Putting Picos In Perspective
Feb12

Putting Picos In Perspective

Fast Fission Podcast #23 – Download mp3 Here Ever thought about how many zeros there are there in a “pico” something? Remember back in grade school when we learned the metric system of measures?  We started out with units that are easy to visualize: meters get 1000 times bigger and become kilometers; meters get 1000 times smaller and become millimeters.  We understand these intuitively because we have a frame of reference and can visualize each of those unites of length and distance.  Units of mass are the same way; we know a gram is a small unit of mass – we can hold a gram of almost any material in the palm of our hand.  For example, a penny weighs 2.5 grams. Stack up 400 pennies and you have a kilogram, or 1000 grams.  Cut a thin copper shaving off a penny and you have a milligram, or one 1,000th of a gram.  Again, these are things we can see, and that makes it easier to understand. As our schooling progressed we learned about very large and very small numbers, exponents, and scientific notation.  We put these principles to use in science and learned there are other units of measure larger than a “kilo” and smaller than a “milli”.  These are harder to visualize because we have to think in terms we can’t see.  For example, the mass of Mount Everest,  is 3E18 grams, or 3 “exa-grams” and the mass of the planet earth is 6×10^24 kg, or 6E27 grams (6,000 “yotta-grams”) (see note below). On the opposite end of the scale is the prefix “nano” or 1E-9 of a unit. A nanometer is 1E-9 meters, and a nanosecond is 0.000000001 seconds.  I had a hard time visualizing a nano second of time until I learned that it takes about 1 nanosecond for a beam of light to travel one foot.  That kind of puts a nano into perspective, doesn’t it?  The newest computer chips, for example have transistors with a thickness of 45 nanometers!  We can only see things that small with powerful electron microscopes. A “pico” is even smaller than a “nano” , 1000 times smaller!  “Pico” means there are 12 places behind the decimal point.  Even for a person like me who deals with engineering and science all the time, it can be difficult to visualize a “pico” of something.  A pico is so small that even a million picos is still very small amount. It takes a million, million pico grams to make one gram.  If you have a million pico-curies in a liter of water, it would take one million liters to provide a...

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“What nuclear waste problem?” (TWiN Podcast 77)

Get the MP3 Here Download printable version here I have a family member that I love dearly and have an infinite amount of respect for.  She is a fantastic mother, a caring person, respected in her chosen profession, and a good friend.  She would do anything she could to help someone in need.  When we first met she was strongly opposed to nuclear energy.  Over the years we have discussed it from time to time and I’ve had some influence on her perspective.  She’s not totally won over yet, but we’re making progress.  Not too long ago she asked me, “But what about the waste?  That really worries me!”  She really didn’t believe me when I said “There’s no such thing as a nuclear waste problem.  That’s nothing but a myth.” Let me explain. Used nuclear fuel is very safely stored in earthquake proof storage pools and dry storage casks at nuclear plants around the USA.  It can stay there until we’re ready to recycle it, and we WILL recycle it eventually because it would be a waste not to do so.  When we remove used fuel from a reactor more than 90% of the potential energy is still in the fuel.  It would be wasteful to even consider putting it in a hole a mile underground!  Also, when we do recycle it, the left over material is much smaller and is much easier to handle, but we’ll talk about that in a few minutes. First we need to look at the components of used power reactor fuel, and recognize that with recycling each of the components can be separated from one another.  A typical batch of used nuclear reactor fuel is made up of the following materials (not counting the structural materials): % Composition (approx) Uranium 93% Plutonium 1.5% Minor Actinides 0.2% Fission Products 5.3% When the fuel is new the concentration of the isotope U-235 is about 4% and U-238 is the rest.  After the fuel is burned in a reactor the uranium is mostly U-238 (very close to the isotopic mix of natural uranium) because most of the U-235 gets burned out by absorbing neutrons and fissioning.  There is also a small but important amount of plutonium that is formed when uranium atoms capture neutrons but do not fission.  This is called “breeding” and in fact at the end of life of a reactor fuel load more than 20% of the heat generated is from the fission of plutonium atoms formed by breeding.  All of this plutonium and uranium can be mixed back together to make new nuclear fuel.  This is what is commonly referred to as mixed oxide fuel,...

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Lessons from Dr. Evil (Episode 67)

Listen to the podcast here. Have you noticed that the numbers we use in daily conversation keep getting bigger and bigger? When I was young my father pointed out to me that a family who had one million dollars could live off the interest alone, and would have a tough time spending it all. While that was certainly true at the time, the value of a million dollars is not what it used to be. If you listen to the podcast you’ll hear an audio clip of one of my favorite movie villains to help illustrate my point.  Even Dr. Evil had trouble comprehending the size of a billion dollars, but what hundreds of billions or even a trillion? We hear and read those numbers in the news and in conversation, but what do they really mean? It’s easy to understand the number of zeros that make them different, but that still be pretty abstract. I contend that many of us really don’t comprehend how large those numbers are when it comes to measuring things in the real world.  We need visual or mental references to help us understand the scale of such large quantities. Let’s use electrical power as an example. The base unit of measure for electrical power is the Watt, but what is the difference between a watt, a KW, a MW, and a GW? 1 watt will barely power a small incandescent light bulb like a bathroom night light. 1 kilowatt (1,000 watts) is equal ~ 1.3 HP, about the same energy output as a small lawn mower engine. The average household in the USA uses about 1 KW of electricity on an on-going basis if averaged over an entire year. 1 Megawatt (1 million watts) is enough electricity to power a small town. Large diesel locomotive engines generate in the 3 to 5 MW range. 1 Gigawatt (1 billion watts) is the size of a large central station power plant, and is enough energy to power about 1 million homes. 1 Terawatt (1 trillion watts) is energy on a continental scale. The total worldwide electricity demand is about 15 TW. Now to the real point of this podcast – I want to talk about carbon capture and storage, and the scale of the challenge this concept presents. To put it bluntly, the scale is bigger than huge, it’s even bigger than enormous. The amount of carbon dioxide gas released by coal and natural gas plants is planetary in scale. Let me describe what I mean by that. The US DOE estimates that US and Canada stationary power plants produce 3.8 billion tones of CO2...

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