Tag Archives: nuclear

Germany’s hydrogen trains and boats almost make sense

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Germany’s green transition is a disaster. Twenty years ago, Germany had 23 nuclear power plants that generated 30% of the country’s electricity cleanly, cheaply, and reliably. These plants have all been shut by the government as part of a commitment to clean energy. What could be cleaner? Germany has switched to a mix of wind and solar, plus a significant shift to coal power. Wind and solar use a lot of land compared to nuclear, and they break down leaving fields of debris. There is now a lack of electricity to power homes and industries, and what power there is, is unreliable, due to the many dark windless days in Germany.

The lack of reliable electricity is crippling German industry now that Russian gas has been cut off. In this environment, why would the Germans order special trains and boats that burn, hydrogen that’s made from electricity and natural gas? My understanding of the reason is that, Germany sometimes has too much wind power and nothing to do with it. They plan to store this excess by making hydrogen that they can use to power their trains and boats. The cost is high, and the efficiency is poor, but the electricity is free.

Hydrogen is not as compact a fuel as gasoline, nor is it as cheap as electricity, but it’s cleaner than gas, and in some ways it’s better than battery-stored electricity. While hydrogen takes a lot of storage space relative to gasoline, high pressure helps, and the storage is cheaper than with batteries. Also, hydrogen fuel is transferred faster than electric fuels. Trains and ships are chosen for hydrogen because they are good at carrying bulky items. The transition to hydrogen is relatively straightforward with trains, since many are already powered by electricity. Hydrogen fuel cells can make the electricity on board (in theory), while avoiding the need for expensive overhead wires. The idea sort-of makes sense.

Germany’s first hydrogen train. cancelled after 1 year of poor operating.

The first German train to use hydrogen powered them with fuel cells that generated electricity. It began service in October 2022, but the fuel cells proved unreliable. Service ended one year later, October 2023, replaced by polluting diesel (see here). The Hannover line plans to replace these with battery-powered trains over the next few years. There are also plans for a hydrogen-powered ferry, but it is not clear why the ferry should prove more reliable than the train, or cheaper.

San Francisco’s hydrogen-powered ferry, $30 million, 15 knots top speed, 75 passengers, no cars. Long delayed.

In the US, the Biden administration has paid, so far, $30 million for a hydrogen ferry in San Francisco. It’s two years behind schedule and over cost, taking only 75 passengers and no cars at 15 knots, 17mph. In the US, and likely in Germany, most of the hydrogen will be made from natural gas. A better solution, I think would be to power the ferris and trains by natural gas and to store the excess electricity in land-based batteries or as land-based hydrogen for land-based fuel cells.

Germany is committed to electric trains, though, and hydrogen provides a route to power these trains with excess electricity. German customers take the train, in part, because they like them, and in part because German politicians have banned short-hop planes on competing routes, and subsidized electric trains. Yet another option to balance times of excess solar and wind power would be to subsidize electric cars, or at least allow theirs owners to trade electricity: to buy electricity when it’s cheap and resell it to the grid when demand and prices are high.

Robert Buxbaum, June 8, 2024

Fusion advance: LLNL’s small H-bomb, 1.5 lb TNT didn’t destroy the lab.

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There was a major advance in nuclear fusion this month at the The National Ignition Facility of Lawrence Livermore National Laboratory (LLNL), but the press could not figure out what it was, quite. They claimed ignition, and it was not. They claimed that it opened the door to limitless power. It did not. Some heat-energy was produced, but not much, 2.5 MJ was reported. Translated to the English system, that’s 600 kCal, about as much heat in a “Big Mac”. That’s far less energy went into lasers that set the reaction off. The importance wasn’t the amount in the energy produced, in my opinion, it’s that the folks at LLNL fired off a small hydrogen bomb, in house, and survived the explosion. 600 kCal is about the explosive power of 1.5 lb of TNT.

Many laser beams converge on a droplet of deuterium-tritium setting off the explosion of a small fraction of the fuel. The explosion had about the power of 1.2 kg of TNT. Drawing from IEEE Spectrum

The process, as reported in the Financial Times, involved “a BB-sized” droplet of holmium -enclosed deuterium and tritium. The folks at LLNL fast-cooked this droplet using 100 lasers, see figure of 2.1MJ total output, converging on one spot simultaneously. As I understand it 4.6 MJ came out, 2.5 MJ more than went in. The impressive part is that the delicate lasers survived the event. By comparison, the blast that bought down Pan Am flight 103 over Lockerbie took only 2-3 ounces of explosive, about 70g. The folks at LLNL say they can do this once per day, something I find impressive.

The New York Times seemed to think this was ignition. It was not. Given the size of a BB, and the density of liquid deuterium-tritium, it would seem the weight of the drop was about 0.022g. This is not much but if it were all fused, it would release 12 GJ, the equivalent of about 3 tons of TNT. That the energy released was only 2.5MJ, suggests that only 0.02% of the droplet was fused. It is possible, though unlikely, that the folks at LLNL could have ignited the entire droplet. If they did, the damage from 5 tons of TNT equivalent would have certainly wrecked the facility. And that’s part of the problem; to make practical energy, you need to ignite the whole droplet and do it every second or so. That’s to say, you have to burn the equivalent of 5000 Big Macs per second.

You also need the droplets to be a lot cheaper than they are. Today, these holmium capsules cost about $100,000 each. We will need to make them, one per second for a cost around $! for this to make any sort of sense. Not to say that the experiments are useless. This is a great way to test H-bomb designs without destroying the environment. But it’s not a practical energy production method. Even ignoring the energy input to the laser, it is impossible to deal with energy when it comes in the form of huge explosions. In a sense we got unlimited power. Unfortunately it’s in the form of H-Bombs.

