Plutonium-244 dating

Re-examination of all known xenon isotopic data for ordinary chondrites reveals that²⁴⁴Pu fission xenon can be resolved in about one-fourth of the meteorites of this class. The amounts of²⁴⁴Pu fission xenon found in these meteorites range from ca. 1–2 up to 6–8·10^?12 ccSTP/g. These meteorites started to retain their xenon some 200–500 million years later than did the carbonaceous chondrites Allende, Groznaya, Mokoia, Murchison, Murray, and Renazzo which began to retain their xenon over 4800 million years ago.     

Plutonium-244 dating

Re-calculation of the²⁴⁴Pu ages of lunar rocks 10057 and 12013 indicates that, while the former started to retain its xenon (4,189 _?74 ⁺⁴⁵ ) million years ago, the latter was formed at a much later time, after the extinct nuclide²⁴⁴Pu had essentially decayed away.     

Plutonium-244 dating

Re-examination of all known xenon isotopic data for the carbonaceous chondrites Renazzo, Mokoia, and Groznaya reveals that these meteorites contain (26±7), (33±1), and (36±4)·10^–12 (ccSTP^136fXe/g) of²⁴⁴Pu fission xenon, respectively. These meteorites started to retain their xenon more than 4,800 million years ago at about the same time as did the carbonaceous chondrites Allende, Murray, and Murchison.     

Plutonium-244 dating VII. Initial abundances of uranium-235 and plutonium-244 in lunar samples

Re-examination of a vast amount of lead and xenon isotope data that have been accumulated since the Apollo 11 landing on the moon in July 1969 reveals that some of the lunar fines and breccia started to retain their radiogenic lead and fissiogenic xenon isotopes about 5 billion years ago when the ratios of²³⁵U and²⁴⁴Pu to²³⁸U in the early solar system were approximately 4 and 2 atoms per 10 atoms of²³⁸U, respectively.     

Plutonium-244 dating VI. Initial ratios of plutonium to uranium in achondrites

Re-examination of all known xenon isotopic data for achondrites reveals that²⁴⁴Pu fission xenon can be resolved in about three-fourths of the meteorites of this class. The amounts of²⁴⁴Pu fission xenon found in these meteorites range from ca. 1–2 up to 20–40·10^–12 ccSTP/g. These meteorites started to retain their xenon some 200–500 million years later than did the carbonaceous chondrites Allende, Groznaya, Mokoia, Murchison, Murray, and Renazzo, which began to retain their xenon over 4800 million years ago.     

Plutonium-244 dating I. Initial ratio of plutonium to uranium in the allende meteorite

Re-examination of all known xenon isotope data for the carbonaceous chondrite Allende reveals that this meteorite contains as much as (22±1)·10^{–1 2} csSTP per gram of fissogenic¹³⁶Xe (^136fXe) from the extinct nuclide²⁴⁴Pu and it appears to have started to retain its xenon more than 4800 million years ago, when the²⁴⁴Pu to²³⁸U ratio in the solar system was 0.113±0.006 (atom/atom).     

Plutonium-244 and strange xenon components in the solar system

A number of strange xenon components have been reported in the literature during the past three decades; for example, AVCC (average carbonaceous chondrite), CCF (carbonaceous chondrite fission) xenon, xenon-X, xenon-H, xenon-L, xenon-S, xenon-U, SUCOR (surface correlated xenon), BEOC (Bern Oberflächen-Correliert) xenon, and so on. It is often assumed that they reprsent the isotopic compositions of more or less pure or primordial components of xenon. If one attempts to interpret the existing xenon isotope data for meteorites and lunar samples, assuming that they are pure or primordial, however, one encounters all sorts of problems and no coherent theory concerning the variation of the isotopic composition of xenon in the solar system emerges. We have therefore re-examined over 4,000 sets of existing xenon isotope data for meteorites and lunar samples. The results indicate that these strange xenon components are mixtures of²⁴⁴Pu fission xenon and atmospheric xenon, whose isotopic compositions have been altered by the processes of a) mass-fractionation, b) spallation and c) neutron-capture reactions.     

