Authors:H. Han, W. Cho, U. Park, Y. Hong, and K. Park
The Korea Atomic Energy Research Institute (KAERI) completed the High-flux Advanced Neutron Application Reactor (HANARO) in 1995 and the radioisotope production facilities(RIPF) in 1997. Many devices and handling tools were developed and applied for the production of radioisotopes. Emphasis on RI production plan was placed on the development of new radiopharmaceuticals, the development of new radiation sources for industrial use and the steady production of selected radioisotopes. The selected items are 166Ho-based pharmaceuticals, fission 99Mo/99mTc generators, and products of 131I and 192Ir and 60Co sources for industrial use. Now KAERI regularly produces radioisotopes (131I, 99mTc, 166Ho, 192Ir, 60Co etc.) and labeled compounds including 99mTc cold kits. Newly developed therapeutic agents are a 166Ho-chitosan complex for liver cancer treatment, a 166Ho patch for skin cancer treatment and devices such as the stent and balloon for the prevention against restenosis of the coronary artery. Feasibility studies on the installation of a 99mTc generator loading facility and on 60Co production for food irradiation were finished. The 192Ir sealed source assembly for NDT has been supplied to domestic users since May 2001. The fission moly process, separation process of non-sealed sources (125I, 33P, 89Sr, 153Sm, 188Re) and fabrication process of sealed sources (169Yb, 75Se) are also under development. For the quality assurance of our final products, we obtained ISO certification in 2000. We are carrying out a feasibility study on a new research reactor for the stable supply of radioisotopes in Korea.
Authors:Chung-Hsin Wu, P. K. Andy Hong, and Ming-Yan Jian
This study utilized Fenton, Fenton-like, photo-Fenton, photo-Fenton-like, sono-Fenton, and sono-Fenton-like systems for the decolorization of Reactive Red 2 (RR2) dye. Fe2+ and Fe3+ were used to catalyze the actions of oxidants H2O2 and Na2S2O8. Pseudo-first order rate constants (k) were obtained by fitting the decolorization kinetics of RR2. With added oxidant at 0.3 mM and iron ion at 0.03 mM, the k values of H2O2/Fe2+, H2O2/Fe3+, Na2S2O8/Fe2+, and Na2S2O8/Fe3+ were 13, 0.67, 6.2, and 0.080 r−1, in order. Higher oxidant and iron concentrations resulted in faster decolorization in Fenton and Fenton-like systems. Additionally, decolorization was accelerated by ultraviolet (UV) and ultrasound (US) irradiation. When ethanol was used as a scavenger for the generated hydroxyl and sulfate radicals, it significantly inhibited the decolorization process in photo-Fenton and photo-Fenton-like systems. The k values obtained for the UV/H2O2/Fe2+, UV/Na2S2O8/Fe2+, UV/H2O2/Fe2+/C2H5OH, and UV/Na2S2O8/Fe2+/C2H5OH systems were 23, 14, 0.36, and 0.69 h−1, in order.
Authors:M. Lee, C. Lee, K. Hong, Y. Choi, and B. Boo
Depth distribution of239,240Pu and137Cs in the soils of South Korea have been studied. The average accumulated depositions were estimated roughly to be 54.8±32.1 Bq·m–2 for239,240Pu, 1.6±1.0 Bq· ·m–2 for238Pu and 1982.8±929.1 Bq·m–2 for137Cs. The activity ratios of239,240Pu/137Cs in soils were found to be in the narrow range of 0.0153 to 0.0364 with a mean value of 0.0230±0.006. The concentrations of239,240Pu and137Cs in soils decrease exponentially with increasing the soil depth. A significant correlation was found between the concentration of239,240Pu and that of137Cs. The activity ratios of239,240Pu/137Cs tend to increase slightly with increasing soil depth.
Authors:K. Park, N. Kim, H. Woo, K. Lee, Y. Yoon, and W. Hong
A radiochemical separation method using an anion exchange resin has been applied to 3N grade Nb for determining nine impurity elements. Five elements (Cr, Fe, Co, Zn and Se) were separated in 2M HF, three elements (Mo, W and Hf) in 32M HF, Nb in 0.5M HF/3M HCl, and Ta in 1M NH4F/4M NH4CCl. The contents of the elements were calculated by a single comparator method using two monitors of Au and Co. The main impurity was revealed to be Ta with a content of over 160 ppm.
Authors:K. Ito, Li Hong-ling, Y. Saito, T Yamamoto, Y. Nishihara, Y. Ujihira, and K. Nomura
The free-volume, of size ranging from 0.2 to 0.4 nm in radius, in an ethylene-vinyl alcohol copolymer was estimated using positronium lifetime measurement to elucidate the dependence of oxygen permeability on the free-volume size and fraction, on the ethylene content and on the crystallinity. The permeability and the free-volume fraction with varying the ethylene content were well related and the relation was interpreted based on the free-volume theory near below and above the glass transition temperature. On the other hand, the crystallinity significantly influenced the fraction of the amorphous region, where the free-volume hole exists, along with a slight change of the free-volume size. The variation of the permeability with the crystalline degree cannot be explained from the averaged free-volume fraction estimated by the whole volume of the polymer, but the permeability correlated with the free-volume size apparently.
Authors:J. Park, K. Lee, C. Lee, Y. Kwon, J. Lee, J. Kim, and W. Hong
A (D3C)2O (d6-acetone) target was irradiated with semi-monoenergetic neutrons generated from 9Be(p,n)9B reaction with 20 MeV protons to convert 13C and oxygen nuclides in the target into 14C. With both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) we measured the (D3C)2O (d6-acetone) liquid targets, which were combustible and easy to afford CO2 for the AMS measurements. The 14C yield measured by the LSC method turned out to be 80 times larger than that by the AMS method. This large discrepancy may
be attributed to the loss of 14C atoms during the sample pretreatment in the AMS method such as combustion and cryogenic trapping of CO2. It means that 14C newly produced by nuclear reactions can exist in various chemical forms, i.e., C3D6O, CO, CO2, hydrocarbons, etc., and a simple sample pretreatment right after production can cause serious isotopic fractionation. Therefore,
using the AMS method, extreme caution in sample pretreatment should be exercised when the 14C yield produced immediately by nuclear reaction is measured.
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.