The End of Nuclear

[Little John]

Steve

Nuclear power currently requires Uranium 235 for its reactors where it is bombarded with neutrons to illicit a controlled reaction. Thing is that only 0.7% is U-235 with over 99% being Uranium 238 therefore all mined ores require enrichment before it is made into fuel rods. You might want to read wiki on nuclear power as a starting point. A by-product of the enrichment process is depleted uranium that has controversially been used in weaponry. Notice the role that the military has in all of this?

So going back to your questions, both parts 2 and 3 are right. The problem is in what form it is now in - alpha emitting particles - which are of the long lasting radioactive variety - are of no health concern if in its natural rock form but when it is in dust or in gaseous form it is extremely hazardous. (Note there is a problem with Radon gas - which is naturally occurring)

There are other options for fission, such as using Thorium which, allegedly, don't produce the high level radioactive waste that uranium does. However it can be converted into uranium 233 which can be used for nuclear warheads.

Does that answer your question?

So, if I have got this right...

* The source material is partially consumed and so what is left must have a lower total amount of radioactivity-emitting potential than was the case prior to it being partially consumed (putting aside, for the moment, any changes that may have been made to the rate at which it is emitted or the physical form it is now in. In other words, dust, instead of rocks).

* The source material that is not used get transformed in some way such that the majority of it emits a low level of radiation for a very long time.

* The source material that is not used gets transformed such that it is no longer trapped in rocks over large areas/volumes in very low physical concentration, but is now in the form of dust in high physical concentration by volume. This means that it is now more easily transmissible through the environment than was the case prior to it being dug up.

In which case, why not spread it evenly and thinly over the world's oceans. The non-liquid waste will sink to the bottom and effectively be taken out of the system to be covered over the millennia by sedimentary deposits and to the the extent to which the liquid waste is recycled around the planet via the worlds oceanic currents, it will now be in sufficiently dilute form as to not make a significant dent to the background radiation levels that exists in any event?

[biffvernon]

As R-B said, but here's one easy bit:

Does the nuclear power generating industry make it's source material (uranium) more radioactive after finishing

Answer - Yes. Plutonium is created in nuclear power stations. It does not occur naturally. It is an alpha-emitter with a half-life a good deal longer than that of human civilisations. That means it is very dangerous forever.

(Other trans-uranic isotopes are also available to worry about.)

[Little John]

As R-B said, but here's one easy bit:

Does the nuclear power generating industry make it's source material (uranium) more radioactive after finishing

Answer - Yes. Plutonium is created in nuclear power stations. It does not occur naturally. It is an alpha-emitter with a half-life a good deal longer than that of human civilisations. That means it is very dangerous forever.

(Other trans-uranic isotopes are also available to worry about.)

Hold on a minute. Are you saying that the nuclear industry creates material that emits more energy in total from it than was the case prior to it being used by them? If you are, then you are essentially saying that they have breached the second law of thermodynamics.

Or are you, in fact, saying that they have transformed material such that it now emits the same total amount of radiation, but at a higher rate? If you are, then it cannot emit it for longer, it must emit it for a shorter period of time than was previously the case or, again, they have breached the second law of thermodynamics.

Please clarify.

[Little John]

I've just had a read and discovered the half life of plutonium is twenty four thousand years.

The half life of uranium (depending on type) is between two hundred and forty five thousand and four billion years.

So, they do not breach the second law of thermodynamics after all. In order to get plutonium, which emits emit more radiation at any given time than uranium, it must reduce the total amount of time it is emitting it. In other words, there really is no such thing as free lunch.

Which leads back to my original argument. Given that the total amount of radiation emitted by the waste is going to be either less than or, at worst, equal to the total amount of radiation emitted by the stuff had it never been dug up and the only significant difference will be that some of it will be emitted at a higher rate for a shorter period of time, then why cannot it simply be spread as evenly and thinly as possible throughout the world's oceans.

