HALF-LIFE OF SELECTED RADIOACTIVE ISOTOPES

Radionuclide

Symbol

Half-life

Americium-241

241Am

432.2 years

Americium-243

243Am

7.38 x 103 years

Antimony-125

125Sb

2.77 years

Argon-41

41Ar

1.827 hours

Beryllium-7

7Be

53.44 days

Californium-252

252Cf

2.639 years

Carbon-14

14C

5.730 x 103 years

Cerium-141

141Ce

32.50 days

Cerium-143

143Ce

1.38 days

Cerium-144

144Ce

284.3 days

Cesium-134

134Cs

2.062 years

Radionuclide

Symbol

Half-life

Cesium-137

137Cs

30.17 years

Cobalt-58

00

о

О

70.80 days

Cobalt-60

о

О

О

5.271 years

Curium-242

242Cm

163.2 days

Curium-244

244Cm

18.11 years

Iodine-129

129i

157 x 107 years

Iodine-131

131i

8.04 days

Krypton-85

85Kr

10.72 years

Krypton-88

88Kr

2.84 hours

Manganese-54

54Mn

312.7 days

Neptunium-237

237Np

2.14 x 106 days

Niobium-95

2

cr

35.06 days

Osmium-185

185Os

93.6 days

Phosphorus-32

32p

14.29 days

Polonium-210

210Po

138.378 days

Plutonium-238

238Pu

87.75 years

Plutonium-239

239Pu

2.41 x 104 years

Plutonium-240

240Pu

6.569 x 103 years

Potassium-40

40K

1.2777 x 109 years

Promethium-147

147Pm

2.6234 years

Protactinium-234m

234mPa

1.17 minutes

Radium-226

226Ra

1.6 x 103 years

Radium-228

228Ra

5.75 years

Ruthenium-103

103Ru

39.35 days

Ruthenium-106

106Ru

368.2 days

Strontium-89

89Sr

50.55 days

Strontium-90

90Sr

28.6 years

Technetium-99

99Tc

2.13 x 105 years

Thorium-228

228Th

1.9132 years

Thorium-230

230Th

7.54 x 104 years

Thorium-232

232Th

1.405 x 1010 years

Thorium-234

234Th

2.41 x 101 day

Tritium

3H

12.28 years

Uranium-234

234U

2.445 x 105 years

Uranium-235

235U

7.038 x 108 years

Uranium-236

236U

2.3415 x 107 years

Uranium-238

238U

4.468 x 109 years

Xenon-133

133Xe

5.245 x 109 years

Xenon-135

135Xe

9.11 hours

Yttrium-90

90Y

64.1 hours

Zirconium-95

95Zr

64.02 days

Source. U. S. Department of Energy (1989). ‘‘Radioactive Decay Data Tables: A Handbook of Decay Data for Application to Radioactive Dosimetry and Radiological Assessments.’’ DOE/TIC-11026.

1. Definition of Ultralight Rail

3. Capacity and Energy Consumption of Highways

4. Ultralight Rail—Operational Characteristics

5. Energy Requirements of Ultralight Rail and Conventional Rail

6. Cost of Ultralight Rail Systems

7. Barriers to Implementation

8. Energy-Saving Opportunities with Ultralight Rail

Glossary

consist An individual unit or multiple vehicles traveling in a linked set.

grade The slope, or inclination, of the guideway.

guideway The rail, support structure, power delivery conductors, and control sensors that make up the path on which ultralight vehicles move.

headway The time period between trains or individual vehicles passing a particular point on the guideway.

kilowatt-hour (kWh) Base energy unit equaling 1 kW of power used for 1 h.

passengers per hour per direction (pphpd) The measure of capacity of a rail transit system, in terms of the maximum number of passengers the system can move in one direction.

To best describe the relationship between ultralight rail and energy, it is necessary to establish a basis of understanding. This basis is best defined in terms of the energy requirements of known and familiar modes of transportation, since there are so few examples of ultralight rail in operation. This article establishes this basis in terms of conventional rail systems and, where applicable, bus, automobile, and truck systems. The basic characteristics of both conventional and ultralight rail systems are de­scribed, followed by a comparison of the two systems, with an emphasis on the energy aspects of

1. Importance of Uranium and Thorium

2. Historical Context of Uranium Exploration

3. Geology and Geochemistry of Uranium

4. Current Uranium Production

5. Conventional Uranium Resources

6. Known Uranium Resources

7. Unconventional Resources

8. New Technologies for Uranium Extraction

9. Impact of Uranium Scarcity and Higher Extraction Costs

10. Summary

Glossary

cross section Probability of neutron interaction with a nucleus, expressed in terms of area, in units of barns, with 1 barn equal to 1.0 x 10-24 cm2.

enrichment The fraction of an isotope, usually fissile 235U, in a mass of uranium; enrichment is commonly quoted as the weight percentage of the particular isotope.

enrichment tails (or depleted uranium) The uranium remaining after the enrichment of natural uranium into fuel; today it is approximately 0.3% 235U, whereas earlier it was 0.20 to 0.25% 235U.

fractionation Crystallization from a magma in which the initial crystals are prevented from equilibrating from the parent liquid, resulting in a series of residual liquids of more extreme composition than would have resulted from continuous reaction.

highly enriched uranium (HEU) Uranium containing more that 20% 235U.

Jth Joule (i. e., watt-second) thermal, with 1 British thermal unit (BTU) equal to 1055 Jth.

low enriched uranium (LEU) Uranium containing less that

20% 235U.

mafic Composed chiefly of dark ferromagnesian minerals.

mega-separative work unit (MSWU) A million separative work units; a separative work unit is the separative work done to change the separation potential of 1 kg of

1. Introduction

4. Data Sets and Analysis Methods

5. Resource Assessment Methods

6. Status of Wind Resource Projects

Glossary

exclusion zone An area that cannot be used for wind power development because of environmental, legal, topographic, or other reasons.

frequency distribution of wind speed The percentage of time that the wind is blowing at each speed (14% at 2-3m/s, 8% at 3-4m/s, etc.).

geographic information system (GIS) The computer hard­ware, software, and technical expertise that inputs, stores, maintains, manipulates, analyzes, and outputs geographically referenced data. A GIS combines the power of spatial database management with high – resolution graphic display to effectively present infor­mation.

grid-connected A project that is connected to a utility distribution system.

power class A single number representing a range of wind power densities (WPD). A typical power classification scheme divides the WPD range from 0 to > 800 W/m2 into seven power classes.

Weibull distribution A mathematical function that is often a good approximation to the frequency distribution of wind speeds at a site.

wind electric potential The total number of megawatts of wind energy generating capacity that could be installed in a given area.

wind power density The average wind power over one square meter expressed in Watts per square meter (W/m2) in a vertical plane perpendicular to the wind direction.

wind resource A measure of how much wind energy is available at a given height at a given point or over a given area. It can be expressed in values of Watts per

[1]——– Surface of Earth

[2] A Brief Discussion of Conventional Rail

[3] Basics of Wind Resource

[4] Baseline Wind Resource Studies

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