Presentation on theme: "Nuclear Waste What is real? What is not? Andrew Kenny Engineer & Commentator on Energy"— Presentation transcript:
Nuclear Waste What is real? What is not? Andrew Kenny Engineer & Commentator on Energy email@example.com
Four fallacies about nuclear power 1. It is dangerous – In fact it is the safest energy source of all 2. It is expensive – In fact it is always economic and often the cheapest source of grid electricity 3. It is unsustainable – In fact, because of the vast amounts of nuclear fuel in the ground and water, it can provide the whole world with electricity for the life of our planet 4. (And worst). It has an insoluble waste problem – In fact, it has the least waste problem of any energy source. – In fact, its waste problem has been easily solved
In Mar 2011, Fukushima gave a spectacular demonstration of nuclear safety: Devastating earthquake & tsunami, killing over 16,000 people Severe damage to 4 units at Fukushima-Daiichi nuclear station Yet nobody (0 people) was killed or harmed by the radiation and nobody likely to be in future
The strange nonsense about nuclear waste Constantly, from greens, politicians & big media, we hear about the unsolved problem of nuclear waste. What does this mean? Every single energy technology, including solar, nuclear, coal, wind, hydro etc, produces waste in its total energy cycle: – mining, processing, manufacture, construction, operation and decommissioning The main difference between nuclear waste and the waste of the other energy sources is that the nuclear waste is much smaller and much easier to manage and store so that it presents no threat to mankind or the environment, now or in future. So whats the problem?
Deadly & Lasts for Millions of Years We keep hearing from the big media that nuclear waste is deadly and lasts for millions of years. If deadly means that the material can kill under certain circumstances, then every material in existence is deadly. Some examples will follow. All stable atoms (those that are not radioactive) last forever - not for millions of years but forever - until the end of time. Only unstable atoms (radioactive ones) do not last forever.
Under certain circumstances every element in the periodic table can be deadly, and most of them have isotopes that last forever - not millions of years but forever
Example of deadly materials that last forever Nitrogen: – 80% of the air in this room – Two lungs full of 100% nitrogen will kill you instantly – Kills more people than any other industrial gas Oxygen: – 20% of the air in this room – Deadly toxic. A syringe full of pure oxygen in your blood will kill you instantly Lead: – Large amounts in the batteries of the cars parked outside – Causes cancer and permanent brain damage, especially in children – Slaughtered millions of people in War Wars 1 and 2. Cadmium – Used in solar photovoltaic cells (unsolved problem of deadly solar waste) – Emitted from stacks of coal power stations – Causes fatal cancers, kidney disease, lung disease etc All of these are deadly and last forever
Should we ban Dihydrous Oxide? Dihydrous oxide forms after explosions. Dihydrous oxide kills tens of thousands of people every year. Young children are especially likely to be killed by dihydrous oxide. Millions of people suffer illness because of dihydrous oxide Dihydrous oxide damages even the strongest steels and causes billions of dollars of losses every year. Dihydrous oxide remains dangerous for thousands of millions of years - in fact forever. Every time an autopsy is done on a patient who has died of cancer, dihydrous oxide is always found in the cancerous tissues - 100% correlation. Should we ban dihydrous oxide? Dihydrous oxide = H 2 0. Dihydrous oxide is water.
Plutonium: Mythology Plutonium, which is hazardous but not exceptionally so, has acquired an almost Satanic reputation among the anti-nukes. They accuse it of being: 1. The most dangerous substance on Earth 2. Manmade. Not occurring in nature Both statements are nonsense Incidentally, Pluto can mean: 1. God of the underworld 2. Outermost planet 3. Mickey Mouses dog
Plutonium: Physics Plutonium is an atom with 94 neutrons in its nucleus (Uranium is an atom with 92 neutrons in its nuclear) There were considerable quantities of plutonium when the Earth was formed but, because of its relatively short half-life, it has decayed away. Half-life of Earth: 4.5 billion years / Half-life of Plutonium: 24 thousand yea rs However, there are vast amounts of uranium in the ground and the water (and some in our bodies) and this can be converted into plutonium when the U-238 nucleus captures a neutron. Neutrons occur widely in nature. The reactions above happen in nuclear reactors and in nature, including in our own bodies.
