Agenda21

More
9 years 10 months ago #441045 by wandering free
Replied by wandering free on topic Agenda21

spark;440548 wrote: Hi,

On the subject of Dounreay, that was in 1956.
The Russians had staged their first successful nuclear weapons test in 1949, the British in 1952, and by 1956 the cold war and the arms race was in full swing. Considering that Dounreay was an R&D facility, given the political climate of the times, I strongly suspect that weapons work was performed there and that winning the cold war was of more concern to the powers that were than the state of the environment.

I understand that in 1956, it was quite acceptable to test nuclear bombs above ground, even though a groundburst bomb transmutes the soil at ground zero into dangerous radioactive isotopes which are thrown up into the air to become fallout. (I wonder how much of the fallout from British tests in Australia made it to New Zealand?)
Also on the subject of ionising radiation, Hannahs on Queen Street in Auckland (and likely other shoe shops back then too www.nzherald.co.nz/opinion/news/article....66&objectid=10828479 & www.nzherald.co.nz/opinion/news/article....66&objectid=10828479 ) used to have a fluoroscope x-ray machine for fitting children's shoes.
Cheers

I agree with what you say but we are dealing with human nature, atomic energy isn't something you can recycle if you stuff it up. and yes we did have our feet fluoroscoped, "Oh look Bryan you can see your feet though the shoes" and a friend died from leukemia from being X rayed in the womb, we must learn from our mistakes.

I can't see why we would need atomic power in NZ even the small power stations are bulk suppliers, you can't switch steam turbines on a off, once they are operating the blades are damaged by condensate if they are allowed to cool down, super heated steam is very damaging to the blades as they are run up to operating temperature.

The car is not going to be around for ever and seems to cause more problems than if cures, we manged very well before the car came along, trains and buses move people far more efficiently, I suppose if you grow up with something it's hard to give it up, my age group never had them until in our 20's, at least not were I grew up in a village in Derbyshire.

Just me and the cat now, on 2 acres of fruit and veg + hazel nuts, macadamia, chestnuts and walnuts,
www.youtube.com/user/bandjsellars?feature=mhee

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441048 by GrantK
Replied by GrantK on topic Agenda21

morioka;440577 wrote: My partner is a scientist working in the area of climate change research and I can assure you that there are no secret govt pacts, hidden agenda 21's or anything similar, only the sheer damn frustration that self serving lobby groups are hell bent, spending millions in the media spouting out long debunked psuedo science trying to protect their own bank accounts for as long as they possibly can.

Tin-Foil Hatters are very adept at synthesising conspiracies out of thin air. Believing that there is a hidden agenda behind everything is their raison d'etre.

Tin Foil Hat

Based on the idea that tin foil protects your brain from being read, this term may also refer to people who embrace paranoid or conspiracy theories.


Live weather data and High/Low records for our farm at: www.keymer.name/weather

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441051 by morioka

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441270 by spark
Replied by spark on topic Agenda21

wandering free;440578 wrote: I agree with what you say but we are dealing with human nature, atomic energy isn't something you can recycle if you stuff it up.

I think that nuclear energy is one of those "low risk of it going wrong in a big way, but really bad if it does go wrong in a big way" situations - like air travel. Fatal crashes of commerical airliners in the developed world are very rare, however, when they happen, it is not unheard of for 300 people to be killed all at once, potentially with more people on the ground hurt or killed as well. This of course makes for sensational world news, and some people get the risk assessment wrong and become more afraid of flying than they are of using the roads, when we manage to kill 300 people a year on our roads, just in NZ. Because most road fatalities are only a small number of people at a time (often only one or two) and happen on a far too regular basis, they are generally not sensational and do not make world news.

When an airliner crashes and kills lots of people, we don't ban airtravel - we try to find out what went wrong so that we can prevent it from happening again. Older, less safe aircraft, either get upgraded, or scrapped and replaced with newer, more safe aircraft that are usualy cheaper to operate per passenger kilometer.

I can't say that nuclear is perfectly safe, because honestly, it isn't, but I think that the considering the big consequences x the small risk it is better than all the "business as usual" problems that are associated with burning stuff like coal.

wandering free;440578 wrote: I can't see why we would need atomic power in NZ even the small power stations are bulk suppliers, you can't switch steam turbines on a off, once they are operating the blades are damaged by condensate if they are allowed to cool down, super heated steam is very damaging to the blades as they are run up to operating temperature.