Robert Buxbaum, January 5, 2023

Ukraine looks like Vietnam or the beginnings of WWI

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The press and our Russian experts claim we’re helping in Ukraine, protecting it from a Russian invasion. I suspect they are wrong, and that our help and protection will prove to be as deadly to all as in the Vietnam war. I’m also uncomfortable with their presentation their framing of Putin as an out of touch autocrat. Putin has popular support, and acts with a strong sense of history, as I see it, just not our version of history. In the Russian version, it was Russia that stopped the Nazis — of Germany and Ukraine. We are not the heroes of WWII in their telling; I doubt we’ll be the heroes of this conflict either.

We have a habit of seeing ourselves as saving heroes as we enter other people’s conflicts. It is how we got into Vietnam, to save the South from the North. It’s also how Europe got into WWI: Russia was saving Serbia, Germany was saving Austria, etc (see cartoon below). We meddle our way, and leave much later than we planned. The result, as in Vietnam and Afghanistan is far more death and destruction than if we’d minded our own business. And US war-dead too. In Vietnam 58,000 US deaths. In Afghanistan 2,400 US dead. and no obvious accomplishment. As Henry Kissinger famously commented: “It’s dangerous to be America’s enemy, but deadly to be America’s friend.”

European aggression in WWII started with the good intention of preventing aggression. It got out of hand, as I fear our good intentions will in Ukraine.

The US troops we’ve sent to Ukraine are not called soldiers. They are “fighting advisors” sent to help the Ukrainians use our weapons. In WWI and Vietnam, fighting advisors are called invaders; it’s how we got drawn into Vietnam. The Russians claimed to send advisors when they entered the Crimea and later the Dundas. We called it an invasion. We can’t be that blind to our own words. Sooner or later, the advisors will start killing each other– something we’ll call an unprovoked attack. Our high tech aid including anti-tank missiles are reported to have killed some 10,000 Russians so far. We don’t seem to think the Russians will mind, or that they’ll give up as the body count mounts. In Vietnam, the more we killed with our high-tech weapons, the more the Vietnamese on both sides called us the villains, and the more Vietnamese joined the fight against us. That’s the future I fear for Ukraine, or worse. The conflict in WWI spiraled quickly beyond the borders of Serbia to include the whole world, and continued through WWII.

Our approach to diplomacy is counterproductive too, in my opinion, and similar to Vietnam too. We call Putin a terrorist, a madman and a narcissist, and then we begin talks with him to end the war. Biden has asked to have Putin removed by assassination.Does he think this will help, or if Putin is removed his successor will be a friend of the US? We demonized Ho Chi Minh, and propped up our favored, corrupt leaders. Minh was popular, as is Putin, and both have valid reasons for opposing us. Putin worries about the expansion of NATO. It’s not an illegitimate worry given Russian history of repeated invasions from the west.

Our desire to remove Russian leadership is a long-standing mistake. It does not lead to peace, or good negotiation, nor even peaceful co-existence.

Russia has been invaded many times. US schools mention Napoleon’s invasion in 1812 and the German’s in 1941, but there are more. They were invaded by the Germans in WWI too, and by the Ukrainian Cossacks in the days of Khmelnytsky, 1646-57. Before that the Polish Lithuanians, 1609-1618, the Swedes, 1701-1709, and in the early days, it was Tartars, Mongols, who invaded and ruled Russia from about 1225 til they joined with the Russian Tzars about 1650. Add to that, our help in the war of the Whites vs the Reds (1917-23) that produced Ukrainian independence — I talk about the relevance here. With a history like that, Russia has every reason to worry about NATO expansion. We should be cognizant of this and stop calling Putin a madman. Let’s accept the Russian version of history, and the sitting ruler of Russia.

Some cite the Budapest memorandum that lead to the removal of “Ukrainian” nuclear weapons –– read it here. It’s short, only 1 page, and deliberately vague. it was signed by Putin’s predecessor, Boris Yeltsin, for the Russian Federation, along with representatives for Ukraine, The US, and The UK. The missiles were not Ukrainian, they were Soviet, and pointed at us. As a result of that agreement, they were dismantled and moved into Russia. There is no sense that this is an invitation for us to protect Ukraine against Russia. The co-signers sort-of agree to protect Ukraine from outsiders (Germany, Turkey,..?), but that’s not clear. We commit ourselves to peace in the region, and can claim that Russia violated the peace first, but there’s no invitation for us to violate it second. Until recently, the UK provided no military aid. China and most of the EU still trades with Russia; if they see a villainy, it’s not enough to stop trade.

Robert McNamara was Secretary of Defense under Kennedy and Johnson, and a key “Whiz Kid” pushing for war in Vietnam. Years later, he decided Vietnam was a mistake. A sad cartoon: the veterans are walking past the grave monument for the 58,000 US dead. I worry we’ll have a similar cartoon after this war.

In my opinion, our best course is to reduce our military aid to providing only basics: bullets, blankets, food… We should reopen discussions with Putin, not demonize him, or try to remove him. Ukraine will likely fight on even without our high-tech weapons. Perhaps they’ll buy from Europe, or from independent dealers. The death rate on both sides will be lower and peace will come quicker without us. Crimea might remain Ukrainian or Russian, but that will not be our decision. We’ve done enough damage for now. It took many years after the end of the Vietnam war for the instigators admit is was a mistake.

