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.
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.
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.
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.
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.
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.
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.
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.
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.