Modern nuclear power generators are big machines - 1000MW and up in size. By world standards, NZ has a small national grid, and adding a 1000MW generator to our grid would cause grid stability issues whenever it tripped offline unexpectedly (the rest of the grid must instantly pick up the load from the tripped generator, else the grid frequency will drop below 50Hz, which causes big trouble).

I understand that individual generators of a size of no more than about 300 to 400MW of capacity can be added to our grid without risking stability issues. Whilst small reactors have been built and they do work, they aren't exactly commerically available at this point in time (currently, it's cheaper to build one 1000MW reactor instead of 4x 250MW ones), though there are some interesting proposals for small mass-produced modular nuclear reactors that might be suitable for our grid in the future.

You don't start and stop a steam turbine as demand for electricity increases and decreases, instead you keep it running at synchronous speed and adjust the supply of steam to control the rate of electricity generation - that way the turbine stays at operating temperature and when it is not fully loaded it is available as spinning reserve to take over load if another generator trips offline. Turbine startup issues applies to all thermal power stations that use steam turbines, including coal, combined cycle natural gas, biomass thermal, solar thermal and nuclear. (nuclear power stations can load follow: www.oecd-nea.org/ndd/reports/2011/load-following-npp.pdf )

wandering free;440578 wrote: The car is not going to be around for ever and seems to cause more problems than if cures, we manged very well before the car came along, trains and buses move people far more efficiently.

I think that using the appropriate technology for the job is a good idea. For example, in a city, when you have lots of people all wanting to go in the same direction at the same time, like commuter traffic in a big city, public transport like busses and trains works extremely well. However, when people are widely dispersed, and wanting to travel in different directions at different times to each other, then cars work very well. From my experience, the rail system in Brisbane works very well and it is easy to get around the city without a car, on the other hand, it is difficult to get around Auckland without a car, and the rush-hour traffic there is terrible.

I would like to think that the car in it's current form is not going to be around forever because we are going to replace it with something better, just like how we can fly from NZ to the UK and back again in the relative luxury of ecconomy class compared to the journey that my ancestors took one way on a sailing ship...

Cheers

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441369 by wandering free
Replied by wandering free on topic Agenda21

spark;440821 wrote:

I understand that individual generators of a size of no more than about 300 to 400MW of capacity can be added to our grid without risking stability issues. Whilst small reactors have been built and they do work, they aren't exactly commerically available at this point in time (currently, it's cheaper to build one 1000MW reactor instead of 4x 250MW ones), though there are some interesting proposals for small mass-produced modular nuclear reactors that might be suitable for our grid in the future.

You don't start and stop a steam turbine as demand for electricity increases and decreases, instead you keep it running at synchronous speed and adjust the supply of steam to control the rate of electricity generation - that way the turbine stays at operating temperature and when it is not fully loaded it is available as spinning reserve to take over load if another generator trips offline. Turbine startup issues applies to all thermal power stations that use steam turbines, including coal, combined cycle natural gas, biomass thermal, solar thermal and nuclear. (nuclear power stations can load follow: www.oecd-nea.org/ndd/reports/2011/load-following-npp.pdf )

Cheers

Hi spark,

That's an interesting article, a lot went over my head I didn't realize they had load following, just thought they dumped the power or blew of steam, They had to get some of the turbine blades repaired at Meremere and from what I was told it was because they had been shuting down and restarting the turbines.

Even after reading the article I'm still a NIMBY when it comes to atomic energy, a few years ago I was interested in installing moncrystalline solar panels, but at the time there were no schemes to pay as you go, but I did a rough costing of the smallest atomic power stations available with running costs and decommissioning, against what it would cost to install solar panels on all the houses in the country and over a 20 year period solar won out, mind you the government wouldn't want every one generating their own power and only using the nation grid for backup, they couldn't sell shares in that and how about Manapouri being used to produce silicon and setting up a PV industry instead of processing bauxite for some overseas conglomerate.

I do understand your concern about coal and the CO2 that's of such concern, now I see methane is catching up as a greenhouse gas, but how about this, we dump the car and we all get battery assisted bikes and I bet you would get to work just as fast as in a car, mind you in Auckland you would get wet, just being sarcastic, Nelson hasn't been that flash hot, rain, rain and more rain.

