Sunday, February 17, 2019

No to Nukes!

Diablo Canyon Nuclear Power Plant

Although I would like to see this country and the world transition from fossil fuels for electric generation,1 I am no fan of nuclear power. I say this as a technical writer and communicator who worked for six years at an engineering and construction company that built large-scale power generation, including two nuclear plants, and then at a public utility that built two units of nuclear generation along the California coast. I supported those efforts with my writing skills but, all the time, I was not a “believer” in nuclear power.

The first large-scale, commercial nuclear power plant in the United States was the Shippingport Atomic Power Station in Pennsylvania. It started operating—or “reached criticality”—in 1957. In the years that followed, and with the support of the Atomic Energy Commission under the rubric that atomic energy in the hands of local utilities would be “too cheap to meter,” more than ninety reactors were installed and brought to power in this country. Usually, two or three reactors would be placed at one site by a utility, to effect economies of scale.

Oddly, this burst of nuclear activity lasted less than twenty years. No ground has been broken on new nuclear plants after 1977, except for four reactors in the current decade at two existing plants which have been licensed by the Nuclear Regulatory Commission to start construction and have not yet been completed. Only one reactor has entered commercial operation since 1996.2

What happened? This dearth of plants in a promising new technology occurred two years before the accident at Three Mile Island. And while the beginning of this falloff in construction was roughly simultaneous with President Carter’s executive order in April 1977, which banned the reprocessing of spent nuclear fuel, building a “nuke”—as the utility business calls these plants—is a long-term endeavor. It usually takes ten to fifteen years from the initial planning stages and application for a license to begin construction until the reactor finally fires up. Nothing that happened in April of that year would have caused this process at so many utilities to stop on a dime.

I happen to remember the reason. My father was a long-time subscriber to Fortune magazine, and I had access to his copies as a young reader. In 1968, while I was still in college, I read an article that laid out the truth behind the “too cheap to meter” claim. A decade later, when I was a communicator at the engineering company, I helped write a similar article for our business development magazine. Here is the story.

The nuclear fuel cycle begins with uranium ore in the ground. That ore has to be dug out, transported to a processing plant, and refined into an intermediate material, uranium oxide, which is called “yellowcake” because it looks just like Duncan Hines cake mix. The chemical formula is U3O8. Mining, transporting, and processing take a lot of energy, usually in the form of fossil fuels.

Uranium is radioactive because its top-heavy atom exists in a number of isotopes. The most common form, accounting for 99% of ore, is U-238—referring to the number of protons in the nucleus that define the element plus the neutrons that provide the final atomic weight of this particular isotope. U-238 is the most stable form. The least stable—that is, most likely to have its nucleus split apart and create some fun—is U-235. A bunch of uranium ore or a block of metal out of the ground is going to kick off the occasional fast neutron or other bit of radiation, which makes it relatively unsafe to be around, but it’s not going to explode or melt down or anything. To make the kind of uranium that will work in a reactor, or a bomb, you have to enrich it by bumping up the percentage of U-235. To do this, you chemically change it into a heavy gas, uranium hexafluoride (UF6), and spin it in a centrifuge to separate the lighter U-235 from the heavier U-238. Spinning those centrifuges takes a lot of energy, usually in the form of electricity.

Once you have the isotopes separated, you can then blend your mix of U-238 to U-235 for either making reactor fuel rods or bomb parts. You want a mixture, not just the pure U-235, for various reasons. First, the most reactive isotope in its pure state is going to be terribly unstable, not good to handle, and won’t last long. Second, your fuel rod makes use of the more stable U-238, because when its nucleus gets hit by a fast neutron from the naturally decaying U-235, it will also tend to split and release heat. And sometimes, instead, the U-238 absorbs that neutron and become plutonium-239, which will eventually decay on its own.

Once you have your mixture, you form the uranium metal into pellets, encapsulate them in a long, cylindrical clay matrix, and clad that matrix in stainless steel. When you have enough rods, you bundle them into a fuel element that is designed, by content and configuration, for a particular type of reactor. After you load the reactor with fresh rod bundles and add a moderator—in the Westinghouse reactors I’m familiar with, it’s boron in the water, which slows the fast neutrons from decaying uranium atoms just enough for them to profitably impact other uranium atoms—you get criticality and a chain reaction. It’s this chain reaction that produces useful amounts of heat to boil the water that drives the power station’s turbine. The reaction also creates byproducts in the pellets, like isotopes of strontium and cesium from the split uranium atoms, and the occasional plutonium atom.

