Fukushima question

[AmdEmAll]

Saw this posted on my FB and it got me thinking..

http://www.activistpost.com/2013/10...uffer&utm_medium=facebook&utm_campaign=Buffer

I know a lot of that is most likely bs but there is clearly still a major problem at Fukushima.

Theoretically if we could extract the rods out of the reactors and storage pools(huge challenge), why couldn't we just ship them to a part of the ocean thousands of feet deep and just drop them in. It would keep them constantly cooled.

Would that radiate the entire ocean? If any of the rods touch, would they create an even worse reaction?

 

[RampantAndroid]

Saw this posted on my FB and it got me thinking..

http://www.activistpost.com/2013/10...uffer&utm_medium=facebook&utm_campaign=Buffer

I know a lot of that is most likely bs but there is clearly still a major problem at Fukushima.

Theoretically if we could extract the rods out of the reactors and storage pools(huge challenge), why couldn't we just ship them to a part of the ocean thousands of feet deep and just drop them in. It would keep them constantly cooled.

Would that radiate the entire ocean? If any of the rods touch, would they create an even worse reaction?

I don't think fissile material is able to have a reaction by itself. Touching isn't an issue. If properly sealed, you'd be safe from radiation, but why put it in the ocean? Deep under a mountain is a far better option. Salt water is incredibly corrosive.

I don't see how Fukushima would cause this much trouble. Chernobyl was far worse in spreading radiated material around since it actually blew concrete the lid off the reactor. The issue with Chernobyl is that the sarcophagus built around it relies on the rubble from the reactor for support - that will eventually fail and collapse. A new cover is needed...and the Ukraine cannot afford it.

 

[AmdEmAll]

This article touches on how dangerous it is if some of the unused fuel rods touch each other upon removal.

http://www.tokyotimes.com/2013/tepc...e-400-tons-of-irradiated-fuel-from-fukushima/

The operation, beginning this November at the plant's Reactor No. 4, is a dangerous one and includes the possibility of a large release of radiation if a fuel assembly breaks, gets stuck or gets too close to an adjacent bundle, said Gundersen and other nuclear experts.

Doesn't say what they plan on doing with these rods.. these rods haven't reacted yet im assuming since they are new so maybe they are safe for now?

A mountain would be a good place but wouldn't the other rods still need to be cooled while being stored inside the mountain?

 

[RampantAndroid]

Rods by themselves give off radiation, not heat. Heat is produced by fission, and that heat is in turn used to make steam which is run through a turbine, condensed again and the cycle repeats. No reaction = no heat. If you pack enough material into a small area maybe you'll get a reaction, but I'm not sure about that.

A fission reaction is kicked off by firing neutrons into the rods. As I understand nuclear power plants, they have a source in the center of the core that is firing out neutrons. As long as the control rods remain in place, they absorb neutrons and prevent a reaction. Pull those rods out, the reaction begins. Remove the neutron source though (and the control rods, while we're at it) and no reaction will occur.

That's my understanding, but I'm no expert. A quick look on google about rods touching turns up nothing but articles about Fukushima. Nothing saying what happens when rods touch.

 

[Atomic Playboy]

That's my understanding, but I'm no expert. A quick look on google about rods touching turns up nothing but articles about Fukushima. Nothing saying what happens when rods touch.

I Googled "Japanese rods touching" and now I have some serious 'splaining to do to the wife.

 

[Matt1970]

I Googled "Japanese rods touching" and now I have some serious 'splaining to do to the wife.

lol. I don't even want to know what was in the drop down blox after you typed Japanese Rods

 

[AmdEmAll]

I Googled "Japanese rods touching" and now I have some serious 'splaining to do to the wife.

Just don't look up kenyan rods touching

 

[gevorg]

The issue with Chernobyl is that the sarcophagus built around it relies on the rubble from the reactor for support - that will eventually fail and collapse. A new cover is needed...and the Ukraine cannot afford it.

http://rt.com/news/chernobyl-new-safe-confinement-773/

 

[shira]

Aren't the rods in three of the Fukushima reactors melted down? How on earth could puddles of molten fuel rods (or at best, re-solidified former-puddles) be "extracted" from the reactors?