I am enjoying the conversation.

Cheers Bryan

Just me and the cat now, on 2 acres of fruit and veg + hazel nuts, macadamia, chestnuts and walnuts,
www.youtube.com/user/bandjsellars?feature=mhee

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441379 by Crusha
Replied by Crusha on topic Agenda21
I am enjoying it as well and find that I have to agree with most of your comments Spark. It is interesting the hysteria that is generated in some quarters whenever the "N" word is used. There seems to be a lot of hope for Thorium based reactors.

I had been following several threads on the looming power crisis in the UK, with their blind adherence to their renewables policy resulting in a very real threat of "brown outs" within the next few years and the prospect of rising numbers of deaths in winter as a result of energy poverty. One of the main points made by some with regard to wind power in particular is its intermittent nature and the fact that conventional power plants have to keep running to pick up the load when the wind is not blowing (or blowing to hard) and that to do that efficiently the power plants have to keep running at full speed as it were.

I see recently that there has been a cabinet reshuffle in the UK and Shale Gas is now being seriously considered as well as a reduction in subsidies for wind (esp. on-shore ) etc.

As for electric vehicles of any kind, does anyone stop to think about where that electricity comes from or rather how it is generated? It is highly unlikely that current renewable generators would be suitable given their erratic nature and the somewhat unpredictable demand. (remember Hydro is not considered a renewable in most countries “schemes”)

As for greenhouse gases, I have yet to see any empirical evidence that CO2 or methane play anything other than a very minor part (and some dispute even that) in the global climate. The current temps are still well below any of the IPCC and Hansen model projections, even after the raw measurements are constantly adjusted upwards and the rapid increase in CO2. There are a growing number of studies that indicate there are far more important factors in influencing the climate, including some that appear to be somewhat cyclical in nature. (e.g. solar activity, various ocean cycles, even earths orbit.)

I am all for reducing pollution, but make no mistake CO2 is not a pollutant and historically the current levels are very low.

Nor is there any evidence that the number or frequency of “extreme” weather events is increasing. Certainly there is more reporting of such events, but statistically the number of storms (Hurricanes, Tornadoes etc has been declining since about the 70’s, droughts are less frequent etc.

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441396 by spark
Replied by spark on topic Agenda21
Hi Bryan,

Solar (PV panels) work well when the sun is shinning, and considering how quickly the price is falling (you can buy 245W panels on trademe for $500 now), I can seriously see them being used for daytime peak generating plant (which will reduce the consumption of gas by gas turbine peaking plant).
Realistically, because solar can't be controlled and has to be backed by reserve generating plant, there could be grid stability issues if solar was more than about 10% of the generating capacity of all the operating generators connected to the grid. Even so, I think that we should be encouraging private generating plant with some kind of feed in tariff or net metering scheme.

Considering that we can't compete with foreign labour costs in the PV manufacturing business (the same reason why your PC is made in Asia), if the Tiwai point smelter is shut down, I'd suggest that we upgrade the lines heading north of Invercargil, because the current lines north do not have enough capacity for all of the surplus electricity that would be available should the smelter close down. Manapouri has resource consent for enough water to produce 800MW of electricity, and with 7x 120MW turbines, tripping one or two turbines offline does not pose big grid stability issues.
I would expect this to greatly strengthen our supply of renewable energy, but the Cook Straight DC link (from Benmore to Haywards) may need to be upgraded to get some of this power to the north island (the old mercury rectifier pole of the DC link is way overdue for replacement but we haven't done so yet...).
If the smelter does close, then there is still the issue of 1500 or so people in Southland all loosing their jobs at the same time, and then the flow-on effects in all the supporting businesses and their employees in the area...

The problems with coal are not just the CO2 emissions. Coal mining is a dangerous business (so is building and maintaining hydro-power schemes, but that kills less people per unit of energy produced). Burning coal liberates lovely chemicals like mercury, lead, arsenic, cadmium, uranium and thorium [}:)], and leaves behind huge quanities of ash which also contains these chemicals.

Lucky for me I don't have to contend with Auckland traffic here in Hawkes Bay (but we don't have much of a public transport system here either).

