material is what gives the asteroid the
impulse.
Ok. I can see why.

That would require putting the bomb inside the asteroid. I suppose that you could have a bunker buster type of bomb blast into the asteroid and then detonate the nuclear bomb. That might work but you would need to blast a large portion of the asteroid and you would need a very large nuclear device.

AM
 
  • #27
Andrew Mason said:
Ok. I can see why.

That would require putting the bomb inside the asteroid. I suppose that you could have a bunker buster type of bomb blast into the asteroid and then detonate the nuclear bomb. That might work but you would need to blast a large portion of the asteroid and you would need a very large nuclear device.

AM

The idea is to blast it outside the asteroid. The radiation will vaporise the surface and that will work as rocket engine pushing the asteroid of its current trajectory. You don't need or want to put the bomb inside the asteroid.

If you do it when its far enough from Earth the nuke doesn't have to be that big. A gentle nudgle when its far away is as effectiv as a massive blast when its close.
 
  • #28
Andrew Mason said:
Ok. I can see why.

That would require putting the bomb inside the asteroid. I suppose that you could have a bunker buster type of bomb blast into the asteroid and then detonate the nuclear bomb. That might work but you would need to blast a large portion of the asteroid and you would need a very large nuclear device.
Andrew,

NOPE - you don't have to put the bomb in the asteroid at all.

You explode the bomb above the surface of the asteroid, and let the
radiation illuminate the surface. When the material on the surface
absorbs the radiation, it will get hot and ablate or vaporize. The
resultant reaction from the vaporization of the surface material will
give you a force that deflects the asteroid.

This is the same way that ICF - Inertial Confinement Fusion works.
The radiation interacts with the material on the surface of the fusion
pellet - and results in a force. However, in the case of ICFl, the
radiation is all around the pellet - so the resultant force implodes it.

Dr. Gregory Greenman
Physicist
 
  • #29
Azael said:
You don't need or want to put the bomb inside the asteroid.
Azael,

You got it exactly correct. I see you know your Physics.

Dr. Gregory Greenman
Physicist
 
  • #30
Azael said:
The idea is to blast it outside the asteroid. The radiation will vaporise the surface and that will work as rocket engine pushing the asteroid of its current trajectory. You don't need or want to put the bomb inside the asteroid.

If you do it when its far enough from Earth the nuke doesn't have to be that big. A gentle nudgle when its far away is as effectiv as a massive blast when its close.
I don't think that would really work. Ultimately, it is the momentum of the radiation that would give you the impulse. The vaporizing surface could not give back more kick than the incoming radiation.

The only way to increase the momentum of the asteroid by absorbing radiation, vaporizing its surface and then expelling that vapour backward, is to build up vapour pressure and then release it suddenly in a burst, creating a jet-effect. But I don't see how that would happen unless you made a cavity and detonated the bomb inside it.

AM
 
  • #31
Andrew Mason said:
I don't think that would really work. Ultimately, it is the momentum of the radiation that would give you the impulse. The vaporizing surface could not give back more kick than the incoming radiation.
Andrew,

WRONG - it's NOT the momentum of the radiation that gives you the impulse.

Why do you think the momentum of the blowoff is constrained by the incoming radiation?
The two don't have ANYTHING to do with each other.

NOPE - when the radiation vaporizes the surface of the asteroid, it is going to throw
matter that was once part of the asterioid off at high speed. That's going to give you the
impulse.

Read up on how Inertial Confinement Fusion works! It's NOT the radiation pressure
due to the fact that the photons have momentum. It's the momentum of the blowoff
that gives the impulse. This is all VERY WELL understood physics from the
inertial confinement fusion programs.

http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/finert.html

"Directed onto a tiny deuterium-tritium pellet, the enormous energy influx evaporates the
outer layer of the pellet, producing energetic collisions which drive part of the pellet inward."


Dr. Gregory Greenman
Physicist
 
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  • #32
Morbius said:
Andrew,

WRONG - it's NOT the momentum of the radiation that gives you the impulse.

Why do you think the momentum of the blowoff is constrained by the incoming radiation? The two don't have ANYTHING to do with each other.

