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Abstract  

At Tsugu mine in Aichi Prefecture, antimony was mined and smelted until 1956. The amounts of antimony present in the soil of the abandoned mine were measured to enable us to detect any traces of the operation of the mine and to measure the level of environmental contamination with antimony. The quantity of antimony in rings of hinoki and sugi was also measured to obtain information about chronological changes in environmental conditions. The quantity of antimony in the samples was determined by INAA. The antimony concentrations in eight soil samples at different points in the Tsugu mine area were 8–17,000 ppm.

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Abstract  

Due to the different 240Pu/239Pu atom ratios from different sources of Pu in the environment, Pu isotopes have been widely used for source identification of radionuclides in sediments. In this work, using sector-field ICP-MS, we investigated Pu inventory and its isotopic composition in a lacustrine sediment core collected in Chenghai Lake, SW China. The 240Pu/239Pu atom ratios in this sediment core ranged from 0.166 to 0.271 with a mean of 0.195±0.021, which was slightly higher than that of global fallout. The 239+240Pu/137Cs activity ratios ranged from 0.0155 to 0.0411, with a mean of 0.0215, and the 239+240Pu inventory was 35.4 MBq/km2; both 239+240Pu/137Cs activity ratio and Pu inventory were close to those values of global fallout at 20–30 °N. Three peaks were observed for both 137Cs and 239+240Pu activities in the examined sediment core; they most probably indicated the maximum deposition of global fallout between 1963 and 1964, the fallout from a series of Chinese nuclear tests during the 1970s, and the deposition of resuspended Pu-bearing particles from the Chernobyl accident. Therefore, the vertical profile of Pu isotopes should provide useful time markers for rapid dating of recent sediments.

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Abstract  

The carbon-14 concentration in tree-ring cellulose of an 80-year-old pine tree which has been used for tritium measurement was measured during the 1941–1987 period. This was done to determine the formation year of each tree ring in order to study the pathway of tritium uptake into the tree rings. In the 1941 to 1953 period, the Δ14C value remained slightly lower than 0%., It began to increase from 1954 to a small broad peak of 250% between 1959 and 1961, followed by rapid increase to the highest value of approximately 800% in 1964. Since 1964, it had been diminishing year by year to reach a level of 190% in 1987. The two peak years coincided with those in the known carbon-14 patterns in tree rings. However, there existed a difference in the amplitude of the Δ14C values during the period of 1963–1967.

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Abstract  

A neutron activation method based on the measurement of tritium radioactivity produced by6Li (n,)3H reaction was applied to determine the isotopic abundance of6Li in aqueous solution with known lithium concentration. Tritium radioactivity was measured with a low background liquid scintillation counter over a period of 2000 min. The present method demonstrated a good linearity between the isotopic abundance of6Li and tritium radioactivity produced per unit amount of lithium in a wide range of lithium concentration. A comparison of the present data with those from mass spectrometry showed agreement, though our method was 10 times less sensitive, than mass spectrometry. The present new approach should thus prove quite useful for determining the isotopic abundance of6Li.

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Abstract  

The fraction of labile hydrogens to total hydrogen atoms in cellulose isolated from a pine tree was found to be 10–11%. Most labile hydrogens in hydroxy groups of the cellulose could be eliminated within 6 h by heat treatment at 110°C with CuO in a flow of gas containing oxygen, due to dehydration of cellulose by interaction with oxygen which was accelerated by the presence of CuO. The contaminating effect of labile hydrogens on the measurement of tritium preserved in cellulose may thus be disregarded when such heat treatment is performed.

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Abstract  

The daily variation of14C concentrations of liberated CO2 in the free fermentation process of Japanese SAKE brewing was studied. Each of the concentrations measured in the initial and final stages of the fermentation process correlated with levels of koji rice and steamed rice used for SAKE production, which had been obtained from different areas. This shows that analysis of fermenting CO2 of SAKE could be used to estimate the14C level in a local environment.

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Abstract  

Explosive depressurization offered an effective pre-treatment for isolating -cellulose from wood chips using the common chlorite method. This operation shortened the time required for isolation of -cellulose of relatively high purity by up to 6 h, and raised the relative crystallinity of the product to 65–72% from 50% or below for the unexploded samples. The steam-explosion was carried out by combining 2 min of pre-hydrolysis at a pressure of 3.55 MPa with a rapid decompression. This was found to be the best operating condition for pine wood chips of 1 mm thickness to analyze the tritium content in tree rings accurately.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Y. Kobayashi
,
Y. Tsuruoka
,
M. Kubo
,
H. Nonaka
,
Y. Yamada
,
Y. Sakai
,
H. Shoji
,
W. Sato
,
A. Shinohara
,
Y. Watanabe
, and
H. Matsue

Abstract  

In order to investigate the physical and chemical effects of neutron capture reaction, a neutron in-beam Mössbauer spectroscopic study on two isomorphs of iron disulfide: pyrite and marcasite, were carried out with a parallel plate avalanche counter at room temperature. In both compounds only two major products accounted for the obtained spectrum: one with Mössbauer parameters close to the parent compound and the other one considered to be a new product. The yield of the parent-like species was different in the two isomorphs.

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Abstract  

We have constructed a new system which could analyze a position distribution of several elements in a sample with 2 dimensional prompt γ-ray analysis (2D PGA) system using focused neutron beam at JAEA. We aimed that the system could analyze local information in a sample with a good signal γ-ray from interested elements to noise of background γ-ray ratio. As a result, this system could determine the position resolution and spatial resolution within 1 mm.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Y Kobayashi
,
M. Kubo
,
Y. Yamada
,
T. Saito
,
H. Ueno
,
H. Ogawa
,
W. Sato
,
K. Yoneda
,
H. Watanabe
,
N. Imai
,
H. Miyoshi
, and
K. Asahi

Abstract  

In-beam Mössbauer spectra of 57Fe, decayed from short-lived 57Mn (T1/2 = 1.45 min) implanted into potassium permanganate, KMnO4, were measured at temperatures between 11 K and 130 K. This is the first application of a secondary RI beam to the study of valence states after nuclear transformation. The in-beam Mössbauer spectra obtained below 90 K could be analyzed with two components, a doublet and a singlet. From the calculations of the molecular orbital wave functions, the singlet is suggested to be substitutional 57Fe atoms for Mn-sites in tetrahedral [MnO4] with an unusually high valence state of Fe8+.

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