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  • Author or Editor: H. Das x
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Abstract  

The improvement in the limits of decision, detection, and determination effected by anti-Compton gamma-ray spectrometry are considered. A simple procedure for the experimental determination is presented.

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Abstract  

Reduction of the diffusional emission of trace constituents from wetted granular waste by application of different types of liners is formulated, which enables their mutual comparison. Laboratory procedures for the measurements of the involved parameters are discussed, together with some examples.

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Abstract  

The emanation of radon from fly-ash and gypsum can be estimated from a simple model. The cases of a fly-ash dump and a room panelled with gypsum plates are considered.

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Abstract  

A general survey on the development of the radiochemistry in the Benelux is given. Production of radionuclides and radiopharmaceuticals, application of gamma-irradiation, the activation analysis and measurement of capture gamma-rays, tracer studies, actinide research and detection of radionuclides in environmental samples are mentioned and briefly discussed as the main subjects, going on in the radioanalytical laboratories of the Benelux.

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Abstract  

Low level measurements of137Cx in lacustrine sediment and its pore water are possible to activity as low as 10 mBq. From this data, the flux of137Cs through the sediment and to the bottom water can be estimated. The value of the diffusion coefficient in the pore water follows from separate radiotracer experiments.

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Abstract  

The control of analytical data by randomly inserted standards or reference materials is quantified in terms of elementary statistics. The consequences of a given number of standard aliquots are interpreted on the basis of the a priori expectation on the average defective fraction. It appears that, in most cases, standards serve to detect sudden large errors only. Some practical examples are considered.

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Abstract  

In activation analysis, recoil causes both contamination from and loss to the packing material. In isotope production, recoil may be used to obtain carrier-free radionuclides. Both phenomena depend on irradiation geometry and recoil range. Their formulation and that of experimental range determinations is addressed for common irradiation practice.

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Abstract  

The promotion of radioanalysis as an elegant, predominantly instrumental, analytical method is a major achievement of Vincent P. Guinn. As an example the sequential analysis for trace elements in the mm-range of small “pure” silica components from the electronic industry of various, often irregular, shapes is presented here. The idea reaches back to our discussions in the early seventies.

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Abstract  

The use of “small” research reactors with applicable thermal neutron fluxes of ≤1012.cm−2.s−1 in (instrumental) activation analysis based on γ-spectrometry, and in isotope production for radiotracer experiments is surveyed on the absis of the experience at ECN, Petten, The Netherlands and elsewhere. The aim is to provide a practical guideline for the application of “small” reactors in both fields. Reproducibility and knowledge of the physical parameters of irradiation and counting are essential and thus the first task of the radioanalyst. Emphasis is laid on the use of short-lived radionuclides. This implies the elimination of an additional source of bias in γ-spectrometry. Some suggestions are made on eventual projects of current interest.

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Abstract  

Assessment of environmental risks of granular wastes, immobilised in monolithic bodies implies at least three independent, preferably standardised, tests: Weight variations during drying and wetting; leaching with water or dilute acid and determination of the available fraction of the micro-constituent involved. Their accuracy, precision and minimal turn-over time depend on the dimensions of the test specimen and the experimental procedure. They are considered here in relation to the inevitable underlying assumptions and the practical limitation of the turn-over time. Two standard geometries of test aliquots are considered in detail. The use of radioanalysis in the determination of some of the characterising parameters is summarised.

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