Robert Buxbaum April 3, 2022. Much of my thinking about Vietnam comes from Francis Fitzgerald’s wonderful book “Fire in the Lake”. I see it all happening again here. Also worth reading is this 2014 letter by Henry Kissinger about how to negotiate a peace: “Damning Putin is not a foreign policy; it’s an alibi for the lack of one.” It’s a nice insight. He seems to understand diplomacy about as well as anyone.

Low temperature hydrogen removal

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Platinum catalysts can be very effective at removing hydrogen from air. Platinum promotes the irreversible reaction of hydrogen with oxygen to make water: H2 + 1/2 O2 –> H2O, a reaction that can take off, at great rates, even at temperatures well below freezing. In the 1800s, when platinum was cheap, platinum powder was used to light town-gas, gas street lamps. In those days, street lamps were not fueled by methane, ‘natural gas’, but by ‘town gas’, a mix of hydrogen and carbon monoxide and many impurities like H2S. It was made by reacting coal and steam in a gas plant, and it is a testament to the catalytic power of Pt that it could light this town gas. These impurities are catalytic poisons. When exposed to any catalyst, including platinum, the catalyst looses it’s power to. This is especially true at low temperatures where product water condenses, and this too poisons the catalytic surface.

Nowadays, platinum is expensive and platinum catalysts are no longer made of Pt powder, but rather by coating a thin layer of Pt metal on a high surface area substrate like alumina, ceria, or activated carbon. At higher temperatures, this distribution of Pt improves the reaction rate per gram Pt. Unfortunately, at low temperatures, the substrate seems to be part of the poisoning problem. I think I’ve found a partial way around it though.

My company, REB Research, sells Pt catalysts for hydrogen removal use down to about 0°C, 32°F. For those needing lower temperature hydrogen removal, we offer a palladium-hydrocarbon getter that continues to work down to -30°C and works both in air and in the absence of air. It’s pretty good, but poisons more readily than Pt does when exposed to H2S. For years, I had wanted to develop a version of the platinum catalyst that works well down to -30°C or so, and ideally that worked both in air and without air. I got to do some of this development work during the COVID downtime year.

My current approach is to add a small amount of teflon and other hydrophobic materials. My theory is that normal Pt catalysts form water so readily that the water coats the catalytic surface and substrate pores, choking the catalyst from contact with oxygen or hydrogen. My thought of why our Pd-organic works better than Pt is that it’s part because Pd is a slower water former, and in part because the organic compounds prevent water condensation. If so, teflon + Pt should be more active than uncoated Pt catalyst. And it is so.

Think of this in terms of the  Van der Waals equation of state:{\displaystyle \left(p+{\frac {a}{V_{m}^{2}}}\right)\left(V_{m}-b\right)=RT}

where V_{m} is molar volume. The substance-specific constants a and b can be understood as an attraction force between molecules and a molecular volume respectively. Alternately, they can be calculated from the critical temperature and pressure as

{\displaystyle a={\frac {27(RT_{c})^{2}}{64p_{c}}}}{\displaystyle b={\frac {RT_{c}}{8p_{c}}}.}

Now, I’m going to assume that the effect of a hydrophobic surface near the Pt is to reduce the effective value of a. This is to say that water molecules still attract as before, but there are fewer water molecules around. I’ll assume that b remains the same. Thus the ratio of Tc and Pc remains the same but the values drop by a factor of related to the decrease in water density. If we imagine the use of enough teflon to decrease he number of water molecules by 60%, that would be enough to reduce the critical temperature by 60%. That is, from 647 K (374 °C) to 359 K, or -14°C. This might be enough to allow Pt catalysts to be used for H2 removal from the gas within a nuclear wast casket. I’m into nuclear, both because of its clean power density and its space density. As for nuclear waste, you need these caskets.

I’ve begun to test of my theory by making hydrogen removal catalyst that use both platinum and palladium along with unsaturated hydrocarbons. I find it works far better than the palladium-hydrocarbon getter, at least at room temperature. I find it works well even when the catalyst is completely soaked in water, but the real experiments are yet to come — how does this work in the cold. Originally I planned to use a freezer for these tests, but I now have a better method: wait for winter and use God’s giant freezer.

Robert E. Buxbaum October 20, 2021. I did a fuller treatment of the thermo above, a few weeks back.

Alice’s Restaurant and Nuclear Waste

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It’s not uncommon for scientists to get inspiration from popular music. I’d already written about how the song ‘City of New Orleans’ inspires my view of the economics of trains, I’d now like to talk about dealing with nuclear waste, and how the song Alice’s Restaurant affects my outlook.

As I see it, nuclear power is the elephant in the room in terms of clean energy. A piece of uranium the size of a pencil eraser produces as much usable energy as three rail cars of coal. There is no air pollution and the land use is far less than for solar or wind power. The one major problem was what to do with the left over eraser-worth of waste. Here’s the song, it’s 18 1/2 minutes long. The key insight appeared in the sixth stanza: “…at the bottom of the cliff there was another pile of garbage. And we decided that one big pile Is better than two little piles…”

The best way to get rid of nuclear waste would be (as I’ve blogged) to use a fast nuclear reactor to turn the worst components into more energy and less-dangerous elements. Unfortunately doing this requires reprocessing, and reprocessing was banned by Jimmy Carter, one of my least favorite presidents. The alternative is to store the nuclear waste indefinitely, waiting for someone to come up with a solution, like allowing it to be buried in Yucca Mountain, the US burial site that was approved, but that Obama decided should not be used. What then? We have nuclear waste scattered around the country, waiting. I was brought in as part of a think-tank, to decide what to do with it, and came to agree with several others, and with Arlo Guthrie, that one big pile [of waste] Is better than two little piles. Even if we can’t bury it, it would be better to put the waste in fewer places (other countries bury their waste, BTW).