After about eighteen months in the reactor running at full capacity, the percentage U-235 is depleted, the remaining U-238 can’t be induced to split, and the pellets have a high concentration of those unpleasant strontium, cesium, and other isotopes that aren’t good for the reaction. You now have spent fuel waste. If you don’t do something productive with it—and we’ll get to that in a moment—you have to keep the rods cool, because the spent fuel is still radioactively and thermally hot. And you have to watch over them for about 10,000 years.

The reason most utilities have given up on nuclear power is simple: the energy cost of mining, processing, concentrating, and fabricating those fuel rods—think of diesel fuel, trucking, chemical processes, and electrically powered centrifuges loaded with heavy gas—is greater than the energy produced by “burning” the rods in a reactor. Nuclear power becomes a net drain on your energy economy. It might be more convenient to burn those rods in a reactor sited along a scenic coastline than to build a coal plant there and have to deal with railcars, coal piles, stack gas, fly ash, and a long plume of carbon dioxide wafting over the nearby valley. But you’re still running at an energy deficit. That was the point of the Fortune article: nuclear power is a way for your energy economy to go broke slowly.

There are people who can make nuclear power work. France and Japan depend on it. In 1987, at a conference sponsored by Energy Daily, I heard the head of Électricité de France S.A. explain how. He noted that the national utility draws about 64% of its power from nuclear because, as he said, “France has no coal. France has no oil. France has no choice.” Unlike the United States, where local utilities run a hodgepodge of reactor makes and designs—Westinghouse, Brown & Root, boiling water reactor, pressurized water reactor, etc.—France installs one design only. And when the nuclear fuel is spent and it’s time to open up the reactor vessel and replace the rod bundles—along with fixing anything else that’s broken in the plant during this downtime—the local operators don’t have to suddenly become reactor maintenance specialists. Instead, EDF sends a flying team of refueling specialists to the plant to break it down and reload the core. And then EDF takes the spent rods and reprocesses them. EDF also takes the spent fuel from Japanese reactors and reprocesses it at a profit.

Reprocessing closes the nuclear fuel cycle. The rods are broken apart and the steel and clay discarded as low-level radioactive waste. The pellets are chemically processed to separate the remaining U-238 and valuable Pu-239 for reuse, while the cesium, strontium, and other isotopes are mixed with molten glass to form pellets of high-level waste that can be more easily cooled and stored. Then fresh amounts of U-235 are added to the fuel mix and new pellets, rods, and bundles are fabricated. By reusing most of the fuel over and over again, nuclear power becomes a net energy producer instead of an energy drain.

But Jimmy Carter banned this reprocessing in the United States and closed down the sites where it could be done out of fear of creating a “plutonium economy” and enabling worldwide nuclear terrorism. We’ve also been slow—to nonexistent—about moving and processing spent fuel from our commercial reactors for long-term underground storage. So each nuclear utility must hold, cool, and watch its growing inventory of spent fuel bundles for an indefinite period of time.

Perhaps there are other forms of reactor that don’t have these problems. One hears promising things about thorium—which is transmuted into U-233 for the nuclear reaction. And physicists have been trying for thirty years to create usable fusion reactions with magnetic containment and laser ignition, but these fusion experiments still haven’t produced more energy than they consume, and the promise of fusion has always been—and still is—“ten years away.”

So it wasn’t the inherent dangers, public reaction, activist agitation, government regulation, or any event at places like Three Mile Island or Fukushima that killed nuclear power in this country. That blow was struck years earlier, when utilities began to discover that for all its clean, efficient, modern, science-fiction-sounding promises, nuclear power just isn’t very efficient and never was “too cheap to meter.” And as the efficiency of turbine technology has improved over the last thirty years, largely due to advances with jet engines, spinning a generator with the heat of a natural-gas flame—essentially putting a jet engine and a generator on a flatbed truck—has become competitive with a huge, cantankerous, steam-powered, baseload generating station.

I wish it weren’t so. I wish we could push banana peels into a household appliance like “Mr. Fusion” and power a flying car that also travels in time. But so far … not.