NOPE - when the radiation vaporizes the surface of the asteroid, it is going to throw matter that was once part of the asterioid off at high speed. That's going to give you the impulse.

Read up on how Inertial Confinement Fusion works! It's NOT the radiation pressure due to the fact that the photons have momentum. It's the momentum of the blowoff that gives the impulse. This is all VERY WELL understood physics from the inertial confinement fusion programs.

http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/finert.html

"Directed onto a tiny deuterium-tritium pellet, the enormous energy influx evaporates the outer layer of the pellet, producing energetic collisions which drive part of the pellet inward."


Dr. Gregory Greenman
Physicist

In the example you gave, enormous energy is concentrated into a small space (using lasers) and this creates large pressure (energy build up) inside these pellets. You need highly concentrated (low entropy) energy to start with. Radiation from an atomic weapon may have a large amount of energy but it is not going to be that concentrated.

Unless energy is allowed to build up in the target, the energy of the vapourized molecules in the target cannot exceed the momentum of the radiation or matter particle striking them. The odd one might get hit by two or more incident particles and end up with more momentum than either ofthe incoming particles, but I think that would be the exception. It seems to me that a laser pulse striking the asteroid could vapourize molecules on the surface of the asteroid and create a jet effect. That would be much easier to deliver than a several tonne nuclear bomb.

As an aside here, on this inertial confinement model, has anyone tried using a heavy transparent outside layer and a tiny inner space occupied by tritium/deuterium? That way, an brief but energetic pulse absorbed by the water would heat the water on the inside. It would be, at least momentarily, confined to a very small space and possibly achieve fusion, if it was hot enough.

AM
 
  • #33
Andrew Mason said:
In the example you gave, enormous energy is concentrated into a small space (using lasers) and this creates large pressure (energy build up) inside these pellets. You need highly concentrated (low entropy) energy to start with. Radiation from an atomic weapon may have a large amount of energy but it is not going to be that concentrated.
Andrew,

You don't know what you are talking about. The radiation from a nuclear weapon even
at a considerable distance is VERY, VERY, VERY...MUCH LARGER than what we
are able to get from a laser - even if we concentrate it.

Unless energy is allowed to build up in the target, the energy of the vapourized molecules in the target cannot exceed the momentum of the radiation or matter particle striking them. The odd one might get hit by two or more incident particles and end up with more momentum than either ofthe incoming particles, but I think that would be the exception.

WRONG! WRONG! WRONG!

Where do you get the idea that the momentum of the radiation is some kind of limit?

Let's say the asteroid is moving in the Z-direction - we use this to define our coordinates.
Therefore, the momentum of the asteroid in the X-direction is ZERO!

Now we blow up a nuclear device above the X-surface of the asteroid. The asteroid
absorbs the radiation - the surface material is vaporized and blows off - some of it
in the X-direction - outward from the asteroid. The momentum of this material is
positive in our chosen coordinate system.

However, by conservation of momentum - the total momentum of the system has to
be ZERO in the X-direction. Therefore the asteroid HAS TO RECOIL in the negative
X-direction in order to conserve momentum. Now how is the momentum of the
recoiling asteroid limited by the momentum of the radiation?

THINK ABOUT IT! You command of the physics here has been TERRIBLY SHODDY!

It seems to me that a laser pulse striking the asteroid could vapourize molecules on the surface of the asteroid and create a jet effect. That would be much easier to deliver than a several tonne nuclear bomb.

This "jet effect" from the laser is what the bomb does. Lasers are TERRIBLY
inefficient. You get only a few percent of the input power out as laser energy.
Additionally, the frequencies that you get from a laser are NOT the frequencies
that you want for absorption by the asteroid. You want energy in the X-ray spectrum.
It's difficult to get lasers to operate there - but that is precisely the region that nuclear
weapons radiate.

Andrew - I'm NOT making this stuff up off the top of my head. In the early '90s
there was a workshop held at Lawrence Livermore National Laboratory - the
"Planetary Defense Workshop" in which the best scientists in the field were brought
together to work on the problem of asteroid deflection.

