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- Author or Editor: H. Nakamura x
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Abstract
By the operation of research reactors, tritium-handling facilities, nuclear power plants, and a reprocessing facility around JAERI TOKAI, tritium is released into the environment in compliance with the regulatory standards.To investigate the levels of tritium concentration in environmental samples around JAERI, rain, air (vapor and hydrogen gas), and tissue-free water of pine needles were measured and analyzed from 1984 to 1993. Sampling locations were determined by taking into consideration wind direction, distance from nuclear facilities, and population distribution. The NAKA site (about 6 km west-northwest from the TOKAI site) was also selected as a reference point.Rain and tissue-free water of pine needles were sampled monthly. For air samples, sampling was carried out for two weeks by using the continuous tritium sampler. After the pretreatment of samples, tritium concentrations were measured by a low background liquid scintillation counter (detection limit is 0.8 Bq/l).Annual mean tritium concentrations in rain observed at six points for 10 years was 0.8 to 8.9 Bq/l, which decreased with distance from the nuclear facilities. Tritium concentrations in rain obtained at Chiba City were around 0.8 Bq/l (1987–1988) and those at the NAKA site were 0.8 to 3.8 Bq/l.Annual mean HTO concentrations in air at three points for 10 years were 9.2×10–2 to 1.1 Bq/m3, although HT concentrations in air, ranging from 1.7×10–2 to 5.8×10–2 Bq/m3, were not influenced by the operation of the nuclear facilities.Annual mean tritium concentrations in tissue-free water of pine needles at four points for 10 years were 1.4 to 31 Bq/l. Those at the NAKA site ranging from 1.4 to 6.2 Bq/l were in good agreement with the reported value by Takashima of 0.78 to 3.0 Bq/l at twenty-one locations in Japan.Monthly mean HTO concentrations in air for 10 years showed a good correlation with absolute humidity, while other samples showed no seasonal variation.Higher level tritium concentrations in rain, in air (vapor), and in tissue-free water of pine needles at the TOKAI site were caused by the tritium released from the nuclear facilities.The committed effective dose equivalent to the member of general public, estimated using the maximum tritium concentration in air (1.1 Bq/m3), was 0.23 
Sv, which was about 1/4000 of dose limit for general public.
Abstract
We measured radiocarbon age of an ancient document “Minamoto no Yoritomo Sodehan Migyosho”. The content tells that it was issued in 1189 by “Minamoto no Yoritomo” known as the virtually first shogun in Japan to grant “Matsugi” family the privilege of controlling craftsmen of foundry industry. Paleographical views, however, suggested that it can be a counterfeit. The radiocarbon dating clarified that the document was written not in the 12th but after the 16th century.
Abstract
The selective transport of yttrium(III) in the presence of iron(III) through a supported liquid membrane (SLM) has been investigated by using di(2-ethylhexyl)phosphoric acid (DEHPA) as a mobile carrier. Yttrium(III) with fast kinetics was preferentially transported from the feed solution of dilute acid into the product solution of 1M H2SO4, while most of iron(III) with slow kinetics remained in the feed solution. The effective separation of yttrium(III) from a large amount of iron(III) was accomplished by the selective transport of yttrium(III) through the SLM.
Abstract
Lanthanides in altered oceanic tholeiite were determined by means of instrumental neutron activation analysis. Potassium content was employed as a measure of degree of alteration. Lanthanide concentrations in moderately altered parts of tholeiite (K2O content below 1%) were identical with those in'unaltered parts while light lanthanide concentrations in more altered parts (K2O content above 1%) increased with degree of alteration.
