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Abstract  

This paper describes the analytical methods for the determination of237Np, Pu isotopes, and241Am, with particular emphasis on237Np by alpha-ray spectrometry and241Pu by liquid scintillation technique. Results are also presented for the sediment cores collected from Mikata Five Lakes in Fukui Prefecture, Japan.

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Abstract  

Tritium concentration of organically bound hydrogen has been measured during the 1941 to 1987 period using a cellulose fraction extracted from pine tree grown in Tatsunokuchi-machi, Ishikawa Prefecture, Japan. It was concluded that most of the tritium bound in cellulose was supplied from the mixture of underground water in the root zone of the pine tree. Underground water was strongly influenced by the precipitation and waters with different residence times.

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Abstract  

Chemical leaching experiments of237Np in the sediments from the Esk Estuary and the Ribble Estuary in the Irish Sea, U. K., have been carried out, in comparison with those of239, 240Pu and241Am, to understand the geochemical associations of these long-lived radionuclides with sediment. Experimental results show that partitioning behavior of237Np is obviously different from those of239, 240Pu and241Am.

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Abstract  

210Pb and210Po in human hair have been measured to serve as an aid in order to estimate the dietary intake and body burden of these radionuclides of Japanese. The210Po concentrations found in 83 hair samples were ranging from 4.0 to 59.3 mBq/g with a mean (median) value of 18.2±12.2 (14.9) mBq/g as compared to the210Pb concentrations from 0.7 to 6.5 mBq/g with a mean (median) value of 2.3±1.1 (2.0) mBq/g. The210Po/210Pb activity ratios (mean: 8.7±5.1, median: 7.1) were surprisingly higher compared with the available literature value of about 2. The high concentration of210Po in human hair of Japanese may be due to the ingestion of animal protein mainly in the form of seafood.

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Abstract  

All of the combustion water samples extracted from cellulose in pine tree rings corresponding to the 1983–1987 period showed elevated tritium concentrations of approximately 65 pCi/dm3, which were 30 to 35 pCi/dm3 higher than those for precipitation and atmospheric vapor in recent years. In addition, other environmental samples, viz. the tissue-free water in tree rings, and of combustion and tissue-free water in pine needles and spring water near the pine tree site also showed concentrations similar to the combustion water of cellulose. These findings suggest that most of the tritium in tree rings was supplied from underground water containing a high tritium concentration in the root zone of the pine tree.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Komura
,
K. Komura
,
Y. Kuwahara
,
Y. Kuwahara
,
T. Abe
,
T. Abe
,
K. Tanaka
,
K. Tanaka
,
Y. Murata
,
Y. Murata
,
M. Inoue
, and
M. Inoue

Summary  

Extremely low activity levels of cosmic ray induced nuclides have been measured in freshly precipitated rainwater by quick chemical separation coupled with ultra low background gamma-spectrometry. The nuclides detected were 38S (T 1/2 = 2.83 h)-38Cl (37.2 m), 39Cl (55.6 m), 24Na (14.96 h), 28Mg (20.9 h), 7Be (53.3 d) and 22Na (2.602 y). The number of atoms in rain water were evaluated to be ranging from 400-1900 l-1 for 39Cl (n = 6, mean: 1200), 30-1500 l-1 for 24Na (n = 16, mean: 520), 80-600 l-1   for 28Mg (n = 13, mean: 260), 1 . 106-4 . 107 l-1 for   7Be (n = 16, mean: 7 . 106) and 2 . 103-1 . 105 l-1 for 22Na (n = 9, mean: 2 . 104). Measurements of activity levels and activity ratios of short-lived cosmic-ray induced short-lived nuclides will open new method to understand atmospheric processes occurred at the altitude of rain cloud.

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Abstract  

Long-lived radionuclides,99Tc,137Cs,237Np, Pu isotopes and241Am were determined in the long sediment cores collected from nine intertidal sites around the west Cumbria of the Irish Sea, UK. The inventories of all nuclides measured varied considerably among the sampling sites, but generally their inventories decreased with increasing distance from Sellafield. Furthermore, the inventory ratios with respect to relationship with distance from Sellafield enabled comparison of transport behavior of99Tc,137Cs,237Np and241Am compared with239,240Pu. As a consequence, the apparent fractional rate of solution transport to the intertidal sediment was found to increase as follows:99Tc>137Cs>237Np>239,240Pu≥241Am.

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Abstract  

The Niigata Prefectural Govemment has been carrying out an environmental radiation monitoring around the Kashiwazaki Kariwa Nuclear Power Station. Most of the gamma-ray dose rate was dependent on the natural radiation from the ground. The investigations wanted to detemine the natural radiation level in the Kashiwazaki Kariwa area. Gamma-ray dose rates were measured with a scintillation detector. Additionally, the quantity of radionuclides and their contribution to the dose rate were obtained by an in situ measurement method.

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Abstract  

In the usual measurements of radionuclides in the environmental samples by g-ray spectrometry, Compton scattering of 1461 keV g-rays from 40K severely interferes with the detection of artificial radionuclides in marine and agricultural products. In order to eliminate the interference of 40K, we have developed a simple and convenient water leaching treatment method applicable to seaweed (sargasso) samples. By this treatment, over 98% of the potassium in seaweed samples is removed without notable losses of artificial and/or natural radionuclides. In combination with the low-level g-ray counting in the Ogoya underground laboratory, the detection limit could be improved by ~1 order of magnitude.

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Abstract  

To estimate fast neutron fluence released by the JCO criticality accident in Tokai-mura, 54Mn, which is produced by the 54Fe(n,p)54Mn reaction, was determined in soil samples by ultra low background g-ray spectrometry after radiochemical separation. Activities of 54Mn, using 30-200 g soil samples were detected in soil samples from 13 points in all directions within a 20 m zone from the precipitation vessel we have used. The levels of 54Mn ranged from 0.015 to 2.12 mBq/g soil. By using these data and MCNP, the fast neutron fluences were estimated.

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