You are pooh-poohing the conclusions of a gathering of the best scientists in the
field! Why don't you LEARN about this - rather than pooh-poohing it.

As an aside here, on this inertial confinement model, has anyone tried using a heavy transparent outside layer and a tiny inner space occupied by tritium/deuterium? That way, an brief but energetic pulse absorbed by the water would heat the water on the inside. It would be, at least momentarily, confined to a very small space and possibly achieve fusion, if it was hot enough.

NOPE - won't work because the density is too low. You need to get to a MUCH
higher compression. You aren't going to get fusion at the low densities without
compressing the fusion fuel.

Take a look at the reaction cross-section as a function of density to see that you don't
have to do an experiment - it's a LOSING IDEA from the start.

Dr. Gregory Greenman
Physicist
 
  • #34
Morbius said:
Andrew,

You don't know what you are talking about. The radiation from a nuclear weapon even at a considerable distance is VERY, VERY, VERY...MUCH LARGER than what we are able to get from a laser - even if we concentrate it.
Of course the energy from a laser pulse from Earth will be many orders of magnitude less than the energy from a nuclear bomb detonated next to the asteroid. My point was that it might be a more efficient mechanism for transferring energy into asteroid momentum.

WRONG! WRONG! WRONG!

Where do you get the idea that the momentum of the radiation is some kind of limit?
I didn't say that. I said that unless the energy is allowed to build up in the target, the kick delivered by the release of vaporised asteroid matter cannot exceed the change in momentum of the incident radiation and matter.

Now there may be something inherent in the process of absorption of radiation by the asteroid that creates such a build up of thermal energy in the asteroid that then causes an explosive release of matter. But I don't know that. All I am saying is that that is what is required.

Let's say the asteroid is moving in the Z-direction - we use this to define our coordinates. Therefore, the momentum of the asteroid in the X-direction is ZERO!

Now we blow up a nuclear device above the X-surface of the asteroid. The asteroid absorbs the radiation - the surface material is vaporized and blows off - some of it in the X-direction - outward from the asteroid. The momentum of this material is positive in our chosen coordinate system.

However, by conservation of momentum - the total momentum of the system has to be ZERO in the X-direction. Therefore the asteroid HAS TO RECOIL in the negative X-direction in order to conserve momentum. Now how is the momentum of the recoiling asteroid limited by the momentum of the radiation?

THINK ABOUT IT! You command of the physics here has been TERRIBLY SHODDY!
It seems to me that it depends on how energy is transferred from the incident photons to the atoms in the asteroid.

If the absorption of radiation energy produces heat in the asteroid and that causes a build-up of pressure of asteroid matter that is subsequently released as a burst of vapour from the asteroid, you are absolutely right that the incident momentum is immaterial.

But if it is simply a matter of individual incident photons knocking off atoms from the surface, I don't see how the atoms can receive an impulse from an incident photon that exceeds the change in momentum of the incident photon.

This "jet effect" from the laser is what the bomb does. Lasers are TERRIBLY
inefficient. You get only a few percent of the input power out as laser energy. Additionally, the frequencies that you get from a laser are NOT the frequencies that you want for absorption by the asteroid. You want energy in the X-ray spectrum. It's difficult to get lasers to operate there - but that is precisely the region that nuclear weapons radiate.

Andrew - I'm NOT making this stuff up off the top of my head. In the early '90s there was a workshop held at Lawrence Livermore National Laboratory - the "Planetary Defense Workshop" in which the best scientists in the field were brought together to work on the problem of asteroid deflection.

You are pooh-poohing the conclusions of a gathering of the best scientists in the field! Why don't you LEARN about this - rather than pooh-poohing it.
I am not pooh-poohing it at all. I am just saying that it requires a build-up of heat in the asteroid followed by a release of vapour.

NOPE - won't work because the density is too low. You need to get to a MUCH higher compression. You aren't going to get fusion at the low densities without compressing the fusion fuel.

Take a look at the reaction cross-section as a function of density to see that you don't have to do an experiment - it's a LOSING IDEA from the start.
You may be right that it is a losing idea - I was just tossing it out. But losing ideas sometimes have surprising turns, so tossing out a losing idea isn't necessarily a bad thing.

