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NE 105 - Introduction to Nuclear Engineering Spring 2011. Classroom Session 3 - Fundamental Concepts Molecular weight Mole Isotopic Abundances Classic and Relativistic Calculations Photon Interactions with Matter. Chart of the Nuclides. Isobars. Isotopes. Z. Isotones. N.
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NE 105 - Introduction to Nuclear EngineeringSpring 2011 Classroom Session 3 - Fundamental Concepts Molecular weight Mole Isotopic Abundances Classic and Relativistic Calculations Photon Interactions with Matter
Chart of the Nuclides Isobars Isotopes Z Isotones N
Atomic Mass Unit • 1/12 of the mass of 12C • Units are: AMU (1 AMU= 1.66e-27 kg) or g/mole • How much a Mole of something weights • Mole (mol) = Avogadro # of entities. • Atomic and molecular weights are given in grams/mole • Concept similar to a “dozen” except it is: 6.022 x 1023 6.02e23 atoms of carbon weight 12 g Notice the mole concept let you convert from mass to number of atoms/molecules
What is the atom density of hydrogen in liquid water (H2O)? = 1 g/cm3, MO= 16 g/mol and MH = 1 g/mol • 6.7e22 at./cm3 • 2 at./cm3 • 6.7e16 at./cm3 • 6.7x1022 cm-3 • 2 g/cm3
Notice equation for atomic density is: • Advice: • Work the units • Think of the concepts • In case of isotopes remember to use abundances (i) • NOTICE: • To find A (molecular weight) of a mixture we need to take into account the composition of it as well. • The periodic table presents the molecular weight of the “natural” mix of isotopes ONLY. It is better to use “understanding“ instead of the equation
What is the 235U atom density in 3% enriched U fuel? (UO2=10.50 g/cm3) • 7.02e20 at./cm3 • 2 at./cm3 • 6.7e16 at./cm3 • 7.02x1020cm-3 • 2 g/cm3 Reminder: Enrichments are usually given in atom % (table C.1), assume only 238U and 235U
What is the 235U atom density of 3% enriched 235U fuel? (UO2=10.50 g/cm3)
What if we use wrong M? • What is the atom density of 3% enriched 235U fuel? (UO2=10.5 g/cm3)
Electron Volt • Work done by one electron accelerated through a potential difference of one volt 1 eV = 1.60217646x10-19 J Example: What is the speed (m/s) of a 12 eV134Xe ion? (from the chart of the nuclides: 134Xe Weights = 133.905394 AMU) Use classic concept of KE for now amu in table 1.5 Joule = Energy, Work = Force (N) x d =kg m2/s2
Correction of the book… REMEMBER! Book: Page 6 Please ignore the c2. It is confusing
4156.4 m/s ~9,300 m.p.hi.e. even very low energy ions are moving pretty fast • Please remember this is ONLY for classical calculations. • At energies close to “c”, need to use relativistic calculations