EMCH 550 University of Florida Nuclear Weapon Proliferation Questions Use at least 1-inch margins all around.Type short answer questions, double spaced using minimum 12 pt font, Times Roman.As appropriate or required by the problem, cite all sources using complete references. For solving problems, work your problems by hand showing all your work. Clearly identify the governing equations, use and identify appropriate units for all quantities and variables, work the problem methodically showing all work, and report intermediate values so that partial credit can be assigned.As with any engineering solution, if you need to make an assumption, please do so by clearly stating that assumption and providing appropriate justification for that assumption. Compare the Pu vectors (isotopic composition) of weapons grade (WG) and reactor grade (RG) plutonium. Calculate and compare the heat load (heat generated i.e. W/kg) for each composition. Describe and compare generally the characteristics of production of each type (grade) of plutonium (i.e. burnup/depletion or time in reactor under irradiation). How are these distinct depending on your goal of producing power/electricity vs. producing Pu for weapons? Type double spaced your response. Choose an example case of proliferation or attempted proliferation (i.e. Pakistan, India, S. Africa, etc.) and discuss the different aspects of the fuel cycle involved. Use materials from the class (i.e. lecture on illicit trafficking and others), text, and your own research (i.e. the library electronic resources) to obtain two additional references. The MOX Fuel Fabrication Plant in Aiken, SC if completed will produce MOX fuel from 35 tonne of weapons grade plutonium. Calculate the plutonium content of the MOX fuel assuming it is fabricated along with natural uranium and is designed to replace or be equivalent to an ordinary UO2 fuel with enrichment 4.9%. If all, 35 tonne of weapons grade plutonium is converted to MOX, how much fuel could be produced? Reprocessing and Recycling
Enriched Uranium*
U234 – 0.035wt%
U235 – 5 wt%
U238 – 95 wt%
Depleted Uranium*
U234 – 0.001wt%
U235 – 0.2 wt%
U238 – 99.8 wt%
U235 is fissile,
will fission with
neutron of any
energy.
Enrichment
necessary for
self-sustaining
chain reaction.
Fissionable U238
requires fast
neutrons and is
more easily
utilized in fast
reactors. U238
can be converted
to Pu239 (fissile).
Natural Uranium
U234 – 0.005 wt%
U235 – 0.711 wt%
U238 – 99.284 wt%
Source: IAEA
Nuclear Fuel Cycle
* varies with enrichment (% U235) or burnup (MWD/MTU)
Used Fuel*
Uranium 93 wt%
U235 0.8 wt%
U236 0.6 wt%
Plutonium 1%
Minor Actinides 0.1wt%
Fission Products 5 wt%
Production of Plutonium
Fission Chain Reaction & Neutron Economy
Duderstadt and Hamilton
Duderstadt 1976
Simple schematic of a fission chain reaction
•
•
Slow down through collisions with medium
Thermal energy (vibration) of atoms of a medium on
order of kT, k is Boltzmann constant 8.617E-05 ev/K,
k=R/Na
– Approximate by Maxwellian distribution
– Most probable energy is (1/2)kT
– Average energy (3/2)kT
– Energy of most probable velocity is kT, at 20˚C
this is 0.0253eV
Born high energy, fission or Chi distribution
Most probably ~0.7 MeV
Average energy ~2 MeV
Very few above ~10MeV
Duderstadt 1976
Production & Transmutation of
Transuranics (TRU)
Transuranics are produced through
nuclear reactions; occurs through
capture of a neutron during reactor
operations.
Through transmutation new elements and
radioisotopes are created. These may decay,
fission, or be transmuted into other isotopes still.
Transmutation-decay chains for U238
(Stacey 2001)
Mass (g/kg HM initial)
Production of Pu
Spent fuel contains
about 1% Pu
~70% fissile
MOX fuel
~9% Pu (RG)
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