That was many years ago, but even the shipping of waste has been held up as being political. Part of the problem is that nuclear waste gives off hydrogen — the radiation knocks hydrogen atoms off of water, paper, etc. and you need to keep the hydrogen levels low to be able to transport the waste safely. As it turns out we are one a few companies that makes hydrogen removal pellets and catalysts. Our products have found customers running tourist submarines (lead batteries also give off hydrogen) and customers making sealed electronics, and we are waiting for the nuclear shipping industry to open up. In recent months, I’ve been working on improving our products so they work better at low temperature. Perhaps I’ll write about that later, but here’s where you’d go to buy our current products.

Robert Buxbaum, July 4, 2021. I’ve done a few hydrogen-related posts in a row now. In part that’s because I’d noticed that I went a year or two talking history and politics, and barely talking about H2. I know a lot about hydrogen — that’s my business– as for history or politics, who knows.

How not to make an atom bomb

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There are many books on how the atom bomb was made. They are histories of the great men who succeeded at site Y, Los Alamos, usually with a sidelight of the economics and politics in the US at the time. It’s sometimes noted that there was an equally great German group working too, and one in Japan and in Russia, that they didn’t succeed, but it’s rarely discussed what they did wrong. Nor does anyone make clear why so many US scholars were needed. What did all those great US minds to do? The design seems sort-of obvious; it appears in the note Einstein sent to Roosevelt, so what were all these people thinking about all that time, and why did the Germans fail? By way of answer, let me follow the German approach to this problem, an approach that won’t get you anywhere, or anywhere that I’ve seen.

It seems that everyone knew that making a bomb was possible, that it would be fearsomely powerful, and that it would be made using a chain reaction in uranium or plutonium. Everyone seems to have understood that there must be a critical mass: use less and there is no explosion, use more and there is one. The trick was how to bring enough uranium together make the thing go off, and as a beginning to that, there is the concept of “a barn.” A barn is a very small unit of area = 10−24 cm², and a typical atom has a cross-section of a few barns. Despite this, it is generally thought to be very easy to hit an atom at the nucleus, that is, at the right spot, as easy as hitting the board side of a barn (hence the name). The cross section of a uranium atom is 600 barnes at room temperature, or 6×10−22 cm². But each cubic centimeter of uranium holds .5 x 1023 atoms. Based on this, it comes out that a thermal neutron that enters a 1 cm cube of uranium has a virtual certainty of hitting an atom — there are 3 cm² of atoms in a 1 cm² box. You could hardly miss.

Each uranium atom gives off a lot of energy when hit with a neutron, but neutrons are hard to come by, so a practical bomb would have to involve a seed neutron that hits a uranium atom and releases two or more neutrons along with energy. The next neutron has to hit another nucleus, and it has to releases two or more. As it happens uranium atoms, when hit release on average 2.5 neutrons, so building a bomb seems awfully easy.

But things get more difficult as the neutron speeds get greater, and as the atoms of uranium get hotter. The cross-section of the uranium atom goes down as the temperature goes up. What’s more the uranium atoms start to move apart fast. The net result is that the bomb can blow itself apart before most of the uranium atoms are split. At high speed, the cross -section of a uranium atom decreases to about 5 barnes you thus need a fairly large ball of uranium if you expect that each neutron will hit something. So how do you deal with this. For their first bomb, the American scientists made a 5 kg (about) sphere of plutonium, a man-made uranium substitute, and compressed it with explosives. The explosion had to be symmetrical and very fast. Deciding how fast, and if the design would work required a room full of human “computers”. The German scientists, instead made flat plates of uranium and slowed the neutrons down using heavy water. The heavy water slowed the neutrons, and thus, increased the effective size of the uranium atoms. Though this design seems reasonable, I’m happy to say, it can not ever work well; long before the majority of the reaction takes place, the neutrons get hot, and the uranium atoms fly apart, and you get only a small fraction of the promised bang for your bomb.

How fast do you need to go to get things right? Assume you want to fusion 4 kg of uranium, or 1 x 1025 atoms. In that case, hitting atoms has to be repeated some 83 times. In tech terms, that will take 83 shakes (83 shakes of a lamb’s tail, as it were). This requires getting the ball compressed in the time it takes for a high speed neutron to go 83 x 3 cm= 250 cm. That would seem to require 1 x 10-7 seconds, impossibly fast, but it turns out, you can go somewhat slower. How much slower? It depends, and thus the need for the computers. And how much power do you get? Gram for gram, uranium releases about 10 million times more energy than TNT, but costs hardly more. That’s a lot of bang for the buck.

Robert Buxbaum, Mar 29, 2020.

Recycle nuclear waste

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In a world obsessed with stopping global warming by reducing US carbon emissions, you’d think there would be a strong cry for nuclear power, one of the few reliable sources of large-scale power that does not discharge CO2. But nuclear power produces dangerous waste, and I have a suggestion: let’s recycle the waste so it’s less dangerous and so there is less of it. Used nuclear fuel rods, in particular. We burn perhaps 5% of the uranium, and produce a waste that is full of energy. Currently these, semi-used rods are stored in very expensive garbage dumps waiting for us to do something. Let’s recycle.