Crusha,
Regarding thorium, I think that molten salt reactors are a very interesting technology. They were built and succesfully run as part of the US govt nuclear powered aircraft (long range bomber) program in the early days of the cold war - the development program was stopped when ICBM technology got good enough to offer a cheaper alternative (the product of the space race).

With a molten salt reactor you could do something like use a gas turbine generator breathing ordinary air with a heat exchanger in place of the usual combustion chamber (no cooling towers or demand for water). You heat the heat exchanger with a non-radioactive molten salt in a pressurised secondary coolant loop. You heat the secondary coolant loop with the molten salt in the reactor (a mix of fuel, fission products and salt), which is running at slightly below atmospheric pressure (if you have a leak in the heat exchanger, the non-radioactive salt will leak into the reactor, diluting the fuel salt and stopping the nuclear reaction). Because there is no water inside the reactor, the containment structure (the big concrete dome) does not have to be big enough and strong enough to withstand the overpressure of a steam explosion. Conventional PWR or BWR reactors have a containment structure (the big concrete dome!) to contain the steam explosion that would result if the reactor vessel ruptured (tons of superheated water), and it is a significant part of the cost of a nuclear power station.

Properly built molten salt reactors do not need multiple redundant diesel generators and emergency cooling systems - if the reactor gets too hot, the "freeze plug" (salt that stays solid because you actively cool it) simply melts and the molten salt drains by gravity from the reactor into the drain tank. In the drain tank the fuel has no neutron moderation so is subcritical (the nuclear reaction stops) and because of the high temperature and surface area of the molten salt, plain old convection and infrared radiation is sufficient to prevent the drain tank from overheating. To restart, you cool the freezeplug, re-melt the salt in the drain tank with an electric heater and pump it back up into the reactor. Molten salt drains through the reactor and solidifies in the now cooled freeze plug preventing the rest of the molten salt from draining back out of the reactor.

I think that a big problem with the molten salt reactor and the nuclear industry is money. I beleive that most nuclear companies (Areva, GE, Westinghouse, etc) make most of their nuclear related profits from selling replacement fuel assemblies (think inkjet printer cartridges). Licensing rules mean that reactor operators have to buy "genuine" fuel assemblies (no 3rd party cheapies). The molten salt reactor is very disruptive to this business model because it does not use fuel assemblies - a reactor operator would simply buy thorium fluoride (or uranium fluoride) salt direct from a mining company (ie competitive global market for thorium salt) and add this to their reactor as required. Needless to say, today's nuclear companies will probably be unlikey to back, fund, or assist with the development of a commercialy viable molten salt reactor as it could be a huge threat to their replacement fuel assembly business.
en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor

Cheers

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441426 by wandering free
Replied by wandering free on topic Agenda21

Crusha;440937 wrote:

As for greenhouse gases, I have yet to see any empirical evidence that CO2 or methane play anything other than a very minor part (and some dispute even that) in the global climate. The current temps are still well below any of the IPCC and Hansen model projections, even after the raw measurements are constantly adjusted upwards and the rapid increase in CO2. There are a growing number of studies that indicate there are far more important factors in influencing the climate, including some that appear to be somewhat cyclical in nature. (e.g. solar activity, various ocean cycles, even earths orbit.)

.

We did an experiment once in our science class that always stuck with me, an ice cube in the glass of water, plotting the rise in temperature against time as it melted, the latent heat of fusion of ice, I grew up working things out with BTU (British Thermal Units) so will stick with what I'm familiar, it takes 144btu to change 1 lb ice to water with no temperature change then a further 180btu to take it to boiling point. so the latent heat is unseen, in the polar regions heat is given of in winter as ice freezes then the reverse happens in the summer as heat is absorbed so stabilizing our worlds temperature, while we have large areas of ice we are unlikely to see much change in average world temperatures, but it doesn't mean global warming isn't occurring and hidden from us by the latent heat of fusion.

According to the Milankovitch cycles the world should be cooling so bit of warming might be a good thing but we might be overdoing it bit, the pollution from fracking is becoming a concern with the leaks of methane and the 10% waste polluted water that flows back out of the wells, it's not looked on as a pollutant when it stays in the ground, human logic for you.

