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Cherenkov radiation

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ralphchadkirk

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Interesting that, but I think it's a bit of red herring. My understanding is that it is not the earthquake that is causing the present problems with the reactors but the combination of earthquake and then tsunami. The reactors behaved as intended during and in the immediate aftermath of the earthquake (i.e. they shut down and switched to back up generators) however when the tsunami hit it knocked out the generators (leaving the cooling running on short term batteries) and caused further damage that has now led to the present situation. If it had just been an earthquake I don' think we would be having the present problems.

That was my understanding of it. It's a testament to modern engineering that you can build reactors to withstand earthquakes though!

See me and ainsworth74 posted almost exactly the same at the same time!
The same time being three minutes difference? ;):lol:
 
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strange6

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More water Captain!

Does the injection of water increase the likelihood of the accumulation of the hydrogen that leads to the explosions? I remember reading something about the Windscale fire about the reluctance to use water to cool the graphite pile, due to the possibility of the extreme temperatures stripping the water into oxygen and hydrogen, and causing an explosion. The Windscale event wasn't quite a meltdown in the traditional sense, rather more of a uranium fire in an air cooled graphite reactor, but the theory is similar.

EDIT: It wasn't the extreme temperatures, rather the molten metal oxidising on contact with water, creating hydrogen. If the Japanese reactor has partially melted, then the water coming into contact with the molten metal may be creating the hydrogen, which in turn is leading to the explosions?


The hydrogen is coming from super-heated steam which, because of the high temperatures and pressures and the presence of Zirconium (which acts as a catalyst in this process), is dissociating into it's components, oxygen and hydrogen. That's why the engineers are having to vent off this pressure from around the reactor. Better to blow up the containment building than the reactor itself!
It is really important, therefore, to keep a constant flow of water flowing around the reactor itself to prevent overheating and therfore pressure increase and dissociation. This is the problem they are trying to solve at the moment because they have no such means to keep it flowing. Hence it's just turning into the gases and exposing the fuel rods
 
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gordonthemoron

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I trust that everything will be allright and that the engineers are doing their best to avoid a meltdown. However, the 1957 Windscale fire seemed to have been brought back under control more by luck than anything else
 

strange6

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I trust that everything will be allright and that the engineers are doing their best to avoid a meltdown. However, the 1957 Windscale fire seemed to have been brought back under control more by luck than anything else

Even if there is a meltdown, there should be little or no escape of radioactivity due to the design of these particular reactors and in particular, the containment vessels - these should keep everything within, even if the rods do fully meltdown. This happened at Three mile island in the US and it's still sealed off to this day. Why? Becuase even though the fuel did fully melt, it was still contained within the reactor vessels and could not be recovered. That's why it's sealed off and that's what will probably happen in the japanese case as well, even with full meltdown. there will be no Chernobyl here - mark my word! :) Why? Because at Chenobyl, the reactor did not shutdown in the first instance like they have done in Japan and the Chernobyl reactor was fatally flawed in its design too! because of crappy design, the explosion was right in the centre of the fuel. Couple this with no reactor containment structures, and you had a lethal monster!
 
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ralphchadkirk

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I need an explanation of hydrogen-14 as well; deuterium and tritium is as far as my knowledge goes.

Ah my apologies. I thought he was asking what an isotope was, not referring to the fact that the only three isotopes hydrogen has are Hydrogen-1, Hydrogen-2 (as you say, deuterium) and Hydrogen-3 (tritium).
 

strange6

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I need an explanation of hydrogen-14 as well; deuterium and tritium is as far as my knowledge goes.

There is no such thing as hydrogen 14. And I understand Isotopes very well for the arguementitave people amongs us. The number is the mass number for the isotope / element. It refers to the number of protons and neutrons within that isotopes nuclei. Isotopes of an element contain the same number of protons (because it is the same element) but may have different numbers of neutrons. For example Uranium 238 will have 3 more neutrons within its nucleus than Uranium 235
Deuterium is an isotope of hydrogen. Like hydrogen, deuterium contains 1 proton but unlike hydrogen it also contains 1 neutron in its nucleus. Tritium contains 1 proton but two neutrons. Thus they can also be refered to as hydrogen-2 and hydrogen-3 respectively
--- old post above --- --- new post below ---
Ah my apologies. I thought he was asking what an isotope was, not referring to the fact that the only three isotopes hydrogen has are Hydrogen-1, Hydrogen-2 (as you say, deuterium) and Hydrogen-3 (tritium).

