This post is the next in a series that dates back several years. In fact, it's been going on for long enough that several posts ago I decided to upgrade from "50 Years of Science" to "60 Years of Science". And, if we group them together, this is the twenty-second main entry in the series. You can go to https://sigma5.blogspot.com/2017/04/50-years-of-science-links.html for a post that contains links to all the entries in the series. I will update that post to include a link to this entry as soon as I have posted it.
I take Isaac Asimov's book The Intelligent Man's Guide to the Physical Sciences as my baseline for the state of science when he wrote the book (1959 - 60). In this post I will review two sections, "Nuclear Power" and "Radioactivity". Both are from the chapter "The Reactor". This is the last chapter in the book. So, the end of this series is neigh.
The book was written in the middle of the Cold War. Then, MAD, Mutual Assured Destruction, the ability of either the U.S. or Russia to start a nuclear conflagration that would literally bomb both countries "back to the stone age" was something in the forefront of people's minds. But nothing happened. The Cold War ended peacefully with the breakup of the Soviet Empire.
And various crises have since come and gone. And wars have come and gone or, in some cases, lingered for what seems like forever. And countries as stable as the United Kingdom and as fringe as North Korea have gotten "the bomb". In all this time no one has exploded a nuclear weapon in anger. So, most people now spend little time thinking about them.
Things were different back then. Nuclear weapons, and the possibility of nuclear war, was a pressing concern. This scared the shit out of people, and legitimately so. As a result there was a real yearning for an alternative, an "atoms for peace" program of one sort or another.
But Asimov starts a little earlier. He notes that there was a legitimate race to be the first to develop an Atom Bomb. The Nazis did have a legitimate program that Hitler hoped would produce he could use. And no one doubted that he would use it if he had it.
It turns out that we now know that they never even got close. But that became clear only after the War was over. In the mean time, this legitimate concern was part of the justification for moving forward rapidly with a U.S. program, a program that eventually succeeded. (Many other countries helped. Principle among them was the U.K. But the U.S. provided all of the money and most of the resources.)
Against the background that, then and now, the U.S. is the only country to ever explode a nuclear weapon in anger, there was a yearning to balance the bad with the good. And the most obvious good was to harness the "power of the atom", in this case nuclear fission, to produce power. This power was first used to propel ships. But it could also be used to produce electric power.
Both of these technologies emerged from "Project Plowshare", named for the biblical quotation about "beating swords into plowshares". But producing power that could be harnessed was not the only idea Plowshare explored. Another was to use atomic bombs for earthmoving. The obvious candidate was a canal from the Atlantic to the Pacific that would be dug by exploding a series of Atomic Bombs underground.
As a proof of concept a bomb was actually exploded underground in Alaska in an attempt to create an artificial harbor. Another possibility was to use it for oil drilling. The reason that you haven't heard of these and other ideas is that they turned out to be far more trouble than they were worth. They were all abandoned. Some persisted after Asimov's book was published. But not for long. The only Plowshares idea that turned out to have any legs was the nuclear reactor.
Demonstrator nuclear reactors of various kinds started popping up within a few years after the end of World War II. But, as I have noted elsewhere, it costs a lot of money to come up with a design. It costs even more money to turn the design into a working device. That made commercial interests reluctant. The U.S. Navy, on the other hand, was not reluctant. As a result, the first nuclear reactor put to practical use was put to use powering a Navy submarine.
The thinking was that submarines are vulnerable on the surface but safer underwater. And a power plant that required an ample supply of oxygen, as any kind of petroleum based engine does, demands considerable surface time. Nuclear power requires no oxygen. And, once a nuclear power plant was developed, a recent conventional submarine design was quickly reworked to make use of it. The result was the "Nautilus", named for the submarine in Verne's 20,000 Leagues under the Sea.