 

[AmdEmAll]

Aren't the rods in three of the Fukushima reactors melted down? How on earth could puddles of molten fuel rods (or at best, re-solidified former-puddles) be "extracted" from the reactors?

Good point.. a lot of it cannot be extracted. What a disaster.

Lets hope these two typhoons don't collide and cause more issues.

 

[slightlyhuman]

man this scares the shit out of me.

can someone give any positive information about this related to cleanup or anything for the future that gives hope?

srs question

 

[RampantAndroid]

Aren't the rods in three of the Fukushima reactors melted down? How on earth could puddles of molten fuel rods (or at best, re-solidified former-puddles) be "extracted" from the reactors?

THey shouldn't be puddles. Rods are housed in graphite IIRC (at least in older reactors they were) and really should not just leak out the bottom. They might be fused into the reactor's structure, but they won't be a mass of glowing fissile material

 

[Llwellyn]

That's my understanding, but I'm no expert. A quick look on google about rods touching turns up nothing but articles about Fukushima. Nothing saying what happens when rods touch.

I'm not an expert either, and without going to quote sources, here's the quick and dirty.

Fuel rod assemblies consist of uranium oxide pellets embedded strategically in a zirconium alloy cladding (basically, advanced ceramics). Each pellet by itself isn't particularly harmful*, and at the outset of a fuel cycle, it's mostly pure fissile material with very little waste*.

As the reactor runs and the material runs through the fission process in the reactor, waste products build up as the fuel converts from one form of uranium into another. These byproducts are non-fissile and much more harmful and radioactive than the uranium itself, and they affect the reaction, which is why they eventually have to change out the rods, and then leave the old rods in spent fuel storage.

The rods themselves will give off heat due to radioactive decay. The fission process itself generates orders of magnitude more heat, which is why it's used to generate the heat that turns the turbines to generate the power.

If the rods were not cooled properly, this decay heat would quickly distort and warp the cladding on the rod, allowing the pellets to move closer to one another and mingle within the same rod and from adjacent rods. At some point, you would reach the critical point of the fissile material (this doesn't mean a nuclear explosion) but it still does mean one hell of a mess to clean up... millions to billions of curies of reaction byproducts released to the atmosphere, and anyone within the vicinity of the criticality dead from radiation poisoning or the explosion.

The overheating of the rods is what fucked them in the first place in three of the reactors; when the cladding breaks down, it reacts with water in some fashion and either electrolyzes it or some other reaction and releases large quantities of hydrogen as a free gas.

If this is happening inside your reactor core and your vents to containment are not working properly, or you shut them on purpose because of other problems, you are going to go BOOM after awhile, which is exactly what happened. They blew out the containment building walls from hydrogen explosions.

Incidentally, this is also the problem that was happening at Three Mile Island once the water level fell critically low. Fortunately, they realized what was happening in time to get water back into the core and someone else also miscalculated how bad hydrogen buildup really was (it wasn't as bad as they expected and they had started emergency mitigation measures), and they didn't get an explosion. The core was still ruined, but Cumberland County is still inhabitable. That's the difference.

 

[shira]

http://rt.com/news/chernobyl-new-safe-confinement-773/

Anarchist has been posting on that website as "Ottoman:"

I believe that Chernobyl disaster planned by US to destroy CCCP. "Three seismic posts of the Soviet Special Control Service located in Ukraine also managed to detect some “strange” seismic activity in connection with the “accident” under the reactor No.4 of the Chernobyl power plant. Seismograms showed a strange pick with magnitude slightly over 3 on the Richter scale right at the moment of the “accident” – representing nothing else than a mini-nuclear explosion of about 0.1 kiloton (100 metric ton) in TNT yield. Showing that the mini-nuke was hidden not sufficiently deep underground to cause the full 3.5 magnitude (exactly as it was in the case with the infamous Oklahoma bombing in 1995 which produced also exactly 3.0 on the Richter scale because the 0.1 kiloton mini-nuke was hidden in shallow sewage opposite the building rather than deep underground). Seismic evidence that shows something truly “unexplainable” in connection to the Chernobyl “nuclear catastrophe” is widely available in nowadays Ukraine, as well as in Russia. But, “strangely enough”, the above article in Wikipedia does not enlighten its reader about that unexplainable particular."

