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Areas abandoned because of high radiation at Chernobyl have radiation levels 1% of the natural radiation levels of some areas in India
Good to see some balancing views here Duncan and to add to your comparative data, a heavy smoker exposes themselves to the equivalent of 2000 Xrays per year because of Polonium! Who would have thought but it might not be a surprise for those smokers who get lung cancer....
Institute of Medicine now estimates that a heavy smoker is exposed to the equivalent radiation as up to 2,000 chest X-rays every year
 

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Cool it guys
There is some absolute nonsense being talked here

[B]He also said , using a helicopter water drop was a terrible idea that could compress the fuel "to a new criticality" they droped that idea [/b]

Rods are out of the core - they are radioactive and emitting heat - they are NOT anywhere near any condition of criticality

CNN; says 50 workers are staying on in lethal radiation conditions

There is a lot of difference between a lethally high radiation environment in your skivvies and in a proper suit

Brave guys but not necessarily suicidal

They also claimed it produced a lot less "incomplete" burn due to the nature of the internal reaction and the liquified fuel (as opposed to solid fuel rods). I was surprised when he explained how much unused uranium comes out with the spent fuel rod in a conventional reactor.

This is the main reason nuclear plants are baseload generators - you get a decent burn rate at full power but cycling up and down poisons your rods

Here is a short bit about AGR's
http://en.wikipedia.org/wiki/Advanced_gas-cooled_reactor

One of the advantages of AGR's is that they use a massive concrete containment chamber

There are a lot of different technologies out there - but the most dodgy MAGNOX/Chernobyl have only killed a few people

Areas abandoned because of high radiation at Chernobyl have radiation levels 1% of the natural radiation levels of some areas in India
" not anywhere near a condition of critically" they were talking about pool having boiled to the point of burning the zirconium and melting the rods . that would be a condition of critically. at this state the radiation danger to life zone is 50 yard radius extending outside the building . On " proper suit" My friend worked on the repair of a crack in reactor (fuel removed)coolent pipe, they needed many inches of lead shielding(istalled in thin sheets to build thickness)to "slow the exposure so a welder could go in and weld 1 stick then he was exposed and let go".
 

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Hi Aero

not anywhere near a condition of critically

In the core surrounded with a moderator to slow the neutrons to their most effective speed a new fuel rod can become critical

Its not easy - a pile of many tonnes of new fuel rods will not become critical

Pure uranium does not have a critical mass - it must be enriched before it can become critical

Weapons grade uranium can form a critical mass - reactor grade can only become critical with the aid of a moderator.

These are used fuel rods - the reason that they have been taken out of the reactor is that they are so poisoned with elements that absorb neutrons (the same function as the control rods) that the criticality cannot be maintained

These rods are hot and they are radiating energy - but its radioactive decay - NOT the fission cycle

they needed many inches of lead shielding(istalled in thin sheets to build thickness)to "slow the exposure so a welder could go in and weld 1 stick then he was exposed and let go".

That would be to keep his dosage to below 20mSv per year

5000 mSv - will kill 50% of people

Even a thin layer of lead will stop most radiation (alpha, Beta) and drop dosage from Gamma significantly
 

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Hi Aero

not anywhere near a condition of critically

In the core surrounded with a moderator to slow the neutrons to their most effective speed a new fuel rod can become critical

Its not easy - a pile of many tonnes of new fuel rods will not become critical

Pure uranium does not have a critical mass - it must be enriched before it can become critical

Weapons grade uranium can form a critical mass - reactor grade can only become critical with the aid of a moderator.

These are used fuel rods - the reason that they have been taken out of the reactor is that they are so poisoned with elements that absorb neutrons (the same function as the control rods) that the criticality cannot be maintained

These rods are hot and they are radiating energy - but its radioactive decay - NOT the fission cycle

they needed many inches of lead shielding(istalled in thin sheets to build thickness)to "slow the exposure so a welder could go in and weld 1 stick then he was exposed and let go".

