Isotopes, xenon

Krypton and Xenon from Huclear Power Plants. Both xenon and krypton are products of the fission of uranium and plutonium. These gases are present in the spent fuel rods from nuclear power plants in the ratio 1 Kr 4 Xe. Recovered krypton contains ca 6% of the radioactive isotope Kr-85, with a 10.7 year half-life, but all radioactive xenon isotopes have short half-Hves. 

Different combinations of stable xenon isotopes have been sealed into each of the fuel elements in fission reactors as tags so that should one of the elements later develop a leak, it could be identified by analyzing the xenon isotope pattern in the reactor s cover gas (4). Historically, the sensitive helium mass spectrometer devices for leak detection were developed as a cmcial part of building the gas-diffusion plant for uranium isotope separation at Oak Ridge, Tennessee (129), and heHum leak detection equipment is stiU an essential tool ia auclear technology (see Diffusion separation methods). 

Xenon fluorides, 77 323-325 binary, 77 335-336 Xenon-gold cations, 77 332 Xenon halides, 77 323-325 Xenon hexafluoride, 7 7 325, 329 uses for, 7 7 336 Xenon ion lasers, 74 685 Xenon isotopes, in fission reactors, 77 375 Xenon oxide difiuoride, 77 326 Xenon oxide fluorides, 7 7 326 Xenon oxides, 77 325-326 Xenon oxide tetrafluoride, 77 326 Xenon testing, in plastics weathering, 79 584-585... 

For use in a radioactive environment the gas centrifuge must be completely maintenance free. It has been used for the separation of xenon isotopes and consideration has been given to its application for separation of fluorohydrocarbons. Worldwide, in the region of a quarter of a million gas centrifuges have been manufactured. As an order of magnitude figure, an investment of 1000 is necessary to obtain 0.3 g/s (10 g/h) of product. 

By the end of the 1970s, support for the fission hypothesis for the origin of CCFXe was waning, and over the next few years the component s name was changed to Xe-HL, which describes the enrichments in Heavy and Light xenon isotopes without ascribing a mode of... 

M (a) Elemental abundances and (b) xenon isotopic abundances for some exotic noble gas components (defined in Table 8.2) in meteorites. Modified from Wieler et al. (2006). 

The half-life of 244Pu (8.2 X 107 years) is short compared with the age of the earth (4.5 X 109 years), and hence this nuclide is now extinct. However, the time interval (a) between the element synthesis in stars and formation of the solar system may have been comparable with the half-life of 244Pu. It has been found recently in this laboratory that various meteorites contain excess amounts of heavy xenon isotopes, which appear to be the spontaneous fission decay products of 244Pu. The value of H calculated from the experimental data range between 1 to 3 X 108 years. The process of formation of the solar system from the debris of supernova is somewhat analogous to the formation of fallout particles from a nuclear explosion. 

Figure 6. Mass-yield distribution of the fissiogenic xenon isotopes in the meteorite Pasamonte (15)...

The Ozima-Nakazawa model requires the right size of a planetesimal a priori to explain the observed xenon isotopic fractionation the xenon fractionation is a natural consequence in this pore-closing model. However, in this model the amount of Xe captured by a planetesimal is too small to account for terrestrial Xe, if the similar nebular density (3 x 10 8gcm 3) as in the case of the Ozima-Nakazawa model were assumed. Zahnle et al., therefore, suggested that adsorbed Xe on dust grains prior to the formation of a planetesimal was the primary source Most of the adsorbed... 

Marty, B. (1989) Neon and xenon isotopes in MORB Implications for the earth-atmosphere evolution. Earth Planet. Sci. Lett., 94, 45-56. 

Ozima, M., Podosek, F. A., Igarashi, G. (1985) Terrestrial xenon isotope constraints on the early history of the Earth. Nature, 315, 471 —4. 

However, light xenon isotopes from 129 to 124 were also over-abundant [61,67,68] in such meteorites and enriched [66] in the tiny host phase although they are not formed in fission. Whether there are at least two anomalous xenon components of different origin, remained controversial for years [69]. Eventually, the fission origin of the anomalous xenon was ruled out [70] because in a host phase containing the excess xenon no enrichment was detected for the adjacent barium isotopes 130 to 138, which are abundant fission products. 

As all known lunar meteorites are finds (and therefore have nonzero terrestrial ages), we need at least four measured quantities to determine the four parameters of a simple one-stage history. Similarly, for a simple two-stage history, we need at least six measured quantities. Typically the data set available comprises He, Ne, Ne, Ar, C1, A1, and e. Occasionally we may have other information— the concentrations of spallo-genic krypton isotopes, spallogenic xenon isotopes, " Ca, and Mn, the densities of nuclear tracks (tracks/unit area), and the concentrations of certain isotopes produced by thermal neutrons, e.g., Ar (from C1) and Gd. 

Gilabert E., Lavielle B., Michel R., Leya L, Neumann S., and Herpers U. (2002) Production of krypton and xenon isotopes in thick stony and iron targets isotropically irradiated with 1600 MeV protons. Meteorit. Planet. Sci. 37, 951—976. 

The xenon isotopic arguments can be extended to fissionogenic xenon. The use of the combined and 244p i32.i34.i36xe (spontaneous... 

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