TEST BANK FOR Problem Solution Manual For Fundamentals of Nuclear Science and Engineering 3rd Edition By J. Kenneth Shultis and Richard E. Faw

Exam (elaborations) TEST BANK FOR Problem Solution Manual For Fundamentals of Nuclear Science and Engineering 3rd Edition By J. Kenneth Shultis and Richard E. Faw PROBLEM SOLUTION MANUAL FOR Fundamentals of Nuclear Science and Engineering Third Edition by J. Kenneth Shultis and Richard E. Faw Dept. of Mechanical and Nuclear Engineering Kansas State University Manhattan, KS 66506 email: Revised June 2016 (c) Copyright All Rights Reserved This typescript is the property of the authors. It may not be copied in part or in total without permission of the authors. Chapter 1 Fundamental Concepts PROBLEMS 1. Both the hertz and the curie have dimensions of s−1. Explain the difference between these two units. Solution: The hertz is used for periodic phenomena and equals the number of “cycles per second.” The curie is used for the random or stochastic rate at which a radioactive source decays, specifically, 1 Ci = 3.7 × 1010 decays/second. 2. Advantages of SI units are apparent when one is presented with units of barrels, ounces, tons, and many others. (a) Compare the British and U.S. units for the gallon and barrel (liquid and dry measure) in SI units of liters (L). (b) Compare the long ton, short ton, and metric ton in SI units of kg. Solution: Unit conversions are taken from the handbook Conversion Factors and Tables, 3d ed., by O.T. Zimmerman and I. Lavine, published by Industrial Research Service, Inc., 1961. (a) In both British and U.S. units, the gallon is equivalent to 4 quarts, eight pints, etc. However, the quart and pint units differ in the two systems. The U.S. gallon measures 3.7853 L, while the British measures 4.546 L. Note that the gallon is sometimes used for dry measure, 4.405 L U.S. measure. The barrel in British units is the same for liquid and dry measure, namely, 163.65 L. The U.S. barrel (dry) is exactly 7056 in3, 115.62 L. The U.S. barrel (liq) is 42 gallons (158.98 L) for petroleum measure, but otherwise (usually) is 31.5 gallons (119.24 L). (b) The common U.S. unit is the short ton of 2000 lb, 907.185 kg, 20 short hundredweight (cwt). The metric ton is exactly 1000 kg, and the long ton is 20 long cwt, 22.4 short cwt, 2240 lb, or 1016 kg. 1-1 1-2 Fundamental Concepts Chap. 1 3. Compare the U.S. and British units of ounce (fluid), (apoth), (troy), and (avdp). Solution: The U.S. and British fluid ounces are, respectively, 1/32 U.S. quarts (0.02957 L) and 1/40 British quarts (0.02841 L). The oz (avdp.) is exactly 1/16 lb (avdp), i.e., 0.02834 kg. Avdp., abbreviation for avoirdupois refers to a system of weights with 16 oz to the pound. The apoth. apothecary or troy ounce is exactly 480 grains, 0.03110 kg. 4. Explain the SI errors (if any) in and give the correct equivalent units for the following units: (a) mgrams/kiloL, (b) megaohms/nm, (c) N·m/s/s, (d) gram cm/(s−1/mL), and (e) Bq/milli-Curie. Solution: (a) Don’t mix unit abbreviations and names; SI prefixes only in numerator: correct form is μg/L. (b) Don’t mix names and abbreviations and don’t use SI prefixes in denominator: correct form nohm/m. (c) Don’t use hyphen and don’t use multiple solidi: correct form Nms−2. (d) Don’t mix names and abbreviations, don’t use multiple solidi, and don’t use parentheses: correct form g cmsmL or better 10 μgms L. (e) Don’t mix names with abbreviations, and SI prefix should be in numerator: correct form kBq/Ci. 5. Consider H2, D2, and H2O, treated as ideal gases at pressures of 1 atm and temperatures of 293.2K . What are the molecular and mass densities of each. Solution: According to the ideal gas law, molar densities are identical for ideal gases under the same conditions, i.e., m = p/RT. From Table 1.5, R = 8. Pa m3/K. For p = 0. MPa= 1 atm., and T = 293.2K , m = 41.56 mol/m3. Multiplication by molecular weights yield, respectively, 83.78 , 167.4, and 749.0 g/m3 for the three gases. 6. In vacuum, how far does light move in 1 ns? Solution:
