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Topic Title: Japan Earthquake
Topic Summary: Nuclear Power Criticality Analysis and Maximum Credibility Analysis
Created On: 13 March 2011 07:25 PM
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Related E&T article: Fukushima - the facts
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 19 March 2011 09:55 PM
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poo

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The radioactivity of all nuclear waste diminishes with time. All radioisotopes contained in the waste have a half-life,-the time it takes for any radionuclide to lose half of its radioactivity
Certain radioactive elements(such as plutonium-239) in "spent" fuel will remain hazardous to humans for hundreds of thousands of years.
Other radioisotopes remain hazardous for millions,yes,millions of years.
Thus these wastes must be shielded for centuries and isolated from the living environment for millennia.
The amount of high level waste produced by nuclear reactors is increasing by 12,000 metric tons a year.(worldwide) About 100 double decker buses.
 20 March 2011 03:03 AM
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oldsloguy

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Originally posted by: poo

The radioactivity of all nuclear waste diminishes with time. All radioisotopes contained in the waste have a half-life,-the time it takes for any radionuclide to lose half of its radioactivity

Certain radioactive elements(such as plutonium-239) in "spent" fuel will remain hazardous to humans for hundreds of thousands of years.

Other radioisotopes remain hazardous for millions,yes,millions of years.

Thus these wastes must be shielded for centuries and isolated from the living environment for millennia.

The amount of high level waste produced by nuclear reactors is increasing by 12,000 metric tons a year.(worldwide) About 100 double decker buses.


My wife has a favorite orange bowl from which she eats her salad. This bowl is glazed with pure uranium oxide, UO3 to be exact. The radiation emission within about 6 inches of this bowl is over 1000 times natural background.

There is only one thing that goes into a nuclear reactor for fuel stable, durable ceramic pellets, fabricated from actinides, all elements heavier than actinium of which the most relevant for reactor fuel purposes are uranium, plutonium and thorium (uranium in current US reactors). The physical and chemical properties of the pellets are very similar to the glazing material on my wife's bowl.

What comes out in spent fuel is a mixture of unused actinides and fission products. When the fission products are removed during reprocessing all of the remaining actinides can be used again as fuel in an appropriately designed reactor. The fission products, all of which are metal oxides will be melted together into a stable, durable glass or ceramic for storage, reducing the waste by well over a 100 times. Within 300 to 500 years or so, those fission products will be less radioactive than the bowl from which my wife is eating her salad. There is absolutely no practical need to store them for millions of years. If fact, at that point, you could glaze my dinner dishes with them as they would make great conversation starters at parties!
 20 March 2011 08:12 AM
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dvaidr

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Originally posted by: poo

The radioactivity of all nuclear waste diminishes with time. All radioisotopes contained in the waste have a half-life,-the time it takes for any radionuclide to lose half of its radioactivity

Certain radioactive elements(such as plutonium-239) in "spent" fuel will remain hazardous to humans for hundreds of thousands of years.

Other radioisotopes remain hazardous for millions,yes,millions of years.

Thus these wastes must be shielded for centuries and isolated from the living environment for millennia.

The amount of high level waste produced by nuclear reactors is increasing by 12,000 metric tons a year.(worldwide) About 100 double decker buses.


Well said, Poo.
 20 March 2011 08:26 AM
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dvaidr

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Uranium oxide is a radioactive mineral made up of black, grey, or brown crystals that are generally opaque and have a greasy lustre. It is also known as uraninite. This ore is the principle source for the commercial extraction of uranium, as it has a relatively high concentration of this element. Uraninite is usually mined from hydrothermal vein deposits and sedimentary rocks, such as sandstone, and can also be recovered as a by-product of gold and silver mining.

Uranium is a metallic chemical element that is weakly radioactive and has the highest atomic weight of all naturally occurring elements. It is approximately 70% more dense than lead, but has a lower density compared to gold. Uranium has a wide range of both military and civilian applications, most notably in nuclear technology due to its capacity to produce a sustained nuclear chain reaction.

It occurs naturally. It''s a mineral and is safe.

