I have always loved to teach. I especially enjoyed the person to person contact when you tell of something and get a smile back – they got it. One of the objects of teaching the so called Capstone Course for engineers to be is to teach cross-science, for it is in the intersection between different branches of science, crafts and engineering disciplines that real breakthroughs are made. The object is to revolutionize the students thinking. Up to now they have learnt – and learnt it well – do as your teacher have taught you, and you will get an A. Any deviation is a negative – and bothersome for the teacher. This is an attempt for me to change that – even in an online session, but since there is no direct feedback, it is really an offline instruction. see what you think – did it change your thinking?
This tree, the green one was planted upside down. The branches became roots, the roots became branches. It is planted just east of Penn State Main building. Think root cause analysis.
Chernobyl was a carbon moderated Nuclear reactor. Its failure mode was to go prompt critical and splat in an uncontrolled nuclear reaction. No containment vessel could contain the explosion, so why go to the extra expense of building one? Rely instead on multiple safety circuits. The night crew disabled some safety circuits to capture power on an orderly shutdown. They had never been properly trained.
The cloud. Sweden was the first to report on the accident. Two reactors shut down due to excessive radiation in the air outside the plants.
With a Molten Salt Reactor, accidents like Chernobyl are impossible. The Three Mile Island accident was bad. The Chernobyl disaster was ten million times worse. Ah yes, I remember it well.
One morning at work, after the Three Mile Island incident, but before Chernobyl a fellow co-worker, a Ph.D. Chemist working on an Electron Capture Detector containing a small amount of Nickel 63, came with a surprising question: You know nuclear science, how come the reactors in Chernobyl don’t have a containment vessel? Well – I answered, it is because they are carbon moderated and their failure mode is that they go prompt critical, and no containment vessel in the world can hold it in, so they skip it. He turned away in disgust. A few weeks later my wife’s father died, and we went to Denmark to attend the funeral. The day of the return back to the U.S. we heard that there had been a nuclear incident in Sweden, too much radiation had caused two nuclear power stations to close down. The Chernobyl disaster had happened 26 April 1986, and this was the first time anyone outside of Chernobyl has heard about it, two days later. This was still the Soviet Union, and nothing ever did go wrong in it worthy of reporting.
(But the carbon moderated Uranium reactors are the most efficient in producing Pu-239 the preferred nuclear bomb material.)
This has nothing to do with anything, but Chernobyl can be translated wormwood. It is mentioned in the Bible, Revelation 8: 10-11 “ And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters; And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter. ”
Molten Salt Thorium reactors cannot be used to supply bomb material, and they are far safer than even Light water Uranium reactors.
With Molten Salt Reactors, a catastrophe like Fukushima cannot happen. It began with a magnitude 9.0 earthquake not far from the Fukushima 6 Nuclear reactor complex. The impact was a magnitude 6.8 earthquake and the operators immediately scrammed the safety rods to stop all the reactors. This succeeded! The reactors were designed with earthquakes in mind, and they passed the test. The backup power started up successfully so the cooling pumps could operate. There was one major problem though. The earthquake was so bad that the water in the spent fuel holding tanks splashed out and exposed the spent fuel rods to air making them emit radioactivity into the air.
The water pumps worked for a while, but then came the tsunami. All the reactors were inside a tsunami wall, so far, so good
But the fuel storage tanks for the backup power generators were outside the tsunami wall and were washed away. The batteries were only supposed to last until backup power was established, and with water circulation ended the meltdown started.
This disaster was even bigger than Chernobyl and contamination is still spreading.
In the periodic table, iron has the densest core. Fusion can occur with elements with a lower atomic number than iron, fission can begin with with elements after lead. What happens in a supernova?
On climate change: Temp records come from boreholes, seashells, and looking at isotope variations among other sources . Of particular interest is the medieval warm period and the little ice age. How did the little ice age happen? There was no decrease in CO2 during that time.
Especially interesting is cosmic radiation that does not come from the sun. It varies a lot, and consists mostly of iron nuclei and comes from distant supernovas. There was two of them, in 1572 and 1604 A.D., both shone brighter in the sky than Venus. Since then we have not seen any supernovas anywhere nearly as bright . Did they trigger the little ice age?
A single iron nucleus can ionize thousands of air molecules, causing condensation and forming the beginning of a cloud.
The iron nuclei enter the earth’s atmosphere with a speed that exceeds the speed of light in atmosphere, causing this eerie blue light. It spreads like a sonic boom.
