Astro 300B: Jan. 26, 2011 Thermal radiation and Thermal Equilibrium.
Nuclear Thermal Rockets - School of Engineering · Nuclear Thermal Rockets Brice Cassenti...
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Nuclear Thermal Rockets Brice Cassenti University of Connecticut
Transcript of Nuclear Thermal Rockets - School of Engineering · Nuclear Thermal Rockets Brice Cassenti...
Nuclear Thermal Rockets
Brice Cassenti
University of Connecticut
Nuclear Energy
• Relativity
• Fission energy
• Radioactive decay
• Cross-sections
• Nuclear thermal rockets
Relativistic Energy
• For all particles
• For photons
• For
( )2
202
22220
2242420
/1 cv
cmmcE
cpEE
cpcmcm
−==
−=
−=
ωπνπ
ν h=
===
=
22
00
hhpcE
m
1/ <<cv22
0 2
1mvcmE +≈
Binding Energy
Fission of 92U235
Energy Value (MeV)
Fission fragment kinetic energy 166.2
Neutron kinetic energy 4.8
Prompt X-rays 8.0
β particles from fragment decay 7.0
γ particles from fragment decay 7.2
Antineutron from fragment decay 9.6
Total released energy 202.8
10
9436
13956
23692
23592
10 3 nKrBaUUn ++→→+
Fission Process
Radioactive Decay
• Consider uranium alpha decay
• Decay rate is proportional to number left
• Activity measured in Sieverts
42
23490
23892 HeThU +→
λλ
λ
λ
692.02ln
/10
≈=
== −
half
mean
t
t
t
eNN
Fission Fragment Decay
Fission Fragment Size
Neutrons Emitted
Neutron Energy
Cross-Section
• Cross-section = σ
• Units
– 1 barn=10-24cm2
nxeII
nIdx
dI
σ
σ
−=
−=
0
Uranium Fission Cross-Sections
Some Cross-Sections in barns
Nucleus Absorption, σσσσa Capture, σσσσc Fission, σσσσf Scattering, σσσσs
92U235 687 107 580 10
94Pu239 1065 315 750 9.6
92U233 585 52 533 ?
92U238 2.75 2.75 0 8.3
U (natural) 7.68 3.50 4.18 8.3
fca σσσ +=: Note
Neutron Moderator
Scattering Cross-Sections
Reactor Schematic
Nuclear Thermal Propulsion
• Solid Core
– 850-950 second Specific Impulse
• Gas Core
– 1800-1950 second Specific Impulse
Solid Core Schematic
NERVA Program
NERVA Core & Fuel Rods
Core Layout
Gas Core Rocket
Nuclear Light Bulb
References
• Bussard, R.W., and R.D. DeLauer, Nuclear Rocket Propulsion, McGraw-Hill Series in Missile and Space Technology, McGraw-Hill Company, Inc. 1958.
• Cork, J.M., Radioactivity and Nuclear Physics, D. Van Nostrand Company, Inc., New York, 1950.
• El-Genk. M.S., (editor) A Critical Review of Space Nuclear Power and Propulsion 1984-1993. American Institute of Physics, New York, 1994.
• El-Wakil, M.M., Nuclear Power Engineering, McGraw-Hill Book Company, Inc., New York, 1962.
• Harper, W.R., Basic Principles of Fission Reactors, Interscience Publishers, Inc., New Your, 1961.
• Muhkin, K.N., Experimental Nuclear Physics, Mir Publishers, Moscow, 1987. • Murray, R.L., Nuclear reactor Physics, Prentice-Hall, Inc., Englewood Cliffs, NJ,
1957. • NASA, Nuclear Thermal Propulsion Workshop, NASA Conference Publication
10079, Cleveland, OH, July 10-12, 1990.