You must all remember the explosion and fire at Buncefield. Fairly catastrophic wasn't it? And wasn't it caused by burning chemicals which made lots of black smoke, which we could see? The calculated blast radius of maximum credible accident analysis was just about spot-on. Contingency plans were well executed and the damage remained relatively, local and the effects were short lived. Those pesky chemicals didn't get away with it!

Edited: 20 March 2011 at 08:36 AM by dvaidr
 20 March 2011 09:41 PM
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poo

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We can all google high level radioactive waste and make our own minds up.
Since reprocessing has been mentioned I will outline some of the problems associated with that activity.
* Reprocessing causes the transport by road, rail and sea of spent fuel to a reprocessing plant and the return transport of the resulting high-level waste and plutonium from the plants of the most hazardous shipments of toxic waste there are today.

* Commercial reprocessing of spent fuel results in huge discharges of radioactivity into the sea and atmosphere - virtually all of Europe's radioactive pollution comes from reprocessing plants - and its marine pollution has been measured as far away as the west coast of Greenland.

* Reprocessing of spent fuel increases the volume of radioactive waste by up to 160 times. The amount of actual radioactivity is not changed - the industrial process of reprocessing just spreads the radioactivity over a vastly greater volume. Most of the waste is low-level, but there is also plutonium-contaminated intermediate-level waste and a small quantity of high-level waste which is so radioactive and hot it must be continually cooled for at least 50 years before anything can be done with it.
* There is widespread concern about the health risks of reprocessing, especially clusters of childhood leukaemia around reprocessing plants.
* Finally reprocessing is the only way of producing plutonium for use in nuclear weapons.
There are too many problems with Nuclear Power.
 21 March 2011 06:50 AM
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dvaidr

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BBC World Service are saying that Iodine tablets are to be distributed in Japan......
 21 March 2011 09:45 AM
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rogerbryant

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'burning chemicals which made lots of black smoke'

And this black smoke was safe? Did it contain toxins and carcinogens? Did it contain PM10 particles?
The chemicals certainly won in Seveso and Bhopal. Both incidents make interesting reading, and the actual death toll from Bhopal is frightening. Give me a nuclear plant at the end of my garden rather than a large chemical plant any day.

'Other radioisotopes remain hazardous for millions,yes,millions of years.'

A very sensationalist statement. Which isotopes? How do you define hazardous? The minimum level of radioactivity that could be described as hazardous would be the natural background level (whether this is hazardous or not is another question). A significant part of natural background radiation comes from long-lived naturally occurring radioactive materials. Are these the ones that you are claiming to be hazardous? If so we should start to plan the evacuation of Cornwall now.

'especially clusters of childhood leukaemia around reprocessing plants'

Another one of the headline grabbers, which was also used in a misguided E&T article regarding cancer clusters around nuclear power plants and the German KiKK report. Childhood leukaemia clusters appear from time to time in all sorts of areas. These must be devastating for the parents who will, of course, look for a cause. There has never been a correlation found with any nuclear facilities. The closest to a correlation seems to be areas where there has been a large influx of people from outside the area. These can include any large development. The two largest clusters were at Woburn, MA in the USA which was possibly linked to chemical contamination of the ground water by local industry, and Fallon, Nevada, also in the USA, which was never explained fully but went away after 16 cases. Fallon was home to a large military base which obviously had large influxes of people but also had the possibility of other chemical contamination.
I would recommend that you look a little more into this, an internet search on Fallon should get you started.

