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Old 2020-08-06, 06:30   #100
retina
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https://revolution-green.com/spacecr...nement-fusion/
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“Lattice confinement” refers to the lattice structure formed by the atoms making up a piece of solid metal. The NASA group used samples of erbium and titanium for their experiments. Under high pressure, a sample was “loaded” with deuterium gas, an isotope of hydrogen with one proton and one neutron. The metal confines the deuterium nuclei, called deuterons, until it’s time for fusion.

“During the loading process, the metal lattice starts breaking apart in order to hold the deuterium gas,” says Theresa Benyo, an analytical physicist and nuclear diagnostics lead on the project. “The result is more like a powder.” At that point, the metal is ready for the next step: overcoming the mutual electrostatic repulsion between the positively-charged deuteron nuclei, the so-called Coulomb barrier.

To overcome that barrier requires a sequence of particle collisions. First, an electron accelerator speeds up and slams electrons into a nearby target made of tungsten. The collision between beam and target creates high-energy photons, just like in a conventional X-ray machine. The photons are focused and directed into the deuteron-loaded erbium or titanium sample. When a photon hits a deuteron within the metal, it splits it apart into an energetic proton and neutron. Then the neutron collides with another deuteron, accelerating it.

At the end of this process of collisions and interactions, you’re left with a deuteron that’s moving with enough energy to overcome the Coulomb barrier and fuse with another deuteron in the lattice.
I have no idea why the article focusses on spacecraft drives when it could be used anywhere (assuming it is a real thing). Probably just to get more clicks.
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Old 2020-11-11, 18:42   #101
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I've been watching a docu-drama simply titled Chernobyl. Why did they design something like an RBMK reactor? Very unstable and prone to wild swings in reaction at low operating levels. Because it was "cheap."

It used Uranium 235 inside Zirconium sleeves surrounded by graphite. The run-down test they tried in 1986, they had tried three times previously, Each failed. They could never get it to hold steady at the output level they wanted. 700 MW, I believe it was.

So, the morning of the test, the operators bring it down slowly to where they wanted it to be. Somebody pushes a button and the output tanks to less then 50 MW. They tried to increase the output by raising the Boron control rods. Nothing happens so they keep raising the rods. Eventually, they have all but a few of the rods pulled completely out.

By this time, there is no water left in the core. The output surges dramatically. An operator presses one particular button meant to fully insert the rods which would completely stop the reaction. Instead, the very heavy lid of the reactor blows off through the roof. Then the core explodes violently.

The operators were never told that the control rods were not made of Boron only. They had graphite tips. The extra graphite increased the output exponentially. So, it blew. Helicopter pilots dumped loads of sand mixed with Boron on the exposed core. This created a blanket causing the remains of the core to begin to get hotter.

Below the reactor was a concrete pad. Below the pad were large water tanks. If the now molten sand and Boron hit the tank, the result would have been a multi-megaton explosion wiping out everything within a 30 kilometer radius. This would have included the three intact reactors and their U-235 fuel. The spread of radioactive material would have been massive.

Three men volunteered to go into the basement and open a valve which would allow the tanks to be emptied. They sacrificed themselves to probably save life on this planet as we know it.

There are still 10 RBMK reactors operating in the Russian Republic now. Thankfully, their control rods were retrofitted which removed the graphite from them. Looking back across the entire event, is is likely that we are fortunate to still be alive now.
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Old 2020-11-11, 21:36   #102
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Indeed, it's a sobering thought.
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Old 2020-11-12, 00:23   #103
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From the IMDB Chernobyl trivia page,
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Pro-Kremlin media continues to deny the extent of the disaster at Chernobyl, saying it has been exaggerated, with state-run media scoffing at the "myths," such as large numbers of leukemia. Segments of the Russian government were so unhappy with this documentary that state TV channel NTV is producing its own more "patriotic" account of the events, involving a wholly fictional storyline based on a conspiracy theory that a CIA agent was in Chernobyl to sabotage the plant.
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Old 2020-11-12, 00:56   #104
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Quote:
Originally Posted by storm5510 View Post
I've been watching a docu-drama simply titled Chernobyl. Why did they design something like an RBMK reactor? Very unstable and prone to wild swings in reaction at low operating levels. Because it was "cheap."



Below the reactor was a concrete pad. Below the pad were large water tanks. If the now molten sand and Boron hit the tank, the result would have been a multi-megaton explosion wiping out everything within a 30 kilometer radius. This would have included the three intact reactors and their U-235 fuel. The spread of radioactive material would have been massive.

Three men volunteered to go into the basement and open a valve which would allow the tanks to be emptied. They sacrificed themselves to probably save life on this planet as we know it.


.
Remarkably, the 3 men lived and I recently read that 2 were still alive.

The fires in the reactor were emitting all sorts of incredibly lethal atoms causing the sky to shimmer with beautiful colors. So much so that people gathered at a bridge near the plant to view the show not knowing they were being massively dosed with radiation. Many of them died on this "Bridge of Death".

The series was excellent and some scenes are available on Youtube. 2 particularly good ones is the one in which Lagasov give a blow-by-blow description of how the accident unfolded at the trial of 3 plant personnel and the one in which Gorbachev is briefed on the impending doomsday explosion.

Xenon poisoning of the core was one of the key reasons the reactor power fluctuated so widley. Its final reading right before it blew was 33000 megawatts!!!

"It's not 3.6 roentgen it's 15000!"

Now all we have to worry about is Fukishima.
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Old 2020-11-12, 17:13   #105
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Quote:
Originally Posted by tServo View Post
Remarkably, the 3 men lived and I recently read that 2 were still alive.