1. And it’s not because of the industry’s “carbon footprint” and the prospect of anthropogenic global warming. Sure, the United States has enough coal to power our society for a thousand years, but it’s still a limited resource in the larger scale of things and a pesky resource to find and use cleanly. Our other fossil choices, oil and gas, are more limited than our coal resources and far more valuable as chemical feedstocks than as fuel in a generating plant. And when I say “larger scale,” I’m thinking two or three thousand years ahead.
    Energy is the stuff of civilized human life: it has been so since the first cave man burned a stick of wood for light and warmth. Eventually, we will have to find a more efficient, cleaner, renewable source of electric power than carbon-based fuels. Wind and solar are too diffuse for reliable, large-scale energy generation. So we might as well start looking for the as-yet undiscovered—and at this point largely theoretical and magical—technology that will power us in the long run. And fission-based nuclear is not that.

2. For a short history of nuclear power in this country, see this Wikipedia entry.

Sunday, February 10, 2019

Gravity

Time warp

As I’ve noted before,1 I am neither a mathematician nor a physicist. I’m an English major by education and a writer of both technical documentation and science fiction by profession. I’m not equipped to analyze a claim mathematically, but I know a good story when I hear it. And I can pick apart a story line when I detect a subtle falsehood.

For a long time I thought of gravity as a “force,” similar to an electromagnetic field or the strong or weak forces in atomic nuclei. In this I was not alone. After all, the mathematical and physical definition of a force is mass times acceleration, F=ma. That is, the force needed to throw a baseball equals the mass of the ball times the acceleration of the pitcher’s arm from the start of the pitch until the release of the ball. Mass times acceleration. Once the ball leaves the pitcher’s fingertips, it is no longer accelerating but just traveling at its final—and perhaps slowly decreasing, due to air resistance—velocity toward home plate.

Similarly, the force exerted by gravity, at least on the surface of planet Earth, is whatever mass is involved—say, a person weighing 150 pounds—times the acceleration of gravity, which in this particular place is 9.8 meters (or, if you like, 32 feet) per second per second, g=9.8m/s2. A thousand kilometers above the surface, and so farther away from the planet’s center of mass, that value drops to 7.33 meters per second squared. And the farther out you go, the slower the acceleration becomes.2

The one thing that physicists could not figure out, however, was how the Earth or any other large body exerted this force to pull people, houses, cars, plants, water, dirt, and everything else downward. Since most forces in physics are represented by a field—the electromagnetic force, for example—with an accompanying particle—in the case of electromagnetism, the photon—quantum mechanics comforts itself by representing gravity with the graviton. And, presumably, the force of gravity is achieved by an exchange of gravitons, from my body to the Earth, and from the Earth to my body.

But for a particle we’ve never seen, touched, or even detected, that’s a lot of gravitons. The Earth is supposedly exchanging these particles back and forth all the time and with every person, car, seed, grain of sand, and even with parts of its own mass like the planet’s layers of atmosphere, lithosphere, mantle, and outer iron core. At the same time, the Earth is also exchanging gravitons with the Moon to hold her in orbit, and with the Sun to stay in its own orbit around the star. You might as well say that tiny pixies grab your feet and hold you down.

Long before I became concerned with this matter of force, Albert Einstein resolved the issue of gravity in another way. The masses of the Earth, the other planets and moons, our Sun and the stars don’t exert a force per se. Instead, they shape or bend both space and time in their immediate neighborhoods. You and I shape space and time with our own masses, too, but the deflection is so small as to pass unnoticed in even the densest of crowds.

To show that this bending of space and time is equivalent to the pull of gravity, Einstein conducted a thought experiment. He mentally placed a person in a room far out in space, away from any stars or planets, and attached a long cable to the room. He then began drawing the room upward, in a direction opposite to the room’s floor, at an acceleration of 9.8 meters per second squared. To the person inside the room, that acceleration was identical to the apparent “force” with which gravity holds him to the floor at the surface of the Earth. The person is allowed to perform whatever experiments within the room that he pleases: throw baseballs, drop coins, pour out pitchers of water, and so on. So long as the pull of that long cable remained at a constant acceleration of 9.8 meters per second per second, the person could not tell he was anywhere but on the home planet.

This, as I understand it, was Einstein’s proof of equivalence, that gravity and acceleration were the same thing.

