Day_4-2-Physics_test-SWWoo

Day_4-2-Physics_test-SWWoo - Reactor Physics and...

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Unformatted text preview: Reactor Physics and Commissioning Tests Oct 22, 2009 Sweng-Woong Woo [email protected] Korea Institute of Nuclear Safety 2 Contents I. Reactor Physics II. Reactivity Calculation Methods III. Reactivity Measurement Methods IV. Physics Tests 3 I . Reactor Physics ¡ Nuclear Reaction by Neutron ¾ Scattering ¢ Elastic Scattering Z X A + n 1 Æ Z X A + n 1- Before and after the scattering, the sum of kinetic energy of the neutron and that of target nucleus remains unchained- During the scattering, high energy neutron gives its kinetic energy to the target nucleus, thus loses its energy - The ratio of its kinetic energy before and after the scattering is depending on the mass number A of the target nucleus and the scattering angle θ 2 2 2 1 1 , ) 1 ( 1 2 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + − = + + + = A A A Cos A A E E i f α θ 4 I . Reactor Physics ¡ Nuclear reaction by neutron ¾ Scattering ¢ Inelastic Scattering Z1 A A1 + n 1 Æ Z1 A A1* + n 1 After the scattering, the target nucleus is excited and the sum of kinetic energy of the neutron and that of target nucleus is smaller than that before ¾ Absorption ¢ Fission 92 U 235 + n 1 Æ 92 U 236* Æ 55 Cs 140 + 37 Rb 93 + 3 n 1 The compound nucleus is excited by the last neutron absorption and splits into two fission fragments and a few neutrons releasing energy ¢ Capture 92 U 238 + n 1 Æ 92 U 239* Æ 92 U 239 + γ The neutron is captured by the target nucleus and compound nucleus is stabilized by emitting gamma-ray 5 I . Reactor Physics ¡ Fission Reaction by Absorption of Neutron ¾ Fission 92 U 235 + n 1 Æ 92 U 236* Æ 36 Kr 92 + 56 Ba 141 + 3 n 1 ¢ The compound nucleus is excited by the neutron absorption and splits into two fission fragments and a few neutrons releasing energy ¢ The mass distribution of fission fragments has two peaks showing uneven splitting of the compound nucleus ¢ The number of released neutron per fission depends on the fissile nuclide and the incident neutron energy 6 I . Reactor Physics ¡ Fission Reaction by Absorption of Neutron ¾ Fission Neutron Energy Spectrum ¾ Number of Released Neutron per Fission 7 I . Reactor Physics ¡ Fission Reaction by Absorption of Neutron ¾ Energy Released by Fission Fission product kinetic energy 168 Neutron kinetic energy 5 Fission gammas (instantaneous) 5 Fission gammas (delayed) 6 Fission product betas 7 Total available as heat 191 Neutrino energy (not available as heat) 11---------------------------------------------------------------------------- Total Energy (MeV) 202 # Energy distribution per fission induced by thermal neutrons 8 I . Reactor Physics ¡ Reaction Cross Sections ¾ If the cross section of target nucleus is σ and the number density of nucleus in the target material is N , the probability of reaction for an incident particle per unit thickness is ( σ N A t / A ) / t = σ N = Σ ¢ σ is called microscopic cross section ( unit of σ : barn → 10-24 cm 2 ) ¢ Σ is called macroscopic cross section ( unit of Σ : cm...
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This note was uploaded on 04/07/2012 for the course PHYSICS 767 taught by Professor Dr.jaouni during the Spring '12 term at Abu Dhabi University.

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Day_4-2-Physics_test-SWWoo - Reactor Physics and...

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