 

[Franz316]

Last I read, TEPCO has absolutely no idea where the molten cores actually are. They could be sitting in a puddle at the bottom of the containment vessel or on the floor of the building, or even worse through everything and in the ground. Given the amount of radiation inside those buildings, I'd imagine that the molten masses are still in there. There is even a chance that there is open air fission going on. It's basically a worst case scenario with no good solution.

Then you factor in the spent fuel rod pools which are an earthquake away from collapsing and you have a real doozy. I really don't know how this all ends.

 

[RampantAndroid]

I'm not an expert either, and without going to quote sources, here's the quick and dirty.

Fuel rod assemblies consist of uranium oxide pellets embedded strategically in a zirconium alloy cladding (basically, advanced ceramics). Each pellet by itself isn't particularly harmful*, and at the outset of a fuel cycle, it's mostly pure fissile material with very little waste*.

As the reactor runs and the material runs through the fission process in the reactor, waste products build up as the fuel converts from one form of uranium into another. These byproducts are non-fissile and much more harmful and radioactive than the uranium itself, and they affect the reaction, which is why they eventually have to change out the rods, and then leave the old rods in spent fuel storage.

The rods themselves will give off heat due to radioactive decay. The fission process itself generates orders of magnitude more heat, which is why it's used to generate the heat that turns the turbines to generate the power.

If the rods were not cooled properly, this decay heat would quickly distort and warp the cladding on the rod, allowing the pellets to move closer to one another and mingle within the same rod and from adjacent rods. At some point, you would reach the critical point of the fissile material (this doesn't mean a nuclear explosion) but it still does mean one hell of a mess to clean up... millions to billions of curies of reaction byproducts released to the atmosphere, and anyone within the vicinity of the criticality dead from radiation poisoning or the explosion.

The overheating of the rods is what fucked them in the first place in three of the reactors; when the cladding breaks down, it reacts with water in some fashion and either electrolyzes it or some other reaction and releases large quantities of hydrogen as a free gas.

If this is happening inside your reactor core and your vents to containment are not working properly, or you shut them on purpose because of other problems, you are going to go BOOM after awhile, which is exactly what happened. They blew out the containment building walls from hydrogen explosions.

Incidentally, this is also the problem that was happening at Three Mile Island once the water level fell critically low. Fortunately, they realized what was happening in time to get water back into the core and someone else also miscalculated how bad hydrogen buildup really was (it wasn't as bad as they expected and they had started emergency mitigation measures), and they didn't get an explosion. The core was still ruined, but Cumberland County is still inhabitable. That's the difference.

Good explanation, and more than I knew before.

Also, I went to college a few miles away from TMI...

 

[TwiceOver]

Good point.. a lot of it cannot be extracted. What a disaster.

Lets hope these two typhoons don't collide and cause more issues.

Ummm.

http://www.usatoday.com/story/news/world/2013/10/25/earthquake-japan/3189061/

That can't be good.

 

[sm625]

There is nothing wrong at fukushima. Just eat your GMO and take your mercury shots and maybe you will die from that before the radiation gets to you.

 

[exdeath]

Rods by themselves give off radiation, not heat. Heat is produced by fission, and that heat is in turn used to make steam which is run through a turbine, condensed again and the cycle repeats. No reaction = no heat. If you pack enough material into a small area maybe you'll get a reaction, but I'm not sure about that.

A fission reaction is kicked off by firing neutrons into the rods. As I understand nuclear power plants, they have a source in the center of the core that is firing out neutrons. As long as the control rods remain in place, they absorb neutrons and prevent a reaction. Pull those rods out, the reaction begins. Remove the neutron source though (and the control rods, while we're at it) and no reaction will occur.

That's my understanding, but I'm no expert. A quick look on google about rods touching turns up nothing but articles about Fukushima. Nothing saying what happens when rods touch.

Neutrons are created by natural spontaneous fission of U235. How much of these neutrons are slowed down and absorbed by other U235 to cause them to fission prematurely is controlled by a neutron moderator and fuel geometry. A neutron initiator may be used to speed up a cold start up but simply removing the control rods and exposing the fuel to itself is enough for a chain reaction to start as the natural decay of U235 produces neutrons and bombards its exposed neighbors, causes more fission events, etc.