x = c
t = (3 × 108 m/s) × (10−9 s) = 3 × 10−4 m = 30 cm. Fundamental Concepts Chap. 1 1-3 7. In a medical test for a certain molecule, the concentration in the blood is reported as 57 mcg/dL. What is the concentration in proper SI notation? Solution: 123 mcg/dL = 10−310−2 g/10−1 L = 1.23 × 10−4 g/L = 57 μg/L. 8. How many neutrons and protons are there in each of the following nuclides: (a) 11B, (b) 24Na, (c) 60Co, (d) 207Pb, and (e) 238U? Solution: Nuclide neutrons protons 11B 6 5 24Na 13 11 60Co 33 27 207Pb 125 82 238U 146 92 9. Consider the nuclide 71Ge. Use the Chart of the Nuclides to find a nuclide (a) that is in the same isobar, (b) that is in the same isotone, and (c) that is an isomer. Solution: (a) 71As, (b) 59Ga, and (c) 71mGe 10. Examine the Chart of the Nuclides to find any elements, with Z less that that of lead (Z = 82), that have no stable nuclides. Such an element can have no standard relative atomic mass. Solution: Promethium (Z = 61) and Technetium (Z = 43) 11. What are the molecular weights of (a) H2 gas, (b) H2O, and (c) HDO? Solution: From Table A.3, A(O) = 15.9994 g/mol; from Table B.1 A(H) = 1. g/mol and A(D) = 2. g/mol. (a) A(H2) = 2 A(H) = 2 × 1. = 2.01565 g/mol (b) A(H2O) = 2 A(H) + A(O) = 2 × 1.+ 15.9994 = 18.0151 g/mol (c) A(HDO) = A(H) + A(D) + A(O) = 1.+ 2.+ 15.9994 = 19.0213 g/mol 1-4 Fundamental Concepts Chap. 1 12. What is the mass in kg of a molecule of uranyl sulfate UO2SO4? Solution: From Table A.3, A(U) = 238.0289 g/mol, A(O) = 15.9994 g/mol, and A(S) = 32.066 g/mol. The molecular weight of UO2SO4 is thus A(UO2SO4) = A(U) + 6A(O) + A(S) = 238.0289+ 6(15.994)+ 32.066 = 366.091 g/mol = 0. kg/mol. Since one mol contains Na = 6.022× 1023 molecules, the mass of one molecule of UO2SO4 = A(UO2SO4)/Na = 0./6.002 × 1023 = 6.079 × 10−25 kg/molecule. 13. Show by argument that the reciprocal of Avogadro’s constant is the gram equivalent of 1 atomic mass unit. Solution: By definition one gram atomic weight of 12C is 12 g/mol. Thus the mass of one atom of 12C is M(12 6C) = 12 g/mol Na atoms/mol = 12 Na g/atom. But by definition, one atom of 12C has a mass of 12 u. Therefore, 1 u = 1 u 12 u/(12C atom)  12 Na g/(12C atom)  = 1 Na g. 14. Prior to 1961 the physical standard for atomic masses was 1/16 the mass of the 16 8O atom. The new standard is 1/12 the mass of the 12 6C atom. The change led to advantages in mass spectrometry. Determine the conversion factor needed to convert from old to new atomic mass units. How did this change affect the value of the Avogadro constant? Solution From Table B.1, the 16 8O atom has a mass of 15. amu. Thus, the pre- 1961 atomic mass unit was 15./16 post-1961 units, and the conversion factor is thus 1 amu (16O) = 0. amu (12C). The Avogadro constant is defined as the number of atoms in 12 g of unbound carbon-12 in its rest-energy electronic state, i.e., the number of atomic mass units per gram. Using data from Table 1.5, one finds that Na is given by the reciprocal of the atomicmass unit, namely, [1.×10−24]−1 = 6.× 1023 mol−1. Pre-1961, the Avogadro constant was more loosely defined as the number of atoms per mol of any element, and had the best value 6.02486×1023. Fundamental Concepts Chap. 1 1-5 15. How many atoms of 234U are there in 1 kg of natural uranium? Solution: From Table A.3, the natural abundance of 234U in uranium is found to be f(234U) = 0.0055 atom-%. A mass m of uranium contains [m/A(U)]Na uranium atoms. Thus, the number of 234U atoms in the mass m = 1000 g are N(234U) = f(234U) mNa A(U) = 0. 