SCI 270: On Nuclear Technology Practice Problems  

Term Test Feb. 13, 2001 8:30 - 9:30 pm, after a short lecture between 7 and 8:30. Please bring a calculator for the test on all of chapters 1 to 4.

4. Radioactivity and Transmutation of Nuclides

  1. The unit curie (= 3.700x1010 Bq (= decay/s)) is defined to be the decay rate of 1.00 g of radium (226Ra), in honour of the Curies who worked on the radium isotope 226Ra. Radium decays according to the equation: 226Ra ® 222Rn + 4He (The a particle) Each decay releases 4.8 MeV of energy as the kinetic energy of the alpha particle. Recall the Avogadro's number NA, and work out the following:

    Number of 226Ra atoms in 1.00 gram of 226Ra ___________________
    The declay constant l ___________________ s-1
    The half-life t1/2 of 226Ra ___________________ y
    The amount of radium that will give a radioactivity of 1 microcurie ___________________ g
    The amount of energy released per day by 1.0 curie of 226Ra ___________________ J
    The amount of helium in moles produced by 1.00 curie of 226Ra per day ___________________ mol
    The number of 226Ra atoms remains after one day from 1.00 curie ___________________
    The decay rate at the start of the second day of 1.00 curie of radium ___________________ Bq
    The number of 226Ra atoms remains after one year from 1.00 curie ___________________
    Radium, 226Ra and its decay decendants 222Rn, 218Po ... emit only a, b and g rays. How many a particles and how many b particles are produced when 226Ra has become a stable 206Pb nuclide? ___________________ a

    ___________________ b

  2. Tritium, 3T, and deuterium, 2D, are isotopes of hydrogen. Nature hydrogen contains 0.015% stable deuterium, but only a trace of tritium, which is radioactive, 3T ® 3He + b (half-life = 12.26 y) A tritium-contaminated water from a nuclear reactor has a radioactivity of 0.10 Bq per gram of water. Evaluate the following:

    The number of T nuclei in one gram of water ___________________
    The decay constant of tritium ___________________ d-1
    Radioactivity in 1.0 L of water, density = 1 g/mL ___________________ Bq
    The mass of T atoms in one gram of water ___________________ g
    The number of all hydrogen atoms in one gram of water ___________________

  3. Describe the following radioactive decay processes: alpha decay, beta decay, gamma emission, proton Decay, double beta decay, and beta delayed emission
Answers to Assignment 4 is available, but do your part first. Your skills earn you the marks and they are yours forever.

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