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Calorimetry linked with GPC analysis has allowed the measurement of the heat of reaction against the oxygen coverage for three french coals ranging from subbituminous to semianthracite. At low oxygen coverage, a complex evolution of the enthalpy is observed mainly attributed to a chemisorption located on radical sites formed and accumulated during the outgassing pretreatment, whereas at higher coverage, the enthalpy becomes independent of the oxygen coverage where the removal of hydrogen as water vapour predominates. At low coverage the degassing pretreatments influence in a persistent way the enthalpy measurements, and in consequence it is generally only at high oxygen coverage, that enthalpy measurements coming from differently pretreated samples may be usefully compared.
Abstract
The determination of boron in zirconium by activation analysis using the10B(d, n)12C reaction with the chemical separation of11C is described. The method was applied to industrial zirconium samples as zircalloy.
Abstract
The use of direct observation of nuclear reactions (p,p′γ) is discussed. The main characteristics of this method are presented and applied to the case of the miroanalysis of Si, S and Zn in GaSb.
Abstract
An international intercomparison exercise was conducted by the IAEA in 1994 on the edible fractions of biological samples collected in Mururoa. This article presents the results of additional measurements made on the inedible parts of marine samples, i.e., the gonads, viscera and livers of fish (groupers) and the hepatopancreas or viscera of mollusks (giant clams and turbos). The spread of data as a function of sampling locations has been investigated, while the concentration factors for several long-lived radionuclides have been determined and discussed. Plutonium-239/240 concentration data for giant clam flesh and hepatopancreas appear to be very close (approximately 0.6 Bq/kg wet weight), whereas60Co concentrations are 100 times less in flesh (3 Bq/kg wet weight) than in hepatopancreas. As regards groupers,239/240Pu and60Co concentrations in flesh are very low and close to the detection limit. These concentration values are 100 to 500 times lower than those recorded in livers. As for turbos, plutonium and60Co concentrations in viscera are 5 to 10 times higher than in soft parts. Based on these data, it becomes possible to determine which fractions of marine samples should be analyzed first in order to detect minute traces of60Co,137Cs and plutonium in Polynesia.
Recent progress in numerical methods for the determination of thermokinetics
Results of multinational programme on the comparison of the methods
Abstract
Within the frame of Comprehensive Nuclear-Test Ban Treaty (CTBT), this paper deals with the development of the new techniques necessary for the xenon monitoring requested by the CTBT. An automatic system called SPALAX™, devoted to the on-site sampling and measurement was developed by French atomic energy commission (CEA). Analytical methods and equipments have been studied at our laboratory, using dual X-γ-spectrometry in order to get independent means with better sensitivity within a robust quality assurance program. In the case of a wide number of potential existing sources and depending on meteorological conditions, several solutions can be arrived at.
Abstract
A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides (40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides in the environment, as well as for the development and validation of analytical methods and for training purposes. The material is available from IAEA in 100 g units.