1000× (6.022 × 1023) 238.0289 = 1.392 × 1020 atoms. 16. A bucket contains 1 L of water at 4 C where water has a denisty of 1 g cm3. (a) How many moles of H2O are there in the bucket? (b) How many atoms of 11 H and 21 D are there in the bucket? Solution: (a) The relative atomic weight of water A(H2O) = 2A(H)+A(O) = 2(1.00794)+ (15.9994) = 18.01528. Then the number of water molecules mols of H2O = mass(H2O) A(H2O) = 1000 g 18.01258 g/mol = 55.5 mol. (b) Number of molecules of H2O = 55.5 mol × Na mol−1 = 55.5 × 6.60221 × 1023 = 3.343 × 1025 molecules. Then the number of atoms of both 11 H and 21 D atoms = 2 × no. of H2O molecules = 6.6856 × 1025 atoms. From Table A.4, the isoptopic abundances are found to be (11 H) = 0. and (21 D) = 0.. Then N(11 H) = (0.)(6.6856× 1025) = 6.69 × 1025 atoms and N(21 D) = (0.)(6.6856× 1025) = 7.69 × 1021 atoms. 17. How many atoms of deuterium are there in 2 kg of water? Solution: Water is mostly H2O, and so we first calculate the number of atoms of hydrogen N(H) in a mass m = 2000 g of H2O is N(H) = 2N(H2O) = 2 mNa A(H2O) ' 2 mNa A(H2O) = 2 2000 × (6.022 × 1023) 18 = 1.34 × 1026 atoms of H. 1-6 Fundamental Concepts Chap. 1 From Table A.4, the natural isotopic abundance of deuterium (D) is 0.015 atom-% in elemental hydrogen. Thus, the number of deuterium atoms in 2 kg of water is N(D) = 0.00015 × N(H) = 2.01 × 1022 atoms. 18. Estimate the number of atoms in a 3000 pound automobile. State any assumptions you make. Solution: The car mass m = 3000/2.2 = 1365 kg. Assume most the this mass is iron. If the atoms in non-iron materials (e.g., glass, plastic, rubber, etc.) were converted to iron, the car mass would increase to about mequiv = 1500 kg. Thus the number of atoms in the car is N = mequivNa A(Fe) = (1.5 × 106)(6.022 × 1023) 56 = 1.6 × 1028 atoms. 19. Calculate the relative atomic weight of oxygen. Solution From Table A.4, oxygen has three stable isotopes: 16O, 17O, and 18O with percent abundances of 99.757, 0.038, and 0.205, respectively. Their atomic masses, in u, are found from Table B.1 and equal their relative atomic weights. Then from Eq. (1.2) A(O) = (16O) 100 A(16O) + (17O) 100 A(17O) + (18O) 100 A(18O) = 99.757 100 15.+ 0.038 100 16.+ 0.205 100 17. = 15.. 20. Natural uranium contains the isotopes 234U, 235U and 238U. Calculate the relative atomic weight of natural uranium. Solution From Table A.4, the three isotopes 234U, 235U, and 238U have isotopic abundances of 0.0055%, 0.720%, and 99.2745%, respectively. Their atomic masses, in u, are found from Table B.1 and equal their relative atomic weights. Then from Eq. (1.2) A(O) = (234U) 100 A(234U) + (235U) 100 A(235U) + (238U) 100 A(238U) = 0.0055 100 234.+ 0.720 100 235.+ 99.2745 100 238. = 238.02891. Fundamental Concepts Chap. 1 1-7 21. Does a sample of carbon extracted from coal have the same relative atomic weight as a sample of carbon extracted from a plant? Explain. Solution The carbon extracted from coal has only two isotopes, namely 12C and 13C with with abundances of 98.93% and 1.07%, respectively. The relative atomic weight is thus is slightly larger than 12 that would result if there were no 13C, namely 12.0107. Carbon extracted from plant material, however, also contains the radioactive isotope 14C produced in the atmosphere by cosmic rays. Thus, the relative atomic weight is conceptually greater than that of carbon from coal in which all the 14C has radioactively decayed away. However, as discussed in Section 5.8.1, the amount of 14C in plant material is extremely small (1.23 × 10−12 atoms per atom of stable carbon). Thus, 14C would increase the atomic weight only in the 12th significant figure! 