Tag: Weekend Geek

Ask The Expert: Spent Nuclear Fuel Handling and Storage

 

nuclear-basilisk A basilisk is a mythical creature able to kill with a single glance. Used or “spent” nuclear fuel would have a similar effect, if you were to stand close to it without benefit of shielding: Within a matter of minutes, you would receive a lethal radiation dose. Unlike basilisks, however, spent fuel isn’t out to get you, and is handled and stored safely at every nuclear power station in the United States. In contrast, new fuel that has never been loaded into a nuclear reactor has a very low — almost negligible level of radiation — and can be touched and directly handled without incurring any significant radiation dose.

The smallest unit of nuclear reactor fuel is a fuel pellet, a cylinder of compressed uranium dioxide, enriched to about 3 – 4.5% of the U-235 isotope. Each fuel pellet is less than half an inch in diameter and less than an inch long. Fuel pellets are loaded into a slender tube (called cladding) about 12 feet long, usually made of Zircaloy (a metallic alloy); the sealed tube is called a fuel rod, which looks similar to a wooden dowel. Fuel rods are arranged in an array called a fuel assembly. A boiling water reactor (BWR) has a 7 x 7 or 8 x 8 array of fuel rods running parallel to each other, in an assembly about five and a half inches square, about 14 to 15 feet long, weighing about 600 pounds; a typical boiling water reactor core holds between 500 and 600 such assemblies.

In contrast, a pressurized water reactor (PWR) has larger fuel assemblies that contain significantly more fuel rods — between 14 and 17 per side, though hexagonal arrays also exist — and weigh 1300 lbs or more. A typical pressurized water reactor core holds fewer than 200 fuel assemblies. A few spaces in each assembly are fitted with guide tubes instead of fuel rods, to allow control rods or in-core instrumentation to be inserted.

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I have always been fascinated by Einstein’s Theory of Relativity, and the strange, counterintuitive things that it predicts.  Special Relativity, the first part of the theory, can be summarized as follows: 1.  The laws of physics are the same in all inertial (non-accelerating) frames of reference, and Preview Open

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I came across a paper a while ago purporting to prove that CO2 is not a greenhouse gas, and in fact the greenhouse effect does not even exist.  Although I am an AGW skeptic myself, I would not go so far as to make either of those claims.  However, there are some interesting points in […]

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  Above is an early prototype of a hoverbike, basically a scaled-up drone that can be ridden like a motorcycle.  The early models were twin rotor like the photo above, but a quad-rotor version is now in development.  Now the Department of Defense is interested and is sponsoring the project, a collaboration of the US firm SURVICE and the […]

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Weekend Geek: Pennies to Heaven

 

stack-of-pennies-365js091509

In case you need to get your mind off the Supreme Court, here’s a fun math problem for the weekend. Imagine a stack of pennies from the surface of the earth to the surface of the moon (equator-to-equator; neglect rotation of both bodies and all other factors that would make this impossible). Use the properties of modern (post-1982) pennies. The distance from the earth to the moon varies a lot, so use the mean (or “semi-major axis”) distance. You may have seen this problem before, but I’m taking it a little further:

1.  How many pennies would be required to reach from the earth to the moon?

Weekend Geek: Keep Your Internet Away From My Things

 

IoT

The Internet of Things (IoT), basically, is the connection of electronic devices not normally used for computation to the Internet. The definition of IoT also includes devices that aren’t necessarily connected directly to the Internet, but communicate with each other via a wireless network that’s in turn usually accessible from the Internet.

Take modern home security systems such as those offered by Xfinity. This kind of system allows you, for example, to go on the Internet while you’re at work and access systems in your house remotely — to lock or unlock doors, turn lights on or off, or view the feed from security cameras. Other IoT devices in your house might let you change the thermostat setting or check food inventories in the refrigerator. IoT also allows devices to act on their own or interact with each other: For example, your refrigerator could be programmed to detect when you’re running out of milk, eggs, or Guinness Stout, and automatically place orders over the Internet to restock itself. Self-driving cars will probably make heavy use of IoT technology. Infrastructure can be modified to provide information about traffic jams, dangerous road conditions, or bridges in danger of imminent collapse, and then automatically apply the brakes or reroute self-driving traffic.

Weekend Geek: Strictly Speaking, One Immortal Monkey Would Suffice

 

monkeysThis will be a recurring (maybe) series of posts on science, mathematics, and related topics. Apparently, there’s an appetite for this sort of thing at Ricochet. Who knew?

I can’t promise this will be a weekly feature, but call it one in a row so far. Some of you may be put off by math. I hope I can reel you in. Trying to discuss science without mathematics is a little like trying to discuss great works of art without seeing them or great musical works without hearing them. I’ll walk the reader through the math and make it as simple as it can be, but no simpler. Relax, you’ll love it.

Shall we begin?

Weekend Geek: Fukushima and the U.S. Nuclear Power Industry

 

smiley-nuclearOn March 11, 2011, a magnitude 9.0 earthquake off the coast of Japan caused a tsunami that engulfed the 6-unit Fukushima Daiichi nuclear power station. Three of the six reactors (Units 1 – 3) were operating at the time, had scrammed (shut down) due to the earthquake that preceded the tsunami, and were beginning the process of cooling down.

Flood waters inundated the emergency diesel generators, rendering them inoperable, and leading eventually to a complete loss of electrical power at the station. Critical safety systems were unable to operate and supply cooling water to Units 1 – 3, leading to core damage due to decay heat, and release of radioactivity into the environment.

This event was the second-worst nuclear accident at a commercial power station in history, after the 1986 accident at Chernobyl in Ukraine. Unlike Chernobyl, a reactor vastly different in many ways from anything used in the United States or Europe and lacking any sort of containment, the Fukushima reactors were similar in design to some older reactors in use in the United States and elsewhere. So the Fukushima accident couldn’t be dismissed with a “can’t happen here” shrug.  Germany reacted by shutting down all of their nuclear power stations. This was in my view an unwise overreaction.