Diffusion length C,(Ⅳ V2Φp(r) ap( DP(r) L=D/b2a(M the root-mean-square distance a neutron will diffuse in the medium before being absorbed Diffusion and slowing-down constants for moderators Moderator D(cm) L(cm (cm HO 0.l6 27 D2O 087 30000 131 Graphite 0.84 2650 368
Diffusion length the root-mean-square distance a neutron will diffuse in the medium before being absorbed Diffusion and slowing-down constants for moderators
Reactor power and fuel consumption R, The reaction probability per R=NΦa=MNAa/A unit time for n nuclei: m is the mass of fissile material if each fission liberates an amount E of recoverable energy, the power output is P= RTE
R, The reaction probability per unit time for N nuclei; M is the mass of fissile material if each fission liberates an amount E of recoverable energy, the power output is Reactor power and fuel consumption
example calculate the power output, rating and fuel consumption for a thermal reactor containing 150 tonnes of natural uranium operating with a neutron flux of 1013 cm-2s-1 r(2U)=579b,(U)=101b 1.5×105×0.0072×6.022×1026 N(°U)= =2.73×102 nuclei 23803 energy per fission E= 200 Mev P=N(UOOFE=507 MW 3. 4 MW/t
example calculate the power output, rating and fuel consumption for a thermal reactor containing 150 tonnes of natural uranium operating with a neutron flux of energy per fission E = 200 MeV 3.4 MW/t
Fuel consumption, leading to a loss of 235U, depends on the total 235U absorption cross section N(23U)aaφ=2.73×1027×680×1024×10 86×1019s =59X1026/year one-fifth of the initial amount of 235u refueling
Fuel consumption, leading to a loss of 235U, depends on the total 235U absorption cross section = 5.9 x 1026 /year one-fifth of the initial amount of 235U refueling
Chapter 4. power from Fission Introduction 2. Characteristics of fission 3. General features 4. Commercial reactors 5. Nuclear reactor Safety 6. Nuclear reactor Accidents 7. Uranium Mining Key elements fuel. neutron moderator. control rod. neutron detector and radioactivity detectors, products
Chapter 4. Power From Fission 1. Introduction 2. Characteristics of Fission 3. General Features 4. Commercial Reactors 5. Nuclear Reactor Safety 6. Nuclear Reactor Accidents 7. Uranium Mining Key elements: fuel, neutron moderator, control rod, neutron detector and radioactivity detectors, products