Nuclear Energy, Controlled Fission and Fusion 2016 презентация

Nuclear Energy: Controlled Fission and Fusion IE350

Fission Break into parts Decay

Atomic Structure Operation of a nuclear reactor depends upon various interactions of neutrons with atomic nuclei protons (p); neutrons (n); electrons (e) protons or neutrons = nucleons - Atomic number Z= # of protons (H=1, He=2…U=92) - Mass number A, # of nucleons, A=p+n=Z+n or n=A-Z - Isotopes – same Z but different A e.g. U – 234, 235, 238 U (235) = 92p+143n

Energy/Mass Equivalence

Binding Energy (Table 2.4) B.E./A = 931/A [ZmH + mn (A-Z) – M] Mev/nucleon 931 is equivalent to 5.6x1026 divided by Avogadro No. = 6.02x1023 mH = 1.008; mn = 1.009 M = in amu (atomic mass unit) 1 amu = 1.660 x 10-24 gm

Binding Energy

Radioactivity Unstable elements; from Z=84-92 Unstable nucleus emits characteristic particles (radiation) -particles (2p);  - particle (e) and gamma rays () The fission process is one such decay or splitting of the unstable atom such as uranium.

The Fission Process Occurs only with nuclei of high Z (and mass) Only 3 nuclides are fissionable by neutrons of all energies (slow/thermal; fast) U-233, 235 and Pu-239, called fissile nuclides Of these only U-235 occurs in nature. The other two are generated by neutron capture Fission releases large amount of energy and creates a chain reaction.

U-235 Fission product A + Fission product B + Energy U-235 Fission product A + Fission product B + Energy 92p +143n U235 + 235 x 7.6 Mev 92p + 143n A and B + 235 x 8.5 Mev Subtracting the two B.E. expressions U-235 fission products + 210 Mev Thus fission of one U-235 nucleus releases 200 Mev energy compared to C(12) combustion releasing 4ev Ergo, U-235 yields 2.5 million times more energy than same weight of carbon [or, 1 lb of U-235 =1400 tons of 13,000 Btu/lb. coal]

Radioactive Decay of Uranium

V

Schematic Representation of Nuclear Reactor System

Specifics of Light water reactors - LWR Uranium oxide, enriched to 3-5% U-235 Moderator and coolant, purified ordinary water; heavy water; graphite. Control rods: neutron absorbing-Cd, Hf, Boron Steam generator and Containment PWR – water coolant at 150 atm; heated to 325C superheated water generates steam in a second loop and operates a turbine BWR – boils within the core at lower pressure; piped directly to turbine generator LWR are re-fueled every 12-18 months, where 25% of the fuel is replaced

New NPP for Armenia 1000MWe; $5billion Metzamorenergatom, 50-50Russian-Armenian joint stock company; will fund 40%; 60% other investors VVER-1000,model V-392; 60yr life If 60yr life, retail price of 1 kWh < 7 cents. Fuel type is UO2

PWR animation

Three types of reactors (for others see handout) 1. Light and Heavy Water Reactors a. LWR/PWR b. LWR/BWR (Medzamor is a PWR-VVER 440 Model) 2. Propulsion Reactors (PWR family) Naval vessels / submarines 3. Liquid metal Cooled Fast Breeder Reactors (LMFBR) Produces more fuel than it consumes (U-238 absorbs neutrons and converts it to PU-239) Molten metal is the coolant liquid

Fusion Merging of nuclei = Fusing nuclei together

Controlled Fusion

Magnetic confinement

Confinement Concepts Equilibrium: There must be no net forces on any part of the plasma, otherwise it will rapidly disassemble. The exception, of course, is inertial confinement, where the relevant physics must occur faster than the disassembly time. Stability: The plasma must be so constructed that small deviations are restored to the initial state, otherwise some unavoidable disturbance will occur and grow exponentially until the plasma is destroyed. Transport: The loss of particles and heat in all channels must be sufficiently slow. The word “confinement” is often used in the restricted sense of “energy confinement”.

ITER International Thermonuclear Experimental Reactor, and is also Latin for "the way") Cadarache facility in Saint-Paul-lès-Durance, south of France

ITER

ITER