The influence of co-ions in the eluent on the separation factor () of lithium isotope separation has been studied by ion exchange chromatography. A strongly acid cation exchange resin (Dowex 50W-X8) was used for the separation of lithium isotopes. The co-ions used in eluent were H+, K+, Ba2+, Cu2+, Al3+ and Cr3+ as their chlorides. From the experiments, it was found that6Li was enriched in the resin phase and7Li in solution phase. At the same distribution coefficient (Kd=30), the separation factor increased linearly with the charge of co-ion (=1.0022 to 1.0039).
Authors:G. Kim, H. Woo, J. Kim, T. Yang, and J. Chang
Monochromatic MeV-energy neutron source for secondary reaction was developed utilizing tritium embedded titanium (Ti-3H) thin film via 3H(p,n)3He reaction. We have measured the neutron energies and the energy spread by resonance reactions of 12C(n,tot) and 28Si(n,tot). The available energy was within the range from 0.6 to 2.6 MeV. Energy spread was 1.6% at energy of 2.077 MeV. The
flux in the beam direction was determined to be 3.76·107 n/s/sr by irradiating 197Au by about 2 MeV neutrons. This source was shown to be useful for measurements of nuclear data by measuring the total cross
sections of neutrons on Fe and comparing these data to the data of ENDF-6.
We extend a theorem of Kist for commutative PP rings to principally quasi-Baer rings for which every prime ideal contains
a unique minimal prime ideal without using topological arguments. Also decompositions of quasi-Baer and principally quasi-Baer
rings are investigated.
Authors:C. Kim, C. Kim, B. Chang, S. Choi, C. Chung, G. Hong, K. Hirose, and H. Pettersson
239+240Pu concentrations and 240Pu/239Pu atom ratios in bottom sediments of the Yellow Sea, Korea Strait, East Sea (Sea of Japan), Sea of Okhotsk, and Northwest Pacific Ocean were determined. In coastal sediments near the Korean Peninsula, 239+240Pu concentrations varied from 0.02 to 1.72 Bq.kg-1, and their 240Pu/239Pu atom ratios from 0.15 to 0.24, with an average of 0.20±0.03. 240Pu/239Pu atom ratios of bottom sediments in the deep NW Pacific Ocean and its marginal seas (East, Okhotsk seas) were in the range of 0.15-0.23. A little elevated 240Pu/239Pu atom ratios in the bottom layer sediment may be due to Pu released into the environment during the pre-moratorium period, having high 240Pu/239Pu atom ratios and low 238Pu/239+240Pu activity ratios.
Authors:J. Park, G. Kim, W. Hong, C. Lee, Y. Kwon, K. Lee, and J. Kim
We have measured the cross sections of the 16O(n,t) reactions above 18.1 up to 33.1 MeV in an neutron activation method. H2O (water) as an 16O target was irradiated with semi-monoenergetic neutrons generated from the 9Be(p,n)9B reaction with 25–35 MeV protons. The neutron flux was obtained with the aid of previous study by Uwamino et al. (Nucl Instr
Methods A 271:546, 1988). The tritium activities were measured by using the liquid scintillation counting (LSC) method. The
present value for the cross section of 16O(n,t) reaction agrees with previous values measured by using the same LSC method at similar neutron energy ranging from 18.1
up to 33.1 MeV.
Authors:G. Kim, W. Hong, H. Woo, J. Kim, C. Eum, J. Chang, and K. Park
A nanosecond proton bunching system has been constructed at Korea Institute of Geoscience and Mineral Resources (KIGAM). This
pulsed ion beam will be converted into corresponding duration of neutron pulse, which can reduce the scattered neutron background
during neutron spectroscopy. The pulsed beam is obtained by deflection and double bunching by RF field. RF fields are applied
to deflection and bunching electrodes as 2 kV p-p, 4 MHz and 2 kV p-p, 8 MHz, respectively. A push-pull RF amplifier has been
designed and constructed with a maximum output power of 300 W continuous wave (CW) between 2 and 30 MHz. The main parameters
of bunching beam were as follows: 8 MHz repetition rate, 2 ns FWHM, approximately 20% of duty factor and the maximum energy
spread of 2 keV within a pulse.
Authors:G. Kim, H. Woo, H. Choi, N. Kim, T. Yang, J. Chang, and K. Park
Neutron capture cross sections on 63Cu and 186W were measured by fast neutron activation method at neutron energies from 1 to 2 MeV. Monoenergetic fast neutrons were produced
by 3H(p,n)3He reaction. Neutron energy spread by target thickness, which was assumed to be the main factor of neutron energy spread,
was estimated to be 1.5% at neutron energy of 2.077 MeV. Neutron capture cross sections on 63Cu and 186W were calculated by reference comparison method on those of 197Au(n,γ). Not only statistical errors of gamma-counts from samples but also systematic errors in the counting efficiency for
HP Ge detector and the uncertainty of areal density of samples were considered in calculating neutron capture cross section.
Estimated neutron capture cross sections on 63Cu and 186W were also compared with ENDF-6 data.
Sorghum bicolor (L.) Moench contains various phenolic compounds such as anthocyanin. Eleven sorghum accessions were classified into five groups by grain colour and their antioxidant activities were measured as well as the contents of total phenolic compounds (TPC) and anthocyanins in sorghum grains. The grain colour was related to TPC content, but not to monomelic anthocyanin content. Moreover, the overall patterns of antioxidant activity levels in 2,2-Diphenyl-1-picrylhydrazyl (DPPH) or 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay were similar to those of the TPC content. Correlations between TPC and anthocyanin contents were statistically significant and positive (P < 0.05). TPC content showed also a strong positive correlation to DPPH and ABTS antioxidant activities. The results provide the basic data for breeding of sorghum varieties containing large amounts of antioxidants.
Authors:M. Baik, S. Kim, J. Lee, S. Lee, G. Kim, and S. Yun
Sorption experiments for radionuclides such as 14C, 99Tc, 137Cs, 90Sr, 63Ni, and 241Am were conducted using two different groundwaters (GM-1 and SS-5) and solid materials (granodiorite and fracture-filling
material) sampled from the Wolsong low- and intermediate-level radioactive waste (LILW) repository, Gyeongju, Korea. The distribution
coefficients of the radionuclides, Kd’s, were obtained and their sorption properties were discussed for each radionuclide. For all sorbing radionuclides, the Kd values for the fracture-filling material were observed to be higher than those for granodiorite regardless of the groundwater.
The Kd values were increased in the sequence 99Tc < 14C < 90Sr < 137Cs < 63Ni < 241Am regardless of sorbent types implying that the sorption of radionuclides onto geological media is affected by their chemical
behavior in accordance with geochemical environments. Anionic radionuclides such as 14C and 99Tc showed very low Kd values both for the granodiorite and fracture-filling material. The mineralogical composition of the geological media and
groundwater conditions was also observed to be important in the sorption of sorbing radionuclides, especially in the case
of strongly sorbing radionuclides.