Fallout Samples Research Articles

A Funnel-Trap for Monitoring Fallout from Forest Canopies after Insecticide Applications

Descriptions of materials and methods used in designing a 1 m^2 trap for collecting fallout samples from forest canopies after treatment with insecticides are presented. These traps were quite effective in collecting the target caterpillars, non-target arthropods, frass, and plant material.

X‐ray emission intensities of radionuclides in fallout from nuclear explosions

AbstractX‐ray emission intensities (number of X‐ray photons per 100 disintegrations) have been computed from gamma ray intensities, internal conversion, electron capture coefficients of the radionuclides and the fluorescence yields of the daughter products of various radionuclides normally observed in fallout from nuclear explosions. X‐ray spectrometry of these radionuclides would supplement the information, currently being obtained by radiochemical separation and subsequent radioactive counting, gamma ray spectrometry of fallout samples using NaI(T1) or Ge(Li) detectors and multichannel analysers. No results are so far available in the literature based on X‐ray spectrometry of radionuclides in fallout because of non‐availability or scanty data on X‐ray emission intensities of various radionuclides.

Some observations based on the measurements on fresh fallout from the recent chinese and french nuclear explosions

China conducted its sixteenth nuclear explosion (fifteenth in the atmosphere) at Lop Nor (40degreeN, 90degreeE) on June 17, 1974. France also started its 1974 test series of nuclear explosions on the same date in the southern hemisphere near Mururoa Atolls (22degreeS, 139degreeW). Radioactive fallout samples from some of these nuclear explosions were collected by swiping certain exposed portions of the aircraft flying between Tokyo/Osaka and Bombay, New York and Bombay (for the Chinese test), and Sydney and Bombay (for the French tests). This paper gives some of our observations based on these studies for samples collected between June 15, 1974, and July 30, 1974. The study involved measurement of a number of radionuclides, i.e., $sup 89$Sr, $sup 99$Mo, $sup 111$Ag, $sup 132$Te, $sup 140$Ba, $sup 237$U, $sup 239$Np, etc. The observed activity ratios for some selected pairs of radionuclides have been interpreted in terms of fissile material used in the device and the type of explosion. (AIP)

A new method for the radiochemical separation of rubidium and cesium

The analytical reactions of bismuth iodide and stannic chloride with cesium and rubidium are used for the radiochemical separation of these two elements. The method consists in precipitating potassium, rubidium and cesium as their cobaltinitrites, selective isolation of cesium as cesium bismuth iodide from glacial acetic acid, and subsequent separation of rubidium from potassium as chlorostannate from conc. HCl. The results obtained by the present method for the rubidium and cesium contents of the different U.S.G.S. standard rock samples are compared with those reported using methods of comparable accuracy. The suitability of the method for the analysis of fall-out samples for their radiocesium (137Cs) contents has been demonstrated.

Observation on the Radioactive Fallout originated from the Chinese Nuclear Explosions

We have observed properties of radioactive fallout originated from the first, the second, the third, the fourth and the fifth Chinese nuclear explosions. The differences in gross beta-activities, activities per unit volume and their particle sizes of highly radioactive particles are discussed with relation to the differences in burst conditions among the five explosions from which they originated.It was found that radioactivities of the highly radioactive particles were roughly proportional to their volumes. The differences in the radioactive decay rates of highly radioactive fallout particles were found in connection with their colors.From the results of decay characteristics of gross beta-activities and γ-ray spectra of fallout samples, it was found that the contribution of radioactivities of 239Np in samples from the fifth Chinese explosion was larger than that from the third Chinese explosion.In comparison between the γ-ray spectra of highly radioactive fallout particles from the third and the fifth Chinese explosions, the particles from the third Chinese explosion were enriched in 95Zr+95Nb and impoverished in 103Ru, while on the particles from the fifth Chinese explosion, the reverse of phenomenon above mentioned was observed.

Radiochemical evidence for antler shot contribution to the September 1961 fallout

In an attempt to resolve contradictory conclusions based on meteorological considerations, we present radiochemical data bearing on the origin of the unusually high radioactive fallout over southeastern United States during the period September 17–22, 1961. The isotopic composition of the escaping cloud from the vented Antler underground shot affords an explanation for the marked enrichment of Ce141 relative to Ce144 in Washington, D.C., fallout samples. The appreciable enrichment of Ce141, Ba140, and Sr90 relative to Ce144 in the fallout over southeastern United States on September 18 and thereafter seems explainable only by the contribution of fractionated debris from the vented underground Antler shot. The radiochemical data are inadequate for an assessment of the relative proportion of Antler shot debris and Soviet atmospheric test debris in the fallout mixture.

Correction factor for self-absorption of flat beta emitters

When measuring the beta radioactivity of samples of atmospheric fall-out it is necessary to make a correction for self-absorption. In this paper the self-absorption factor obtained by a large number of measurements is compared with the theoretical results. Correction curves for fresh atmospheric fall-out (up to the age of 1 month) as well as for an older one (an age of 6–12 months) were determined. As yet no mathematical expression for self-scattering has been derived. For the measuring apparatus in question it was determined experimentally.