I don’t doubt that they are equivalent, at least conceptually and mathematically. But I detect a hitch in the story: the equivalence is purely subjective. From the viewpoint of the person in the room, and only so long as he doesn’t look out a window, the acceleration of the room and the acceleration of gravity on the Earth’s surface are the same. But objectively, they are different.

Objectively, a person standing in a room on Earth isn’t going anywhere, at least relative to the center of the planet’s mass. He may be traveling eastward at a thousand miles an hour if the room is at the equator, or around a little circle with a circumference of only a few feet during a whole day spent at the North Pole. He may be moving with the planet along its orbit around the Sun, and with the Sun in its orbit around the galaxy. But relative to the center of the Earth, he moves not one millimeter, so long as the floor holds.

Meanwhile, objectively, a person in a room being hauled along at an acceleration of 9.8 meters per second squared is traveling through space at an ever-increasing speed. Within a finite amount of time, something on the order of ten years, at that acceleration—initially about 22 miles per hour, but speeding up all the while—the room and the person would achieve about ten percent of light speed. Within a hundred years or so, if the physics of spacetime allowed it, the person would be traveling at and then exceeding light speed. Of course, according to Einstein, the person’s mass would then increase toward infinity while his perception of time would stop. But otherwise, the person would have no sense of any difference from being quietly positioned on Earth—except that if he had a window, he would see the stars outside blur their colors into the bluer part of the spectrum ahead of him and to red behind him. And if he made a radio call to a friend on Earth, his own voice would be getting lower and slower, while his friend would start sounding more and more like a chipmunk.

Objectively, traveling in a long-haul elevator or on a runaway rocket is not the same as standing on the Earth. The fact of physical acceleration matters. In one case, on the planet’s surface, the acceleration is merely conceptual, the equivalent of increasing speed time over time, but without the actual effects of acceleration. In the other, in the elevator or the rocket, the acceleration is a real motion and has predictable consequences.

The fact is, each of us is accelerating toward the center of mass of the planet from the day we’re born to the day we die and our atoms disperse, and then they keep accelerating in some other form. Conceptually and mathematically, we are all going faster and faster, eventually exceeding theoretical light speed, and yet going nowhere. This is the conundrum I find with any current definition of gravity. And it is associated in the posts referenced at the beginning of this piece as well, which deal with our definitions and conceptions of space and time—the two key components of either gravity-as-force or gravity-as-distortion of that slippery thing called “spacetime.”

We can measure gravity, space, and time. We can envision them as forces or dimensions or other real things. We can write equations about them and manipulate them mathematically. But we don’t really know what they are. And until we do—or meet up the people who have solved this conundrum—our notions of the physical world will remain those of a child.

1. See previous posts in this vein, starting with Fun with Numbers (I) from September 19, 2010, and (II) from September 26, 2010.

2. Need I say here that when orbiting at a comfortable near-Earth distance—say, the Space Shuttle’s maximum service ceiling of 643 kilometers—the apparent weightlessness of people and things is not at all due to this drop-off in, or any kind of final disappearance of, the accelerations of gravity? Instead, in order to achieve a stable orbit, the ship moves fast enough that its fall toward the planet, due to gravity, is countered by its forward momentum, so that the ship is still falling but its point of impact is forever over the horizon.
    In the same way, if you jump out of an airplane and fall toward the planet’s surface, you will apparently become weightless for the time you are still falling. If you take, say, a coin from your pocket and release it from your hand, it will appear to be weightless, too, while falling beside you—except for any difference in wind resistance which may allow the thin coin to fall somewhat faster than your large and obstructive body. Above the atmosphere, however, with no resistance you and the coin would drop in perfect synchrony.

Sunday, February 3, 2019

Basic Civility

Munch Scream

This is not a new topic, and I don’t have many original ideas on the subject. But I feel I have to comment on the decline in civil discourse in this country in the past few years.

Public discussion has become toxic, especially in the wonderful new social media, which was supposed to open the internet to a free exchange of ideas. And this exchange was supposed to be a good thing. It still is, mostly, in my opinion. The fact that so many people can go on exchange forums like Facebook, Twitter, Tumblr, and Instagram tells me that a large portion of our population is literate, interested, able to type, enjoys abundant leisure time, and has access to the internet with a convenient computing device. Those are all positive characteristics in a developed society.

