Half-life determination of 88Kr and 138Xe.

The half-lives of (88)Kr and (138)Xe have been determined with two high purity germanium (HPGe) detectors by the position relay method. Data have been recorded at regular time intervals during measurements covering more than nine times the respective half-lives. This article describes in detail the principle and process of the position relay method with two HPGe detectors. The determined half-lives of (88)Kr and (138)Xe are 2.804±0.015 h and 14.18±0.10 min, respectively.

Noble gas radionuclides in RBMK-1500-type reactor.

The presence of noble gas and other short-lived radionuclides in air borne effluents from RBMK-1500-type reactor has been investigated using experimental and theoretical instrumentation for detection purposes. Activity concentrations of (85m)Kr, (87)Kr, (88)Kr, (135m)Xe, (135)Xe, (133)Xe and (41)Ar were measured in air emissions from Ignalina NPP using a special method and special equipment. Theoretical detection of reactor-borne radionuclides and investigation of their behaviour in a nuclear fuel during operation of nuclear reactor was performed using an analytical model based on reactor physics. An innovative method for the estimation of noble gas flow time from the defective nuclear fuel element through the ventilation stack of NPP to the atmosphere based on comparison of the experimentally and theoretically evaluated activity ratios of (88)Kr/(85m)Kr; (135)Xe/(133)Xe has been proposed. The estimated flow time of noble gas provides an excellent possibility to obtain modelling-based information about the qualitative and quantitative content of atmospheric releases from NPP.

Flow calorimetry of the sorption of butanols to elastin preparations and comparison with surface areas determined by krypton-85 adsorption.

1. The apparent surface areas of elastin samples as well as of several other fibrous protein preparations (collagen, keratin, polymeric stroma of aorta) were determined using two different approaches: (a) the Brunauer-Emmett-Teller method with 85Kr and (b) microflow calorimetry with n- and tert.-butanol as adsorbents in a heptane stream. 2. Areas of heat signals obtained by flow calorimetry for the adsorption and desorption of n- and tert.-butanol were substantially equivalent; desorption was more protracted than adsorption, the difference between the speed of desorption and adsorption increased with decreasing chain length of the alcohols (methanol, ethanol, n-propanol and n-butanol). 3. An inverse linear relationship was found between the energy change recorded during the adsorption process and the chain length of the alcohols (methanol, ethanol, n-propanol, n-butanol). 4. Heats of adsorption of tert.-butanol were systematically found to be significantly lower than those of n-butanol with all the protein samples investigated. 5. The apparent surface areas of the protein samples determined with tert.-butanol were on the average of the same order or only slightly higher than those obtained with 85Kr. Results obtained with n-butanol were significantly higher. The difference between surface areas obtained with n- and tert.-butanol depended on the nature of the protein sample, on its method of preparation and to some extent on the residual humidity of the sample. 6. The results could be explained on the basis of the hydrophobic theory of elastin structure (see ref. 4) and confirmed our former conclusions (see ref. 3) concerning the significantly higher surface areas of elastin samples purified by different procedures as compared to collagen or to keratin. They also confirmed the accessibility of the surface of elastic fibers to the molecular probes used in the polymeric stroma of aorta.