• Journal of Radiation Protection and Research
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• v.39 no.1
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• pp.14-20
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• 2014

A lot of radiation exposure for radiation workers who are engaged in Nuclear Power Plants, especially PWRs, have been caused during the outage by CRUD, such as $^{58}Co$, $^{60}Co$, in Reactor Coolant System. And therefore we need to know source terms to achieve optimization of protection for the radiation workers from radiation exposure at Nuclear Power Plants efficiently. This study analyzed source terms at domestic NPPs (PWRs) nearby Steam Generator with CZT semiconductor detector using by IN-VIVO method during the outage for the first time in the country. We checked difference for the detected source terms between old and new NPP. It was performed especially to see a change of source terms by water chemistry process as well. There was not any difference by water chemistry process both NPPs. The main source terms are $^{58}Co$ and $^{60}Co$ at all NPPs. $^{59}Fe$ only appears in the new NPP. $^{137}Cs$ and $^{95}Zr$ are shown in the old NPP. The fraction of $^{58}Co/^{60}Co$ in the new NPP is higher than the old NPP for increasing the specific activity of $^{60}Co$.

• Journal of the Korean Magnetics Society
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• v.9 no.5
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• pp.251-255
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• 1999

NiFe(60 $\AA$)/Co(0$\AA$$\leq$x$\AA$$\leq$15$\AA$)/Cu(60$\AA$)/Co(30$\AA$) spin valve thin films were prepared on 4$^{\circ}$ tilt-cut Si(111) substrates with a 50 $\AA$ thick Cu underlayer without applying any external magnetic field during the deposition, and the effects of inserted ultrathin Co layer on magnetic anisotropy and GMR properties of the NiFe(60 $\AA$)/Cu(60$\AA$)/Co(30$\AA$) spin valves were investigated. As the ultrathin Co layer was inserted into the NiFe/Cu interface of the spin valves, GMR ratio was increased from about 1.5% to 3.5%, and the easy axis of NiFe(60 $\AA$) layer was rotated by 90$^{\circ}$. Accordingly, it was aligned along the same direction with the easy axis of Co(30 $\AA$)layer. Therefore, squared R-H curves was obtained in the spin valves, which is favorable properties for the digital GMR devices such as MRAM. In order to investigate the change of magnetic anisotropy of NiFe layer of the spin valves in more details,XRD measurement was performed using NiFe(500 $\AA$) and NiFe(500 $\AA$)/Co(10 $\AA$) thin films on the same templates. Strong (220) NiFe peak was observed in both films regardless of the inserted Co layer, so it was thought that the variation of magnetic anisotropy of NiFe layer is from the interface effect, the change of interface from NiFe/Cu to NiFe/Co, rather than the volume effect such as the change of magnetocrystalline effect.

• Food Science and Preservation
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• v.12 no.6
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• pp.540-545
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• 2005

This study was conducted to evaluate the efficacy of high a)z pre-treatment (60, $100\%$ for 3, 6, 12 hr) on quality of 'Hikawa Hakuho' peach fruits. High a)z treatment inhibited the respiration and ethylene production, especially with long tenn treatment for more than 6 hr. Discoloration of peel, softening and decay were reduced by high $CO_2$ treatment $CO_2$ concentration of $60\~100\%$ did not affect soluble solids content and titratable acidity of fruits. $CO_2$ treated fruits, however, showed higher sweetness score compared with control. As the $CO_2$ concentration and treatment duration increased from 60 to $100\%$ and from 3 to 12 hr, respectively, the efficacy on quality increased. Fruits treated with $100\%\;CO_2$ for 3 hr and $60\%\;CO_2$ for 12 hr, however, showed very low flavor score due to the residual $CO_2$ in flesh. High $CO_2$ injury was not noted at any $CO_2$ levels tested in this study. Above results suggest that $60\%\;CO_2$ treatment for 6 hr resulted in as good control of respiration, ethylene production, decay, discoloration and softening without off-order.

• Progress in Medical Physics
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• v.8 no.1
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• pp.37-45
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• 1997

The present work is determine to the dose distribution reduced by the insertion of a shielded into a vaginal cylinder around a $\^$60/CO source in brachytherapy, and to the source calibration. It was investigated by measuring the relative dose around a 2.5cm diameter shielded vaginal cylinder in a polystyrene phantom by use of a ionization chamber. Measurements were made with the cylinder unshielded and 0.55cm thick 90$^{\circ}C$ lead shields inserted. Also, the dose distribution compared measurement value with calculation value according to the device manufacturer and the multiple-divided dose tables. A reduction in dose was observed on the unshielded side of the cylinder which increased with distance from the source and it does 4.4％ within 1cm from the surface of the cylinder. On the shielded side of the cylinder, the dose at the surface is reduced to about 20.4％ of its value without the shield. The effective attenuation factor entered for the 90$^{\circ}C$ lead shielded cylinder was average 0.2 in a $\^$60/CO moving source. In comparision with the dose calculation mathods, the multiple-divided dose tables are difference less than ${\pm}$4.1％ with measured data in a $\^$60/Co source.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.2
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• pp.145-153
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• 2004

