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Summary  

Main sources of radionuclides in steel in nuclear decommissioning are the unintentional melting of orphan sources and scrap. This paper presents data about the activity of γ-emitters in German steels obtained by low-level γ -ray spectrometry in an underground laboratory. The 60Co activity exceeds only 2% of the 215 analyzed samples with a detection limit of 4.4 . 10-5 Bq . g-1. Even the maximum measured 60Co activity of 2.5 . 10-4 Bq . g-1 is a factor of 400 lower than the clearance level. The determination of the detector efficiency is also described for these unusual samples using Monte Carlo calculations.

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Abstract  

A fast and simple separation method for the determination of low activities of 237Np in enriched uranyl nitrate solutions (U » 10 mg.ml-1) is presented. The extraction chromatographic isolation of neptunium by means of an Ln resinÒ resulted in high separation factors of neptunium from uranium and a nearly complete removal of other interfering nuclides. The chemical yield was determined through a 239Np tracer, which was isolated from a 243Am standard solution during the same separation. The detection limits of 50 mBq.ml-1 were obtained by g-ray spectrometry, sufficiently low to meet the requirements of waste management.

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Bioassays were carried out with antagonists to suppress sporulation by F. culmorum and F. graminearum on cereal debris. A differential effect was found for temperatures on the effect of antagonistic fungal isolates. Isolates 10 and 11 were more effective at low temperature of 5 °C, while isolate 2 works well at higher temperature of 15 °C and fails at 5 °C. On the other hand, antagonism varied little when antagonists were tested on stubble from different cereals.

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Community Ecology
Authors:
F. Kohler
,
F. Gillet
,
M.A. Progin
,
J.M. Gobat
, and
A. Buttler

A cell-grid method was used to survey seasonal changes in four herbaceous communities of a wooded pasture. Permanent plots consisted in 1-m2 grids subdivided into 100 cells of 1 dm2. In each cell of each plot and every month from May to September, we estimated dominance, and grazing occurrence of all species. Plant communities included an eutrophic grazed meadow, a temporary refused meadow, an underwood herb community and an oligotrophic lawn. Our results showed that seasonal changes in species composition were very strong and scale-dependent. Changes at plot scale were mainly driven by a seasonal shift. Changes at cell scale suggested high small-scale dynamics of species. Despite high changes at cell scale, the structure of the community did not change and local species richness did not show any trend. We found no correlation between the turnover at cell scale and cattle activity. We conclude that dynamics and internal species turnover of the community at fine scale and short time seem more driven by internal characteristics of the community than by disturbances induced by cattle. Furthermore, at seasonal scale, plant communities may be stable in their structure despite fluctuations in their texture.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Pham
,
M. Betti
,
P. Povinec
,
M. Benmansour
,
R. Bojanowski
,
P. Bouisset
,
E. Calvo
,
G. Ham
,
E. Holm
,
M. Hult
,
C. Ilchmann
,
M. Kloster
,
G. Kanisch
,
M. Köhler
,
J. La Rosa
,
F. Legarda
,
M. Llauradó
,
A. Nourredine
,
J.-S. Oh
,
M. Pellicciari
,
U. Rieth
,
A. Rodriguez y Baena
,
J. Sanchez-Cabeza
,
H. Satake
,
J. Schikowski
,
M. Takeishi
,
H. Thébault
, and
Z. Varga

Abstract  

A new Reference Material (RM) for radionuclides in mussel (Mytilus galloprovincialis) from the Mediterranean Sea (IAEA-437) is described and the results of the certification process are presented. Four radionuclides (40K, 234U, 238U, and 239+240Pu) have been certified, and information values on massic activities with 95% confidence intervals are given for nine radionuclides (137Cs, 210Pb(210Po), 226Ra, 228Ra, 228Th, 230Th, 232Th, 235U, and 241Am). Results for less frequently reported radionuclides (90Sr, 129I, 238Pu, 239Pu, and 240Pu) are also reported. The RM can be used for quality assurance/quality control of the analysis of radionuclides in mussel samples, for the development and validation of analytical methods and for training purposes. The material is available in 200 g units.

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