I will now go and look up molten salt reactors, it's good to have someething to while away a wet afternoon,

Cheers

Just me and the cat now, on 2 acres of fruit and veg + hazel nuts, macadamia, chestnuts and walnuts,
www.youtube.com/user/bandjsellars?feature=mhee

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441437 by RhodeRed
Replied by RhodeRed on topic Agenda21

Crusha;440937 wrote: I am all for reducing pollution, but make no mistake CO2 is not a pollutant and historically the current levels are very low.


EXACTLY!

This is just more UN/banker control freak nonsense.

There is no reason they should be targeting CO2 emission as they are.

CO2 is a part of the lifecycle here on earth, in focusing on CO2 they (the over-reaching UN and their banker founders) are attempting to set controls on life itself, from food production through to your very right just to exist, live and breathe.

Remeber the banal "fart-tax" here in NZ? Farmers being taxed for the flatulence of their livestock, ... utter nonsense.

The extrapolated end-game of this CO2 regulatory BS is a tax on breathing (oh I can hear the cries of "tinfoil-hat" already) well not exactly a breathing tax - breathing oxygen will be free - exhaling the CO2 will not and you will be taxed on your very existence via breathing.

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441440 by wandering free
Replied by wandering free on topic Agenda21

spark;440821 wrote:

I can't say that nuclear is perfectly safe, because honestly, it isn't, but I think that the considering the big consequences x the small risk it is better than all the "business as usual" problems that are associated with burning stuff like coal.

Cheers

Hi Spark,

Just found this:-Due to breeding, a Fast Breeder Reactor can generate enough fissile fuel to replace that used up plus enough fuel for other reactors. In other words it compounds the amount of fuel similar to the growth of money under compound interest. The reactor fuel elements must be taken out periodically because of fuel element clad damage. The remaining U 235 and bred plutonium Pu 239 in the old fuel elements is then put into new fuel rods for the original reactor as well as others. In this manner a kilogram of uranium could produce 3.5 million kWh of electricity energy rather that the 50,000 kWh it does now in the non-breeder commercial water cooled reactor plants.

It's the reason we have all this waste material, if breader reactors were used it could consume most of the fuel and what was left would have a very short half life, havent gone into the molten salt reactors to the extent you have but it looks as if they to can be breeder reactors, to what extent they would consume all the radioactive materiel I don't know, at least the process looks better than the one we have know.

As important as electrical energy is, it's still oil that will be our biggest concern in the near future and why I'm opposed to the car and the millions we spend on roads, without cheap oil food production will suffer, and compared to food the car is not something I need, we hear all this talk of how much is left but what the oil industry and our politicians fail to mention is the oil that's left is the hardest to get, lower EROEI, and with it a rise in pollution, marine, tar sands and fracking, it's nothing like traditional oil extraction.

Read somewhere we couldn't even go back to the iron age, we have extracted all the easy ore and the ore that's left would be beyond the capabilities of people in the future to smelt. and how much have we wasted on the car over the last 50 years.

Hope you are having better weather than we are, will have to spray again for black spot,

Cheers Bryan

Just me and the cat now, on 2 acres of fruit and veg + hazel nuts, macadamia, chestnuts and walnuts,
www.youtube.com/user/bandjsellars?feature=mhee

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441448 by morioka
Replied by morioka on topic Agenda21

Crusha;440937 wrote:

As for greenhouse gases, I have yet to see any empirical evidence that CO2 or methane play anything other than a very minor part (and some dispute even that) in the global climate. The current temps are still well below any of the IPCC and Hansen model projections, even after the raw measurements are constantly adjusted upwards and the rapid increase in CO2. There are a growing number of studies that indicate there are far more important factors in influencing the climate, including some that appear to be somewhat cyclical in nature. (e.g. solar activity, various ocean cycles, even earths orbit.)

I am all for reducing pollution, but make no mistake CO2 is not a pollutant and historically the current levels are very low.

Nor is there any evidence that the number or frequency of “extreme” weather events is increasing. Certainly there is more reporting of such events, but statistically the number of storms (Hurricanes, Tornadoes etc has been declining since about the 70’s, droughts are less frequent etc.

Here's a little bedtime reading then.
grist.org/series/skeptics/

An open mind is all that is needed

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441460 by spark
Replied by spark on topic Agenda21
Hi Bryan,

wandering free;441000 wrote:

Just found this:-Due to breeding, a Fast Breeder Reactor can generate enough fissile fuel to replace that used up plus enough fuel for other reactors.