Unfortunately, so many people who participate in social media are also wildly unhappy. For every picture of a pretty sunset or a charming kitten, or a positive comment about life in general, we get reams of political comment laced with vitriol and innuendo. It used to be, in this society, that people with strongly held views could “agree to disagree.” One person might not agree with another’s viewpoint, conclusions, or grasp of basic facts, but that did not invalidate the other person’s basic humanity or his or her right of free speech.

Somewhere along the way, the notion has crept into public discourse that the people who disagree with us are not merely wrong but dangerous and evil. Their thoughts and the supposed actions that will stem from those thoughts—particularly in the voting booth—will damage society, invalidate other people, and poison the planet. Silencing them, stopping them, is not merely a matter of desired public policy but in the interest of saving the world.

When thoughts and their expression become, in your opinion, not merely wrong or ill-considered but an active danger that must be opposed with force of law if not direct physical action, then we are on the slippery slope of fascism. There are many definitions of “fascism,” colored by historical example and political persuasion, but the most basic would be a paradigm under which the public good and presumed public safety outweigh personal freedoms. For the good of the nation, the state, the party, the environment, and people of a particular ethnic, or cultural, or sexual orientation—or whatever else you hold dear—these others must be silenced and prevented a priori from speaking and taking action.

We have already reached a point that, while notions of racial and sexual differences between human beings are held to be equally if not more important than individual achievements and character,1 any mention of those differences is also irredeemably tainted as racist and sexist. We have already reached the point where it is taboo to suggest that all human beings are one kind, one species, with only minor physical differences, and that most differences attributable to “race” are instead cultural—is irredeemably racist. We have already reached the point where it is taboo to suggest that women are in any way different from men, and yet to acknowledge openly that they still need special treatment, such as revised physical standards to perform the rigorous or dangerous jobs traditionally held by men, or particular encouragement to enter academic fields traditionally attended by men—is irredeemably sexist.

Now we have a movement to deny that gender, the condition of being either male or female, is binary but instead to insist that human sexual orientation and, presumably, physical and emotional characteristics as well, are represented by a spectrum of possibilities. More, that these possibilities are not fixed but instead are fluid and subject to change with the opinion and preference of the person stating his or her or its or their identity. This is personal freedom that has run off the cliff and into the thin air. And yet people are willing to scream that this is so and to denigrate2 anyone who denies it as “sexist,” “homophobic,” “transphobic,” or some other irredeemably bad thing.

Aside from the fact that our society, especially in the most educated, literate, technologically sophisticated, and vocal segments of the population, has gone crazy, this current level of civil discourse tells me we have a lot of truly unhappy people here. Our best and brightest people seem to be suffering huge existential angst, despite the fact that we live in a country that has never been richer, freer, or more advantaged. We have more and better food, access to education and information, access to medical advances and health care, access to energy resources and computing power assigned to personal use, access to housing and transportation, entertainment, and every other human comfort than in any other country today and in any other human society throughout history. But we’re still unhappy.

Perhaps it’s because we have so much that is so readily available without our having to work too hard for it, that we can imagine the last unobtained one percent of such availability and access and so cry for physical and existential perfection. Why can’t everything be freely available right now? If a person can imagine this condition of perfection, in the most advanced society in the world, then why can’t he or she (or it or they) have it?

As someone raised since childhood not to cry for the Moon, because I’m simply not going to get it, I find this level of discourse to be borderline insane. It is also useless and ugly. But there we are …

The only good thing I can say is that most of the people you meet in the street, rather than online, are still basically civil. Casual encounters in the grocery store with, say, two carts contending in a narrow aisle, are generally resolved with a smile and one party giving way. Casual encounters on the street with, say, two cars meeting at a stop sign, are generally settled with a wave. We haven’t devolved into fistfights in Safeway and rammings on the freeway. So we still have some basic civility in physical life.

But if this trend of dehumanization towards people of different opinions, stations in life, and complexions doesn’t change, we may end up in a war zone both online and in the streets.

1. That old content of character vs. color of skin thing, such as Martin Luther King, Jr., described.

2. And yes, sigh, that word is probably considered racist because of the four letters at its core, although it comes from a Latin root meaning simply “to blacken.”