Category Archives: Modern Power Station Practice

Fissionable materials

Consider the compound nucleus uranium 239 formed by the absorption of a neutron by U-238. For the neutron to induce fission the sum of the binding and kinetic energy transferred to the U-239 compound nucleus must exceed its fission activation energy. From the liquid drop model the activation energy of U-239 is 7 MeV; the difference between the binding energies […]

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Interaction of ionising radiation with matter

1.5.1 Ionising radiations When radiations pass through matter they may react with the atoms they encounter. The reactions often lead to the ionisation of atoms and their displacement from their normal position in the structure. All or part of the energy of the incident radiation may be transferred to these disturbed atoms. In this way ra­diation may damage the structures […]

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Alpha particles

These are identical with the helium nucleus and are emitted with a well-defined speed from unstable nu­clei. They are relatively heavy, being about 7000 times heavier than the orbital electrons with which they collide, and travel relatively slowly compared with 0 particles. The alpha particle carries two positive charges; orbital electrons are therefore attracted to the a particle and pulled […]

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The diffusion theory

4.6.4 Neutron flux distribution Evaluation of the non-leakage probability factor re­quires knowledge of the rate of diffusion and the distribution of neutrons throughout the reactor core. The neutrons tend to diffuse from regions of high flux to regions of lower flux. Thus a stable distribution is established such that the production, absorption and diffusion of neutrons into and out of […]

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