Breeder reactors are an interesting technology. I understand that a huge problem that breeder reactors face is the political issues surronding spent fuel recycling, plutonium and nuclear weapons. The other big problem that breeder reactors face is that using lots of natural uranium is cheaper than paying the increased capital costs of breeder reactors and fuel reprocessing facilities. For example, if electricity only cost 1c/kwhr, everyone would heat their homes with $30 fan heaters instead of $3000 heat pumps that only use 1/4 of the electricty - breeder reactors are like that heat pump, more efficient, but more expensive.

If you mine naturally occuring uranium ore, refine it to uranium hexafluoride salt, about 0.7% of the uranium atoms are U235, which are fissionable, and about 99.2% of the uranium atoms are U238 which is not fissionable, but can be converted into plutonium-239 by neutron capture. If you use a heavy water (eg CANDU) or graphite (eg RBMK - aka Chernobyl) moderated reactor, you can fission unenriched uranium. However, to make fuel for most of the world's BWR and PWR reactors, you need to enrich the so that about 5% of the uranium atoms in the fuel are U235 - this creates a large pile of low-level radioactive "waste" depleted uranium (the U238 that you remove from the fuel in the enrichment process). Because U235 atoms are slightly lighter than U238 atoms, centrefuges can be used to enrich uranium (but it is still hard work), much like how a centrefuge can be used to separate light cream from heavy milk.
If you want to make a bomb, you don't stop enriching at 5% U235 level, you keep going until you get to 90+% U235 content, at which point you have weapons grade uranium which is seriously potent stuff (50kg or so is enough for a Hiroshima scale weapon). Politically, uranium enrichment is a hot potatoe due to "prolifferation concerns" eg Iran says that they only want to enrich uranium for civil power generation, but the USA accuses the Iranians of enriching uranium for a weapons program...

When uranium atoms are bombarded with neutrons inside a nuclear reactor, some of them fission into fission products, releasing enormous quantities of energy, some of them are transmuted into "transuranic" elements by neutron capture which can subsequently be fissioned the next time they are struck by a neutron, and the majority of atoms don't get hit by any neutrons during the fuel cycle and thus remain unchanged. As the fissionable uranium in the fuel is used up, and fission products (neutron poisons) accumulate, it becomes harder and harder to keep the reactor critical (control rods must be withdrawn futher, concentration of boron in the water reduced, etc). Eventually you have to shut the reactor down and change the fuel rods even if the rod cladding is undamaged.
Most of the radioactivity from the spent fuel rods comes from the fission products, which have short half-lives, which means that while these atoms are highly radioactive and very dangerous, they don't stay that way for more than a few hundred years. There also aren't that much of them - a conventional 1000MW nuclear power station running flat out for a year will produce about 1000kg of fission products. The rest of the spent fuel is unfissioned U235, transuranics like plutonium (which are radioactive and will be for thousands of years, but they are no where near as "hot" as the fission products) and U238. If you remove the fission products from the spent fuel, pretty much everything else can be put into new fuel rods and put back into a reactor for another fuel cycle.

Plutonium breeder reactors don't have a neutron moderator because fast neutrons are more likely to transmute U238 into plutonium than moderated (slow neutrons). The catch is that moderated neutrons are more likely to fission U235 or plutonium than fast neutrons, so a fast breeder reactor needs to use fuel with a higher level of fissionable atoms (20% and up, I beleive) to maintain criticality.

The big political problem is that when you reprocess spent fuel, especially breeder reactor fuel, you have access to large quanities of plutonium - it takes less than 5kg of plutonium to make a bomb! (plutonium has a much smaller critical mass than U235).
A small plutonium bomb acting as the trigger, combined with a large quantity of lithium and deuterium (the heavy isotope of hydrogen, extracted from heavy water) results in a "hydrogen" or thermo-nuclear bomb, which can potentially have an explosive yeild measured in millions of tons of TNT...
Reactor grade plutonium that comes from fuel that has been inside a reactor for a year isn't the best stuff for making bombs though as it quite radioactive and is much more dangerous to handle than plutonium that has come from fuel that has only spent a few weeks or months inside a reactor. eg both the British Magnox and Russian RBMK were designed for regular online refueling (don't have to stop the reactor to refuel) with very short fuel cycles to enable easy production of weapons grade plutonium (for the cold war and the arms race).