It was so successful that almost all U.S. Navy subs that have been built since have been nuclear powered. They can easily stay underwater for 6 months straight. The biggest ships in the U.S. Navy's inventory were also soon adapted to nuclear power. Since the '60s, all large Aircraft Carriers are nuclear powered. These ships have a large fuel budget. But it is for the planes they carry and not the ship itself.
Efforts to use nuclear power in other ship types has failed. A nuclear powered cargo ship was built. It was a technical success but a practical failure. Everything worked just as it was supposed to. But it was barred from most seaports for political reasons. These same political reasons are the reason no other ship type has been attempted.
Most of this happened after Asimov's book was finished. He spends some time on the Nautilus and mentions several other nuclear powered vessels. For instance, the keel for the "Enterprise", the first nuclear powered Aircraft Carrier, had been laid down in time for that information to make it into the book. But she had not yet entered service.
As CVN-65, she entered active service in 1961. After over fifty years of active service, she was decommissioned in 2017. Construction of a replacement of the same name, CVN-80, is scheduled to begin in 2022. CVN-80 is scheduled to enter service in 2027 or 2028.
The first civilian nuclear power plant was built by the Russians in 1954. The U.K. followed in 1956. The U.S. joined the club in 1958. At the time coal fired power plants were cheaper to build and cheaper to operate. It was hoped that as nuclear power plant construction and operation moved down the learning curve, they would eventually become the cheapest option.
We now know that was never going to happen. Outside of the Soviet sphere of influence, most designs differed little from each other. They also differed little from the design used to power the Nautilus. At the time Asimov wrote his book it was believed that Uranium was hard to find. It turned out that there was a learning curve when it came to finding Uranium.
Uranium is now known to be plentiful. It is also known to follow the same rule that applies to pretty much any commodity that is mined. The higher the price, the more ore deposits there are that can be mined economically. We are not going to run out of Uranium to mine any time soon.
The construction of many plants of similar design should have driven construction costs down. But it didn't. The anti-nuclear people got more and more effective. They forced regulators to pile on more and more requirements that were supposed to improve safety. They didn't. What they did do was to keep pushing construction costs higher and higher.
Three Mile Island, followed by Chernobyl, followed by Fukushima have caused the pressure to only increase. I have plowed this territory extensively elsewhere so I am not going to go over it again. Suffice it to say that nuclear power does not now, and doesn't in the near future, look to be a substantial contributor to new electric power generation.
Asimov includes a schematic diagram of a "gas cooled" nuclear power plant. It describes a design that is more sophisticated than the one used in most nuclear power plants operating today. Instead of being "gas cooled", they are "water cooled". But, other than the details of the cooling method, so little has changed since that it accurately portrays how most nuclear power plants work to this day.
A Uranium shortage was them a serious concern. Asimov responded to this concern by noting that "breeder reactors", reactors that can covert the common U-238 isotope of Uranium into Plutonium, effectively multiply the amount of nuclear fuel available by many times. Only minor design changes need to be made to turn a Uranium fueled design into a Plutonium fueled design. He also discusses Thorium as a third alternative.
None of this went anywhere after the book was published. The primary reason was the discovery that there actually was a lot of Uranium around. Safety and proliferation issues doomed Plutonium. It turns out to be relatively easy to harvest reactor grade Plutonium and turn it into a bomb. The risk associated with Plutonium, and other concerns I am going to skip over, means that breeder reactors are only used in military programs designed to create fuel for bombs.
I am not familiar with the reasons Thorium never took off. I suspect that it too was doomed by cheap and widely available Uranium. But I don't actually know for sure. On to "Radioactivity".
Asimov characterizes radioactivity as a new threat. He justifies this on the basis that naturally occurring radiation is usually of a pretty low intensity. High intensity radioactivity he associates with new man made activities like Atom Bombs. He is correct in the sense that "the bomb" made people acutely aware of radioactivity.
Scientists had known about if for about fifty years by then. But outside of certain scientific circles it was pretty much unknown. To his credit he does discuss early radiations induced deaths and illnesses. Two early victims were Marie Curie and her daughter. For a while X-Rays were considered completely benign. But that slowly changed. Now, of course, safety protocols are routinely followed in places like dentist offices.