Plutonium-244 fission xenon in carbonaceous inclusions of primitive meteorites

A total of 13 samples of diamond separates studied so far, all contain excess ²⁴⁴Pu fission xenon. On the other hand, none of the SiC separates contains excess ²⁴⁴Pu fission xenon, while 5 out of 10 samples of graphite separates studied so far contain excess ²⁴⁴Pu fission xenon.     

Plutonium-244 fission xenon and primordial xenon in the Allende meteorite

The carbonaceous chondrite Allende contains (22±1)·10⁻¹² cm³STP/g of²⁴⁴Pu fission xenon and two kinds of primordial xenon: Type I and Type II. The former represents the isotopic composition of a primordial xenon, which resided in the vicinity of a supernova shortly before it exploded, while the latter represents that of the xenon, which resided in the supernova. The isotopic composition of xenon found in the pink inclusion of the Allende meteorite, corrected for the presence of very large excesses of²⁴⁴Pu fission xenon,¹²⁹Xe from the decay of¹²⁹I, and of¹²⁸Xe from the neutron-capture reactions on¹²⁷I, resembles that of Type-I primordial xenon. The isotopic composition of xenon found in the diamond inclusions of the Allende meteorite, on the other hand, represents that of Type-II primordial xenon and it resembles that of a mixture of Type-I primordial xenon whose isotopic composition is severely altered by a combined effect of (a) mass-fractionation, (b) spallation, (c) stellar-temperature neutron-capture reactions, and (d) the presence of a large excess of²⁴⁴Pu fission xenon.     

Plutonium-244 fission xenon and primordial xenon in lunar samples and meteorites

Xenon found in lunar samples is a binary mixture of²⁴⁴Pu fission xenon and a trapped xenon, whose isotopic composition often shows a striking resemblance to that ofTakaoka's¹ primitive xenon. The decay product of¹²⁹I is conspicuously absent in lunar samples and this may be attributed to the facts that (a) the half-life of¹²⁹I is much shorter than that of²⁴⁴Pu, and (b) the separation of xenon from plutonium may take place easily, since the former is a gaseous element, while the latter is a refractory element. The separation of xenon from iodine may not take place easily, however, since the former is a gaseous element, while the latter is a volatile element. The isotopic compositions of the trapped xenon released from ordinary chondrites and achondrites resemble that ofTakaoka's primitive xenon, which has been mass-fractionated in such a manner that the heavier isotopes are systematically enriched relative to the lighter isotopes.     

Noch 5 ppm Ameriemm-241 in Plutonium-239

Ohne Zusammenfassung     

Die Bestimmung von Mikrogrammengen Thorium in Plutonium-, Neptunium-und Uranylnitratlösungen

Analytical and Bioanalytical Chemistry -     

Die Bestimmung von Mikrogrammengen Thorium in Plutonium-, Neptunium-und Uranylnitratl?sungen

Ohne Zusammenfassung     

Plutonium-239, 240 atmospheric radioactivity measurements at Mururoa from 1986 to 1991

The measurement of re-suspended materials during cleanup operations is currently a concern at many formally-contaminated locations that are being restored. This paper addresses this issue by indicating that the yearly^239,240Pu air concentrations increased by a factor of 6 due to re-suspension during cleanup operations at Mururoa. Five sites on the atoll were monitored continuously from 1986 to 1991. The data presented are compared with other data from various parts of the world.The Service Mixte de Sécurité Radiologique is a joint department (Ministry of Defence-Commissariat à l'Energie Atomique) of the Direction des Centres d'Expérimentations Nucléaires.     

Zur Bestimmung von Americium-243 in Curium-244

Ohne Zusammenfassung     

Plutonium-238, 239-240 inventories in sediment cores from Stechlin Lake, Germany

^{238, 239-240}Pu were measured in German lake sediment coresby counting after radiochemical separation. Their distribution over the bedof the lake was determined. The lake contain 3 basins and for each basin 3sediment cores have been sliced in two subsamples. The results show that theactivity distribution is not the same over the lake and that the sedimentationrate changes in the 3 basins.