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pwnasaurus
Stranger



Registered: 07/16/08
Posts: 12,317
Loc: Canada
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Re: Fukushima cooling systems down, global nuclear catastrophe imminent? [Re: Moonshoe]
#17986941 - 03/20/13 09:21 PM (10 years, 11 months ago) |
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Quote:
Moonshoe said: Im glad I reinforced my survival supplies and planning. Now I have time to buy proper gas masks and tyvek suits before the shit really hits the fan!

                                
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akira_akuma
Φύσις κρύπτεσθαι ὕψιστος φιλεῖ


Registered: 08/28/09
Posts: 82,455
Loc: Onypeirophóros
Last seen: 4 years, 2 months
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Re: Fukushima cooling systems down, global nuclear catastrophe imminent? [Re: pwnasaurus]
#17987035 - 03/20/13 09:39 PM (10 years, 11 months ago) |
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*waits for doomsday*
*gets bored, heads to the microwave*
hmm
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Sophistic Radiance
Free sVs!



Registered: 07/11/06
Posts: 43,135
Loc: Center of the Universe
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Re: Fukushima cooling systems down, global nuclear catastrophe imminent? [Re: akira_akuma]
#17987043 - 03/20/13 09:40 PM (10 years, 11 months ago) |
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So I have to keep studying?
-------------------- Enlil said: You really are the worst kind of person.
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mel0n420
Sgt. Spock


Registered: 01/28/13
Posts: 250
Loc: On mescaline in Nevada
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Re: Fukushima cooling systems down, global nuclear catastrophe imminent? [Re: unknown1123]
#17987098 - 03/20/13 09:50 PM (10 years, 11 months ago) |
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Quote:
unknown1123 said: I just watch the battle of Chernobyl and holy fuck that was bad
haha right? that shit was crazy.
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Katzenjammer
Lurker



Registered: 03/02/09
Posts: 418
Loc: Ontario
Last seen: 8 years, 8 months
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: starfire_xes]
#17987287 - 03/20/13 10:27 PM (10 years, 11 months ago) |
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Quote:
starfire_xes said:
Quote:
Katzenjammer said: Bear in mind these are SPENT fuel rods, meaning they are not easily fissile and won't explode Chernobyl-style if they boil off all the coolant. It will just suck really hard for the engineers who would have to figure out a way to deal with the rods without being able to send living workers into the general vicinity after a major loss of water.
Sorry to say, but there's no Doomsday happening anytime soon due to Fukushima.
Actually, they do fission but you don't get an explosion from the fission--that requires a very precise geometry. You get low level fission which is represented by the colored glow of cherenkov radiation, which is what happens when a charged particle is emitted from an atom and passes through a dielectric medium faster than the phase velocity of light. So you get lots of energy given off in the form of heat and light, but not an explosion.
I believe what happened in Cherobyl was an expolsion caused by superheated steam contained in the domes, it wasn't a nuclear explosion.
Now I doubt you'd want to be close to a cooling pond with rods melting and giving off massive amounts of cherenkov radiation.
Maybe someone who is a Physicist could correct me, I'm just an engineer.
Excellent clarification, you know your shit man From a few sources I've come across, there was not only the steam explosion that blew the top of the reactor housing off at Chernobyl; but there was a second, larger explosion caused by the resulting sudden , massive chain reaction in the rods without a moderator. So technically, it WAS a nuclear explosion, but not in the sense that most would initially picture.
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grayrey
Registered: 03/21/13
Posts: 335
Last seen: 10 years, 6 months
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: Katzenjammer]
#17987986 - 03/21/13 03:32 AM (10 years, 11 months ago) |
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It’s really hard to get straight facts about anything dealing with radiation from media sources. I’m a long time lurker and figured I could shed some light on this topic. I’m currently studying in the field, I know people that used to work at fukushima, and several of my colleagues were part of the US Navy Nuke response effort when the shit was hitting the fan…
When a nuclear reactor “explodes” it really is not considered a nuclear explosion. The nuclear reaction is supplying heat to a pressure vessel, in the case of Chernobyl the pressure vessel is what exploded. The fuel is actually all relatively in the same place in a massive blob referred to as the elephant’s foot, the industry calls melted fuel “corium” mostly because it becomes rather difficult to really identify chemical makeup of the core after meltdown. Fission creates a large neutron flux and anything that comes into contact with the core can become activated and form its own decay chain of radionuclides.
Chernobyl was fundamentally different than Fukushima in that no reactor vessels ever exploded. Nuclear fuel is incased in a metal called zirconium, the zirconium acts to keep the harmful fission products of the uranium fission process contained and out of the atmosphere and reactor water. The fuel rod assemblies in the reactors at fukushima got hot enough for the zirconium to begin braking down. The zirconium itself started reacting with superheated water producing hydrogen as a byproduct. When the crew was forced to depressurize the reactor vessels the hydrogen collected in the buildings causing explosions of the reactor service floors (the portion of the building above the reactor). However the reactors themselves remained intact. I believe one reactor was breached later on due to superheated corium that made its way through the bottom of the reactor however it wasn’t in an explosive matter.
Fuel: Spent nuclear fuel still undergoes fission and needs to be cooled, the fuel is still fairly “hot” after it comes out of a reactor and typically has an active cool down period of 5-10yrs in a spent fuel pool. After this period the fuels activity has decreased enough to be stored in dry casks and the heat will naturally self-regulate. The primary concern for Fukushima is reactor 4, this reactor was refueling during the time of the quake and all of the spent fuel for this reactor was placed in the holding pond of the service floor. It is a lot more fuel than the other pools and it is still very fresh and a primary concern. Among the 50yr Fukushima cleanup plan, handling this spent fuel is the top priority however it’s much easier said than done.
Last thing: Cerenkov radiation. Cerenkov radiation, while rather spectacular to the eye (I have seen it in person) is not really much of a concern. Cerenkov radiation is caused by high energy beta particles. The primary concern for melted fuel is the fission products that escape if the zirconium barrier is breached. Strontiun-90, Tritium, Cesium-137, Iodine-131, and the list goes on.. Even if the fuel is intact, the gamma radiation produced by the extremely high levels of cesium will reach out further than the Cerenkov. Unfortunately many of these products are aerosolized by the super-heated fuel and form a giant cloud of mixed radionuclides in the area creating an external radiation hazard and an inhalation hazard. Many of these radionuclides are gamma emitters so you can see how the radiation field can be far reaching and unpredictable. I have only ever been taught one rule about melted fuel (corium): if you see it, run.
Edited by grayrey (06/25/13 07:51 PM)
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Moonshoe
Blue Mantis