Best regards

Roger
 21 March 2011 07:03 PM
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poo

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Of particular concern in nuclear waste management are two long-lived fission products, Tc-99 (half-life 220,000 years) and I-129 (half-life 17 million years), which dominate spent fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Np-237 (half-life two million years) and Pu-239 (half life 24,000 years).[20] Nuclear waste requires sophisticated treatment and management to successfully isolate it from interacting with the biosphere. This usually necessitates treatment, followed by a long-term management strategy involving storage, disposal or transformation of the waste into a non-toxic form.[21] Governments around the world are considering a range of waste management and disposal options, though there has been limited progress toward long-term waste management solutions.[22]
The time frame in question when dealing with radioactive waste ranges from 10,000 to 1,000,000 years,[33] according to studies based on the effect of estimated radiation doses.[34] Researchers suggest that forecasts of health detriment for such periods should be examined critically.[35] [36] Practical studies only consider up to 100 years as far as effective planning[37] and cost evaluations[38] are concerned. Long term behavior of radioactive wastes remains a subject for ongoing research projects
Man is faced with time scales that transcend his experience.
Reprocessing is not allowed in the United States.The Obama Administration has disallowed reprocessing of nuclear waste,citing nuclear proliferation concerns.
 21 March 2011 07:42 PM
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OMS

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Good old Wikipedia - where would a good argument be without it

Regards

OMS

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 21 March 2011 08:57 PM
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poo

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As I said before,50 years on and we still don't know what to do with the high level waste. Every year we pile up another 100 double decker buses of the stuff hoping we can safely look after it into an unknown future.
 21 March 2011 10:28 PM
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poo

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But wait,there is more from Wikipedia:
Because some radioactive species have half-lives longer than one million years, even very low container leakage and radionuclide migration rates must be taken into account.[40] Moreover, it may require more than one half-life until some nuclear materials lose enough radioactivity to cease being lethal to living things. A 1983 review of the Swedish radioactive waste disposal program by the National Academy of Sciences found that country's estimate of several hundred thousand years - perhaps up to one million years - being necessary for waste isolation "fully justified."[41]
 22 March 2011 03:38 AM
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oldsloguy

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Originally posted by: poo

* Reprocessing causes the transport by road, rail and sea of spent fuel to a reprocessing plant and the return transport of the resulting high-level waste and plutonium from the plants of the most hazardous shipments of toxic waste there are today.


Some misunderstanding of the concept of toxicity here.

Anything in the periodic table can be made fatally toxic in some manner. Take Calcium for example, produce metallic calcium pellets, eat them and you will quickly be dead. Eat plutonium oxide fuel pellets and they will simply pass through your system with no effect! Calcium can be way more toxic than Pu but no one worries about it.

Plutonium is significantly toxic only if inhaled in micron size particles that are too small to be expelled from the lungs. There are only two ways to make Plutonium toxic, other than intentionally producing some weird organic cocktail. You could intentionally grind the oxide to this size or you could produce Pu metal that will spontaneously shed particles in this size range. Some processes of producing fuel pellets could use grinding to size, although this would most likely be done wet if at all. Pu metal is not used in the nuclear fuel cycle.

In short, the Pu fuels pellets are stable, durable ceramic oxides. The physical and chemical properties of the pellets are very similar to the UO3 glazing on my wife's bowl that I mentioned in my post above. If my wife's bowl were glazed with PuO2 (a nice avocado green) rather the UO3 (brilliant orange) it would be somewhat more radioactive but she could still eat from it with no biological effects.

Plutonium is certainly not the "most toxic material known to mankind" as it has been described.

As far as shipments go, driving beside a gasoline tanker is much more dangerous than next to a spent fuel truck.
 22 March 2011 03:41 AM
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oldsloguy

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Originally posted by: poo

* Commercial reprocessing of spent fuel results in huge discharges of radioactivity into the sea and atmosphere - virtually all of Europe's radioactive pollution comes from reprocessing plants - and its marine pollution has been measured as far away as the west coast of Greenland.


I do not what "huge" means, but I think you got some bad information here. Maybe you could link where you heard this so that we could comment.
 22 March 2011 03:43 AM
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oldsloguy

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Originally posted by: poo

* Reprocessing of spent fuel increases the volume of radioactive waste by up to 160 times. The amount of actual radioactivity is not changed - the industrial process of reprocessing just spreads the radioactivity over a vastly greater volume. Most of the waste is low-level, but there is also plutonium-contaminated intermediate-level waste and a small quantity of high-level waste which is so radioactive and hot it must be continually cooled for at least 50 years before anything can be done with it.


