No abstract available

No abstract available

[en] The physical bases of hydrogen determination in materials samples by neutrons thermalization are presented. The neutron hydrogen meter is described. (A.S.)

[en] A measuring technique for hydrogen determination in liquids flowing through pipelines based on neutron thermalization is described. With a fast neutron source emitting 5 x 10⁵ neutrons/s and 200 s counting time, the relative standard deviation of hydrogen determination in liquid hydrocarbons by this technique is less than 0,5%. The usability of the technique for measuring the concentration of sulphuric acid is shown. 23 refs., 4 figs. (author)

[en] An original method of calculating the slowing down length of neutrons (Lsub(s)) using the multigroup approach is presented. The method takes into account the elastic scattering, the inelastic scattering and the neutron absorption during slowing down. The computational procedure applies for soils and rocks of any chemical composition and for neutron sources of energies up to 10.5 MeV. The method has been employed for the water saturated sandstone, limestone, dolomite and some other media, for different neutron sources. A satisfactory agreement between the calculated Lsub(s) values and the available experimental data has been obtained. The dependences of Lsub(s) on the neutron energy and chemical composition of the rocks have been investigated. (author)

[en] The authors comment on a paper by Ivauovich and Smith (1978) regarding the determination of acquifer parameters by a two-well pulsed method using radioactive tracers. They discuss the method of the interpretation of data as well as the understanding of the definitions and physical laws. (Auth.)

[en] Short communication

[en] A new simple rapid and cost effective method of determining the thermal neutron absorption cross section of rocks is proposed. It uses samples of about 2 kg and a measuring set-up consisting of paraffin block, Pu-Be neutron source emitting roughly 5 x 10⁵ n/s, BF₃ proportional counter and conventional counting equipment. The method has been tested with a set of 49 artificial samples and 95% confidence intervals of about 0.27 m^-1 have been estimated for 2 x 300 s counting times. Measurements carried out for several basalt samples have been compared with results obtained by a pulsed neutron technique. (author)

No abstract available

[en] There are two definitions of the concentration of dissolved or suspended material in a flowing fluid, namely the resident concentration and the flux concentration. The validity of the dispersion equation with a chemical reaction term is considered for the cases of the flux concentration. This concentration has to be considered when the mass transfer is of interest. Depending on the injection-detection mode the solute is either injected and measured in terms of the flux concentration or in terms of the resident concentration. It is shown which solutions to the dispersion equation are most adequate to the common experimental situations. Problems related to the determination of the mean flow velocity and the dispersion coefficient from tracer experiments are considered. A new simple method of interpretation suitable for highly dispersive systems is proposed. (author)