Abstract
The stability constants, 
1, of each monochloride complex of Nd(III) and Tm(III) have been determined in the mixed system of methanol and water with 1.0 mol·dm–1 ionic strength using a solvent extraction technique. The values of
1 of Nd(III) and Tm(III) increase as the mole fraction of methanol in the mixed solvent system (X
s) increases. However, the variation mode of
1 againstX
s in the region of 0.00
X
s
0.40 differs from each other, a concave curve for the Nd(III) and a convex curve for the Tm(III). The LnCl2+ formed is present as a solvent-shared ion-pair. Since Cl– is a structure breaking ion, it was assumed that the primary solvation sphere of Ln3+ directly contacted with Cl–. Calculation of Ln3+–Cl– distance using Bom-type equation revealed the followings: (1) for Tm3+ with coordination number 8, the estimated distance between Tm3+ and Cl– increases linearly withX
s in 0.00
X
s
0.40. The results mean an increase of the primary solvation sphere size of Tm3+ withX
s. (2) For Nd3+, the distance between Nd3+ and Cl– decreases linearly withX
s in 0.00
X
s<0.13, where both coordination numbers of 9 and 8 coexist, while it increases withX
s in 0.13<X
s
0.40. The results mean a decrease of the primary solvation-sphere size of Nd3+ withX
s in 0.00
X
s<0.13 and an increase of that withX
s in 0.13<X
s
0.40.
Abstract
The stability constants
, of monochloride complex of Eu(III) in the tracer concentrations have been determined in the mixed system of dimethyl sulfoxide
(DMSO) and water with 1.0 mol·dm−3 ionic strength using a solvent extraction technique. The values of
decrease up to about 0.2 mole fraction of DMSO (X
s
) in the mixed solvent system and then increase. Calculation of Eu3+−Cl− distance using a Born-type equation of the Gibbs' free energy derived from the
revealed that the estimated distance between Eu3+ and Cl− (d
Eu−Cl) increases linearly withX
s
in 0≤X
s
<0.043 and 0.043<X
s
<0.172, but their slopes are different. The line in the first region means a linear enlargement of the thickness of the primary
solvation sphere of Eu3+ with increasingX
s
. The larger slope againstX
s
in 0.043<X
s
<0.172 is attributable to lowering of
, based on the increase in the solvation number of the primary solvation sphere of Eu3+. The considerably large value ofd
Eu−Cl atX
s
=0.202 might result from lowering of
by a coordination of ClO
4
−
into the secondary solvation sphere of Eu3+ and the extremely drop ofd
Eu−Cl atX
s
=0.276 might reflect on a conversion of the ion-pair type, i.e., the coexistence of two kinds of a solvent-shared ion-pair
and a contact one by the appearance of the contact one.
Abstract
Neutron activation analyses were performed for the newly issued reference rocks, GSJ JA-1 and JB-2, and also for the widely distributed GSJ JG-1 and JB-1. The contents of fourteen elements could be newly determined for the former two rocks and those of eleven elements were re-determined for the latter rocks.
Abstract
Phase transition process of polyester from phenanthrene, poly(oxyheptamethyleneoxy-2,7-phenantrenedicarbonyl), a main chain type liquid crystalline polymer, was investigated by simultaneous DSC-XRD measurements using the synchrotron radiation facility (PF). Three exothermic DSC peaks were observed during cooling from the isotropic liquid state. These DSC peaks were assigned to the transition from the isotropic liquid to the smectic A, that from the smectic A to C, and that from the smectic C to the crystalline state, respectively, as determined by XRD profiles. The rate of transition from the smectic A to C was very slow compared with the liquid crystalline transition and the crystallization. From the DSC-XRD results, the thermal expansion along c-axis in the crystal and smectic phases are 4.110−4 and 1.410−3 nm K−1 , respectively.
Abstract
A rapid method based on extraction chromatography was developed for the separation of uranium from soil samples for TIMS. The isotope ratios were measured on three standards using a VG 54-30 thermal ionisation mass spectrometer in static mode with Faraday cup and Daly ion counting system. The use of a WARP (Wide Aperture Retardation Potential) energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector TIMS. An abundance sensitivity of 28 ppb at mass 237 with respect to 238U can be achieved. By correcting mass bias as a function of ion beam intensity, precision of the 235U/238U ratio was enhanced with a sample load of around 300 ng U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations. Uranium isotopic compositions have been determined in soil samples and compared between Chernobyl nuclear accident site and the criticality accident, which occurred in Japan at the JCO site.
Abstract
This paper describes effect of base profile for precise measurement of photon energy in prompt 
-ray analysis (PGA). The base profile has been examined in the vicinity of full energy (FE), single escape and double escape peaks. Major origins of step-wise base profiles are single and double escape events for triple photon annihilation and single and double Compton escape events for double photon annihilation in the detector, in addition to general events for the FE peak. A formula has been proposed for the quantitative characterization of the base profile.
