Uranium-235
Decay mode Decay energy (MeV) | | |
Alpha | 4.679 | |
---|---|---|
Isotopes of uranium Complete table of nuclides |
Uranium-235 (235U or U-235) is an
fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nature as a primordial nuclide
.
Uranium-235 has a
fast neutrons it is on the order of 1 barn.[2]
Most neutron absorptions induce fission, though a minority result in the formation of uranium-236.[citation needed
]
Fission properties
The fission of one atom of uranium-235 releases 202.5 MeV (3.24×10−11 J) inside the reactor. That corresponds to 19.54 TJ/mol, or 83.14 TJ/kg.[3] Another 8.8 MeV escapes the reactor as anti-neutrinos. When 235
92U nuclei are bombarded with neutrons, one of the many fission reactions that it can undergo is the following (shown in the adjacent image):
research reactors and nuclear weapons
.
If at least one
nuclear bombs, the reaction is uncontrolled and the large amount of energy released creates a nuclear explosion
.
Nuclear weapons
The
implosion geometries, trigger tubes, polonium triggers, tritium enhancement, and neutron reflectors can enable a more compact, economical weapon using one-fourth or less of the nominal critical mass, though this would likely only be possible in a country that already had extensive experience in engineering nuclear weapons. Most modern nuclear weapon designs use plutonium-239 as the fissile component of the primary stage;[5][6]
however, HEU (highly enriched uranium, in this case uranium that is 20% or more 235U) is frequently used in the secondary stage as an ignitor for the fusion fuel.
Source | Average energy released [MeV][3] |
---|---|
Instantaneously released energy | |
Kinetic energy of fission fragments | 169.1 |
Kinetic energy of prompt neutrons | 4.8 |
Energy carried by prompt γ-rays | 7.0 |
Energy from decaying fission products | |
Energy of β− particles | 6.5 |
Energy of delayed γ-rays | 6.3 |
Energy released when those prompt neutrons which do not (re)produce fission are captured | 8.8 |
Total energy converted into heat in an operating thermal nuclear reactor | 202.5 |
Energy of anti-neutrinos | 8.8 |
Sum | 211.3 |
Natural decay chain
Uses
Uranium-235 has many uses such as fuel for nuclear power plants and in nuclear weapons such as
References
- ^ "#Standard Reaction: 235U(n,f)". www-nds.iaea.org. IAEA. Retrieved 4 May 2020.
- ^ ""Some Physics of Uranium", UIC.com.au". Archived from the original on July 17, 2007. Retrieved 2009-01-18.
{{cite web}}
: CS1 maint: unfit URL (link) - ^ a b Nuclear fission and fusion, and neutron interactions, National Physical Laboratory Archive.
- ^ "FAS Nuclear Weapons Design FAQ". Archived from the original on 1999-05-07. Retrieved 2010-09-02.
- ^ Nuclear Weapon Design. Federation of American Scientists. Archived from the original on 2008-12-26. Retrieved 2016-06-04.
- LCCN 68029938.
- ^ Schmidt, Glen (February 2011). "SNAP Overview – radium-219 – general background" (PDF). American Nuclear Society. Retrieved 27 August 2012.
- ^ "RORSAT (Radar Ocean Reconnaissance Satellite)". daviddarling.info.
External links
- Table of Nuclides.
- DOE Fundamentals handbook: Nuclear Physics and Reactor theory Vol. 1 Archived 2017-07-31 at the Wayback Machine, Vol. 2 Archived 2016-12-20 at the Wayback Machine.
- Radionuclide Basics: Uranium | US EPA
- NLM Hazardous Substances Databank – Uranium, Radioactive
- "The Miracle of U-235", Popular Mechanics, January 1941—one of the earliest articles on U-235 for the general public