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Volume 45, Issue 1
Displaying 1-12 of 12 articles from this issue
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Shoichi FUMA, Yoshikazu INOUE1996 Volume 45 Issue 1 Pages 1-7
Published: January 15, 1996
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe authors tried to determine 14C in environmental samples by the simplified and relatively precise method employing a CO2 absorbent and a liquid scintillation counter. Commercially available CO2 absorbent, CARBO-SORB (Packard Instrument Co.) and its scintillator, PERMAFL UOR E+ (Packard Instrument Co.) were used.
A counting sample of 100 ml could contain carbon up to 2.78g. No reemission of CO2 from CO2 absorbent was observed for 5 months after absorption. Any colorations, which disturb liquid scintillation counting and were observed in previous CO2 absorption methods, were not observed in this method. The external standard channel ratio (ESCR) decreased for the first two weeks after sample preparation and then became constant while the counting rate was constant. Measurement of 14C was therefore carried out at least two weeks after sample preparation.
Absorption of CO2 reduced the quenching caused by CO2 absorbent, a kind of amine compound. The background counting rate and the counting efficiency increased with CO2 saturation fraction but could be estimated by ESCR. Lower detection limit was approx. 0.2 dpm/gC, which is obviously lower than the present 14C level, when the counting sample in a 100 ml quartz vial was saturated with CO2 and counting time was 2000 min. The 14C in environmental samples could be precisely determined by using a 20 ml vial as well as by using a 100 ml vial.
The 14C concentration in a sample of rice harvested in Chiba Prefecture, Japan in 1993 was determined as 15.1±0.2 dpm/gC by this method. This value was close to 14C concentrations which other researchers determined in environmental samples collected in Japan in 1993.View full abstractDownload PDF (639K) -
Hiroshi IMAIZUMI, Tatsuya ISHII1996 Volume 45 Issue 1 Pages 8-13
Published: January 15, 1996
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe tritium (T) labeled polyacrylamide (abbreviated PAAm (T) below) was synthesized using the hydrogen-isotope exchange reaction (gas-solid reaction) between HTO vapor and PAAm. The degree of the polymerization of PAAm used was 2 800 (and 80 000) (abbreviated PAAm2800 (and PAAm80000) below) . Using the PAAm (T) thus obtained, the hydrogen-isotope exchange reaction (liquid-solid reaction) between PAAm (T) and each liquid organic material has been observed at the temperature range of 50 to 90°C.
Applying the A″-McKay plot method to the data thus obtained, the rate constant (k) for the reaction was obtained. Including k obtained previously, the value of k thus obtained were compared with each other. The following six items consequently have been confirmed. (1) The reactivity of PAAm80000 is larger than that of PAAm2800. (2) PAAm2800 is about 0.4 times PVA2900 in reactivity. (3) The temperature dependence of the reactivity of PAAm2800 is about 6 times that of PVA2900. (4) The reactivity of these three compounds for several liquid organic materials can roughly be expressed as follows: (PVA2900) : (PAAm80000) : (PAAm2800) =1: 1: 0.3. (5) It is possible to use PAAm as a solid material in the liquid-solid reaction (instead of PVA) . (6) The method used in this work can be useful to clarify the reactivity of a certain material, and to obtain the data for the prevention of tritium-contamination.View full abstractDownload PDF (629K) -
Ryuhei KUROSAWA, Takeshi IIMOTO, Takeshi ICHIJI, Shinji TOKONAMI1996 Volume 45 Issue 1 Pages 14-19
Published: January 15, 1996
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSPractical interpretative method for indicating values of the potential alpha energy concentration (PAEC) continuous monitor, especially a gross-alpha-counting type, is discussed. Radon WL Meter developed by Thomson & Nielsen Electronics Ltd. in Canada is adopted for the numerical analysis as a typical example of this kind of monitor.
There is a time-lag of response to time-variation of PAEC due to the half life of radon decay products. As regards Radon WL Meter, the measuring interval being 60 min, the output counts are es-timated to be in proportion to the mean PAEC about 80 min before the actual output time.
Indicating values of the Radon WL Meter are infected with thoron decay products in the air. Thus the ratio between alpha counts due to thoron decay products and the total output counts increases over 10% as the sampling period exceeds 10h. A proposed method for the correction of this influence from thoron decay products, assuming that the concentration of these products is in proportion to the output counts, is discussed.View full abstractDownload PDF (669K) -
Iwao UMEDA, Toshio MUTO, Raita KITSUTAKA1996 Volume 45 Issue 1 Pages 20-25
Published: January 15, 1996
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSFor application of dual energy gamma-ray transmission techniques to practical mineral grade analysis, some problems including selection of gamma-ray energies, influence of sample thickness and main causes of errors in measurement have been examined.
The relationships between the R-values (the ratio of mass attenuation coefficients for low and high energy gamma-rays) and the effective atomic numbers for various samples (e.g., iron ore, coal and coke, limestone, minerals and gem stones) were determined using different energy combina-tions of gamma-rays from 152Eu. On the basis of the experimental results, the optimum conditions for analysis of minerals were discussed.View full abstractDownload PDF (529K) -
Kimitsugu NAKAMURA, Hiroyuki KYUSHIMA1996 Volume 45 Issue 1 Pages 26-37
Published: January 15, 1996
Released on J-STAGE: December 13, 2010
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Takeo HAMA, Junko HAMA1996 Volume 45 Issue 1 Pages 38-46
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
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IV. Biodosimetry for Local Overexposure (Skin Exposure)Yuko BESSHO1996 Volume 45 Issue 1 Pages 47-54
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
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Masatoshi SAKKA1996 Volume 45 Issue 1 Pages 55-62
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
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[in Japanese]1996 Volume 45 Issue 1 Pages 63-64
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
JOURNAL FREE ACCESSDownload PDF (313K) -
[in Japanese], [in Japanese]1996 Volume 45 Issue 1 Pages 65-66
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
JOURNAL FREE ACCESSDownload PDF (232K) -
[in Japanese]1996 Volume 45 Issue 1 Pages 67-68
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
JOURNAL FREE ACCESSDownload PDF (274K) -
[in Japanese]1996 Volume 45 Issue 1 Pages 69-70
Published: January 15, 1996
Released on J-STAGE: July 21, 2010
JOURNAL FREE ACCESSDownload PDF (325K)
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