I’ve called nuclear power the elephant in the room for clean energy. Nuclear fuel produces about 25% of America’s electricity, providing reliable baseline generation along with polluting alternatives: coal and natural gas, and less-reliable renewables like solar and wind. Nuclear power does not emit CO2, and it’s available whether or not the sun shines or the wind blows. Nuclear power uses far less land area than solar or wind too, and it provides critical power for our navy aircraft carriers and submarines. Short of eliminating our navy, we will have to keep using nuclear.

Although there are very little nuclear waste per energy delivered, the waste that there is, is hard to manage. Used nuclear fuel rods in particular. For one thing, the used rods are hot, physically. They give off heat, and need to be cooled. At first they give off so much heat that the rods must be stored under water. But rod-heat decays fractally. After ten years or so, rods can be stored in naturally cooled concrete; it’s still a headache, but a smaller one The other problem with the waste rods is that they contain about 1.2% plutonium, a material that can be used for atomic bombs. A major reason that you can’d just dump the waste into the ocean or into a salt mine is the fear that someone will dig it up and extract the plutonium for an a- bomb. The extraction is easy compared to enriching uranium to bomb-grade, and the bombs work at least as well. Plutonium made this way was used for the bomb that destroyed Nagasaki.

The original plan for US nuclear power had been that we would extract the plutonium, and burn it up by recycling it to the nuclear reactor. We’d planned to burry the rest, as the rest is far less dangerous and far less, long-term radioactive. We actually did some plutonium recycling of this sort but in the 1970s a disgruntled worker named Silkwood stole plutonium and recycling was shut down in the US. After that, political paralysis set in and we’ve come to just let the waste sit in more-or-less guarded locations. There was a thought to burry everything in a guarded location (Yucca Mountain, Nevada) but the locals were opposed. So the waste sits waiting to leak out or be stolen. I’d like to return to recycling, but not necessarily of pure plutonium as we did before Silkwood: there is no guarantee that there won’t be other plutonium thieves.

Instead of removing the plutonium for recycling, I’d like to suggest that we remove about 40% of the uranium in the rod, and all of the “ash”, this is all of the lighter atom elements created from the split uranium atoms. This ash is about 5% of the total. The resultant rods would have about 2% plutonium, 97.5% enriched uranium (about 1% enriched at this stage) plus about 0.5% higher transuranics. This composition would be a far less dangerous than purified plutonium. It would be less hot and it would not be possible to use it directly for atom bombs. It would still be fissionable, though, at the same energy content as fresh rods.

There is an uncommonly large amount of power available in nuclear fuel

Several countries recycle by removing the ash. Because no uranium is removed, the material they get has about half the usable life of a fresh rod. After one recycle, there is not much more they could do. If we remove uranium material is a lot more easily used, and more easily recycled again. If we keep removing ash and uranium, we could get many, many recycles. The result is a lot less uranium mining, and more power per rod, and fewer rods to store under guard.

The plutonium of multiply recycled rods is also less-usable for fission bombs. With each recycle, the rods build up a non-fisionabl isotope of plutonium: Pu 240. This isotope is not readily separated from the fissionable isotope, Pu 239, making multiply used rods relatively useless for fission bombs.

Among the countries that do some nuclear waste recycling are Canada, France, Russia, China, and Germany. Not a bad assortment. I would be happy to see us join them.

Robert Buxbaum September 9, 2019

Estimating the strength of an atom bomb

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As warfare is a foundation of engineering, I thought I’d use engineering to evaluate the death-dealing power of North Korea’s atomic/hydrogen bomb, tested September 3, 2017. The key data in evaluating a big bomb is its seismic output. They shake the earth like earthquakes do, and we measure the power like earthquakes, using seismometers. I’ve seen two seismographs comparing the recent bomb to the previous. One of these, below, is from CTBTO, the Center for Test Ban Treaty Oversight, via a seismometer in western Kazakhstan (see original data and report).

Seismic output of all North Korean nuclear tests.

Seismic output, to scale, of all declared DPNK nuclear tests as observed from IMS station AS-59 in Western Kazakhstan

North Korea’s previous bomb, exploded 9 September 2016, was reported to be slightly more powerful than the ones we dropped on Hiroshima and Nagasaki, suggesting it was about 20 kilotons. According to CTBTO, it registered 5.3 on the Richter scale. The two tests before that appear somewhat less powerful, perhaps 7-10 kilotons, and the two before that appear as dismal failures — fizzles, in atomic bomb parlance. The MOAB bomb, by comparison, was 9 Tons, or 0.009 kiloTons, a virtual non-entity.

To measure the output of the current bomb, I place a ruler on my screen and measure the maximum distance between the top to bottom wiggles. I find that this bomb’s wiggles measure 5 cm, while the previous measures 5 mm. This bomb’s wiggles are ten times bigger, and from this I determine that this explosion registered 6.3 on the Richter scale, 1.0 more than the previous — the Richter scale is the logarithmic measure of the wiggle amplitude, so ten times the shake magnitude  is an addition of 1.0 on the scale. My calculation of 6.3 exactly matches that of the US geological survey. The ratio of wiggle heights was less on the, NORSAR seismometer, Norway, see suggesting 5.8 to 5.9 on the Richter scale. The European agencies have taken to reporting 6.1, an average value, though they originally reported only the 5.8 from NORSAR, and a bomb power commensurate with that.