Substancelethal dose [mg]Death in Ingested: botulism toxin0.00005hours to days nicotine60-100seconds to days aflatoxin (in mushrooms)0.01hours to days aconitin (in flowers)1-2hourS strychnine100-200,hours cyanide200minutes plutonium6000more than 15 years In blood: snake poison0.005-1hours to days plutoniummore than 15 years Inhaled: nerve gas1hours cadmium vapors90hours plutonium5more than 15 years Plutonium Toxicity B L Cohen, Hazards from plutonium toxicity, Health Physics, Jan 1977 After World War 2, twenty-six workers in the USA were contaminated with large doses of plutonium. Thirty- seven years later no ill effects were observed in them as a result of the plutonium (Radioactivity and Health, a History, JN Stannard, 1988). There is no known victim of plutonium toxicity. Ingested, plutonium is ten times as toxic as pure caffeine.
Both hold 1 kg of radioactive materials. But very different half-lives. Who is in more danger? AB A. Half-life: 5 billion yearsA. Half-life: 5 minutes Life times and danger of radioactive materials This man is quite safe This man will die shortly
Why is a short half-life much more dangerous than a long one? Consider a candle & a stick of dynamite, both weighing 200 g. Which contains more energy? The candle. Candle: 8.4 MJ (42 MJ/kg). Dynamite: 0.8 MJ (4 MJ/kg) Which is more dangerous? Because it discharges its energy in a very short time - in a fraction of a second compared with 24 hours or more for the candle. The dynamite.
Radioactive & Chemical Toxins: Life time & Danger For danger from radiation, for all materials: – The longer the half-life, the lower the radioactivity – And the danger reduces over time – A gram of radium will be much less dangerous in a million years time than it is now For danger from chemical reactions, for all materials: – The danger remains exactly the same over time – A gram of lead, cadmium, mercury etc will be exactly as dangerous in a million years time as it is now
The only true question about the storage of wastes We are all, all the time, surrounded by deadly materials, lasting millions of years, if not forever. It is quite impossible – and ludicrous – to suppose that for any waste (including solar & wind) we can – Either set up a disposal site to store it safety until the end of time – Or plan to recycle it safely until the end of time The only true question about the risk of the storage of any such waste is this: – What are the chances of this waste escaping from this storage, now or in the future, in such concentrations as to endanger man or the environment? Nuclear waste from civilian nuclear power has never caused harm to man or the environment since it began almost 60 years ago. Waste from other energy source has caused harm. Lets look at a few examples.
Coal Waste Disaster: Aberfan, Wales. 21 Oct 1966 Coal dump collapsed and fell into the town 116 children, 28 adults killed
Wind Waste in Baotou, China Official studies carried out five years ago in Dalahai village in China confirmed there were unusually high rates of cancer along with high rates of osteoporosis and skin and respiratory diseases. (SIMON PARRY in China and ED DOUGLAS in Scotland. Daily Mail. 26 Jan 2011.) Toxic chemical wastes are causing illness, diseases, infant abnormalities in communities near these mines. Fish are dying in the rivers. In China, there are filthy mines for neodymium, a rare earth used in the generators of wind turbines One of the radioactive wastes is thorium but because of its very long half-life (14 billion years) this is not much of a problem. Note: neodymium can be mined cleanly. The lake of toxic waste at Baotou, China. Mining for neodymium, used in wind generators No newspaper headline saying: Local people in danger from deadly radioactive wind wastes lasting billions of years
NuclearCoal 20 tons of radioactive materials, with half-lives from seconds to billions of years At least 8 tons of radioactive materials (including uranium, half-life 4.5 billion years, & thorium, half-life 14 billion years) 40 thousand tons of sulphur oxides (air pollution causing lung & heart disease) 20 thousand tons of nitrogen oxides (air pollution causing lung disease) 2500 tons of heavy metals such as lead, arsenic, mercury, cadmium (all last forever) Organic compounds, including carcinogens such as polycyclic aromatic hydrocarbons) 6 million tons of carbon dioxide One years operational waste from 1000 MW coal & nuclear plants
What happens to coal & nuclear waste? Coal waste: – It is either thrown on huge, unprotected ash tips or blown into the air we breathe, scattered all over the environment. – It is quite impossible for it all to be collected and stored safely Nuclear waste: – It never moves. It just stays inside the fuel rods. – It is already collected, and is easy to store safely
Types of Nuclear Power Waste 1. Low level – Gloves, protective clothing, tools etc Intermediate level – Resins, contaminated metals, filters etc High level – Spent fuel
Nuclear fuel: Fresh & Spent Essentially the nuclear reactor converts long-lived radionuclides to short-lived ones (more radioactive, lasting less time)
PWR / Reactor Theory / Chapter 6 / TP 6 - 22 REV 2 Fig 6-1 FISSION PRODUCT YIELD CURVE 0.01 70 MASS NUMBER 0.1 1 10 8090100110120130140150160 A 95 A 139 LIGHT FISSION FRAGMENTS HEAVY FISSION FRAGMENTS FISSION YIELD (%)
Typical Nuclear Fuel Pellet (uranium oxide) Typical Nuclear Fuel Assembly (about 3.7 metres long) Nuclear Fuel Before Going into Reactor Nuclear Waste Coming Out of the Reactor The spent fuel is much more dangerous than the fresh fuel because it contains radionuclides with short half-lives
Disposal of Low & Medium Level Nuclear Wastes Koeberg disposes of these at Vaalputs in the Northern Cape. It was chosen for its geological stability, aridness, very low commercial value and very low population density It is an ideal site.
