Neutron activation analysis of nickel purified by floating zone-refining and anion exchange.

Nondestructive neutron activation analysis was performed on the nickel purified by floating zone-refining and anion exchange. It is found that floating zone-refining in vacuum is effective to remove Na, Sc, Cr, Zn, As, Ag, Sb and Hg through vaporization in addition to elimination of Se, Sb, Ta, Sm and Tb through segregation. Anion exchange method is also effective to separate Fe, Co, Zn, Mo, Hg, Th and U usually contained in the commercial nickel sources. It is concluded that combination of these two purification methods is required to obtain high purity nickel, since floating zone-refining is known ineffective to eliminate Fe and Co, main impurities in commercial nickel sources.

Study on trace impurity elements in highly purified iron and aluminum by neutron activation analysis.

Activation analysis was carried out on the purified iron and aluminum to study the behavior of trace impurities on purification process, and to estimate the purity of the purified samples. Thermal neutrons with high Cd ratio through D2O column or graphite column were used for the activation of samples to reduce the interference effects by fast neutrons, the reactions, (n, p) or (n, a), from matrix elements. On the zone refined aluminum, the segregation of impurity elements was cleary observed. In the case of iron, decrease of impurity content was confirmed on superposing the various purification processes.

Determination of thorium series nuclides in thorotrast patients.

Application of gamma-ray spectrometry with a Ge(Li) detector and then instrumental neutron activation analysis to tissue samples from a Thorotrast patient using the same standard reference sample makes it possible to determine both 232Th concentrations and activity ratios of the descendant nuclides to 232Th in living tissues. This analytical method is nondestructive, being simpler and more reliable than the methods previously used. In the present study, the activity ratio of 228Ra/232Th in living tissue was estimated at 0.37 to 0.44, being somewhat lower than the value reported by Kato. As for the activity ratio of 228Th/228Ra, our value agreed fairly well with Kato's value. A stomach sample from a Thorotrast patient was found to contain the same level of 232Th as liver and spleen samples; trace amount of 232Th was also found in kidney and brain samples.

[Simultaneous analyses of gaseous and particulate sulfur in the atmosphere by X-ray fluorescence spectrometry--discussion on the results of observation and presentation of the problems involved in the methods of sampling and analysis (author's transl)].

Following the previous article, the results of observation are discussed in relation to meteorological conditions. The frequency distribution of gaseous sulfur concentrations (1 hr mean values) was bimodal as the result of the alternation of land and sea winds. The frequency distribution of particulate sulfur concentrations was also bimodal, but this can be rather ascribed to the variation of weather. The correlation between the concentrations of gaseous and particulate sulfur was not so great as was expected. Autocorrelations of the concentrations of gaseous and particulate sulfur were respectively investigated, and it was found that the variation of gaseous sulfur concentration showed daily cycle, and, against this, the variation of particulate sulfur concentration did not show appreciable daily cycle, but had weather correlation. Some discussions are presented concerning the selection of sampling points suitable for clarifying the behavior of sulfur in the atmosphere as well as the improvement of the methods of sampling and analysis.

[Simultaneous analyses of gaseeous and particulate sulfur in the atmosphere by X-ray fluorescence spectrometry--results of observation and discussion-- (author's transl)].

Concentrations of gaseous and particulate sulfur in the atmosphere were simultaneously measured for 24 hours at a time interval of one hour by the use of the method described in the previous report (this journal, 24, 312 (1975)). Such measurements were made sixteen times in the period from April to September, 1975. As the result of the measurements, it was found that the method used can be applied to practical observation with sufficient reliability. The concentration of gaseous sulfur showed always a larger variation coefficient than that of particulate sulfur. Both the concentrations of gaseous and particulate sulfur were found strongly dependent on the wind direction and velocity and other meteorological conditions. After hot and fine days continued, the concentration of particulate sulfur rose considerably reaching 20 microgramS/m3.

Plutonium-238 in fallout.

The observed variation in the activity ratio of plutonium-238 to plutonium-239 plus plutonium-240 in rainwater in Japan over the period from 1961 through 1968 seems to indicate that the influence of the plutonium-238 released by the burnup of the nuclear auxiliary power generator (SNAP-9A) became noticeable within about 6 months and that variation in the isotope ratio with time is affected by nuclear debris produced in the latest explosions as well as by the plutonium-238 released from the SNAP-9A generator.