Very good :)
 
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ralphchadkirk

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:) I really don't know. The only isotopes with mass number 14 belong to Nitrogen and Carbon. Perhaps he can get back to us and tell! Maybe he knows full well and is trying to test us lol

Nitrogen-14 is non-radioactive, and thus has no half life, and Carbon-14's half life is ~5730 years or thereabouts! So where did 5 seconds come from? :s
 

strange6

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Nitrogen-14 is non-radioactive, and thus has no half life, and Carbon-14's half life is ~5730 years or thereabouts! So where did 5 seconds come from? :s

I await the response. Atomic science is really weird you know. How come U-235 is fissile and yet U-238 is not? Why do the addition of just 3 neutrons in a massive nucleus enable the atom to become nuclear non-active? I did do the theory of this 15 years ago but luckily, i don't need to know now :)
 

Spaceflower

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After the Chernobyl explosion, miners had to dig a tunnel underneath the reactor to seal it. They wore no protection, were hailed as national heroes and many are now dead. News footage from aircraft flying over the reactor and from reporters on the ground shows 'radiation burns' in the film. Many of these reporters suffered radiation sickness. Wildlife in the Pripyat area is not flourishing, it suffers greatly. There was a study on birds in the area not so long back. The results were not good. There is a good documentary here:
http://www.youtube.com/watch?v=uoEgkGNO-sQ&feature=related
 

strange6

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After the Chernobyl explosion, miners had to dig a tunnel underneath the reactor to seal it. They wore no protection, were hailed as national heroes and many are now dead. News footage from aircraft flying over the reactor and from reporters on the ground shows 'radiation burns' in the film. Many of these reporters suffered radiation sickness. Wildlife in the Pripyat area is not flourishing, it suffers greatly. There was a study on birds in the area not so long back. The results were not good. There is a good documentary here:
http://www.youtube.com/watch?v=uoEgkGNO-sQ&feature=related

According to the BBC, the wildlife is flourishing! But thanks for the comment

http://news.bbc.co.uk/1/hi/world/europe/4923342.stm

But you're right about tthe many individuals who risked their own life for the protection of others. True hero's who should never be forgoten
 

WatcherZero

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According to the BBC, the wildlife is flourishing! But thanks for the comment

http://news.bbc.co.uk/1/hi/world/europe/4923342.stm

But you're right about tthe many individuals who risked their own life for the protection of others. True hero's who should never be forgoten

If you read the article:

Four square kilometres of pine forest in the immediate vicinity of the reactor went ginger brown and died, earning the name of the Red Forest.
Some animals in the worst-hit areas also died or stopped reproducing. Mice embryos simply dissolved, while horses left on an island 6km from the power plant died when their thyroid glands disintegrated.

Cattle on the same island were stunted due to thyroid damage, but the next generation were found to be surprisingly normal.

Now it's typical for animals to be radioactive - too radioactive for humans to eat safely - but otherwise healthy.

It goes on to say the animals flourishing are the ones that move in and out of the hot zones while those that stay within the zones are still suffering.

Things going from bad to worse in Japan, the explosion of No. 3 reactor occured when a fire engine ran out of fuel and the explosion took out four of the five water pumps making cooling reactor No. 2 even harder, its now been fully exposed three times in the last 24 hours. the valves to release steam keep clogging now too (possibly as their using sea water?) theyve managed to reopen one to let steam out so they could add more water but now they suspect leaks as the water level isnt rising.
 

strange6

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If you read the article:



It goes on to say the animals flourishing are the ones that move in and out of the hot zones while those that stay within the zones are still suffering.