H$_2$SO$_4$ and citric acid were used as additives for the electrokinetic remediation experiment to increase removal efficiency of $^{137}$ Cs and $^{60}$ Co from the radioactive soil waste stored for more than 10 years. The average effluent velocity discharged from the elctrokinectic remediation experimental column was 2.0${\times}$10$^{-2}$ cm/min and the discharged soil wastewater volume for 10 days is 3.6 pore volume of the column. 97% of $^{60}$ Co in the column was decontaminated for 10 days of operation, while only 54% of $^{137}$ Cs was decontaminated. These results are considered that the absorption equilibrium coefficient of $^{137}$ Cs is higher than that of $^{60}$ Co. The predicted values of the residual concentration by the proposed mathematical model were well coincided with the experimental results within the experimental error range

• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.77-82
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• 1986

Determination of the relation between the kerma(Kinetic Energy Released in Material) and the absorbed dose is one of the basic problems of dosimetry. Kerma and absorbed dose were measured for 6 MV X-ray from the high energy medical linear accelerator and $^{60}Co$ gamma-ray. The experimental results show that the absorbed dose in the transient equilibrium region practically coincide with the kerma in water and Al for $^{60}Co$. The maximum dose depths were $1.45g/cm^2$ for 6MV X-ray and $0.48g/cm^2\;for\;^{60}Co$ gamma-ray. The ratios of the absorbed dose at maximum build-up to the collision kerma at the surface, ($K^{att}$), were 0.949 for 6MV X-ray and 0.992 for $^{60}Co$ gamma-ray. No difference was found between water and Al when the standard field size was used. This results show that the dependence of $K^{att}$ on the material is very small.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.149-153
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• 1984

Postoperative radiotherapy of breast cancer makes it possible to reduce loco-regional recurrence of breast cancer. The treatment technique, which can reduce the low-dose region at the junction and lung, is required. To produce proper dose distribution of internal mammary chain and chest wall, authors tried to find the method to expose $^{60}Co\;\gamma-ray$ on internal mammary region and 7MeV electron on chest wall. Exposure time of $^{60}Co\;\gamma$ and monitor unit of 9MeV were selected so that dose of $^{60}Co$ at 4cm depth was the same as that of 7Mev electron at $80\%$ dose depth. The position and direction of electron beam were changed for $^{60}Co$ beam: $0^{\circ},\;5^{\circ}$ for 0cm seperation; $0^{\circ},\;5^{\circ},\;10^{\circ}$ for 0.5cm seperation; $5^{\circ},\;10^{\circ},\;15^{\circ}$ for 1cm seperation. The results are as followings. 1. When the seperation of two fields was increased, dose on the axis of $^{60}Co$ beam was increased and dose at the junction region decreased while the volume of lung to be exposed to high dose and hot spot size were irregularly changed. 2. The dose distribution in the target volume of internal mammary and chest wall was most ideal when the seperation of two fields was $0\~0.5cm$ and the direction of electron beam was parallel to $^{60}Co$ beam.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.26-31
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• 2004

The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) exposed to $^{60}Co$ $\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co$ $\gamma-ray$ to doses in the range of 200 to 1000kGy. Various properties of the irradiated PVDF were studied using FTIR, differential scanning calorimetry (DSC), gel fraction and elongation. $^{60}Co\gamma-ray$ irradiation was found to induce changes in chemical, thermal, mechanical and structural properties of PVDF and such changes vary depending on the radiation dose.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.437-440
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• 2004

The radiation-induced changes taking place in poly(vinylidene fluoride)(PVDF) exposed to $^{60}Co\;\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co\;\gamma-ray$ to doses in the range of 200 to 1000 kGy. Various properties of the irradiated PVDF were studied using nm, differential scanning calorimetry(DSC) and gel fraction. $^{60}Co\;\gamma-ray$ irradiation was found to induce changes in chemical, thermal, structural properties of PVDF and such changes vary depending on the radiation dose.

• Journal of Radiation Protection and Research
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• v.29 no.1
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• pp.1-8
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• 2004

Diphosil, a new version of the organic-inorganic composite resin developed by ANL has a structure of the chelating diphosphonic acid groups grafted to a silica support. To apply Diphosil for the treatment of liquid radioactive waste from nuclear power plants, the adsorption equilibrium and column experiments were carried out for the main radionuclides, $^{137}Cs\;and\;^{60}Co$, in the liquid radwaste stream. Through the adsorption equilibrium experiments, the removal efficiencies of $^{137}Cs\;and\;^{60}Co$, and the effects of non-radioactive ions on the removal efficiency have been measured in various conditions using radiotracers. The breakthrough curves for the tested tracers were obtained from the laboratory scale column tests using the simulated liquid radioactive waste. In addition, the removal capacity of Diphosil is compared with that of Amberlite IRN 77 resin, generally used in nuclear power plants.