Define and discuss why mass equivalence is a key to understanding why energy is released in nuclear reactions. Define rest energy and use examples. Correlate rest energy to potential energy. Use Einsteins's formula to show the relationship between mass and energy. Indicate that resting energy can be converted into other forms, and discuss examples. Discuss mass defect which occurs in chemical and nuclear reactions.
Discuss why a great deal of energy is released during a nuclear reaction. Introduce, define, and discuss rest energy as potential energy. Show that when mass decreases in a nuclear reaction, the rest energy is released. Relate the energy to Einstein's formula. Discuss that rest energy can be converted to other forms
Discuss why a great deal of energy is released by nuclear reactions Define rest energy and compare it to potential energy. Show how rest energy is related to mass using Einstein's formula. Discuss how rest energy can be converted to other forms. Review the formula for work and discuss how much work, energy is needed to overcome the strong nuclear force
Online plutonium fission reaction, starting from U-238 through. series of beta emissions and neutron bombardments until plutonium is produced. Discuss that plutonium is a poison which attacks the nervous system system leading to paralysis and death. Write and discuss the nuclear reaction in which U-238 (stable) is transformed into U-239 (unstable) by neutron bombardment , and then transformed from U-239 into neptunium which is unstable.
Session Minutes
90
Minutes Student Attended
90
Lesson Comments
Lab was unavailable today, but we discussed some lab procedures to be used next time.
Discuss nuclear fission reactors as nuclear reactions for controlling fission. Elicit that their main function is to produce heat to boil water and produce steam to run the generators. Watch 2 short videos which explains the working of the reactor, all important parts and functions. Discuss the fission of the nuclear fuel and view how the controlled chain reaction works. Present the problem with waste disposal and outline how the waste is disposed of.
View and discuss the operation of a nuclear reactor. Work with images and a schematic, outline an discuss 3 three major parts, the nuclear reactor, the condenser and turbine, and the electric generation section. Concentrate on the nuclear reactor, the control rods, the radiation shielding, the graphite modulator, and the fuel rods.
Discuss the major problem of waster disposal.
Discuss the two major isotopes of Uranium, 235 and 238. Define that the fissionable one is 238, which is found in uranium ore, like UF6 at a % of 0.7. For reactor use, 3% is required, and for weapon use 90%. Discuss methods for uranium enrichment, separation of the two isotopes. Discuss and use diagrams to indicate that they can only be separated physically, by gas diffusion and/or by centrifugation. Each method can take years to separate the isotopes, with centrifugation being the newer and quicker method. Discuss critical mass needed to produce a chain reaction. Use diagrams and images to show how the critical masses can be produced by colliding subcritical masses together, as in a bomb.
Review the formula for uranium fission and chain reactions. Present that the U-235 isotope does not undergo fission, while the U-238 isotope does. Discuss the separation by physical means only, not chemically. Present that uranium ore contains only 0.7% of U-235, the fissionable isotope. Use diagrams and sketches to elicit that the isotopes are separated by gas diffusion through a porous membrane. In order for a sample of uranium to act in a reactor, it must be at least 3%, and act as a bomb, 90%. Separation of the isotopes can take years of diffusion just to obtain a small amount. Discuss the newer method of separation using centrifuges.
Assignment
Take photos of all whiteboard notes and save them in your google doc.
Discuss artificial radioactivity produced by isotopes bombarded by either alpha, beta, protons or neutrons.
Introduce nuclear fission by discussing the early history of atomic nuclear division. Define nuclear fission by using examples of nuclear isotopes dividing into 2 new elements. Present the division using images depicting the nuclei splitting into two new nuclei. Introduce how the nucleus elongates and the strong nuclear force becomes weakened and the electromagnetic force of repulsion is strong enough to "split" the nuclei. Write the general expression for uranium fission to form barium and krypton with the release of energy.
