[en] A radon monitor, able to perform the measurement of the radon and its progeny volumic activity, in a gamma-ray or natural radiation background field, was developed. The instrument consists of a 10 l ionization chamber, a high voltage source, an integrating preamplifier, a data acquisition system and a personal computer. A new method for self-calibration of Radon volumic activity measurements, based on the alpha counting with an ionization chamber is also presented

[en] By using the statistical discrimination technique, the components of an ionization current, due to a mixed radiation field, may be simultaneously measured. A functional model, including a series manufactured gamma-ray ratemeter was done, as an intermediate step in the design of specialized nuclear instrumentation, in order to check the concept of statistical discrimination method. The obtained results are in good agreement with the estimations of the statistical discrimination method

[en] The continuously increasing number of industrial facilities involving nuclear techniques, such as nuclear power stations, gamma irradiators, particle accelerators a.s.o., lead to new requirements concerning the control of the ambient background. By considering the ambient background as being composed by two components the natural background and the industrial component - it is of great practical interest to measure separately this two components of different origins. As concerns the industrial component of the ambient background, it is represented mostly by the penetrating gamma-ray field, the other radiation fields being, more or less rapidly, absorbed after emission. In this way the problem considered by us was to separate the natural background from the gamma -ray field of industrial origin (the usual method of subtracting the natural background from the mixed natural background + gamma-ray field is connected very often with some difficulties, as the unknown industrial gamma-ray field can not be canceled for the natural background measurement). For this purpose we decided to use the statistical discrimination method based on the ionization chamber as radiation detector. (author)

[en] The ambient radiation background, sometimes considered as a gamma-ray background, is actually composed by a natural radiation field and an industrial radiation field, produced by nuclear facilities. This work presents a possibility to separate and to measure simultaneously both components by using the statistical discrimination method. As the statistical discrimination method is able to measure mixed radiation fields, characterized by essentially different statistical factors k = σ ² / I (I - the mean value and σ ² - the variance of the ionization current), this basic assumption of the method is checked, for the natural background and the gamma-ray checked, for natural background and the gamma-ray fields. The obtained value of the ratio k_B / k _γ = 9 has confirmed the validity of the statistical discrimination method as well as the assumption of a small contribution of the gamma-ray field to the ambient radiation background. Some estimations of the statistical uncertainties, associated with the measurement of two components of the ambient background field have been made. For a 10 liters, atmospheric pressure air - filled ionization chamber (or its equivalent, i.e. 2 liters, 5 atmospheres air -filled chamber) and a 30 s integration time constant, the minimum detectable absorbed dose rate of gamma-rays, for a 0.1 μ Gy / h natural background absorbed dose rate, is equal to 0.02 μ Gy / h. The statistical relative uncertainty of measurement for a 0.5 μ Gy / h absorbed dose rate gamma-ray field, corresponding to the admissible value of the equivalent dose rate of 0.6 μ Sv / h, for non-professional population is about 4 %. (authors)

[en] The purpose of the present work is to present a fast method for testing and calibration of the airborne tritium measuring equipment used in nuclear power plans area, factories of production or handling tritium in air. (Author)

[en] An experimental study of the statistical fluctuations of the ionization chambers current, by using conventional techniques, has been performed. In order to get the needed statistical accuracy, sets of up to three hundreds repeated measurements have been done. The dependence of the ionization current variance on the main parameters taken into account has a structure similar to that described by the shot noise formula, but it leads to much larger values for the variance. (Author)

[en] For the purpose of getting more detailed information concerning the processes leading to statistical fluctuations of an ionization chamber current, measurements with various radioactive sources have been done. By using the experimental arrangement described elsewhere [A. Necula et al. Nucl. Instr. and Meth. A 332 (1993) 501] the mean value and the standard deviation of the ionization current for ³H (water vapours), ⁶⁰Co (sealed source), ⁸⁵Kr (gas), ²⁰⁴Tl (8 mm diameter disk) and ²³⁹Pu (10 mm diameter disk), beta, gamma and alpha sources have been measured. A statistical model explaining the experimental data is proposed. ((orig.))

[en] The CANDU nuclear power plant releases large quantities of HTO in air. For radiation protection of people living near the NPP it is important to survey the concentration of HTO in air, including the low level of the order of Bq/m³. This method implies using molecular sieves (3 A and 5 A) for retention of air moisture, the extraction of water from molecular sieves and the measurement of HTO concentration with liquid scintillation analyser. Using 100 g of molecular sieves, 2 m³ of air, and 100 minutes for measuring the sample with scintillation liquid, we obtain a detection limit of 1.3 Bq/ m³. (Author)

[en] By using the statistical discrimination techniques, an equipment for simultaneous measurement of natural background and gamma-ray fields has been done. The equipment uses a commercial area monitor, model REUTER-STOKES, RS-111, filled with Argon at high-pressure, ionization chamber and a conventional 586-PENTIUM personal computer, with an incorporated DAS-800 acquisition board, for the statistical processing of the analog signal, furnished by the RS-111 area monitor. (authors)

[en] Due to the low decay energy of tritium the electrical signal corresponding to the volume activity is rather well influenced by almost any other present radiation and, particularly, by the gamma radiation, frequently encountered in atmospheric radioactivity measurements. In this way the measurement of tritium requires the use of special methods of compensation as concerns the effect due to gamma radiation. The mostly used compensation methods are analyzed and their limitation concerning the geometry of measurement and the non-linear behaviour of the measuring chain, are emphasized. The conditions to be carried out by the tritium instrumentation, in order to fulfill the international standard requirements, are underlined. (Author)