Registered: 05/28/04
Posts: 27,202
Loc: Iceland
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: grayrey]
#17989113 - 03/21/13 11:30 AM (10 years, 11 months ago) |
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Great post thanks for sharing your knowledge. So to clarify how would you compare fuku and Chernobyl in terms of severity ? And how bad would the worst case scenario be at reactor 4?
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Everything I post is fiction.
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hidenseek1
Its got all the dinks.
Registered: 12/22/12
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: Moonshoe]
#17989503 - 03/21/13 12:56 PM (10 years, 11 months ago) |
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well fuku too!
-------------------- You can drink at 7 A.M., because the Beastie Boys fought for that right -------------------------------------------------------------------------- pons asinorum -------------------------------------------------------------------------- lsd and the vietnam war changed music forever
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JesusIsLord
Jesus freak


Registered: 08/10/12
Posts: 8,061
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: Moonshoe]
#17989876 - 03/21/13 02:29 PM (10 years, 11 months ago) |
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Quote:
Moonshoe said: Great post thanks for sharing your knowledge. So to clarify how would you compare fuku and Chernobyl in terms of severity ? And how bad would the worst case scenario be at reactor 4?
fukushima = tornado
chernobyl = fart
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And I will bring you out from the people, and will gather you out of the countries wherein ye are scattered, with a mighty hand, and with a stretched out arm, and with fury poured out.
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grayrey
Registered: 03/21/13
Posts: 335
Last seen: 10 years, 6 months
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: Moonshoe] 1
#17990293 - 03/21/13 03:57 PM (10 years, 11 months ago) |
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Severity is hard to quantify, the numbers are really all over the place. It’s impossible to know exactly how much radiation is released in these events but the numbers tend to go something like this. Fukushima was 5-10 times less severe than Chernobyl, and Chernobyl was 50-100 times less severe than the nuclear weapons testing era. There are so many complexities involved with measuring radiation releases that the numbers can be skewed all over the place. Regardless, the biggest anthropogenic releases were definitely during the nuclear testing era.
A worst case scenario at reactor 4 fuel pond could potentially be a bigger problem than what fukushima started with. The fuel is still in the early stages of cool down and capable of melting if not activly cooled. The fuel pond is located on the reactor service floor several stories above ground level. If the fuel melted it could potentially compromise the pools integrity making it impossible to fill with water. Another earthquake or catastrophic event could also initiate this scenario. I don’t really see how they could possibly control the situation if the pool was to become significantly damaged, this would basically be a zero containment scenario. Very different than having control of the release (albeit limited control) like in fukushimas original situation. The fuel would likely make way down into the reactor building and eventually settle like it did in Chernobyl, fire would likely ensue minus the explosions because we aren’t dealing with a pressure vessel in this situation. However at least two of the neighboring reactors need active cooling to remain in cold shut down status, if these systems were affected by a catastrophe in reactor 4 who really knows how bad the situation could get… That particular pool receives the most attention and hopefully they can sit on it for 5 yrs or so until it cools down a bit. I don’t personally see them being able to remove the fuel before then.