With enough U235 in close proximity and/or neutron reflectors you can achieve a chain reaction on your kitchen table with nothing else but a few seemingly harmless chunks of cold metal using your bare hands and be relatively safe. Until you are at 99% criticality and your hand slips. Suddenly there is a flash of light, a heat wave, and a metal taste in your mouth that confirms you are a walking dead man. You just achieved your runaway chain reaction. At least until run away thermal expansion changes the fuel density and geometry enough to reduce your neutron gain and stop the reaction on its own.

But in that fraction of a second that you put the materials too close together and went prompt supercritical, the majority of cells in your body were just bathed in ionizing gamma radiation that tore apart the electron bonds that comprise the chemical structure that make up your bodily tissues. This most significantly includes your DNA so you can no longer replicate healthy cells and recover from it. As well as atoms like the carbon in your tissues absorbing neutron flux and transmutating into other elements that are not conducive to organic compounds. With half your body already dead and the healthy half unable to reproduce healthy tissue, even though you feel fine now, you will die a slow agonizing death in next 10 days as the rest of your body shuts down, unable to repair itself or function at a molecular level.

U235 itself isn't the greatest concern as its relatively stable (that's why we can still find and mine it on Earth). Stable means long lived which means less radioactive. Its the unstable fission products that are left after U235 splits that are much more active and therefore unstable, as well as the remaining 95% of non U235 fuel that has been transmutted into active isotopes via neutron exposure, eg Pu239. Pure 5% enriched uranium isn't even a real hazard by itself, other than being a toxic heavy metal and very long term neutron irradiation of its container.

The extremely active byproducts decay rather fast and "use" all their half lifes in a matter of days until there is none left, while the stable stuff like U235 last long enough that the decay is slow enough that its not a significant source of radiation. When its bad are the random elements that have a half life of 10-1,000 years. Short enough to be highly radioactive but long enough that it doesn't decay away quickly so we are stuck with storing it.

 

[exdeath]

Saw this posted on my FB and it got me thinking..

http://www.activistpost.com/2013/10...uffer&utm_medium=facebook&utm_campaign=Buffer

I know a lot of that is most likely bs but there is clearly still a major problem at Fukushima.

Theoretically if we could extract the rods out of the reactors and storage pools(huge challenge), why couldn't we just ship them to a part of the ocean thousands of feet deep and just drop them in. It would keep them constantly cooled.

Would that radiate the entire ocean? If any of the rods touch, would they create an even worse reaction?

Oceans move. Materials would be dispersed making the water a radiological hazard. We also get food from the ocean, and the oceans touch the land we live on, evaporation and rain cycles, rivers, etc. Oh and the wild life and other ethics issues. Its just a bad idea all around to introduce such substances to the ecosystem. It needs to be contained indefinitely, reprocessed and elements separated and dealt with independently, or shipped off the planet.

 

[werepossum]

I don't think fissile material is able to have a reaction by itself. Touching isn't an issue. If properly sealed, you'd be safe from radiation, but why put it in the ocean? Deep under a mountain is a far better option. Salt water is incredibly corrosive.

I don't see how Fukushima would cause this much trouble. Chernobyl was far worse in spreading radiated material around since it actually blew concrete the lid off the reactor. The issue with Chernobyl is that the sarcophagus built around it relies on the rubble from the reactor for support - that will eventually fail and collapse. A new cover is needed...and the Ukraine cannot afford it.

They don't even have to be touching; too many rods in close proximity can cause a chain reaction. Remember that most substances are not good at damping a nuclear reaction.

Folks may remember a couple decades ago that Japan inadvertently started a chain reaction in a nuclear landfill by simply putting in too many spent rods.

I Googled "Japanese rods touching" and now I have some serious 'splaining to do to the wife.

LMAO!

Neutrons are created by natural spontaneous fission of U235. How much of these neutrons are slowed down and absorbed by other U235 to cause them to fission prematurely is controlled by a neutron moderator and fuel geometry. A neutron initiator may be used to speed up a cold start up but simply removing the control rods and exposing the fuel to itself is enough for a chain reaction to start as the natural decay of U235 produces neutrons and bombards its exposed neighbors, causes more fission events, etc.

