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  • Author or Editor: K. Kimura x
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Abstract  

There are two types of lakes in the vicinity of the nuclear fuel cycle facilities in Rokkasho-mura. One is a brackish lake, Obuchinuma Lake, and the other is a freshwater lake, Takahokonuma Lake. Tritium concentrations in Obuchinuma Lake had a good negative correlation with salinity at any sampling point and period. We consider that the water of Obuchinuma Lake has been only slightly influenced by precipitation depending on the ratio of seawater and river water of the Futamata River. Tritium concentrations in Takahokonuma Lake ranged from 0.6 to 1.5 Bq·1-1, and were higher than that in precipitation in Rokkasho-mura. Tritium concentration in rivers flowing into the lakes ranged from 0.7 to 2 Bq·l-1, and were higher than that in the precipitation. It is assumed that ground waters with higher levels of tritium inflow into the rivers.

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Abstract  

A versatile system has been developed for the TL-reader of geological samples by using a personal computer system combined with a ceramic heater and a photon counting technique. A handy heater stack consisting of four ceramic heater plates was operated to ensure constant heating rate by applying phase-control circuit up to 400°C to a normal laboratory AC-power supply in order to obtain the TL-results as quantitatively as possible. From the results of the artificially irradiated quartz, a small amount of sample like 5 mg was verified to be applicable to obtain useful geochronological and geothermal information.

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Abstract  

Excess enthalpies of six binary mixtures of CH3 OD+CH3 OH, CH3 OD+CD3 OD, CD3 OD+CH3 OH, C2 D5 OD+C2 H5 OH, C2 D5 OD+C2 H5 OD, C2 H5 OD+C2 H5 OH have been determined over the whole range of mole fractions at 298.15 K in order to know the isotopic effect on hydrogen-bonding accurately, although there are many reports on the differences in the strength of hydrogen-bonding between OH and OD. All excess enthalpies measured are very small and endothermic. The mixtures of CH3 OD+ CH3 OH, and C2 D5 OD+C2 H5 OH showed the largest excess enthalpies among each methanol and ethanol mixtures. The difference of intermolecular interaction between OH and OD in methanol and ethanol was almost same value of (1.820.04) J mol-1 Excess enthalpies of 1,4-dimethylbenzene+1,3-dimethylbenzene and 1,4-dimethylbenzene+1,2-methylbenzene were measured by three different principle calorimeters at 298.15 K in order to know the precision of calorimetry for a small enthalpy change.

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Abstract  

14C dating of 6 Japan cedars having the relative growing ages were made. On the basis of correlation analysis of our data to a14C age data set, INTCAL of CALIB (Stuiver), the growing ages of these Japan cedars were estimated (BC 1090-2375). The atmospheric14C concentration (Δ14C) at their growing ages were obtained from the14C age data. The variation of Δ14C shows basically the same pattern with that of Europe or America (r=0.783).

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Abstract  

Three commercial nuclear fuel cycle facilities, a reprocessing plant, an uranium enrichment plant and a low level radioactive waste disposal center, have been constructed or are in partial operation at Rokkasho-mura in Aomori prefecture, about 700 km north of Tokyo. A monitoring program has been settled on the modulation between Japan Nuclear Fuel Ltd. (JNFL) and Aomori Prefectural Govemment. The basic goal of environmental monitoring is to make sure that the dose equivalent received by the public, living around the facilities, is much lower than the annual dose equivalent limit. The target is as follows: (1) to estimate the dose equivalent received by the public, (2) to understand the accumulation of radioactive materials in the environment and (3) to estimate the influence on the environment due to unexpected release from the nuclear facilities and to make judgement for the enforcement of routine monitoring or not. This paper describes the contents of the monitoring program such as the object of nuclides, measuring/sampling point, kinds of samples etc.

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Abstract  

Aomori Prefectural Govemment and Japan Nuclear Fuel Limited started environmental radiation monitoring around Nuclear Fuel Cycle Facilities in April 1989. External radiation is measured by NaI(TI) scintillator and Themoluminescence dosimeter. The level of external radiation is relatively low in the winter due to snow. We have collected terrestrial samples of drinking water, soil, agricultural products and marine samples of seawater, sea sediment, seafood, etc. periodically. We have measured many radionuclides and fluoride in these samples. In soil sample,239+240Pu ratio to137Cs was almost constant at all sampling points. A correlation was observed between salinity and concentration of tritium, uranium and fluoride in lake water of Lake Obuchinuma. The correlation between137Cs and239+240Pu in lake sediment was observed in each lake.

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Abstract  

The molar excess enthalpies of 1,2- and 1,3-propanediamine+1,2- and 1,3-propanediol have been determined at 298.15 K by using a twin-microcalorimeter which requires each component liquid 1 to 1.5 cm3 for a series of runs over the whole range of mole fraction. All excess enthalpies are exothermic and large. An equilibrium constant K1 expressed in terms of mole fractions and standard enthalpy of formation of 1:1 complex have been evaluated by ideal mixtures of momomeric molecules and their associated complexes.

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Abstract  

The heat capacities of binary aqueous solutions of 1,2-ethanediol, 1,2-propanediol and 1,2-butanediol were measured at temperatures ranging from 283.15 to 338.15 K by differential scanning calorimetry. The partial molar heat capacities at the infinite dilution were then calculated for the respective alkanediols. For 1,2-ethanediol or 1,2-propanediol, the partial molar heat capacities at the infinite dilution of increased with increasing temperature. In contrast, the partial molar heat capacities of 1,2-butanediol at the infinite dilution decreased with increasing temperature. Heat capacity changes by dissolution of the alkanediols were also determined. Heat capacity changes caused by the dissolution of 1,2-ethanediol or 1,2-propanediol were increase with increasing temperature. On the other hand, heat capacity changes caused by the dissolution of 1,2-butanediol are decrease with increasing temperature. Thus our results indicated that the structural changes of water caused by the dissolution of 1,2-butanediol differed from that of the two other alkanediols.

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Abstract  

The complex formation of LaCl3 with dipivaloylmethane (dpm) was investigated in a view of the applicability to a rapid chemistry. It was found that the complex formation of lanthanum chloride with dpm in a gas phase was recognized and a volatile LaCl2 (dpm) which was formed by substitution of a chloride atom in LaCl3 by dpm molecule was mainly produced. A temperature dependence of LaCl2 (dpm) formation was examined and the activation energy of the reaction was deduced.

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Abstract  

The preparation of no-carrier-added48V(IV) and48V(V) from a natural titanium target irradiated by a proton beam has been developed. The48V recovered from the target by solvent extraction was purified as48V(V) with a cation exchange column and then converted to48V(IV) by reduction with ethanol. One hour irradiations at 10 A of 18 MeV protons gave approximately 2mCi (a radiochemical yield of 41%) of radiochemically pure and almost salt-free48V(IV) and48V(V) with high specific activities. They were shown to be suitable for biological tracer use.

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