We calculate the bomb power from the Richter-scale measure, or the ratio of the wiggles. Bomb power is proportional to wiggle height to the 3/2 power. Using the data above, ten times the wiggle, this bomb appears to be 10^3/2 = 31.6 times as powerful as the last, or 31.6 x 20kTon = 630kTon (630,000 tons of TNT). If we used the European value of 6.1, the calculated power would be about half this, 315 kTons, and if we used the NORSAR’s original value, it would suggest the bomb had less than half this power. Each difference of 0.2 on the Richter scale is a factor of two in power. For no obvious reason we keep reporting 120 to 160 kTons.

NORSAR comparison of North Korean bomb blasts

NORSAR comparison of North Korean blasts — suggests the current bomb is smaller; still looks like hydrogen.

As it happens, death power is proportional to the kiloton power, other things being equal. The bombs we dropped on Hiroshima and Nagasaki were in the 15 to 20 kTon range and killed 90,000 each. Based on my best estimate of the bomb, 315 kTons, I estimate that it would kill 1.6 million people if used on an industrial city, like Seoul, Yokohama, or Los Angeles. In my opinion, this is about as big a bomb as any rational person has reason to make (Stalin made bigger, as did Eisenhower).

We now ask if this is an atom bomb or a hydrogen-fusion bomb. Though I don’t see any war-making difference, if it’s a hydrogen bomb that would make our recent treaty with Iran look bad, as it gave Iran nuclear fusion technology — I opposed the treaty based on that. Sorry to say, from the seismic signature it looks very much like a hydrogen bomb. The only other way to get to this sort of high-power explosion is via a double-acting fission bomb where small atom bomb sets off a second, bigger fission bomb. When looking at movies of Eisenhower-era double-acting explosions, you’ll notice that the second, bigger explosion follows the first by a second or so. I see no evidence of this secondary-delay in the seismic signature of this explosion, suggesting this was a hydrogen bomb, not a double. I expect Iran to follow the same path in 3-4 years.

As a political thought, it seems to me that the obvious way to stop North Korea would be to put pressure on China by making a military pact with Russia. Until that is done, China has little to fear from a North Korean attack to the south. Of course, to do that we’d likely have to cut our support of NATO, something that the Germans fear. This is a balance-of-power solution, the sort that works, short of total annihilation. It was achieved at the congress of Vienna, at the treaty of Ghent, and by Henry Kissinger through détente. It would work again. Without it, I see the Korean conflict turning hot again, soon.

Robert Buxbaum, September 11, 2017.

Why I don’t like the Iran deal

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Treaties, I suspect, do not exist to create love between nations, but rather to preserve, in mummified form, the love that once existed between leaders. They are useful for display, and as a guide to the future, their main purpose is to allow a politician to help his friends while casting blame on someone else when problems show up. In the case of the US Iran-deal that seems certain to pass in a day or two with only Democratic-party support, and little popular support, I see no love between the nations. On a depressingly regular basis, Iranian leaders promise Death to America, and Death to America’s sometime-ally Israel. Iran has acted on these statements too, funding Hezbollah missiles and suicide bombers, and hanging its dissidents: practices that lead it to become something of a pariah among its neighbors. They also display the sort of nuclear factories and ICBMs (long-range rockets) that could make them much bigger threats if they choose to become bigger threats. The deal just signed by US Secretary of State and his counterpart in Iran (read in full here) seems to preserve this state. It releases to Iran $100,000,000,000 to $150,000,000,000 that it claims it will use against Israel, and Iran claims to have no interest in developing multi-point compression atom bombs. This is a tiny concession given that our atom bomb at Hiroshima was single-point compression, first generation, and killed 90,000 people.

Iranian intercontinental ballistic missile, several stories high, brought out during negotiations. Should easily deliver nuclear weapons far beyond Israel, and even to the USA.

Iranian intercontinental ballistic missile, new for 2015. Should easily deliver warheads far beyond Israel -even to the US.

The deal itself is about 170 pages long and semi-legalistic, but I found it easy to read. The print is large, Iran has few obligations, and the last 100 pages or so are a list companies that will no longer be sanctioned. The treaty asserts that we will defend Iran against attacks including military and cyber attacks, and sabotage –presumably from Israel, but gives no specifics. Also we are to help them with oil, naval, and fusion technology, while leaving them with 1500 kg of 20% enriched U235. That’s enough for quick conversion to 8 to 10 Hiroshima-size A-bombs (atom bombs) containing 25-30 kg each of 90% U235. The argument in favor of the bill seems to be that, by giving Iran the money and technology, and agreeing with their plans, Iran will come to like us. My sense is that this is wishful-thinking, and unlikely (as Jimmy Carter discovered). The unwritten contract isn’t worth the paper it’s written on.

As currently written, Iran does not recognize Israel’s right to exist. To the contrary, John Kerry has stated that a likely consequence is further attacks on Israel. Given Hezbollah’s current military budget is only about $150,000,000 and Hamas’s only about $15,000,000 (virtually all from Iran), we can expect a very significant increase in attacks once the money is released — unless Iran’s leaders prove to be cheapskates or traitors to their own revolution (unlikely). Given our president’s and Ms Clinton’s comments against Zionist racism, I assume that they hope to cow Israel into being less militant and less racist, i.e. less Jewish. I doubt it, but you never know. I also expect an arms race in the middle east to result. As for Iran’s statements that they seek to kill every Jew and wipe out the great satan, the USA: our leaders may come to regret hat they ignore such statements. I guess they hope that none of their friends or relatives will be among those killed.

Kerry on why we give Iran the ability to self-inspect.

Kerry on why we give Iran the ability to self-inspect.