Storage of Low & Intermediate Radioactive Waste at Vaalputs
Disposal of High Level Nuclear Waste (Spent Fuel) After it leaves the reactor, the spent fuel is kept under water in the spent fuel ponds for 10 years or more, after which it has lost 99.99% of its radioactivity. Then it may be kept in dry storage casks, at The power station or somewhere else. No final storage site has been decided. This is purely a matter of politics not a technical problem. A large number of possible storage sites exist, including Vaalputs
Reprocessing Nuclear Waste Remember: At reprocessing plants, such as Le Hague in France, the fission products are separated out and disposed of separately (in glass in steel containers) The uranium and plutonium can then be used again in Mixed oxide fuel (MOx) fuel.
Radiation: The Primary Concern for Nuclear Waste The primary concern with nuclear waste storage is to protect people and the environment against leakage of radiation. Radiation is entirely natural and inescapable. Every living thing, including all of us, is always bathed in natural radiation every second of its life – Most of the natural radiation dose is internal (from breathing in radon gas and from radioactive substances in our food and body tissues The radiation we receive from nature is thousands of times higher than the radiation we receive from the nuclear industry. No harm has ever been seen to humans at radiation doses below 100 mSv (milliSievert). Natural background in Cape Town is about 2.5 mSv / y Natural background in Paarl is about 7.5 mSv / y (because of the granite) It is difficult, if not impossible, to imagine any radiation escaping from any nuclear waste facility at such levels to harm any people.
Proliferation Risk from Nuclear Waste Nuclear fission bombs can be made from: 1. Over 90% enriched uranium (over 90% U-235) – Enrichment is very difficult but bomb making is very easy (HEU is the most dangerous explosive substance on Earth) 2. Over 90% Plutonium-239 – Plutonium made in a production reactor – Bomb making is very difficult In spent fuel from a PWR reactor (Koeberg): 1. The enrichment of the uranium is about 2% – Therefore useless for a uranium bomb 2. The Pu-239 is heavily contaminated with Pu-240 (a powerful neutron poison) – Therefore, even if you managed to extract the plutonium chemically, which is very difficult, and even if you managed to solve the very difficult problem of the chemical implosion, you would only be able to get a low level nuclear explosion – For practical purposes this is impossible for a terrorist group. It is in theory possible to make a Hiroshima uranium bomb by collecting uranium from the granite of Paarl Rock and enriching it. But it will never happen. Nor will any bunch of terrorists make a nuclear bomb from nuclear power waste.
Final Disposal Sites for Nuclear Waste Around the world, various countries are building or proposing final depositories for high level nuclear waste. I must honestly tell you I find this rather ludicrous. It invents a huge problem that doesnt really exist. The idea that you must set up a waste repository that will guarantee that over the next 10,000 years (or whatever), without human intervention, you will never have more than some miniscule releases is quite absurd. All other energy technologies (wind, coal, solar etc),with far worse waste problems, have no such repositories. But some examples...