In fact, I would appreciate it if anyone could actually come up with the numbers for how much such a procedure would increase the total background radiation by. My guess would be half of next to bugger all. However, guessing is not good enough. Does anyone know the numbers?

[raspberry-blower]

Steve

From what I know of nuclear physics you're pretty much on the money.

WRT to Biff's point:

This may come in useful to understand Uranium
With regards to Plutonium this might help - it all depends on the isotope.

Here are the comparable radioactive decay rates of first Uranium:

Uranium-238 is the most stable isotope of uranium, with a half-life of about 4.468×109 years, roughly the age of the Earth. Uranium-235 has a half-life of about 7.13×108 years, and uranium-234 has a half-life of about 2.48×105 years.[72] For natural uranium, about 49% of its alpha rays are emitted by each of 238U atom, and also 49% by 234U (since the latter is formed from the former) and about 2.0% of them by the 235U. When the Earth was young, probably about one-fifth of its uranium was uranium-235, but the percentage of 234U was probably much lower than this.

And here is the radioactive decay rates of Plutonium:

Twenty radioactive isotopes of plutonium have been characterized. The longest-lived are plutonium-244, with a half-life of 80.8 million years, plutonium-242, with a half-life of 373,300 years, and plutonium-239, with a half-life of 24,110 years. All of the remaining radioactive isotopes have half-lives that are less than 7,000 years. This element also has eight metastable states, though none are stable and all have half-lives less than one second.

As Pu-239 is the most common isotope from nuclear fission, the answer to your question is b - the transformation will emit radiation at a higher rate but for geological shorter time span. (I don't think any of us will be around in 25,000 years time )

[RenewableCandy]

Given that the total amount of radiation emitted by the waste is going to be either less than or, at worst, equal to the total amount of radiation emitted by the stuff had it never been dug up and the only significant difference will be that some of it will be emitted at a higher rate for a shorter period of time, then why cannot it simply be spread as evenly and thinly as possible throughout the world's oceans.

A back a fag packet

quite. But don't inhale

A lot of the radiation being emitted after the power-extraction process, is done so by particles which are in dust. These will do a lot more damage to higher types of life than the equivalent radiation energy being emitted by large solid lumps of material, because dust can attack a creature from the inside: radiation in lungs or guts will do a lot more damage than the same dose experienced by skin, and the particles can't be brushed off lungs or guts, but they can be washed off skin so reducing the exposure time.

All this is why I'm in favour of vitrifying the stuff in deep granite (which is an expensive process, so we shouldn't be generating any more need for it!). At 4 km below surface, it won't be getting into any lungs, and as you say, in total it won't do any more damage than the original ores would have done if left in the ground.

[Little John]

Given that the total amount of radiation emitted by the waste is going to be either less than or, at worst, equal to the total amount of radiation emitted by the stuff had it never been dug up and the only significant difference will be that some of it will be emitted at a higher rate for a shorter period of time, then why cannot it simply be spread as evenly and thinly as possible throughout the world's oceans.

A back a fag packet

quite. But don't inhale

A lot of the radiation being emitted after the power-extraction process, is done so by particles which are in dust. These will do a lot more damage to higher types of life than the equivalent radiation energy being emitted by large solid lumps of material, because dust can attack a creature from the inside: radiation in lungs or guts will do a lot more damage than the same dose experienced by skin, and the particles can't be brushed off lungs or guts, but they can be washed off skin so reducing the exposure time.

All this is why I'm in favour of vitrifying the stuff in deep granite (which is an expensive process, so we shouldn't be generating any more need for it!). At 4 km below surface, it won't be getting into any lungs, and as you say, in total it won't do any more damage than the original ores would have done if left in the ground.

I can certainly see the argument for vitrification RC.

However, I would still like to know how much the global background radiation would be lifted by spreading it evenly throughout the world's oceans as this would be fanatically simpler in technological terms.