With that said, the fukushima catastrophe means something different for Japan than it does for the rest of the world.. When you look at the numbers and don’t really understand them it is easy to get alarmed, the media tends to report radiation contamination numbers in a way that does not always paint an accurate picture of the risks. When a release happens the radiation is highly concentrated at the point of origin but in reality it dilutes to concentrations that aren’t readily traceable thereafter.
An average Americans lifetime radiation dose looks something like this

You encounter radiation every day, you inhale radon, you ingest foods with natural radioactivity, you receive radiation dose from standard medical procedures, smoking, and even if you somehow avoid all of that you can’t escape the cosmic radiation zipping through your body every day and even right now as you read this post. Anthropogenic (manmade) radiation releases like nuclear accidents and atomic weapons testing only account for about 0.167% of your lifetime radiation dose. You live on a very radioactive planet powered by a very radioactive Sun.
The people most affected by nuclear disasters are the first responders and people in the immediate area of the disaster. Radiation emanation follows the inverse square law, basically this means that if you double your distance from the radiation source you decrease your exposure by 4 times. And If you quadruple your distance from the source the exposure decreases by 16 times and so on…
The ICRP model for stochastic risk assessment states that a dose of 1 Sv (Sievert) = 5% chance of developing a cancer. Looking at some random numbers to grasp dose:
Highest exposure to an individual at fukushima was approximately 650 mSv 0.650 Sv * 5% = 3.25% chance of developing a cancer from the exposure.
Average fukushima emergency worker dose was approximately 100 mSv 0.100 Sv * 5% = 0.5% chance of developing cancer from the exposure
Highest exposure at Chernobyl was approximately 16 Sv (16,000 mSv) 16 Sv * 5% = 80% chance of cancer. Many of the individuals with doses this high suffered from radiation sickness and died in the years following the event.
Average CT Scan of the abdomen is approx. 8 mSv 0.008 Sv * 5% = 0.04% chance of developing a cancer from the exposure.
Annual dose from background radiation is approximately 3.5 mSv 0.0035 Sv * 5% = 0.0175% chance annually.
The recent fish caught at fukushima that was over 7000 times the safe food limit had about 740,000 Bq/kg of Cesium contamination, which equates to approximately 100 mSv/kg for cesium gamma. 0.100 Sv * 5% = 0.5% of cancer per kilogram of fish
A few fish caught off the coast of California were said to have 5 times the normal amount of radiation activity from cesium contamination. This was about 5 Bq/kg which equates to approximately 0.000676 mSv 6.75X10^-7 Sv * 5% = 0.0000034% chance of cancer… These numbers are so low they are meaningless, and frankly way beyond the intended use of the ICRP model to begin with. Yet it still gets reported… This type of miscommunication happens all the time, just because radiation is detectable does not mean it’s dangerous.
The calculations above follow the simplest form of the linear no threshold model and are based on numbers I could conveniently find or remember. All I am really trying to do is paint a picture of general observations as a function of dose. Primarily you can see that the worst of the Chernobyl exposures were much more severe than the worst of the fukushima exposures.
Let’s take the most exposed fukushima worker with a 3.25% risk and compare it to normal background radiation risk of 0.0175%. The difference appears monumental, but does it tell us anything tangible? The media headline would read something like “fukushima workers now 185 times more likely to develop cancer”. Say that the fukushima worker shows up to a clinic with cancer in 20yrs, was it caused by the radiation exposure? Maybe he was a smoker (~30% chance of causing cancer). Maybe he ate copious amounts of red meat every day, or had a woodworking hobby and worked with solvents.. These might be crappy examples but the overall point is that it is very difficult to say whether or not a cancer was induced by a small to moderate radiation exposure because there are far more potent carcinogens that people readily expose themselves to.
I’m not trying to downplay the fukushima tragedy, it was a very unfortunate event that displaced hundreds of thousands of people. But on the global scale, even if there were a second incident, life would continue normally for the vast majority of the world population. Fukushima will mostly remain a localized problem despite what you may read in the paper..
Edited by grayrey (04/24/13 12:27 AM)
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Moonshoe
Blue Mantis


Registered: 05/28/04
Posts: 27,202
Loc: Iceland
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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: grayrey]
#17990578 - 03/21/13 04:53 PM (10 years, 11 months ago) |
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Amazing effort on that post, thank you! Five shrooms.
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Everything I post is fiction.
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snoot
look alive ∞



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Re: Fukushima cooling systems down, global nuclear catastrophe immanent? [Re: Moonshoe]
#18746628 - 08/23/13 10:37 AM (10 years, 6 months ago) |
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ray is banned? awww.
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∞ I am incapable of conceiving infinity, and yet I do not accept finity. - Simone de Beauvoir -
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