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Ask any question you want about Physics

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posted on May, 12 2019 @ 09:52 AM
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Ok thanks.
a reply to: Phantom423




posted on May, 12 2019 @ 10:42 AM
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originally posted by: Hyperboles
that accident did not start a chain or nuclear reaction. pendulum? where does it fit in here.
a reply to: Arbitrageur
Yes, it did start a chain reaction. The chain reaction released so much radiation that the man stacking the blocks died 28 days later. All of the incidents described in that pdf are related to chain reaction accidents, why do you think they titled the paper "A review of criticality accidents"?

Criticality accident

A criticality accident is an uncontrolled nuclear fission chain reaction. It is sometimes referred to as a critical excursion


By the way, Chernobyl was a bigger accident where the nuclear chain reaction went supercritical, and again there was no impact loading to initiate that. Operators retracted too many control rods, and lost control of the chain reaction.

You made a demonstrably false statement about impact requirements for criticality, just as you made demonstrably false statements about using pendulums as timekeeping devices in varying gravitational fields, and other false statements too numerous to mention, which indicate a pattern of your misconceptions in the field of science. There's nothing wrong with having misconceptions, as long as they are corrected by evidence, but it's that last part which creates the most concern, failing to correct your misconceptions even when you are provided with contrary evidence.

edit on 2019512 by Arbitrageur because: clarification



posted on May, 13 2019 @ 01:39 AM
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that report is in error, there couldn't have been a chain reaction, they are lying, for what reason I do not know.
why use a detonator then in the weapons. super critical or otherwise if you get a chain reaction from some lousy bricks.
pendulum and others: all physical processes pertaining to time keeping/ flow have to tally with one another. there can be no contradiction. I hope understanding of all above comes to you, if you get your head out of the sand
a reply to: Arbitrageur



posted on May, 13 2019 @ 06:20 AM
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a reply to: Hyperboles
Wow... just wow... Hyperboles you absolutely have no clue it seems, its not even amusing to play this game anymore. You have no idea how any of GR works, no idea about atomic physics or nuclear physics and are calling people liars who have done more experimentation than you have ever hoped to even dream to do.

You constantly just want reality to shape around what you think it to be... its kind of troubling and a little bit sad to be honest.

If you said the sky was Green, and that anyone who says its Blue or Red depending on time of day are liars id not be too shocked anymore.

By what you just said, nuclear reactors don't work at all... they must be in a constant state of nearly exploding at any one time because that is the only way you get energy or radiation out of Uranium.
edit on 13-5-2019 by ErosA433 because: (no reason given)



posted on May, 14 2019 @ 12:29 AM
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Wow,, just wow, you do have a problem with the English language, don't you? Brilliant conclusions, keep it up.
a reply to: ErosA433



posted on May, 14 2019 @ 08:03 AM
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a reply to: Hyperboles
There could be a language issue on your end, or else a complete lack of understanding of how the little Boy design worked, or maybe some of both. Let's look at this language of yours:



why use a detonator then in the weapons.
I have personally worked with high explosives (not nuclear), and in that context, a detonator is a specific type of device, also called a "blasting cap".

I'm not sure what you're calling a "detonator" in this schematic of the major "little boy" components:

en.wikipedia.org...


Are you referring to the Mark XV electric gun primers? The cordite bags? Nothing is labeled a "detonator" so this is a language issue in trying to figure out what you are talking about.


why use a detonator then in the weapons. super critical or otherwise if you get a chain reaction from some lousy bricks.
In the Los Alamos criticality accident mentioned earlier, the reflectors were tungsten-carbide blocks. The "Little Boy" design also employs Tungsten-carbide reflectors, see components labelled F, I and T.

The other thing I'd like you to notice in this illustration is that unlike smashing two protons together in a collider where we want a head-on impact, the design here is quite different where in some sense the mating pieces (subcritical masses) are designed to NOT impact with each other, which makes your language about "impact loading" difficult to comprehend. You can see the sort of "donut-shaped" projectile "S" is a stack of rings forming a hollow cylinder which is designed not to directly impact the other subcritical target mass "H", but to slide all the way around it, thus the objective is to join the subcritical masses together to create a supercritical mass, and not to "impact" or smash the two masses together like we try to do with protons.

So yes there seem to be some possible language issues, and/or maybe conceptual issues as well, but they seem to be on your end, because this design is not showing any "impact loading" of the two subcritical masses which are more designed to miss each other so "S" can slide around "H", rather than smash into it as "impact" suggests. So this design does not show what you say here:


originally posted by: Hyperboles
the amount of impact loading is huge otherwise you will not get the critical mass/density/gravity to start a nuclear process, so time compression has to be huge
a reply to: Arbitrageur


The design shows the critical mass is achieved by joining the two subcritical masses, not by "impact loading".

Here is another point of interest to further clarify it was joining of the subcritical masses which created the supercritical mass needed for the explosion. Additional bombs of this design were made but they were dismantled. One reason as I understand it was a safety concern that the bomb could go off accidentally if the two subcritical masses were joined by accident, let's say by the plane crashing, which possibly could happen even if the cordite powder bags were never ignited.

The replacement bombs presumably had better safety mechanisms to prevent them from going off accidentally, even if the plane carrying them had an accidental crash.

edit on 2019514 by Arbitrageur because: clarification



posted on May, 14 2019 @ 09:43 AM
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Lol joining? they are pulling your leg
a reply to: Arbitrageur



posted on May, 14 2019 @ 10:02 AM
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originally posted by: Hyperboles
that report is in error, there couldn't have been a chain reaction, they are lying, for what reason I do not know.