All of these low level wastes can be calcined and sintered into harmless ceramic pellets.
 22 March 2011 03:46 AM
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oldsloguy

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Originally posted by: poo

* There is widespread concern about the health risks of reprocessing, especially clusters of childhood leukaemia around reprocessing plants.


Leukemia can only be generated by very high levels of radiation exposure. The US Academy of Sciences has been studying the Japanese bomb blast survivors for over 60 years now and regularly publishes the results in what are called the BEIR (Biological Effects of Ionizing Radiation) reports. Leukemia can only be observed in the very highest dose cohort (>200 REM - Acute radiation syndrome) and that effect is only 2 in 1000. UNSCEAR found no leukemia at Chernobyl except for a slight possibility in the high dose plant response personnel that survived. If these tiny clusters are to be explained by radiation, I think you need to explain why Ramsar Iran, a city with an average bkg. of 5 to 30 Rem/yr does not have excess leukemia!

Google unscear.org/.../2008/Advance_copy_Annex_D_Chernobyl_Report.pdf
Link removed/7.../background-radiation/
 22 March 2011 03:51 AM
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oldsloguy

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Originally posted by: poo

* Finally reprocessing is the only way of producing plutonium for use in nuclear weapons.


Although it is probably theoretically possible to produce a very low yield nuclear explosive device with LWR reactor waste it would be a daunting task. Even with the highest weapons grade plutonium it is extremely difficult to produce an explosive device as the high specific neutron yield makes assembly of the device during ignition very unstable. The design of a Pu weapon is so difficult that none of the 10 countries known to have produced weapons have chosen to use Pu waste from commercial LWR type power reactors.

Many have chosen uranium and that is even considering the difficulty of enriching the uranium. Design of a uranium weapon would require a government sized effort involving thousands of people but could done without testing provided they had top quality physics and nuclear engineering people. Design of a plutonium weapon (using weapons grade Pu) would require a government sized effort involving hundreds to thousands of people and IMHO is very difficult to do even with a test program. (Ref: N. Korea)

Spent reactor fuel contains a lot of PU240 and 242 that makes this problem even worse. Yes, theoretically, experienced designers at places like Livermore and Los Alamos could probably do it. Testing IMO would be required. If you are determined to build a weapon from Pu, it would much easier to build a graphite reactor and make the "good stuff" rather than futzing around with the junk from a power rector. Proof, every country that has assembled the massive resources necessary to make Pu weapons has taken the easiest path and built a graphite reactor to produce the material.
 22 March 2011 04:05 AM
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oldsloguy

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Originally posted by: poo

Of particular concern in nuclear waste management are two long-lived fission products, Tc-99 (half-life 220,000 years) and I-129 (half-life 17 million years), which dominate spent fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Np-237 (half-life two million years) and Pu-239 (half life 24,000 years).[20] Nuclear waste requires sophisticated treatment and management to successfully isolate it from interacting with the biosphere. This usually necessitates treatment, followed by a long-term management strategy involving storage, disposal or transformation of the waste into a non-toxic form.[21] Governments around the world are considering a range of waste management and disposal options, though there has been limited progress toward long-term waste management solutions.[22]

The time frame in question when dealing with radioactive waste ranges from 10,000 to 1,000,000 years,[33] according to studies based on the effect of estimated radiation doses.[34] Researchers suggest that forecasts of health detriment for such periods should be examined critically.[35] [36] Practical studies only consider up to 100 years as far as effective planning[37] and cost evaluations[38] are concerned. Long term behavior of radioactive wastes remains a subject for ongoing research projects

Man is faced with time scales that transcend his experience.

Reprocessing is not allowed in the United States.The Obama Administration has disallowed reprocessing of nuclear waste,citing nuclear proliferation concerns.


You seem to have missed the post above. All of the actinides are usable as reactor fuel. Why would you throw them away? The fission products as a total will be less radioactive than the uranium mined from the earth in a few hundred years.