22. Dry air at normal temperature and pressure has a mass density of 0.0012 g/cm3 with a mass fraction of oxygen of 0.23. What is the atom density (atom/cm3) of 18O? Solution: From Eq. (1.5), the atom density of oxygen is N(O) = woNa A(O) = 0.23 × 0.0012 × (6.022 × 1023) 15.9994 = 1.04 × 1019 atoms/cm3. From Table A.4 isotopic abundance of 18O in elemental oxygen is f18 = 0.2 atom-% of all oxygen atoms. Thus, the atom density of 18O is N(18O) = f18N(O) = 0.002× 1.04 × 1019 = 2.08 × 1016 atoms/cm3. 23. A reactor is fueled with 4 kg uranium enriched to 20 atom-percent in 235U. The remainder of the fuel is 238U. The fuel has a mass density of 19.2 g/cm3. (a) What is the mass of 235U in the reactor? (b) What are the atom densities of 235U and 238U in the fuel? Solution: (a) Let m5 and m8 be the mass in kg of an atom of 235U and 238U, and let n5 and n8 be the total number of atoms of 235U and 238U in the uranium mass MU = 4 kg. For 20% enrichment, n8 = 4n5, so that MU = n5m5 + n8m8 = n5m5 + 4n5m8 = n5m5  1 + 4 m8 m5  . Here n5m5 = M5 is the mass of 235U in the uranium mass MU. From this result we obtain using m5/m8 ' 235/238 M5 = MU  1 + 4 m8 m5 −1 = 4 kg  1 + 4  238 235 −1 = 0.7919 kg. 1-8 Fundamental Concepts Chap. 1 The mass of 238U M8 = MU −M5 = 3.208 kg. (b) The volume V of the uranium is V = MU/U = (4000 g)/(19.2 g/cm3) = 208.3 cm3. Hence the atom densities are N5 = M5Na A5V = (791.9 g)(6.022 × 1023 atoms/mol) (235 g/mol)(208.3 cm3) = 9.740×1021 cm−3 N8 = M8Na A8V = (3208 g)(6.022 × 1023 atoms/mol) (238 g/mol)(208.3 cm3) = 3.896×1022 cm−3 24. A sample of uranium is enriched to 3.2 atom-percent in 235U with the remainder being 238U. What is the enrichment of 235U in weight-percent? Solution: Let the subscripts 5, 8 and U refer to 235U, 238U, and uranium, respectively. For the given atom-% enrichment, The number of atoms in a sample of the uranium are N5 = 0.0320NU and N8 = 0.9680NU. The mass M5 and M8 of 235U and 238U in the sample is M5 = 0.0320NUm5 and M8 = 0.9680NUm8, where m5 and m8 is the mass of an atom of 235U and 238U, respectively. The enrichment in weight-% is thus e(wt-%) = 100 × M5 M5 +M8 = 100 × 0.0320m5 0.0320m5 + 0.9680m8 = 100 × 0.0320 0.0320 + 0.9680(m8/m5) ' 100 × 0.0320 0.0320+ 0.9680(238/235) = 3.16 wt-%. 25. A crystal of NaCl has a density of 2.17 g/cm3. What is the atom density of sodium in the crystal? Solution: Atomic weights for Na and Cl are obtained from Table A.3, so that A(NaCl) = A(Na) + A(Cl) = 22.990 + 35.453 = 58.443 g/mol. Thus the atom density of Na is N(Na) = N(NaCl) = NaClNa A(NaCl) = 2.17 × 6.022× 1023 58.443 = 2.24 × 1022 cm−3. Fundamental Concepts Chap. 1 1-9 26. A concrete with a density of 2.35 g/cm3 has a hydrogen content of 0.0085 weight fraction. What is the atom density of hydrogen in the concrete? Solution: From Eq. (1.5), the atom density of hydrogen is N(H) = wHMa A(H) = (0.0085)(2.35 g/cm3)(6.022 × 1023 atoms/mol) 1 g/mol = 1.20 × 1022 atoms/cm3. 27. How much larger in diameter is a uranium nucleus compared to an iron nucleus? Solution: From Eq. (1.7) the nuclear diameter is D = 2RoA1/3 so that DU DFe =  AU AFe 1/3 '  238 56 1/3 = 1.62. Thus, DU ' 1.62DFe. 28. By inspecting the chart of the nuclides, determine which element has the most stable isotopes? Solution: The element tin (Sn) has 10 stable isotopes. 29. Find an internet site where the isotopic abundances of mercury may be found. Solution: 30. The earth has a radius of about 6.35 × 106 m and a mass of 5.98 × 1024 kg. What would be the radius if the earth had the same mass density as matter in a nucleus? Solution: From the text, the density of matter in a nucleus is n ' 2.4×1014 g/cm3. The mass of the earth M =  × V where the volume V = (4/3)R3. Combining these results and solving for the radius gives R =  3M 4 1/3 =  3(5.98 × 1027 g) 4(2.4 × 1014 g/cm3) 1/3 = 1.81 × 104 cm = 181 m.