Dots of a mixture of Radium and phosphors that would light up were applied to watch dials to make watches easier to read in the dark. The work was done by women using small brushes. They would often lick the brushes as they worked. This resulted in horrible cancers of the face and mouth, and sometimes death. This practice was outlawed but I don't know whether this happened before or after Asimov's book came out.
Asimov speculated on whether enough radiation would be unleashed to cause widespread harm. We now know that the answer is no. But even very small amounts of radiation can be easily measured. This has allowed scientists to perform some very unusual "tracking" experiments.
Oceanographers have been able to accurately measure the amount of radiocarbon in ocean water. It spiked during the short period when extensive above ground bomb testing was occurring. The sharp edge between radiocarbon enhanced water and water containing normal amounts allows them to calculate just how "old" the water was. That is, how long it's been since the water was at the ocean's surface.
Another interesting development was the discovery of natural nuclear reactors. Chain reactions depend of the concentration of Uranium being unusually high. But there are natural events that concentrate Uranium. And in some cases, these have resulted in chain reactions taking place. We know this because this situation leaves distinctive isotope profiles behind.
Concentrations never reached the levels necessary to cause a nuclear explosion. But it never occurred to anyone to think that even a low level chain reaction was possible. That is, until someone accidently stumbled across the first one. Since then, many more have been found.
Asimov quickly moves on to a discussion of the mechanics of radioactive decay. These are subjects I have already covered elsewhere. He just hits the highlights. But a lot was known at the time and far more is now known. But it is detail. The main picture is clear and hasn't changed in the sixty years since the book was written.
He discusses the concept of a "decay chain". This isotope decays into that isotope, which then decays into some other isotope. He also notes that an isotope may decay in several ways. But in all cases the probabilities are fixed.
He moves on to "half life", a subject which I have already discussed extensively. From there, he goes on to note that some kinds of radiation are deadlier than other kinds. The converse of this, which he doesn't discuss, is that it is easier to create an effective shield against some kinds of radiation than it is to create one against other kinds.
He then segues from the fact that everything is radioactive to the subject of "background radiation". This is another topic I have already treated. He notes but doesn't go into detail on the idea that background radiation can contribute to evolution.
DNA had just been discovered. We now know that radiation can damage DNA. This can result in mutations. A mutation can be either beneficial or detrimental. Over time, the beneficial mutations cause species to evolve. But there are cellular mechanisms for repairing DNA damage, regardless of the cause. And their are many other ways to cause damage.
Other big causes of mutations are transcription errors, reading errors, and the like. DNA gets duplicated. The duplication process is not 100% accurate. Various processes "read" DNA. As an example, the cell manufactures thousands of different proteins.
The blueprint describing the specifics each of the many different proteins a cell manufactures is found in the DNA. A process that is different from, but related to, the duplication process is used to read the DNA. But the information found that way is used much differently.
Instead of being used to duplicate the DNA itself, a translation process is used to drive a protein assembly process. DNA provides the details that determine the order and type of the subunits that snap together to make each specific protein. An error in this process causes the wrong protein to be made.
It is not a wonder that things go wrong with these cellular processes. What is a wonder is just how infrequently they do go wrong. It is thought that cancer is caused by key cellular mechanisms going consistently wrong. Scientists are attacking cancer by figuring out how to get these broken processes back on track.
Various efforts are now under way to reclassify cancers. The current methods of classifying cancers depend on the symptoms or what organ is affected. The new method depends on classifying what cellular mechanism goes wrong and how it goes wrong. This may lead to a single cure that is successful against many cancers, not just one or a few.
This deeper understanding of DNA, the way radiation damages DNA, and all that follows has taken place since Asimov wrote his book. So, let's get back to it.