Go to: Link removed/RWD Then scroll down to the Chapman and Curtis RPT. You should be able to find the plots showing the decay of waste products relative to natural uranium.
 22 March 2011 07:20 PM
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poo

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When I say huge discharges of radioactivity into the sea I mean 8 million litres a day. This is from greenpeace international:


Sellafield is a nuclear complex situated on the coast of north-west England. Originally named Windscale with the purpose of producing plutonium for the British nuclear weapons program, it is now predominantly a commercial site with reprocessing facilities, fuel fabrication and other installations. It has one of the highest concentrations of radioactive waste on the planet, a disastrous safety record with hundreds of accidents involving the release of radioactive substances into the environment and their radiation of workers.

The reprocessing plants at Sellafield discharge some 8 million litres of nuclear waste into the sea each day. The Irish Sea is one of the most radioactively contaminated seas in the world. In the vicinity of the complex, groundwater, estuaries and soil are contaminated, with levels in the area around Sellafield exceeding contamination inside the Chernobyl exclusion zone. Compared to the British average, there has been a ten-fold increase of childhood leukaemia around Sellafield. Plutonium dust has been found in the houses of residents living along the Irish Sea coast.

This is from today's Mail on Line: 22-3-2011

A fresh legal bid to close down Sellafield's nuclear reprocessing plant is one of the most significant cases the Irish Republic has ever taken.

Environment minister Martin Cullen said today's action at a United Nations court was essential to protect Ireland's interests.

Ministers are taking the UK to the UN Convention on the Law of the Sea amid concerns that radioactive discharge from the Cumbrian site is polluting the Irish Sea. Mr Cullen said he regretted that such a step was necessary.

He said: "These cases are among the most significant legal actions ever taken by Ireland.

"They represent the Irish government's absolute commitment to ensuring that Ireland's rights under these international conventions in relation to Sellafield and its operations are fully vindicated. I know the team, led by the Attorney General, will make the strongest possible arguments in support of our concerns."

He said there were several worrying issues, including claims of pollution from the discharge of radioactive waste from the MOX plant into the Irish Sea.

Mr Cullen also expressed concern at the "inadequacy" of the environmental assessment undertaken by the UK in relation to the facility and the failure to properly assess the risk of terrorist attack on the site. International movements of radioactive materials associated with the site were also a cause for concern.

Irish government chief whip Mary Hanafin said the fresh legal action was a sign of Ireland's determination to use every means possible to close down the plant.

"My constituents along the coastline of Dublin Bay are living with the very real threat of Sellafield. They can be assured the hearing in The Hague represents the most significant case this country has ever taken against Sellafield to date."

The hearings will take place before a five-member tribunal. They will proceed for around three weeks and will be open to the public with some exceptions where material being referred to is of a confidential nature.

Read more: http://www.dailymail.co.uk/new...eld.html#ixzz1HME4y9j4
 22 March 2011 10:51 PM
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poo

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From: Scientific American Magazine, January 26th 2009


Although a dozen years have elapsed since any new nuclear power reactor has come online in the U.S., there are now stirrings of a nuclear renaissance. The incentives are certainly in place: the costs of natural gas and oil have skyrocketed; the public increasingly objects to the greenhouse gas emissions from burning fossil fuels; and the federal government has offered up to $8 billion in subsidies and insurance against delays in licensing (with new laws to streamline the process) and $18.5 billion in loan guarantees. What more could the moribund nuclear power industry possibly want?

Just one thing: a place to ship its used reactor fuel. Indeed, the lack of a disposal site remains a dark cloud hanging over the entire enterprise. The projected opening of a federal waste storage repository in Yucca Mountain in Nevada (now anticipated for 2017 at the earliest) has already slipped by two decades, and the cooling pools holding spent fuel at the nation's nuclear power plants are running out of space.
 23 March 2011 09:00 AM
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OMS

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The reprocessing plants at Sellafield discharge some 8 million litres of nuclear waste into the sea each day.


So that would be 8 million Kgs of waste or 8 thousand tonnes of waste 24/7/365. No wonder sea levels are risng then !!

OMS

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Failure is always an option
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