What does this even mean? Why couldn't there have been a chain reaction. Highly fissile material like 235Uranium, or 239Plutonium once over a certain mass and of certain geometry will be in a state of self-sustaining chain reaction. The Demon Core shown in Arbitrageur's post was a sphere of Plutonium designed to be 5% below the critical mass for a self sustained fission state. Materials in this close to critical mass and genometry typically self heat because the fission process is occurring within it, and the resultant energy absorbed. That is why Plutonium is used in Thermoelectric generators in satellites the material will constantly produce heat that can be used to power systems for a very long time.

The Demon core killed 2 people, both times caused by accidental experimental error.

The first was during neutron reflection experiments in which the core was placed into a tungston carbide castle, each piece of the reflector bringing the core closer to being critical, due to neutrons that would otherwise be lost are then being reflected back at the core. The experimentalist dropped one of the bricks onto the core, which was enough to compress the core and further reflect more neutrons into it causing it to enter a prompt chain reaction until he was able to lift the brick off of it. The result being he received a fatal dose of neutrons and died 25 days later. The other person in the room died 19 years later, receiving a far lower dose.

The second was an experiment to determine how close to critical the mass was, the core being placed in a hemisphere of beryllium (neutron reflector). The idea is to have a second hemisphere lowered over the top of it, and count the activity using scintillator counters. Now, the actual proper procedure was to have shims in place to prevent the two hemispheres from fully closing around the core, which would definitely make it go critical. So the process is, lower the top hemisphere and monitor activity at each position.

The experimentalist in question had taken to performing this test not using shims to maintain separation, but the edge of a screw driver. He had done it on many occasions, and it had been pointed out by many that one mistake would cause his death... non the less he thought he knew better and it wouldn't happen to him... on that day, the screw driver blade slipped and the hemispheres were allowed to close, causing the core to go critical. He described how he saw a flash of blue light in his eyes, and feel heat instantly over his skin, attributed to large burst of neutrons which are readily thermalized in water. To prevent a sustained reaction he was able to flip the top hemisphere off of the core. He however was a dead man walking, getting 5 times the dose the first victim of the core, and died 9 days after the incident. Other people present that day were tracked, all dying many years later, but many of the deaths attributed to radiation related complications and illnesses


So now that it is all spelt out in detail how the experiments and accidents occurred... tell me, how do you get a fatal dose of neutrons out of a piece of material without it going critical or entering a state where a chain reaction briefly occurs?



why use a detonator then in the weapons. super critical or otherwise if you get a chain reaction from some lousy bricks.


Your flippant and arrogant dismissal shows how little you understand nuclear technology and the control of run away conditions. When a mass like this goes critical, it doesn't instantly explode. If you think it does then you are very sadly mistaken. Surrounding a core with shielding would make it energy a super critical state and begin to produce large amounts of radiation and heat. There is a lag time between the initial critical state and the chain reaction entering an explosive state. The heat can cause physical and geometric changes in the material which can do three things... either prevent the core going into a explosive state, dropping it sub critical, melt the core or enter an explosive state. Typically you'd not want to melt the core as that is quite dangerous and tends toward the explosive state.

To get such a system to explode you need to hold the core in a super critical state, well over its critical point and maintain that critical mass. THEN it will explode, the chain reaction rapidly accelerating and producing heat and radiation contained within the device. In that state the energy density becomes so high that an explosion from the rapid expansion and liquefaction and vaporization of the device become inevitable simply from the amount of highly penetrating radiation being produced.

So the point of having a detonation mechanism is for safety.... there is a very good reason while modern high explosives are somewhat 'safe' these days... because too many people died using unstable materials in which mishandling can cause them to go off. Nitrate based blasting material in mines for example, are actually not that explosive in their normal state. Its with the addition of a blasting cap or energy delivery device which makes them explode. Until then, even tossing a cigarette on them doesn't have a huge probability to cause an explosion (id still not recommend it though, just in case) It is such if you are designing a nuclear device, you wouldn't want it so dangerously close to critical in a standby configuration. You would also want the core of it to be able to go critical very rapidly upon triggering. It is such that a typical device works on either gun type combination of the core material to a single super critical mass... or a configuration in which you melt and compress the core using high explosives to produce the criticality.

Clear? So exactly why make a statement demonstrating your ultimate lack of ability to comprehend any nuclear technology as to try and demonstrate you know better than everyone in the world?



pendulum and others: all physical processes pertaining to time keeping/ flow have to tally with one another. there can be no contradiction. I hope understanding of all above comes to you, if you get your head out of the sand
a reply to: Arbitrageur


A Pendulum is a composite mechanical object and its very operation is driven by the acceleration due to gravity... not the bending of space time directly. As we already discussed at exacerbating length... because a pendulum wont swing when placed at a lagrange point, does in no way mean time stops there. To claim that a pendulum clock is = to an atomic clock is to show supreme ignorance.

edit on 14-5-2019 by ErosA433 because: (no reason given)

edit on 14-5-2019 by ErosA433 because: (no reason given)



posted on May, 15 2019 @ 12:22 AM
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so you do need impact loading in a bomb don't you?
you need to read up on the pendulum in this thread and btw space is not bent
a reply to: ErosA433







 
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