The fires in the reactor were emitting all sorts of incredibly lethal atoms causing the sky to shimmer with beautiful colors. So much so that people gathered at a bridge near the plant to view the show not knowing they were being massively dosed with radiation. Many of them died on this "Bridge of Death".

The series was excellent and some scenes are available on Youtube. 2 particularly good ones is the one in which Lagasov give a blow-by-blow description of how the accident unfolded at the trial of 3 plant personnel and the one in which Gorbachev is briefed on the impending doomsday explosion.

Xenon poisoning of the core was one of the key reasons the reactor power fluctuated so widley. Its final reading right before it blew was 33000 megawatts!!!

"It's not 3.6 roentgen it's 15000!"

Now all we have to worry about is Fukishima.
You have seen it too. The three men who opened the valve in the basement did survive. Saying they did not was probably propaganda at the time.

A lot of the dialog, I couldn't understand what they were saying. Jared Harris, who played Legasov, sounds incredibly like his father, Richard Harris, when he speaks.

Dyatlov was an abusive idiot. He absolutely believed he could do no wrong. A different documentary I watched said he had been scolded by "the party" for his treatment of his subordinates. He had also been heavily dosed with radiation previously when he was installing reactors in submarines. "K19" may have been one of them.

The reactor operators should have been told about the graphite tips on the rods on day-one. If they had known, perhaps they would have acted differently and not pulled them out entirely. The second large enclosure over the reactor incorporates a heavy-lift crane on the inside that is operated remotely. The goal is to disassemble and remove pieces of what remains over time. The life expectancy of the enclosure is estimated at 100 years.

There are actually two plants at Fukushima. "Diiachi" which we are all familiar with. Another, a short distance down the coast, is "Diani." I don't know what the designers were thinking about when they decided to place the backup generators and electrical panels in a basement at Diiachi. Hubris. They didn't believe the plant could ever be flooded.

The layout at Diani was different. It had an extra generator in a building on an elevated area behind the plant. It did not get flooded. They laid several miles of heavy cable to connect their pumps to the generator. They were able to get water flowing through their reactors before a melt-down started. IIRC, they had a fresh water source a short distance behind the plant. No salt, no damage to the reactors. Salt water was used at Diiachi. They needed something in a hurry and the reactors were already ruined from the meltdowns.

I was amazed when I heard that both plants used Plutonium for fuel. Japan probably does not have enough, or any, naturally occurring Uranium to enrich. Plutonium can be manufactured in a special reactor like the U.S. did at Hanford during WWII for The Manhattan Project.

The last I heard, the cleanup at Diiachi is expected to take 40 years. Whether they are still dribbling radioactive water into the Pacific Ocean, I don't know. If I had to guess, I would say they are.

My interest in all this began with, of all people, my mother when I was in grade-school. She understood the theory like most people would understand 1 + 1. She could also speak Latin fluently. Having children removed the possibly of her getting a job in the field. Back in the 1950's and 1960's, women were not much welcomed in scientific endeavors. And so it goes...
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Old 2020-11-12, 17:43   #106
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We have a 2MW reactor to play with at the Technical University in Delft.
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Old 2020-11-13, 00:37   #107
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Quote:
Originally Posted by Nick View Post
We have a 2MW reactor to play with at the Technical University in Delft.
That's amazing. An excellent learning tool. Of course, the NRC (Nuclear Regulatory Commission), would never allow such a thing here in the U.S.

Something I forgot regarding Chernobyl: There is an RBMK reactor simulation program which a person can download and experiment with. I've seen screenshots. It's really complex. Whoever wrote it put some serious time into it. There's a video on YouTube here.
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Old 2020-11-13, 14:11   #108
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One final note about Chernobyl. The heat exchanger, for which the miners tunneled under the lower concrete pad, was never installed. Those involved realized the molten mass of U-235 would not melt through the pad as it began to solidify. Only radiation and temperature sensors were placed in the tunnel. Those stopped working years ago.

Attached is a photo of a large mass of solidified U-235. It came to be known as "The Elephants Foot." There is a man in the image. Only his white hard-hat is clearly visible. The rest of him has a ghostly appearance. One of the artifacts in the photo looks like a cat lying on the floor. It is amazing that a photograph was possible in the presence of so much radiation.
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Old 2020-11-14, 14:22   #109
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Quote:
Originally Posted by storm5510 View Post
<snip>
Attached is a photo of a large mass of solidified U-235. It came to be known as "The Elephants Foot." There is a man in the image. Only his white hard-hat is clearly visible. The rest of him has a ghostly appearance. One of the artifacts in the photo looks like a cat lying on the floor. It is amazing that a photograph was possible in the presence of so much radiation.
The man's "ghostly appearance" and the bright squiggles indicate to me that the photo is a time exposure. That would be necessary, because it's dark in there! The man has lamps on both his hard hat and his boots.

EDIT: He might have a lamp on his right wrist too.

Last fiddled with by Dr Sardonicus on 2020-11-14 at 14:24 Reason: As indicated
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Old 2020-11-14, 16:51   #110
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Ah, the Chernobyl coud... stopped at the frontier between Germany and France.

I remember a reporter , with a foot un each country, holding a lettuce in each hand.... on the germany side, the lettuce wasn't allowed to be sold, while on France side, it was allowed.


https://www.sciencesetavenir.fr/deco...francais_30269


Gov did deny that the Chernobyl radioactive cloud ever entered France, and no special measure were ever taken

Last fiddled with by firejuggler on 2020-11-14 at 16:56
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