That would be to keep his dosage to below 20mSv per year

5000 mSv - will kill 50% of people

Even a thin layer of lead will stop most radiation (alpha, Beta) and drop dosage from Gamma significantly
is the neutron radiating energy from the spent pool increasing as over heating increases, increasing neutron radiation and more heat you get more radiation ,etc. until you hit thermal expansion of spent fuel . isn't that a state of critically .then if this hot melted pile is compressed would it not go to a higher critically (self sustaining neutron emitting state)
 

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is the neutron radiating energy from the spent pool increasing as over heating increases, increasing neutron radiation and more heat you get more radiation ,etc. until you hit thermal expansion of spent fuel . isn't that a state of critically .then if this hot melted pile is compressed would it not go to a higher critically (self sustaining neutron emitting state)

Basically No

Radioactivity is not effected by things like temperature, (Not unless you are talking fusion and solar core temperatures)

- the temperature effects in a reactor core are due to changes in the effectiveness of the moderator

The spent rods are radioactive - but not emitting enough neutrons to get anywhere close to a chain reaction (criticality)
 

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prime ministers assistant was being questioned by a reporter . He was so evasive and used so much misdirection ,I can't believe it. I understand this is part of the culture .
 

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is the neutron radiating energy from the spent pool increasing as over heating increases, increasing neutron radiation and more heat you get more radiation ,etc. until you hit thermal expansion of spent fuel . isn't that a state of critically .then if this hot melted pile is compressed would it not go to a higher critically (self sustaining neutron emitting state)

Basically No

Radioactivity is not effected by things like temperature, (Not unless you are talking fusion and solar core temperatures)

- the temperature effects in a reactor core are due to changes in the effectiveness of the moderator

The spent rods are radioactive - but not emitting enough neutrons to get anywhere close to a chain reaction (criticality)
if not temp. dependent , overheating causes no problems no increase in neutrons .then why bother with a spent rod pool .
 

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prime ministers assistant was being questioned by a reporter . He was so evasive and used so much misdirection ,I can't believe it. I understand this is part of the culture .

this "politeness "would make tech/science( or any other) communication much more repressed and hampered .
 

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Hi Aero

The pool keeps the temperature down - chemical reactions are heat effected!

Won't effect the radiation - it will just do its half life thing

The most powerful radiation is from the shortest half lives - so after a while you can store it without the pool to take the heat away

and it provides a first stage shield for radiation
 

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Hi Aero

The pool keeps the temperature down - chemical reactions are heat effected!

Won't effect the radiation - it will just do its half life thing

The most powerful radiation is from the shortest half lives - so after a while you can store it without the pool to take the heat away

and it provides a first stage shield for radiation
Hi Duncan , what chemical reactions are important .if the zirconium is oxidized in the over heated scenario .
 

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Hi Aero

New rods contain uranium dioxide in pellet form in a zircalloy housing - with some helium to help the heat transfer

Uranium dioxide melts at ~2800C
Zircalloy ~1800C

Used rods contain a witches brew of fissile products as well from the uranium that has been "burnt"

The ponds are because the rods are generating a great deal of radioactive heat until the shortest half-life isotopes decay away -
You don't want the rods to heat up and swell or burst because they could spill some of the other fissile products and because you do want to do something with the rods eventually

Its a lot easier to do something with a nice cylindrical metal piece than with a distorted and swelled object

And of course you get a handy radiation shield

Without the ponds they will overheat and may release some of the fissile products the uranium and zircalloy are unlikely to get hot enough to melt

If they are using MOX - recycling old fuel,
There would be plutonium oxide in there as well - melts at 2400C no great problem

The worry with MOX is that terrorists will get a hold of it and chemically extract the plutonium - personally I think that is far too difficult and a much more likely scenario is a chemical bomb with anything radioactive strapped on top to be dispersed by the chemical explosion
 

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Hi Aero

New rods contain uranium dioxide in pellet form in a zircalloy housing - with some helium to help the heat transfer

Uranium dioxide melts at ~2800C
Zircalloy ~1800C

Used rods contain a witches brew of fissile products as well from the uranium that has been "burnt"