AM
 
  • #35
Andrew, the energy from a nuclear bomb is omnidirectional, so sure, it isn't as "concentrated" as a laser. Still, if you detonate the bomb near an astroid, almost half of the energy will be captured by the asteroid. Maybe that's how you define efficiency (50% vs 100%), but since there is no laser that comes anywhere close to the power output of a nuclear bomb, you still get much more oomph from the nuclear bomb - efficiency really isn't a relavant concept here. [and that's without considering the efficiency of generating the laser]

To get an idea of the scale difference, the worlds largest laser, (actually a collection of 192 lasers) will have a total energy capacity of 346mj (it is still under construction). That's .000008256 kilotons. So you'd need to fire it one hundred twenty thousand times to impart the same amount of energy on an asteroid as a small nuclear bomb. [someone check my math...]

http://www.specialtyphotonics.com/knowledge_base/newsletter/0707/largest_laser.html [Broken]
 
Last edited by a moderator:
<h2>1. What are anti-nuclear laws?</h2><p>Anti-nuclear laws refer to legislation that restricts or prohibits the use of nuclear energy or weapons. These laws are in place to regulate the production, storage, and disposal of nuclear materials in order to protect public safety and the environment.</p><h2>2. Why should we reconsider these laws?</h2><p>There are several reasons why some argue that it is time to reconsider anti-nuclear laws. These include advancements in technology that have made nuclear energy safer and more efficient, the need for clean and reliable energy sources to combat climate change, and the potential economic benefits of nuclear power.</p><h2>3. What are the potential risks of lifting anti-nuclear laws?</h2><p>The potential risks of lifting anti-nuclear laws include the possibility of accidents or malfunctions at nuclear power plants, the risk of nuclear weapons proliferation, and the challenge of safely disposing of nuclear waste. These risks must be carefully considered and managed in any decision to reconsider anti-nuclear laws.</p><h2>4. What are the potential benefits of reconsidering anti-nuclear laws?</h2><p>Some potential benefits of reconsidering anti-nuclear laws include reducing reliance on fossil fuels and decreasing carbon emissions, creating jobs and stimulating economic growth through the construction and operation of nuclear power plants, and providing a reliable and consistent source of energy.</p><h2>5. What is the current status of anti-nuclear laws?</h2><p>The status of anti-nuclear laws varies by country. Some countries have strict laws in place that prohibit the use of nuclear energy, while others have more relaxed regulations. In some cases, countries have recently lifted or are considering lifting their anti-nuclear laws in light of changing attitudes and advancements in technology.</p>

1. What are anti-nuclear laws?

Anti-nuclear laws refer to legislation that restricts or prohibits the use of nuclear energy or weapons. These laws are in place to regulate the production, storage, and disposal of nuclear materials in order to protect public safety and the environment.

2. Why should we reconsider these laws?

There are several reasons why some argue that it is time to reconsider anti-nuclear laws. These include advancements in technology that have made nuclear energy safer and more efficient, the need for clean and reliable energy sources to combat climate change, and the potential economic benefits of nuclear power.

3. What are the potential risks of lifting anti-nuclear laws?

The potential risks of lifting anti-nuclear laws include the possibility of accidents or malfunctions at nuclear power plants, the risk of nuclear weapons proliferation, and the challenge of safely disposing of nuclear waste. These risks must be carefully considered and managed in any decision to reconsider anti-nuclear laws.

4. What are the potential benefits of reconsidering anti-nuclear laws?

Some potential benefits of reconsidering anti-nuclear laws include reducing reliance on fossil fuels and decreasing carbon emissions, creating jobs and stimulating economic growth through the construction and operation of nuclear power plants, and providing a reliable and consistent source of energy.

5. What is the current status of anti-nuclear laws?

The status of anti-nuclear laws varies by country. Some countries have strict laws in place that prohibit the use of nuclear energy, while others have more relaxed regulations. In some cases, countries have recently lifted or are considering lifting their anti-nuclear laws in light of changing attitudes and advancements in technology.

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