One way or another, we have to get this stuff back into the earth from where it came. The very worst thing that could be done with it would be to leave it in concentrated form in singular locations on the surface of the land.

Why not spread it evenly and thinly across all of the oceanic subduction trenches?

[Little John]

Steve

From what I know of nuclear physics you're pretty much on the money.

WRT to Biff's point:

This may come in useful to understand Uranium
With regards to Plutonium this might help - it all depends on the isotope.

Here are the comparable radioactive decay rates of first Uranium:

Uranium-238 is the most stable isotope of uranium, with a half-life of about 4.468×109 years, roughly the age of the Earth. Uranium-235 has a half-life of about 7.13×108 years, and uranium-234 has a half-life of about 2.48×105 years.[72] For natural uranium, about 49% of its alpha rays are emitted by each of 238U atom, and also 49% by 234U (since the latter is formed from the former) and about 2.0% of them by the 235U. When the Earth was young, probably about one-fifth of its uranium was uranium-235, but the percentage of 234U was probably much lower than this.

And here is the radioactive decay rates of Plutonium:

Twenty radioactive isotopes of plutonium have been characterized. The longest-lived are plutonium-244, with a half-life of 80.8 million years, plutonium-242, with a half-life of 373,300 years, and plutonium-239, with a half-life of 24,110 years. All of the remaining radioactive isotopes have half-lives that are less than 7,000 years. This element also has eight metastable states, though none are stable and all have half-lives less than one second.

As Pu-239 is the most common isotope from nuclear fission, the answer to your question is b - the transformation will emit radiation at a higher rate but for geological shorter time span. (I don't think any of us will be around in 25,000 years time )

Thanks for clarifying that RB. That's pretty much what I had assumed must be the case.

[RenewableCandy]

Why not spread it evenly and thinly across all of the oceanic subduction trenches?

Ah I thought you meant scatter it on the ocean surface and assume it's going to sink (when in fact it might get ingested by whales and filter-feeding things).

Well the subduction zones might be a goer but iirc they're often accompanied by volcanoes (Mt Fuji is just "downstream" from the one off the coast of Japan, for example). Which means you might risk a volcano throwing out a lot of radioactive stuff you thought had been safely, erm, subducted.

[Little John]

Why not spread it evenly and thinly across all of the oceanic subduction trenches?

Ah I thought you meant scatter it on the ocean surface and assume it's going to sink (when in fact it might get ingested by whales and filter-feeding things).

Well the subduction zones might be a goer but iirc they're often accompanied by volcanoes (Mt Fuji is just "downstream" from the one off the coast of Japan, for example). Which means you might risk a volcano throwing out a lot of radioactive stuff you thought had been safely, erm, subducted.

Well, yes, some of it might get ingested by organisms on the way down to the ocean bed. However, the oceans are already contaminated with naturally occurring uranium at the concentration of 3 parts per billion. So, again, it comes down to the numbers. If spreading it evenly on the surface of the oceans raises that concentration to, say, 4 parts per billion, that really wouldn't be something to write home about would it. Naturally, I don't know the numbers and so the above is merely by way of illustration of the general point. In any event, it would not be an especially difficult technology to set up a flexible, mobile pipeline pumping system that fed it directly to the ocean floor, particularly the deepest oceans, where, in the pumping process, it was diluted with uncontaminated seawater so that the correct concentration hit the ocean floor at any given point.

Regarding spreading it directly on the subduction trenches. As far as my limited understanding extends, I believe the volcanoes occur at the side that is overlaying the other side which is undergoing subduction. So, the answer would be to spread the material on the subducting side.

[biffvernon]

Oh Steve, it really doesn't work like that.

[Little John]

Oh Steve, it really doesn't work like that.

I'll assume you actually know what you are talking about (and are not engaging in clumsy condescension in order to close down an argument you don't like) by asking you what it is, exactly, that doesn't work like what?