Proposed Swedish Nuclear Waste Storage Facility
The absurdity of the problem of nuclear waste storage Here follows three examples to illustrate the absurdity of: – pretending that nuclear waste presents an insoluble problem – the expensive silliness of these elaborate long term nuclear waste depositories.
Absurdity 1. Calculations of Radiation Exposure from Leaks from Nuclear Storage Facility in 10,000 Years Time Over the next 10 million years, the highest radiation dose from this nuclear waste depository to the closest members of the public will be less than 0.001 mSv /y. Everyone in this room is now receiving a radiation dose over 2 thousand times greater
Absurdity 2: Original Uranium Ore Compared with Nuclear Waste Here is the original Uranium ore lying In the ground Here is the nuclear waste from the fuel made from that uranium ore. After some centuries, this becomes less radioactive than the original ore.
Absurdity 3 Lessons from Nature Instead of doing theoretical calculations about the release of radioactive elements from nuclear fission over long periods of time, lets look at a real example. Lets use actual observation instead of modeling. Lets look at what happened to the waste from the worlds first nuclear fission reactors.
When did the worlds first nuclear fission reactor stop operating? 2 billion years ago (2,000,000,000 years ago) The natural Oklo reactors in Gabon, West Africa 2 billion years seems a reasonably long enough period to assess its nuclear waste
How the Oklo Reactors Worked 2 billion years ago, in a valley in Oklo, were the four necessary conditions for sustained nuclear fission: 1. A sufficient mass of concentrated uranium. 2. A sufficent moderator (slowing the neutrons down to improve fission): – water. 3. Absence of neutron poisons, which remove neutrons. 4. sufficiently high percentage of U-235 compared with U-238. Then 3.68%. Now 0.72%. Half-lives (years): U-238: 4.5 bn U-235: 0.7 bn
Operation of the Oklo Reactors All of this has been determined by studying the remaining ore, which is slightly depleted in U-235 compared with other natural uranium. 17 reactors in all. Average power: about 100 kW. Operating life: several hundred thousand years. When water flowed over the uranium, the increased moderation would cause self-sustaining fission. This would heat up the water and boil it off. The fission would stop. When more water came the process would be repeated. Examining the wastes from these reactors, scientists can calculate how far the plutonium and other transuranics (actinides) moved in the last 2 billion years: – About 10 metres
Lessons from Oklo, 2 billion years ago The Oklo reactors were accidentally situated by nature in valleys regularly flooded with water. There were no barriers against the migration of nuclear waste materials. Yet in 2 billion years the plutonium and other transuranics seem to have moved no more than a few metres (lighter fission products, being much more mobile, would have moved much further). If nature finds it so easy to contain nuclear waste, without even trying, than mankind can easily contain it. If we took all of Koebergs high level nuclear waste (after 10 years or more) to Vaalputs, and treated it in the same way as intermediate waste is now being treated there, this would be a 100% solution – and an easy, cheap solution - to the problem of nuclear waste. All it needs is a politicians signature. If Vaalputs became a high level waste repository, would I be prepared to live near it? – Gladly! If you give me a good job living right next to it, Id be pleased to take it.
Conclusions Nuclear waste is tiny in volume and mass – All the high level waste from the USAs total nuclear power production would fit onto one rugby field, 3 metres high. Nuclear waste is solid, stable and becomes less dangerous with time – It cannot explode or react violently. The radiation dies away all the time Nuclear waste from civilian nuclear power has never harmed anybody in almost 60 years of operation – Unlike coal and wind waste There is nothing in nuclear waste that is not found in nature, including – Plutonium: natural reactions given previously – Fission products: from spontaneous fission in natural uranium All energy sources produces waste that lasts for millions of years – Nuclear is no exception, except that its waste is much easier to store. Nature, at Oklo, 2 billion years ago, has shown how small the problem of nuclear waste is. Right now, every nuclear energy country on Earth, could easily set up a simple, cheap nuclear waste facility that would be a thousand times safer than the local landfill dump. All it needs is political courage and commonsense.
Koeberg Nature Reserve. Choosing Energy Sources Wisely & Responsibly (in this case, for electricity supply) We must always act in such a way as to cause the most benefit and least cost to man and the environment. Nature has given us great gifts of energy. We must accept them respectfully and use them wisely, each in its proper place. We must work WITH Nature, not against her. We must act rationally, according to science, facts and logic, and not according to fashion and superstition.