U-Xe, U-Kr, and U-Pb systematics for dating uranium minerals and investigations of the production of nucleogenic neon and argon

Journal Article · Mon Mar 01 00:00:00 EST 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90040-4· OSTI ID:6863595

Eikenberg, J; Signer, P; Wieler, R ^[1]

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1. ETH-Zuerich (Switzerland)

U-rich minerals were investigated for the products of radioactive decay, fission, and specific nuclear reactions induced thereby. Geologically undisturbed uranium minerals with concordant U-Pb ages were used to determine the product of the [sup 238]U spontaneous fission decay constant [lambda][sub sf] and the yield [sup i]Y[sub sf] of a specific Xe or Kr isotope, the isotopic ratios of spontaneous fission xenon and krypton, and the [sup 136]Xe/[sup 86]Kr spontaneous fission ratio. Values of (5.7 [plus minus] 0.4)[center dot]10[sup [minus]18]/a and 6.1 [plus minus] 0.1 were obtained for [lambda][sub sf][center dot][sup 136]Y[sub sf] and ([sup 136]Xe/[sup 86]Kr)[sub sf], respectively. With the result for [lambda][sub sf][center dot][sup 136]Y[sub sf] and literature data on [sup 238]U spontaneous fission yields, the authors propose that the proper value for [lambda][sub sf] is around 8.6[plus minus]10[sup [minus]17]/a rather than the 6.4[center dot]10[sup [minus]17]/a as mainly proposed by fission track investigators. Isotopic ratios of neon and argon differ significantly from atmospheric composition. No evidence for nucleogenic neon and argon from strongly asymmetric fission or from (n,[alpha]), or (n,[gamma]) reactions was found. These gases are produced by the nuclear reactions [sup 18]O([alpha],n)[sup 21]Ne, [sup 19]F([alpha],n)[sup 22]Ne, [sup 35]Cl([alpha],p)[sup 38]Ar and [sup 35]Cl(n,[gamma])[sup 36]Ar as already proposed in 1954 by Wetherill. For these reactions the production ratios P(21)[sub norm], P(22)[sub norm] and P(38)[sub norm] of [sup 21]Ne[sub nuc], [sup 22]Ne[sub nuc] and [sup 38]Ar[sub nuc] relative to the [alpha]-dose and the target element concentrations in the minerals were deduced. The contributions of [sup 22]Ne[sub nuc] and [sup 38]Ar[sub nuc] to the Earth's atmosphere are negligible, whereas up to 2.4% of [sup 21]Ne in the atmosphere may be nucleogenic. 78 refs., 9 figs., 10 tabs.

• OSTI ID: 6863595
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 57:5; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ARGON ISOTOPES
NUCLEOSYNTHESIS
KRYPTON ISOTOPES
ISOTOPE RATIO
NEON
ATMOSPHERIC CHEMISTRY
NEON 21
NEON ISOTOPES
URANIUM 238
SPONTANEOUS FISSION
XENON ISOTOPES
ARGON 36
ARGON 38
CHLORINE 35
FLUORINE 19
GASES
KRYPTON 86
NEON 22
NUCLEAR REACTIONS
OXYGEN 18
URANIUM MINERALS
XENON 136
YIELDS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CHEMISTRY
CHLORINE ISOTOPES
DECAY
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FISSION
FLUIDS
FLUORINE ISOTOPES
HEAVY NUCLEI
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATERIALS
MINERALS
NANOSEC LIVING RADIOISOTOPES
NONMETALS
NUCLEAR DECAY
NUCLEI
ODD-EVEN NUCLEI
OXYGEN ISOTOPES
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RADIOISOTOPES
RARE GASES
SPONTANEOUS FISSION RADIOISOTOPES
STABLE ISOTOPES
SYNTHESIS
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES
050100* - Nuclear Fuels- Reserves
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663470 - Fission- (1992-)
663590 - Nuclear Mass Ranges- A=220 & Above- (1992-)