The ponds are because the rods are generating a great deal of radioactive heat until the shortest half-life isotopes decay away -
You don't want the rods to heat up and swell or burst because they could spill some of the other fissile products and because you do want to do something with the rods eventually

Its a lot easier to do something with a nice cylindrical metal piece than with a distorted and swelled object

And of course you get a handy radiation shield

Without the ponds they will overheat and may release some of the fissile products the uranium and zircalloy are unlikely to get hot enough to melt

If they are using MOX - recycling old fuel,
There would be plutonium oxide in there as well - melts at 2400C no great problem

The worry with MOX is that terrorists will get a hold of it and chemically extract the plutonium - personally I think that is far too difficult and a much more likely scenario is a chemical bomb with anything radioactive strapped on top to be dispersed by the chemical explosion
Hi Duncan , whats the percentage of uranium in new fuel ,I understand that about 5% of that is is burned in the fuel cycle . Some 1% of the unburned fuel is enriched to plutonium ? Other enriched products are also produced from unburned uranium ?Is the process of neutron bombardment slowed by enriched products and depleted products acting as moderators ? The other moderators ( non uranium products ) in the new fuel are poisoned by neutron bombardment , adding neutrons to them fating them up so they moderate even more ? With heating and expansion of these, would they pass more neutrons ( moderate less ) ? thermal expansion it's self have the effect of moving everything apart slowing the neutron emissions ? So two opposing effects from thermal expansion ?
 

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Hi Aero

Some of the things you are asking will be proprietary information - in other words I don't know and I don't think will be public
But here goes

Natural Uranium is ~ 0.7% U235 - 99.3% U238
This has to be enriched to about 3% U235 97% U238 for a PWR

I think
that about 5% pf the U235 is "burned"
1% for the U238 turned to plutonium seems high for a "thermal"(slow neutron) reactor - It may be right but I think it is more like 0.1%

Moderators - these work by slowing the neutrons - think of billiards if a neutron hits a heavy nucleus and bounces it does not lose much energy (slow down) if it hits a nucleus that is the same weight as the neutron it shares its energy equally and slows down a lot
A good moderator need to be light and not "sticky" - if it absorbs neutrons its no good!

Control rods are intended to mop up surplus neutrons so they are as sticky as possible

Fission products are too heavy to be good moderators and some of them are "short of" neutrons - these are very "sticky"

The result is the fission products soak up the neutrons and "poison" the fuel rods - the fission products don't moderate much at all

Thermal expansion could have a tiny effect but the rods will be so far from being critical that it won't make any difference

The real big disaster would be a fire that sent particles up into the stratosphere like Chernobyl
But Chernobyl had a big hot graphite core that burned like a demon
There is nothing really to burn in a PWR

Concrete, Steel, Zircalloy, Uranium oxide - not real good fuel for a fire
 

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What just amazes me is that all of the angst is pretty much limited to 50 year old technology. We have so many other variants of nuclear power possible today that are virtually impossible to cause such disasters, yet we are clinging to stifling regulations that lump all forms of energy derived from radioactive material under the same umbrella irrespective of the actual danger.

Really, it's all pretty stupid. Let them build the new models, and decommission the old ones in a controlled manner sooner rather than later.
 

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Discussion Starter · #77 ·
What just amazes me is that all of the angst is pretty much limited to 50 year old technology. We have so many other variants of nuclear power possible today that are virtually impossible to cause such disasters, yet we are clinging to stifling regulations that lump all forms of energy derived from radioactive material under the same umbrella irrespective of the actual danger.

Really, it's all pretty stupid. Let them build the new models, and decommission the old ones in a controlled manner sooner rather than later.
I've wondered about that dynamic too. While on the one hand we know nuclear power does work, we are scared of what could happen if things go wrong. That russian reactor was a horrible design from the start - like most soviet nukes for that matter. Look up the reactor in the k3 nuclear sub for a real horror story, then contrast that with the more conservatively designed nautilus submarine that put occupant safety ahead of overall performance and cost savings.