I’d now like to turn to fusion technology, an area I know better than most. Nowhere does the treaty say what Iran will do with nuclear fusion technology, but it specifies we are to provide it, and there seem to be only two possibilities of what they might do with it: (1) Build a controlled fusion reactor like the TFTR at Princeton — a very complex, expensive option, or (2) develop a hydrogen fusion bomb of the sort that vaporized the island of Bimini: an H-bomb. I suspect Iran means to do the latter, while I imagine that, John Kerry is thinking the former. Controlled fusion is very difficult; uncontrolled fusion is a lot easier. With a little thought, you’ll see how to build a decent H-bomb.

My speculation of why Iran would want to make an H-bomb is this: they may not trust their A-bombs to win a war with Israel. As things stand, their A-bomb scientists are unlikely to coax more than 25 to 100 kilotons of explosive power out of each bomb, perhaps double that of Hiroshima and Nagasaki. But our WWII bombs “only” killed 70,000 to 90,000 people each, even with the radiation deaths. Used against Israel, such bombs could level the core of Jerusalem or Tel Aviv. But most Israelis would survive, and they would strike back, hard.

To beat the Israelis, you’d need a Megaton-size, hydrogen bomb. Just one Megaton bomb would vaporize Jerusalem and it’s suburbs, kill a million inhabitants at a shot, level the hills, vaporize the artifacts in the jewish museum, and destroy anything we now associate with Israel. If Iran did that, while retaining a second bomb for Tel-Aviv, it is quite possible Israel would surrender. As for our aim, perhaps we hope Iran will attack Israel and leave us alone. Very bright people pushed for WWI on hopes like this.

Robert E. Buxbaum. September 9, 2015. Here’s a thought about why peace in the middle east is so hard to achieve,

Nuclear fusion

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I got my PhD at Princeton University 33 years ago (1981) working on the engineering of nuclear fusion reactors, and I thought I’d use this blog to rethink through the issues. I find I’m still of the opinion that developing fusion is important as the it seems the best, long-range power option. Civilization will still need significant electric power 300 to 3000 years from now, it seems, when most other fuel sources are gone. Fusion is also one of the few options for long-range space exploration; needed if we ever decide to send colonies to Alpha Centauri or Saturn. I thought fusion would be ready by now, but it is not, and commercial use seems unlikely for the next ten years at least — an indication of the difficulties involved, and a certain lack of urgency.

Oil, gas, and uranium didn’t run out like we’d predicted in the mid 70s. Instead, population growth slowed, new supplies were found, and better methods were developed to recover and use them. Shale oil and fracking unlocked hydrocarbons we thought were unusable, and nuclear fission reactors got better –safer and more efficient. At the same time, the more we studied, the clearer it came that fusion’s technical problems are much harder to tame than uranium fission’s.

Uranium fission was/is frighteningly simple — far simpler than even the most basic fusion reactor. The first nuclear fission reactor (1940) involved nothing more than uranium pellets in a pile of carbon bricks stacked in a converted squash court at the University of Chicago. No outside effort was needed to get the large, unstable uranium atoms split to smaller, more stable ones. Water circulating through the pile removed the heat released, and control was maintained by people lifting and lowering cadmium control rods while standing on the pile.

A fusion reactor requires high temperature or energy to make anything happen. Fusion energy is produced by combining small, unstable heavy hydrogen atoms into helium, a bigger more stable one, see figure. To do this reaction you need to operate at the equivalent of about 500,000,000 degrees C, and containing it requires (typically) a magnetic bottle — something far more complex than a pile of graphic bricks. The reward was smaller too: “only” about 1/13th as much energy per event as fission. We knew the magnetic bottles were going to be tricky, e.g. there was no obvious heat transfer and control method, but fusion seemed important enough, and the problems seemed manageable enough that fusion power seemed worth pursuing — with just enough difficulties to make it a challenge.

Basic fusion reaction: deuterium + tritium react to give helium, a neutron and energy.

Basic fusion reaction: deuterium + tritium react to give helium, a neutron and energy.

The plan at Princeton, and most everywhere, was to use a TOKAMAK, a doughnut-shaped reactor like the one shown below, but roughly twice as big; TOKAMAK was a Russian acronym. The doughnut served as one side of an enormous transformer. Hydrogen fuel was ionized into a plasma (a neutral soup of protons and electrons) and heated to 300,000,000°C by a current in the TOKOMAK generated by varying the current in the other side of the transformer. Plasma containment was provided by enormous magnets on the top and bottom, and by ring-shaped magnets arranged around the torus.

As development went on, we found we kept needing bigger and bigger doughnuts and stronger and stronger magnets in an effort to balance heat loss with fusion heating. The number density of hydrogen atoms per volume, n, is proportional to the magnetic strength. This is important because the fusion heat rate per volume is proportional to n-squared, n2, while heat loss is proportional to n divided by the residence time, something we called tau, τ. The main heat loss was from the hot plasma going to the reactor surface. Because of the above, a heat balance ratio was seen to be important, heat in divided by heat out, and that was seen to be more-or-less proportional to nτ. As the target temperatures increased, we found we needed larger and larger nτ reactors to make a positive heat balance. And this translated to ever larger reactors and ever stronger magnetic fields, but even here there was a limit, 1 billion Kelvin, a thermodynamic temperature where the fusion reaction went backward and no energy was produced. The Princeton design was huge, with super strong, super magnets, and was operated at 300 million°C, near the top of the reaction curve. If the temperature went above or below this temperature, the fire would go out. There was no room for error, but relatively little energy output per volume — compared to fission.

Fusion reaction options and reaction rates.

Fusion reaction options and reaction rates.