Things going from bad to worse in Japan, the explosion of No. 3 reactor occured when a fire engine ran out of fuel and the explosion took out four of the five water pumps making cooling reactor No. 2 even harder, its now been fully exposed three times in the last 24 hours. the valves to release steam keep clogging now too (possibly as their using sea water?) theyve managed to reopen one to let steam out so they could add more water but now they suspect leaks as the water level isnt rising.

Cheers. The design of the reactors should still be able to contain the fuel, even if molten. Let's pray and wait to see! Thanks
PS And remember, the reactor itself did not explode. What exploded was the actual containment building in which the reactor sits deep underground. This was due to the pressure (i.e hydrogen) being released into the containment building from the reactor by the engineers
 
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Hydro

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Plus the after images of the explosion from the first reactor show that the outer containment building is still remarkably intact given the impressive look of the explosion. The steel framework is still standing, and the concrete cladding attached to it was what actually blew off.
 

strange6

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Plus the after images of the explosion from the first reactor show that the outer containment building is still remarkably intact given the impressive look of the explosion. The steel framework is still standing, and the concrete cladding attached to it was what actually blew off.

Yup! The Japanese are not stupid. That's why most of the world's best people have confidence in their engineering abilities. Remarkable race of people.
 

WatcherZero

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The US fleet providing helicopter refueling assitance off the coast which this morning put out to sea after it detected radiation is now going to attempt to get closer again. They will be taking 'measures to minimise radiation exposure to the 15,000 sailors' presumably battening down the hatches and going in with NBC air flitration systems on.
 

strange6

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An interesting article that you may find worth reading which kind of puts the whole thing in to perspective.

El Reg

Good article and true to the facts. Modern day reactors are even safer because they have design features built into them that even in the event of no coolant reaching the core, decay heat will be dispersed of through naturally conventional means. Nuclear power is expensive and waste is still a problem (but can be burried within glass deep underground quite safely) but with today's technology, it is very safe indeed. Besides, it's the only genuine source of energy that can satisfy the world's energy needs without resort to burning carbon in one form or another
 

Hydro

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An interesting article that you may find worth reading which kind of puts the whole thing in to perspective.

El Reg

Excellent article. I think it's too early to start back slapping yet, but I definitely agree that these reactors have so far stood up to a one in a million test of one of the most powerful earthquakes to hit Japan, plus a gigantic tsunami, two massive hydrogen induced explosions within their housing buildings, and come out rather well.
 

WatcherZero

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Theyve just admitted there is a crack in the casing of reactor No. 3 and it is still unstable but claim theres no increase in radiation.
 

jon0844

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Okay boys and girls.. all this talk about neutrons, uranium 238, deuterium, tritium and so on is all very easy and a waste of our time. Frankly, it's rather patronising to think we don't all know everything there is to know already.

Can we therefore get back to talking about the more complicated things like UK railway ticketing and interpreting the NrCOC?
 

ainsworth74

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Can we therefore get back to talking about the more complicated things like UK railway ticketing and interpreting the NrCOC?

No! This is our thread for talking about neutrons and such like! If you want to talk about NRCoC then go do it somewhere else!!

;)
 

Hydro

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Nuclear physics pales in comparison to deciphering UK ticketing, routeing and the NRCoC.
 

ainsworth74

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A third explosion is being reported:

BBC News said:
Japan earthquake: New blast at Fukushima nuclear plant

A fresh explosion has been heard at a quake-hit nuclear plant in northern Japan, local media say.

Technicians have been battling to stabilise reactor 2 at the Fukushima Daiichi plant, after two other reactors exploded in three days.

International nuclear watchdogs said there was no sign of a meltdown but one minister said it was "highly likely" that the rods might melt.

The crisis was sparked by a 9.0-magnitude quake and tsunami on Friday.

Japanese authorities have so far given no details about the cause or nature of the third explosion.

Thousands of people are believed to have died, and millions are spending a fourth night without water, food, electricity or gas. More than 500,000 people have been left homeless.

On Monday, a hydrogen blast at the Fukushima Daiichi's reactor 3 injured 11 people and destroyed the building surrounding it. The explosion was felt 40km (25 miles) away and sent a huge column of smoke into the air.

It followed a blast at reactor 1 on Saturday.

Source
 
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