Cosmic radiation in the form of iron nuclei is the major source of the generation of Carbon 14. When fossil fuel is burned there is very little C14 in the CO2 generated, but if it is burned by digestion of food, by fermentation, by burning wood or by wildfire, it contains the same concentration of C14 as was in the air at the time of the generation of the biomass. Since C14 has a half life of 5700 +- 40 years, we could find out the age of that biomass – or could we?
This is one of my very favorite slides. The best way of finding out how a black body responds is by introducing an impulse and see what happens. In this case the impulse was open air Nuclear bomb tests, performed mostly by United States and the Soviet Union, but all in the Northern Hemisphere. Test stations to see the amount of C14 in the air were set up in Austria and New Zealand. What did we learn? We learn that the air mixes between the Northern and the Southern Hemisphere in about 2 years, and because the half-life of C14 shown here is 12.5 years, not 5700 years, it shows the absorption rate in the oceans. Both of these values would have been difficult if not impossible to find out without open air Nuclear tests, Were they bad? You bet, but since they happened, glean what you can from it. What else did we learn? You can no longer use carbon dating if there is any chance of chance of contamination with newer biomass, or if it is newer than 1955 A.D. Is the specimen appearing to be older or younger?
Since we have shown that the amount of C14 in the air has not been constant over time the age curve has to be calibrated. How do we do that? By using artifacts of known age.
The radioactive fallout decay from a Nuclear test occurs faster than from the Chernobyl disaster. Every nuclear fallout fingerprint is different.
A Liquid Fluoride Thorium based fast breeder nuclear reactor produces much less TRansUranium waste, 0.01% waste products compared to a Uranium-235 fast breeder. The Thorium process has a much higher efficiency of fission than the Uranium process.
Pu = Plutonium, Am = Americum, Cm = Curium, all TRansUraniums, nasty stuff.
With Thorium based Nuclear power, there are no real problems, with traditional U235 power long tern storage is an immense and urgent problem, and has been since the 1960’s. At that time Sweden had a heavy water U-238 nuclear power program going, but abandoned it in favor of traditional U-235 power. U.S. promised to provide the material and take care of the reprocessing and final storage of all nuclear waste at cost if Sweden joined the nuclear proliferation treaty. Reprocessing was to be done in Washington State, and one of the final storage sites mentioned was Yucca Mountain in Nevada, having the ideal Geological properties.
Time goes by and in 1982 – Congress passed the Nuclear Waste Policy Act, requiring the establishment of a deep geologic repository for nuclear waste storage and isolation. Yucca Mountain was high on the list out of 9 possible sites.
Time goes by, and Congress is still not able to decide on a solution. Meanwhile, TRU’s from spent and reprocessed fuel is piling up in less than ideal locations. Thorium based nuclear power would go a long way to alleviate this problem.
Radioactive waste from an LFTR (Liquid Fluoride Thorium Reactor) decays down to background radiation in 300 years instead of a million years for U-235 based reactors. Initially LFTRs produce as much radioactivity as an U-235 based nuclear reactor, since fission converts mass to heat, but the decay products have a much shorter half-life.
And Fukushima is still aglow.
The first thing we must realize is that rare earth metals are not all that rare. They are a thousand times or more abundant than gold or platinum in the earth crust and easy to mine, but a little more difficult to refine. Thorium and Uranium will also be mined at the same time as the rare earth metals since they appear together in the ore.
The U.S. used to have a strategic reserve of rare earth metals, but that was sold off in 1998 as being no longer cost effective or necessary. Two years later the one U.S. rare earth metals mine that used to supply nearly the whole world, the Mountain Pass Mine in California closed down, together with its refining capacity. From that day all rare earth metals were imported. In 2010 it started up again together with the refining capacity but went bankrupt in 2015, closed down the refining but continued selling ore to China. They will start up refining again late 2020. Meanwhile China is slapping on a 25% import tariff on imported ore starting July 1 2020. Rare earth metals may be in short supply for a while.
U.S. used to be the major supplier of rare earth metals, which was fine up to around 1984. Then the U.S. regulators determined that Uranium and Thorium contained in the ore made the ore radioactive, so they decided to make rare earth metal ore subject to nuclear regulations with all what that meant for record keeping and control. This made mining in the U.S. unprofitable so in 2001 the last domestic mine closed down. China had no such scruples, such as human and environmental concerns, so they took over the rare earth metals mining and in 2010 controlled over 95% of the world supply, which was according to their long term plan of controlling the world by 2025.