Radioactive Fallout in California During the Winter 1961–2

Collections of nuclear debris in dry and precipitation fallout samples were made during the winter 1961–2 at Palo Alto and Santa Barbara, Calif., following resumption of nuclear testing by the USSR. The samples were radiochemically analysed for the fallout radionuclides Sr90 and Sr89. The data show the expected increase in radioactivity levels at each location in precipitation following the Soviet detonations. Palo Alto and Santa Barbara, separated by 300 miles, exhibit close similarity in fallout results. Two interesting changes in fallout concentrations were observed which may be attributed to meteorological influences.

Composition and deposition in Italy of fallout from U.S.S.R. explosions-fall 1961.

Samples of fallout collected at various stations throughout Italy since Sept. 1981 were analyzed for gross composition and levels of Sr/sup 89/, Sr/sup 90/, and Y/sup 90/. Air samples were also analyzed. Food chain contamination was evaluated by analysis of samples of milk and sea mollusks. Ten explosions of the U.S.S.R. nuclear test series were dated. (C.H.)

Seasonal Variation and Age of Radioactive Fall-Out

Seasonal variations in the concentration of long-range fall-out material are discussed, and various meteorological conditions which may account for a spring maxima are reviewed. Data are tabulated from measurements of Sr/sup 9// sup 0/ in rain samples collected in Great Britain during 1960, specific concentrations of Rh/sup 1//sup 0//sup 6/, Sb/sup 1//sup 2//sup 5/, Cs/sup 1//sup 3//sup 7/ and Ce/sup 1//sup 4//sup 4/ in fallout samples, and the fission yield for various types of fission. From calculations based on available information on the dates of megaton explosions, it is concluded that the majority of the fall- out material originated from American and British equatorial tests of 1958. Discrepancies in the yield of Sb/sup 1//sup 2//sup 5/ and Rh/sup 1//sup 0//sup 6/ were found. It is concluded tha t these discrepancies may be explained if, in addition to the 14-Mev fission of U/sup 2//sup 3//sup 8/, other fission processes are involved. (C.H.) .

核分裂生成物のγ線スペクトロメトリ, (V)

The method of analysis of fission products described in the previous paper was applied to some fallout samples. They included snow, dust in the open air and ashes of a plants. Comparison was made between the apparent ages of samples from the experimental γ ray spectra with those from the β decay curves of same samples. The agreement was good in one case, but not in other.The convincible cause of this disagreement was found extraordinary in the predominance of Peak VI in the γ ray spectrum of the latter sample.The data of the plants sample were obtained from other reference. The present method was applied to them and some nuclides were identified in the sample. The good agreement was found between both values of analyzing 95Zr+95Nb, one of which being obtained from the normal method of γ ray spectrometric analysis, and the other of which from present method.Furthermore, some attempts were made to estimate the errors inherent in the method of the present type, viz. misjudgement of “age”; mixing of different “age” fission products; products due to other types of fissions; and depletion of some components in fission products mixtures.It was concluded that the absolute errors of analysis of individual fission products were less than 50% in normal cases.

The sequential analysis of long range fallout debris

A method for the determination of the principal radionuelides of Sr, Ba, Ce, Cs, Y, Zr, Nb, and W in single fallout samples containing bulk Si, Fe, and Ca is presented. The sample and added carriers are dissolved by fusion with sodium carbonate. The melt is leached first with hot water and then with hydrochloric acid. W and Cs are recovered from the water leach. Sr, Ba, Y, and the heavier rare earths appear in the hydrochloric acid leach. Ce is found in the leach residue and Nb in both the residue and the hydrochloric acid leach. The Zr and Nb in the residue are separated from Ce by absorption on an anion-exchanger from hydrochloric acid. The Zr and Nb in the hydrochloric acid leach are separated from Sr and Ba by precipitation of Sr and Ba as nitrates and then separated from Y and the heavier rare earths by absorption on the anion-exchanger. The combined Zr fractions are eluted with dilute hydrochloric acid and Nb with a hydrochloric-hydrofluoric acid mixture.

Detection of manganese-54 in radioactive fallout.

An isolation procedure was adapted to the analysis of a ..gamma..-emitter with an energy of 0.84 m.e.v. from fallout samples following nuclear test explosions. /sup 54/Mn, Ce, and Zr carriers plus the sample were oxidized with NaClO/sub 3/. The insoluble MnO/sub 2/ was reduced with NaHSO/sub 3/, dissolved in HCl, and the mixture was freed of interfering nuclides with Fe(OH) (OAc). The Mn was precipitated as MnNH/sub 4/PO/sub 4/ and ignited to Mn/sub 2/P/sub 2/O/sub 7/, which was counted. The ..gamma..-spectrum of the isolated sample was identical with that of authentic /sup 54/Mn. This nuclide accounted for 40% of the total ..gamma..-activity of the sample. Calculations indicate that megacurie quantities were produced at the time of detonation, possibly from stable Mn and Fe, emphasizing the importance of induced radioactivity in fallout.