He moves on to the "nuclear waste disposal" problem. This is also something I have discussed extensively elsewhere. Before moving on I will note that he assumes that the nuclear power industry will grow rapidly. He also assumes it will eventually become quite large. That would have resulted in a large amount of nuclear waste. But the industry did not ever grow very large. So, the waste disposal problem is actually quite modest.
And, since he overestimates the size of the problem, he ends up taking off on what now look like tangents. One of them involves building devices that produce small amounts of power for long periods of time. They work just fine. But they have not gone into general use due to the public's fear of radiation. They have only found one use.
We routinely send space missions to the outer solar system. These missions need power. The standard solution is solar panels. Various Mars rovers, the International Space Station, and all manner of other space gadgets, use solar panels for power very successfully.
But the farther from the sun, the less bright sunlight is. And that means you need giant arrays of solar panels to produce the necessary power. Queue the RTG, the Radioisotope Thermoelectric Generator. It is based on the SNAP device Asimov discusses.
Modern RTGs use Plutonium for fuel. They are radioactive enough to be dangerous. So they are often put on the end of a boom that distances them from the bulk of the spacecraft. RTGs power both Voyager spacecraft, now the two most distant man made objects. One powers the spacecraft that did the flyby of Pluto. (BTW, that spacecraft is still working fine.) Their other successes are too numerous to list. But this application is the only one where "Isotope Power" is used routinely.
Asimov discusses various other attempts at the peaceful use of radioactive materials. There has been some successful use of radioactive materials in medicine. That success continues but it is modest. The other things he discusses never ended up going anywhere. The public fear of radioactivity eventually blocked any chance of success they might have otherwise had.
He then returns to how to dispose of radioactive material. It would be nice if the topic had advanced productively since Asimov's day. But it hasn't. The same old options are still on the table. The same arguments are still advanced against each option. The fact that radioactivity poses no unusual danger, and the fact that we are talking about a very small volume of material, are both still being ignored.
He then moves on to radioactive fallout and the fact that very tiny amounts could be detected, even back then. He concludes from this that "it is virtually impossible for any nation to explode a nuclear bomb in the atmosphere without detection". That truth eventually became self evident. It led to the "Nuclear Test Ban" treaty, which outlawed above ground testing.
At the time that left a loophole. Countries cold explode bombs in caverns below the ground. But seismology has grown in sophistication by leaps and bounds since Asimov's time. It was then possible to detect the underground detonation of a medium or large sized nuclear weapon. But what about a small one?
In Asimov's time it was thought that such a detonation stood a good chance of going undetected. But, as I said, seismology has since gotten much better. It eventually became apparent that even the detonation of a small nuclear weapons would be detected. There was some nonsense thrown up postulating that there were circumstances under which a detonation could still go undetected.
But the arguments were nonsense and this eventually became apparent. There is now a treaty banning underground nuclear explosions. But the U.S. and a number of other countries have not signed it. Most conspicuous among the non-signers is North Korea. But that hasn't stopped all of their underground nuclear tests from being detected.
No one has succeeded in concealing an underground nuclear test and no one will. But that doesn't mean that a country won't develop a nuclear weapon and test it. North Korea did just that. It just means that, if they do so but try to keep it a secret, everybody will still find out what they did.
Asimov then launches into a long discussion of the isotope Strotium-90. It is highly radioactive. It is particularly dangerous because it is readily absorbed into the bones of growing children. In this situation, it doesn't take a lot to constitute a dangerous amount.
Another highly radioactive isotope is Iodine-131. It is particularly dangerous because it is taken up and concentrated by the thyroid gland in the neck. Again, as a result it doesn't take a lot to constitute a dangerous amount. Asimov does not discuss Iodine-131.
You will typically see a lot of press coverage of Strontium-90 and Iodine-131 whenever there is an event that releases a lot of radioactive material. These two materials were discussed extensively in conjunction with the Fukushima nuclear disaster, for instance. Now you know why they rightly attract so much press attention.
And on that cheery note, . . .
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