The the lack of reprocessing is one of the reasons why spent fuel pools at nuclear power stations are being used for long term storage of spent fuel (which they were not designed for). Originally, the idea was that power companies would store their spent fuel underwater for a year or two, after which the residual heat generation from radioactive decay had dropped to the point that the fuel could be safely transported in dry casks to a fuel reprocessing plant. Well, in the closing years of the cold war, due to various arms treaties, many nuclear weapons countries including Russia and the USA have agreed not to reprocess spent reactor fuel, which of course leaves the reactor operators in the lurch. This is why if you go to one of the older nuclear power stations in the USA, you are likely to see dry casks full of spent fuel simply stored in a yard outside the power station, waiting for the truck or train that will never come to take them away to the reprocessing plant.

Comming back to the subject of uranium enrichment, and the mountain of depleted uranium that you end up with, the world has over 1 millon tons of depleted uranium, already mined, processed and stockpiled.

Should we decide to use breeder reactors for energy production, the energy content of this depleted uranium is absolutely enormous, though sadly, to date, the best thing that we use it for today is making armour peicing bullets. Uranium is very hard and dense (denser than lead), and it is also pyrophoric (burns in air when struck, just like a ciggarete lighter flint). These properties make it ideal for armour peicing bullets - it carries enough momentum and a hard enough point to go through the side of a tank or a concrete wall, and the impact makes it start to burn at very high temperatures which is very effective at starting fires inside of tanks and other targets. The big problem is that when depleted uranium burns, it burns to fine glassy spheres, only a micron or so in diameter, that are readily inhaled and remain lodged in the lungs for life (just like asbestos). Depleted uranium is mostly only an alpha emitter, and considering that alpha particles have very low penetrating power (they can't get though a sheet of paper or a few inches of air) it is relatively safe to handle the uranium bullets before they are shot from a gun, however, once the fine dust gets inside your body and stays there, there is nothing to stop the alpha particles from causing double stand breaks in your DNA (whilst alpha particles have the weakest penetrating power, they also do the most damage to whatever they hit). Uranium is also a heavy metal, and it is chemically toxic too.

A standard 30mm DU projectile weighs about 300grams, and for example, the machinegun on an A-10 thunderbolt (US ground attack aircraft) spits them out at about 3900 per minute (65 every second!), they are used in many other weapons too. How many tons of these rounds were used, and how does the nuclear energy content of them (with breeder reactors) compare to the engergy content of all the extractable oil under Iraq?

wandering free;441000 wrote:
Read somewhere we couldn't even go back to the iron age, we have extracted all the easy ore and the ore that's left would be beyond the capabilities of people in the future to smelt. and how much have we wasted on the car over the last 50 years.
Cheers Bryan

Considering how much steel per capita is above ground and easily accessable today, I can't envisage shortage of iron being a problem if you only had iron age technology and an iron age lifestyle. Recycling of steel into wrought iron isn't exactly high tech provided that you have a suitable source of carbon (coal, biochar, etc)
More of a concern would be trying to sustain a world population of 7 billion with only iron-age technology.

Cheers

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441472 by wandering free
Replied by wandering free on topic Agenda21

spark;441024 wrote: Hi Bryan,

More of a concern would be trying to sustain a world population of 7 billion with only iron-age technology.

Cheers

Hi Spark,

And no way of reducing the population, Agenda 21 thinks education and improving living standards will fix it, but we don't have much time and then again it imposes more demand on depleting oil supplies.

For those not familiar with atomic weapons you only need enriched uranium to make a dirty bomb, take 2 non critical amounts that together result in critical mass, place them in either end of a piece of tubing and an explosive devise to crash them together and you have an atom bomb, Iran is a worry as is Israel, as someone said all this power in the hands of an animal only a chromosome removed from a chimpanzee.

I thought they had tried to extract the plutonium from waste fuel but all the best efforts had come to nothing, that's why they needed breeder reactors to produce the pure stuff, it seems such a shame to waste all that energy when it would be impossible for anyone to extract the plutonium, but if the cost is to high to recycle, then they are not going to bother about the needs of the future, profit first.

