Food for thought: We have a small pop-up trailer. Recently (2/04), State Farm sent us a notice "Important Notice Regarding Changes To Your Recreational Vehicle Policy" that included the following:
"b. There is no coverage for loss to any vehicle that results from: 1) nuclear reaction; 2) Radiation or radioactive contamination from any source; or 3) the accidental or intentional detonation of, or release of radiation from, any nuclear or radioactive device."
I think if my trailer suffers from any of the above, my trailer will be the least of my concerns.


Journal Exercise: What geologic factors likely influence and/or should influence whether a given country pursues nuclear power as an option or not? You should be able to think of at least three factors. Think it through. Don't hesitate to get feedback from me. Due next Monday (Feb. 23rd).

Readings:


What is radioactivity?

A synopsis: Atoms contain a nucleus with protons and neutrons. It is the number of protons that defines an element, i.e. that a particular atom is hydrogen versus helium. While the number of protons for a given element is fixed, the number of neutrons is not. The different variants of an element caused by different numbers of neutrons are known as isotopes. Isotopes come in two basic varieties - stable isotopes (nonradioactive, e.g oxygen-16 and oxygen-18) and unstable isotopes (these are radioactive). The number refers to the atomic weight, and is basically equal to the number of neutrons and protons together. Unstable isotopes have a built in probability they will spontaneously come apart and change to another isotope (known as the daughter product), giving off heat and particles (radiation) as they do so. For a large aggregate of radioactive isotope atoms the probability that decay will occur can be described by the half life. After one half life, half the atoms have undergone decay. The heavier an element, the more likely the isotopes will be radioactive. There are exceptions, such as deuterium and tritium, which are radioactive isotopes of Hydrogen. You can also force decay by hitting the atom with a heavy enough particle traveling fast enough.


How do we measure radioactivity and what are related safety concerns?


How do nuclear reactors work?

In addition to spontaneous decay, the Uranium 235 isotope can also decay if it gets hit with a neutron - in other words it is fissionable. Most uranium is U-238. Enriched uranium is where U-235 comprises about 3%. . Neutron decay can be a secondary byproduct of Uranium decay. So one decaying isotope can trigger another to decay. Think about the geometry below. If atom A decays and produces a neutron that flies off in a random direction what determines the chances that a neutron will hit a fissionable Uranium atom? Basically the size of B and the distance between them. The distance between them can be controlled by how closely the Uranium atoms are packed together. In nature they are so spread out that their is virtually zero chance that this will happen. Pack them too close together, in what is called a critical mass, and one impact triggers another, which triggers another in a runaway release of energy. This is the essence of a fission bomb. A nuclear reactor is a device where you very precisely control the packing or spacing so that you stay sub-critical. This is what happens in the reactor core. The Uranium fuel is in rods. To cause more decay and energy release, either, more fuel rods are inserted into the core, or rods of neutron blocking material between the fuel rods are removed.You cause more decay and have the desired release of energy, but you keep a chain reaction from occurring.

 

Virtual tour of University of Wisconsin nuclear reactor.

Breeder reactors are based on the fact that when U-238 is bombarded by neutrons it is converted to plutonium-239, which is fissionable, so the reaction can 'breed' more fissionable fuel. But remember the concerns associated with plutonium.


Cradle to grave approach for nuclear power: for each 'step', what are the associated environmental concerns and/or costs?


Where does radioactive fuel come from? Case history of Crow Butte Mine - Uranium mining at Crawford Nebraska:

Chemistry of Uranium - helpful in understanding how the deposits are formed, how they can be mined, and what concerns might be during safe disposal.

Geology of the area, and how the deposit formed.

Solution mining methodology used.

History of events to date.

  • Link to description of the geology and discovery of the Crow Butte deposit.
  • A short United States Uranium History from the Rocky Mountain Scout Viewpoint, by Robert D. (Bob) Odell, Uranium Geologist and Minerals Scout, CPG 7327*
  • EPA copy of NRC license for the Crawford mine. This includes a nice summary of the on site extraction and processing.
  • Minding the mine - a news story about local concerns, and the history of accidents at the mine site.

  • The Boyd County Controversy:

    LLRW - Low Level Radioactive Waste. What is it?

    History that led up to Boyd County Controversy

    Geology and design:

    Nebraska presently being sued for bad faith. Lost the first big round. In excess of $20 million in lawyer fees. Fine in excess of $120 million. We just lost the appeal (2/18/04)!

    Links:


    Reactor disposal: Hallam, Nebraska.

    Hallam is a small town SW of Lincoln, Nebraska. It was the site of an experimental sodium cooled reactor. I had heard it was the site of a reactor core failure (from a DOE representative at a Geological Society of America meeting). There is a large cement sarcophagus at the site now, and the site is being actively monitored (see below).

    "135 (DOE/CH/10865--1)
    Description of the U.S. Geological Survey's water-quality sampling and water-level monitoring program at the Hallam Nuclear Facility, June through September 1996. Geological Survey, Lincoln, NE (United States). [1997]. 7p. Sponsored by USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States). DOE Contract AI02-96CH10865. Order Number DE97008069. Source: OSTI; NTIS; INIS; GPO Dep.

    A water-quality and water-level program of the US Department of Energy (USDOE) in cooperation with the US Geological Survey (USGS) was re-established in June 1996 to develop six new USDOE observation wells, collect one set of water-quality samples from 17 of the 19 USDOE observation wells, and take monthly water-level measurements for a 3-month period in all 19 USDOE observation wells at the Hallam Nuclear Facility, Hallam, Nebraska. Thirteen of the observation wells were installed by HWS Consulting Group, Inc., in June 1993 and the remaining six were installed by Applied Research Associates in August 1995."

    DOE site regarding Hallam.

    A detailed explanation that there never was a meltdown at Hallam.

    Moral of the story - check your facts when issues as emotionally charged as nuclear power and radioactivity are involved.


    Harmon D. Maher Jr. reserves copyrights to the materials in this site. Material may be used for non-profit educational purposes as long as proper attribution is given. For permission for any other use please contact author. Thank you.