| SCI 270: On Nuclear Technology Practice Problems |
9. Nuclear Fission Energy and Reactions
Give the nuclear reactions for the syntheses of neptunium and plutonium used
in the fast breeder reactor for their productions.
Consult a handbook or a nuclear data source and give the range of
known (or synthesized) plutonium isotopes. Which one has
the longest half life and what is its decay mode?
|Range of mass numbers|
of Pu isotopes: From ________ to _________
|Isotope with the|
longest half life ____________
Assume the thermal-neutron induced fission of 235U (mass
= 235.0439) gives two fragments of mass 140 and 93, and the some neutrons.
After having consulted the properties of nuclides of mass numbers 140 and 93,
we know that 140Ce (mass = 139.90539) and 93Nb
(mass = 92.90638) are stable nuclides. Write the nuclear reaction equation
for this fission process. Estimate the total energy (including energies
of beta-decay of the fission products) in this fission process.
released: _ Q = ___________ MeV/fission
released: _ Q = ___________ J/mole
How much natural uranium must be processed in order to produce
1.0 kg of 235U, if only 50% of this isotope is extracted
from natural uranium?
What methods are used to separate 235U from natural uranium?
of 235U ___________ %; 238U ________________ %
|Amount of natural |
uranium required: _________________ kg
|Methods used for extracting 235U:
- Gas diffusion of UF6 based on mass difference. _
The following question are provided to help your study
Answers to Practice Problems 9 are available, but
do your part first. Your skills are tested and they are yours forever.
What is a moderator? What are the desirable properties of a compound
to make it a good moderator?
Why are heavy water and graphite used as moderator for nuclear reactors
using natural uranium as fuel, but normal distilled water not a suitable
Assume the abundance of 235U to be 5.0% when the earth was created.
Calculate the age of the earth from the distribution of 235U and
238U (now 0.72 % and 99.28 %). Note that the assumption may not
This problem may be a challenge to some of you, but hint will be given on
the page linked below.