Cars were not always as safe as they are today, but that doesn't mean we banned them, instead we studied them, smashed them, studied them some more, and eventually got better and making them safer (along with massive improvements in signage, roads, barriers and other elements outside the car that can benefit occupant safety).

I think we could do a lot better with nuclear power today and ideas like this should at least be looked at. If we're destined to abandon the idea completely then so be it, but shouldn't we at least explore some of these ideas first? If anything the status quo is the more dangerous route to take due to ageing equipment and technology that was not as well understood when they were built than today.

Thats before we get into the none sense about banning the reprocessing of spent fuel rods and the encouragement of reactors that produce waste that is readily converted into weapons. As I understand it, these other reactors are much harder to manipulate in that way.
 

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Hi Karlos

Looked at your video -

Apart from an initial rise in thyroid cancer - which should have been prevented by iodine tablets but wasn't
There is no evidence that the raise in radiation (to levels less than 1% of some natural backgrounds) caused any issues

Besides what has the failure of a MAGNOX - without containment got to do with a PWR - with containment??

I agree with David and Phantom on this one


Energy Source----------------Death Rate (deaths per TWh)

Coal – world average----------61 (26% of world energy, 50% of electricity)
Coal – China------------------278
Coal – USA-------------------15
Oil ---------------------------36 (36% of world energy)
Natural Gas--------------------4 (21% of world energy)
Biofuel/Biomass----------------12
Peat--------------------------12
Solar (rooftop)-----------------0.44 (less than 0.1% of world energy)
Wind--------------------------0.15 (less than 1% of world energy)
Hydro------------------------------0.10 (europe death rate, 2.2% of world energy)
Hydro - world including Banqiao)-----1.4 (about 2500 TWh/yr and 171,000 Banqiao dead)
Nuclear ---------------------------0.04 (5.9% of world energy)


http://nextbigfuture.com/2011/03/lowering-deaths-per-terawatt-hour-for.html
 

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Illinois has the most reactors of any state. There are some that have reached their 40 year planned lifetime and then have been given another 20 year extension.

There is supposed to be a tear down fund that is to be used for decommisioning them.. It would be interesting to see just how much is in these funds.

The amount of over-run that it took to build them was large. Just think of how much it is going be to remove/seal decommission them.

The storage of spent fuel at each reactor site is getting large. Removing it from the ponds and storing it in above ground casks may present a problem.

Byron and Dresden are doing it now.

Today I received my ComEd bill and they show how little waste is made for each 1000KW of production. They don't really tell you just how much it really is, or how much is stored on-site at this time.

Time to try a better design, but how can that happen while we get rid of these? The costs to accomplish this would be out of sight....
 

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Illinois has the most reactors of any state. There are some that have reached their 40 year planned lifetime and then have been given another 20 year extension.

There is supposed to be a tear down fund that is to be used for decommisioning them.. It would be interesting to see just how much is in these funds.

The amount of over-run that it took to build them was large. Just think of how much it is going be to remove/seal decommission them.

The storage of spent fuel at each reactor site is getting large. Removing it from the ponds and storing it in above ground casks may present a problem.

Byron and Dresden are doing it now.

Today I received my ComEd bill and they show how little waste is made for each 1000KW of production. They don't really tell you just how much it really is, or how much is stored on-site at this time.

Time to try a better design, but how can that happen while we get rid of these? The costs to accomplish this would be out of sight....
All things considered, I'm far less worried about nuke plants in Illinois than many other places. It is one of the most geologically stable areas on earth. Living 25 miles from Chicago for 15 years of my life, there was exactly one earthquake shock enough to notice - and most people didn't. it was from a quake several hundred miles away (maybe Yellowstone?).

Yes, I agree that the likelihood that the decommissioning funds are "mysteriously absent." I would rate that probability at least a million times higher than the possibility of an Illinois plant meltdown.... :D

To me one of the most exciting nuclear areas of study is the type of plant that consumes the "spent fuel" created over the past 60 years of nuclear plant operation. Talk about killing two birds with one stone!
 
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