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Unformatted text preview: Reactor Physics and Commissioning Tests Oct 22, 2009 SwengWoong 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 gammaray 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 → 1024 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.
 Spring '12
 Dr.Jaouni
 Physics

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