Proliferation Aspects of Plutonium Production in Nuclear Reactors



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Proliferation Aspects of Plutonium Production in Nuclear Reactors

  • Dwight L. Williams, Ph.D., P.E.

  • Martin Luther King Visiting Professor Department of Nuclear Science and Engineering Massachusetts Institute of Technology


Overview



About the Speaker -- the “New Guy”

  • Education and Registration (Nuclear Engineering)

    • B.S., North Carolina State University (NCSU)
    • M.S., NCSU, Plasma Physics/Fusion
    • Ph.D. University of Maryland, Radionuclide Detection
    • P.E., Commonwealth of Virginia
  • Professional Experience

    • Nuclear Analyst, Prototype International Data Centre
    • Senior Nuclear Engineer, Department of Defense (DoD)
    • Chief Engineer/Principal Nuclear Physicist, DoD


Introduction

  • Why knowledge of nuclear proliferation is useful within peaceful nuclear academic program

    • expands upon foundational knowledge
    • fosters effective nonproliferation and counterproliferation efforts
    • facilitates nuclear security planning
    • enables better public relations and perceptions to be cultivated


Weapons Development Pathways



Weapons Development Pathways



Typical Reactor Isotopes of Interest

  • Plutonium (Pu-239)

    • product of natural and depleted uranium irradiation
    • one of many Pu isotopes generated
  • Uranium (U-235)

    • U-235 abundance customarily of 3 - 5% in reactors
  • Tritium (H-3)

    • product of heavy water irradiation
    • product of Li-6 and Li-7 irradiation
    • possible fission product


Relevant Plutonium Isotopes

  • Pu-239: U-238 + n → U-239 → Np-239 → Pu-239

    • most desirable for nuclear weapons use
  • Pu-240: Pu-239 + n → Pu-240 (if no fission)

    • neutron emitter/spontaneous fission
  • Pu-241: Pu-240 + n → Pu-241

  • Pu-238: U-235 or U-238 + n → → → Pu-238

    • generates heat from rapid decay


Plutonium Isotope Properties

  • Notes,

    • Pu-241 decays into Am-241, an intense  emitter
    • Most even Pu isotopes (238, 240, etc.) decay by SF


Production of Weapons Grade Pu

  • At least 94% Pu-239

  • Typically generated in weeks to months in reactor

    • frequent refueling required for optimum production
    • separating isotopes is nontrivial effort
  • Typically affects power production



Comparison of Plutonium Grades

  • In general,

    • Weapons Grade: < 7% Pu-240
    • Reactor Grade: > 18% Pu-240


Pu Isotopes as a Function of Burnup



Pu Production in Various Reactors

  • Pu in Fuel at 1000 MWd/MTU



Estimated Pu in Fuel at Discharge



Pu Production Rules of Thumb



Conclusions

  • Roles exist for nuclear proliferation knowledge within peaceful nuclear program

  • Pu-239 is generated prolifically in reactors

  • Pu-239 is most useful isotope for weapons, but generating weapons grade plutonium (>94% Pu-239) is nontrivial

  • Typical power reactor operations are not conducive for weapons grade plutonium production





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