The most likely reaction involved deuterium and tritium, referred to as D and T. This was the reaction of the two heavy isotopes of hydrogen shown in the figure above — the same reaction used in hydrogen bombs, a point we rarely made to the public. For each reaction D + T –> He + n, you get 17.6 million electron volts (17.6 MeV). This is 17.6 million times the energy you get for an electron moving over one Volt, but only 1/13 the energy of a fission reaction. By comparison, the energy of water-forming, H2 + 1/2 O2 –> H2O, is the equivalent of two electrons moving over 1.2 Volts, or 2.4 electron volts (eV), some 8 million times less than fusion.

The Princeton design involved reacting 40 gm/hr of heavy hydrogen to produce 8 mol/hr of helium and 4000 MW of heat. The heat was converted to electricity at 38% efficiency using a topping cycle, a modern (relatively untried) design. Of the 1500 MWh/hr of electricity that was supposed to be produced, all but about 400 MW was to be delivered to the power grid — if everything worked right. Sorry to say, the value of the electricity did not rise anywhere as fast as the cost of the reactor and turbines. Another problem: 1100 MW was more than could be easily absorbed by any electrical grid. The output was high and steady, and could not be easily adjusted to match fluctuating customer demand. By contrast a coal plant’s or fuel cell’s output could be easily adjusted (and a nuclear plant with a little more difficulty).

Because of the need for heat balance, it turned out that at least 9% of the hydrogen had to be burnt per pass through the reactor. The heat lost per mol by conduction to the wall was, to good approximation, the heat capacity of each mol of hydrogen ions, 82 J/°C mol, times the temperature of the ions, 300 million °C divided by the containment time, τ. The Princeton design was supposed to have a containment of about 4 seconds. As a result, the heat loss by conduction was 6.2 GW per mol. This must be matched by the molar heat of reaction that stayed in the plasma. This was 17.6 MeV times Faraday’s constant, 96,800 divided by 4 seconds (= 430 GW/mol reacted) divided by 5. Of the 430 GW/mol produced in fusion reactions only 1/5 remains in the plasma (= 86 GW/mol) the other 4/5 of the energy of reaction leaves with the neutron. To get the heat balance right, at least 9% of the hydrogen must react per pass through the reactor; there were also some heat losses from radiation, so the number is higher. Burn more or less percent of the hydrogen and you had problems. The only other solution was to increase τ > 4 seconds, but this meant ever bigger reactors.

There was also a material handling issue: to get enough fuel hydrogen into the center of the reactor, quite a lot of radioactive gas had to be handled — extracted from the plasma chamber. These were to be frozen into tiny spheres of near-solid hydrogen and injected into the reactor at ultra-sonic velocity. Any slower and the spheres would evaporate before reaching the center. As 40 grams per hour was 9% of the feed, it became clear that we had to be ready to produce and inject 1 pound/hour of tiny spheres. These “snowballs-in-hell” had to be small so they didn’t dampen the fire. The vacuum system had to be able to be big enough to handle the lb/hr or so of unburned hydrogen and ash, keeping the pressure near total vacuum. You then had to purify the hydrogen from the ash-helium and remake the little spheres that would be fed back to the reactor. There were no easy engineering problems here, but I found it enjoyable enough. With a colleague, I came up with a cute, efficient high vacuum pump and recycling system, and published it here.

Yet another engineering challenge concerned the difficulty of finding a material for the first-wall — the inner wall of the doughnut facing the plasma. Of the 4000 MW of heat energy produced, all the conduction and radiation heat, about 1000 MW is deposited in the first wall and has to be conducted away. Conducting this heat means that the wall must have an enormous coolant flow and must withstand an enormous amount of thermal stress. One possible approach was to use a liquid wall, but I’ve recently come up with a rather nicer solid wall solution (I think) and have filed a patent; more on that later, perhaps after/if the patent is accepted. Another engineering challenge was making T, tritium, for the D-T reaction. Tritium is not found in nature, but has to be made from the neutron created in the reaction and from lithium in a breeder blanket, Li + n –> He + T. I examined all possible options for extracting this tritium from the lithium at low concentrations as part of my PhD thesis, and eventually found a nice solution. The education I got in the process is used in my, REB Research hydrogen engineering business.

Man inside the fusion reactor doughnut at ITER. He'd better leave before the 8,000,000°C plasma turns on.

Man inside the fusion reactor doughnut at ITER. He’d better leave before the 8,000,000°C plasma turns on.

Because of its complexity, and all these engineering challenges, fusion power never reached the maturity of fission power; and then Three-mile Island happened and ruined the enthusiasm for all things nuclear. There were some claims that fusion would be safer than fission, but because of the complexity and improvements in fission, I am not convinced that fusion would ever be even as safe. And the long-term need keeps moving out: we keep finding more uranium, and we’ve developed breeder reactors and a thorium cycle: technologies that make it very unlikely we will run out of fission material any time soon.

The main, near term advantage I see for fusion over fission is that there are fewer radioactive products, see comparison.  A secondary advantage is neutrons. Fusion reactors make excess neutrons that can be used to make tritium, or other unusual elements. A need for one of these could favor the development of fusion power. And finally, there’s the long-term need: space exploration, or basic power when we run out of coal, uranium, and thorium. Fine advantages but unlikely to be important for a hundred years.

Robert E. Buxbaum, March 1, 2014. Here’s a post on land use, on the aesthetics of engineering design, and on the health risks of nuclear power. The sun’s nuclear fusion reactor is unstable too — one possible source of the chaotic behavior of the climate. Here’s a control joke.