With enough U235 in close proximity and/or neutron reflectors you can achieve a chain reaction on your kitchen table with nothing else but a few seemingly harmless chunks of cold metal using your bare hands and be relatively safe. Until you are at 99% criticality and your hand slips. Suddenly there is a flash of light, a heat wave, and a metal taste in your mouth that confirms you are a walking dead man. You just achieved your runaway chain reaction. At least until run away thermal expansion changes the fuel density and geometry enough to reduce your neutron gain and stop the reaction on its own.

But in that fraction of a second that you put the materials too close together and went prompt supercritical, the majority of cells in your body were just bathed in ionizing gamma radiation that tore apart the electron bonds that comprise the chemical structure that make up your bodily tissues. This most significantly includes your DNA so you can no longer replicate healthy cells and recover from it. As well as atoms like the carbon in your tissues absorbing neutron flux and transmutating into other elements that are not conducive to organic compounds. With half your body already dead and the healthy half unable to reproduce healthy tissue, even though you feel fine now, you will die a slow agonizing death in next 10 days as the rest of your body shuts down, unable to repair itself or function at a molecular level.

U235 itself isn't the greatest concern as its relatively stable (that's why we can still find and mine it on Earth). Stable means long lived which means less radioactive. Its the unstable fission products that are left after U235 splits that are much more active and therefore unstable, as well as the remaining 95% of non U235 fuel that has been transmutted into active isotopes via neutron exposure, eg Pu239. Pure 5% enriched uranium isn't even a real hazard by itself, other than being a toxic heavy metal and very long term neutron irradiation of its container.

The extremely active byproducts decay rather fast and "use" all their half lifes in a matter of days until there is none left, while the stable stuff like U235 last long enough that the decay is slow enough that its not a significant source of radiation. When its bad are the random elements that have a half life of 10-1,000 years. Short enough to be highly radioactive but long enough that it doesn't decay away quickly so we are stuck with storing it.

Something like the bolded happened in Oak Ridge in the 40s. Nuclear reactions were poorly understood and two sub-critical masses were brought too close together, resulting in a runaway reaction which also immediately trashed the screw drive. The scientist who ran into the room and physically moved the masses apart is something of a hero locally, as he knowingly embraced a slow, inevitable and very painful death to save the others in the building. Sadly I no longer recall his name.

From our standpoint, extracting the rods, encasing them in concrete (to slow the emissions), and dumping them into deep, still parts of the ocean would work just fine. The mass of the ocean is unimaginably huge and the resulting increase in radioactivity would be unmeasurable. However, there are potential problems, such as accidents in extraction and transport, choosing an area we only thought was still, and possibly driving to extinction some rare deep sea fauna. Oh, and pissing off Godzilla.

 

[RampantAndroid]

Something like the bolded happened in Oak Ridge in the 40s. Nuclear reactions were poorly understood and two sub-critical masses were brought too close together, resulting in a runaway reaction which also immediately trashed the screw drive. The scientist who ran into the room and physically moved the masses apart is something of a hero locally, as he knowingly embraced a slow, inevitable and very painful death to save the others in the building. Sadly I no longer recall his name.

You're not talking about the demon core are you? Slotin?

 

[werepossum]

You're not talking about the demon core are you? Slotin?

Possibly, although it's been almost forty years since I was at Oak Ridge reading that story (high school field trip.)

 

[Agent11]

Yes that was the demon core. I watched a re enactment on the science channel.

 

[Llwellyn]

I left a mess of a post, I'm glad exdeath came along and posted some science behind what I was trying to say. I was hoping Quantum or someone else that actually knew the science would come along and fix the glaring mistakes that I didn't have time to polish up or fix.

The * in my posts that went unreferenced were supposed to indicate that the uranium itself is a lot less harmful than the byproducts the fission process generates... until it goes supercritical. It's also not as biologically toxic; plutonium and polonium are much more so.

Most of our early experiments are downright scary to think about these days... how little we knew. The demon core incident is amazing to think about both in how utterly horrifying it must have been and the act of utter bravery that took place all in the same matter of seconds.