ABSTRACT
I. Overview ............................................................................................................................ 42
A. Separation Factor, Material Balance, and Cascade of Separation Stages ................ 42
II. Enrichment Processes......................................................................................................... 44
A. Enrichment Processes Based on Steady State Phenomena
of Reversible Processes.............................................................................................. 44
1. Distillation ........................................................................................................... 50
2. Chemical Exchange............................................................................................. 50
3. Gas Centrifugation .............................................................................................. 53
B. Enrichment Processes Based on Nonsteady State Phenomena
of Reversible Processes.............................................................................................. 53
C. Enrichment Based on Irreversible Processes............................................................. 53
1. Laser Isotope Separation ..................................................................................... 53
2. Gaseous Diffusion ............................................................................................... 54
3. Thermal Diffusion ............................................................................................... 55
4. Electrolysis .......................................................................................................... 55
5. Electromagnetic Method: Calutron..................................................................... 56
III. Separation Cascade ............................................................................................................ 56
A. Ideal Cascade: Thermodynamic Efficiency and No-Mixing..................................... 56
B. Product-End Refluxer................................................................................................. 58
C. McCabe-Thiele Diagram for Square Cascade ......................................................... 61
1. Case of Total Reflux ........................................................................................... 63
2. Case of Minimum Reflux Ratio.......................................................................... 63
D. Separative Capacity for Close-Separation, Ideal Cascade ........................................ 64
E. HETP (Height Equivalent of Theoretical Plate) ....................................................... 65
IV. Startup of Isotope Enrichment Cascade ............................................................................ 66
A. Time-Dependence of Enrichment Profile along the Length
of Cascade during Startup.......................................................................................... 66
B. Rate of Attainment of Steady-State Profile vs. Holdups .......................................... 67
V. Empirical Determination of HETP and Separation Factor a............................................ 67
A. By Use of Analytic Solution of Material Balance Equation under
Transient Condition.................................................................................................... 67
B. From Graphical Solution of Material Balance Equation under
the Condition of Zero Time-Dependence at All Stages............................................ 69
VI. Miscellaneous Other Considerations ................................................................................. 69
A. Possible Needs of Chemical Waste Disposal ............................................................ 70
B. Possibility of Failure to Achieve a High Target Enrichment ................................... 70
C. Possible Explosion of Working Material .................................................................. 71
D. Consideration of Supply for the Feed ....................................................................... 72
VII. Enrichment by Nonsteady State Phenomena Involving Reversible Process .................... 72
A. Ion Exchange Isotope Separation .............................................................................. 72
B. Chromatographic Isotope Separation......................................................................... 74
C. Nonsteady-State Enrichment...................................................................................... 75
1. Enrichment Profile............................................................................................... 75
2. HETP ................................................................................................................... 77
D. Isotope Separation by Ion Exchange ......................................................................... 78
1. Boron Isotope Separation.................................................................................... 78
2. Nitrogen Isotope Separation................................................................................ 79
3. Uranium Isotope Separation................................................................................ 81
VIII. Concluding Remarks............................................................................................................... 82
Acknowledgments .......................................................................................................................... 83
References....................................................................................................................................... 83
Similarity in the chemical and physical properties of isotopomers is the basis of isotopic tracer
techniques, while isotope effect studies take advantage of the slight differences, and isotope
separation works against the similarities. Isotope separation is thus one of the practical applications
of the theories of isotope effects (IE), which suggest which features of molecules would cause an
effective separation of isotopes. The theoretical basis of isotope effects is presented by Jacob
Bigeleisen
in the present publication and in other excellent reviews, of which Refs. 2-18
are classic examples.