[RenewableCandy]

Well for a start, to spread it evenly would probably involve pulverising it, see my previous comment about lungs (well, gills in this case but you get the idea...).

For the subduction bit you need a diagram but basically the heavier layer gets subducted, and the volcano is part of the lighter layer. The volcano has a "vent" that comes up from part of the heavier layer that was subducted a while ago. The issue here is the length of that "while"...if less than a few thousand years, the subducted stuff is going to come to the surface again, via the "vent" of the volcano, while it's still harmful.

Also, spreading it on the surface gets it into the food chain, and things (Mercury being a topical example) tend to concentrate up into the living beings at the top. Erm, that can include us.

[Little John]

Well for a start, to spread it evenly would probably involve pulverising it, see my previous comment about lungs (well, gills in this case but you get the idea...).

For the subduction bit you need a diagram but basically the heavier layer gets subducted, and the volcano is part of the lighter layer. The volcano has a "vent" that comes up from part of the heavier layer that was subducted a while ago. The issue here is the length of that "while"...if less than a few thousand years, the subducted stuff is going to come to the surface again, via the "vent" of the volcano, while it's still harmful.

Also, spreading it on the surface gets it into the food chain, and things (Mercury being a topical example) tend to concentrate up into the living beings at the top. Erm, that can include us.

Fair enough RC.

However, that still leaves my original question regarding how much the overall level of concentration of radiative material in the world's oceans would be raised above its current level if all of the human generated nuclear waste was to be pulverised and then spread evenly on the oceans' beds? In this regard, I have just had another read of the relevant literature and the figure I initially quoted of 3 parts per billion of radioactive material in the oceans does not actually include the radioactive material that lies on or in the top few inches of the oceans' beds. There, it is many times more concentrated than 3 parts per billions. This, apparently, is due to sedimentation of naturally radioactive material washing down off the land and into the oceans over geological time

Indeed, it turns out that that aquatic organisms, due to the concentration of radioactive material in sea water water plus the much higher concentrations of radioactive material lying on or just underneath the oceans' beds, are far more exposed to radiation and radioactive material than organisms that dwell on the land. That is the case even if you take into account radiation coming in from outer space, apparently. All of which continues to beg the question I am asking.

In other words, if radioactively contaminated material can be ingested by aquatic organisms and get concentrated up the food chain to eventually reach us humans, then that process is already in operation due to the background levels of radioactive material already existing in the world's oceans. The pertinent question, then, is how much that process of concentration up the food chain will be increased by disposing of man-made nuclear waste in the way I have described. If the increase is minuscule to the point of being essentially indistinguishable from current background levels, then that is something we should know. on the other hand, if the increase is significant, then that is also something we should know. The calculations should not be that hard to make and so I would assume someone has already made them.

[biffvernon]

Here's a new bit of news:

Exposure to radioactive material released into the environment has caused mutations in butterflies found in Japan, a study suggests.

Scientists found an increase in leg, antennae and wing shape mutations among butterflies collected following the 2011 Fukushima accident.

The link between the mutations and the radioactive material was shown by laboratory experiments, they report.

The work has been published in the journal Scientific Reports.

Two months after the Fukushima Daiichi nuclear power plant accident in March 2011, a team of Japanese researchers collected 144 adult pale grass blue (Zizeeria maha) butterflies from 10 locations in Japan, including the Fukushima area.

When the accident occurred, the adult butterflies would have been overwintering as larvae.

Unexpected results

By comparing mutations found on the butterflies collected from the different sites, the team found that areas with greater amounts of radiation in the environment were home to butterflies with much smaller wings and irregularly developed eyes.

"It has been believed that insects are very resistant to radiation," said lead researcher Joji Otaki from the University of the Ryukyus, Okinawa.

"In that sense, our results were unexpected," he told BBC News.

http://www.bbc.co.uk/news/science-environment-19245818

And of course Fukushima released only a tiny proportion of it's radioactive material.