Do we wait for a visit from the SAS to see what bombs we might have hidden away, only joking, hope they realize that.

Cheers Bryan

PS A great bit of info on your part good reading,

Just me and the cat now, on 2 acres of fruit and veg + hazel nuts, macadamia, chestnuts and walnuts,
www.youtube.com/user/bandjsellars?feature=mhee

Please Log in or Create an account to join the conversation.

More
9 years 10 months ago #441483 by spark
Replied by spark on topic Agenda21

wandering free;441036 wrote:
And no way of reducing the population, Agenda 21 thinks education and improving living standards will fix it, but we don't have much time and then again it imposes more demand on depleting oil supplies.

I beleive that education and improved living standards will deal to the "population bomb", but that to have a decent crack at it, the world needs to stop fighting all these wars and replace fossil fuels with something better.

wandering free;441036 wrote:
For those not familiar with atomic weapons you only need enriched uranium to make a dirty bomb, take 2 non critical amounts that together result in critical mass, place them in either end of a piece of tubing and an explosive devise to crash them together and you have an atom bomb

Yep - that is the type of bomb that was dropped on Hiroshima. The Americans were so sure that it would work that they didn't think it would be necessary to test one first (the test in the desert in the USA was a plutonium bomb of the same type that was later dropped on Nagasaki).

However, to make it work, you need weapons grade uranium - if you only have 5% or even 20% enriched reactor grade uranium, your weapon will need to be much much bigger and heavier to acheive prompt criticality, and when you initiate it, it will likely only fizzle and disassemble itself before it produces a yeild of more than a few tons of TNT equivalent (which is practically nothing on the scale of nuclear weapons).

A "dirty bomb" doesn't actualy fission atoms, it simply scatters radioactive material about the place, and is much much less dangerous than a real atomic bomb. As far as I am aware, it hasn't actually been used as a weapon yet, but it is something that the security people are concerned that terrorists might try to do. For example, a bad guy wanting to make a dirty bomb would get hold of something like a medical or industrial radioactive source (eg en.wikipedia.org/wiki/Goi%C3%A2nia_accident ), combine it with conventional explosives, and then detonate it in an area that they wish to pollute with radioactive material. War and Terrorism is not cool - ok?

wandering free;441036 wrote:
I thought they had tried to extract the plutonium from waste fuel but all the best efforts had come to nothing

Conventional moderated reactors fission more uranium235 atoms than they convert uranium238 into plutonium atoms. Fast neutron reactors (can be used as breeders) fission less u235 and plutonium atoms than they convert u238 atoms into plutonium.

Pretty much all of the worlds plutonium has been extracted from "spent reactor fuel". Reactors like Hanford in the USA www.nonplused.org/panos/b_reactor/index.html and Windscale in the UK en.wikipedia.org/wiki/Windscale_fire are examples of reactors that were built soley for weapons grade plutonium production. Both were simple graphite moderated "piles" that fissioned unenriched uranium (0.7% U235) in order to irradate the U238 contained therein with the neutrons required to transmute some of it into plutonium. The plutonium was then extracted chemically from the spent fuel - eg PUREX en.wikipedia.org/wiki/PUREX

wandering free;441036 wrote:
Do we wait for a visit from the SAS to see what bombs we might have hidden away, only joking, hope they realize that.

Well, if the "kim dot com" spying saga is anything to go by, I wouldn't be too surprised if the GCSB and or SIS decided to check us out [}:)]

Cheers

Please Log in or Create an account to join the conversation.

More
9 years 9 months ago #441509 by wandering free
Replied by wandering free on topic Agenda21

spark;441047 wrote: Windscale in the UK en.wikipedia.org/wiki/Windscale_fire


Hi spark

The radiation leak was played down at the time, they did a hush up job while confiscating milk from the area but never warned breast feeding mothers about the risk to their babies, it was the start of the disillusion I have with atomic energy. Then when we got married in Oct 1962 they had the Cuban missile crisis, not that we new anything about it until we got home, but it does alter your perception when you live on the firing line.

Cheers


Just me and the cat now, on 2 acres of fruit and veg + hazel nuts, macadamia, chestnuts and walnuts,
www.youtube.com/user/bandjsellars?feature=mhee

Please Log in or Create an account to join the conversation.

Time to create page: 0.238 seconds