• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.123-130
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• 2015

For the analysis of ⁹⁰Sr, which is a pure beta emitter, radiochemical separation from the main interfering elements such as Ca, Ba and Ra is required due to their similarity in chemical behavior to strontium. This study describes a radioanalytical procedure using extraction chromatography for separating Sr from interfering elements. The maximum capacity of the resin for Sr was approximately 6 mg per 1.5 mL of bed volume (BV). The recovery of Sr on the resin 1.5 mL (BV) was quantitative for the calcium level of 200 mg at the flow rate of 1 mL min^-1. However the chemical yield declined by increasing the flow rate by up to 5 mL min^-1 even at the calcium level of 200 mg. When using the same BV of Sr resin, the performance of the resin was enhanced as the cross-sectional area of the Sr resin column is small.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.207-213
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• 2003

Carbon-14 is one of the major radionuclides released by CANDU Nuclear Power Plants(NPPs). It is almost always emitted as gas through the stack. From CANDU NPPs about 95% of all carbon-14 is released as carbon dioxide. Carbon-14 is a low energy beta emitter which, therefore, gives only a small skin dose from external radiation. As carbon dioxide Is physiologically rather inert gases for man's metabolism, the inhalation dose is probably less than 1 % of the ingestion dose. But this source of carbon-14, formed in a closed, nor-oxidative environment, was subsequently released into the workplace as an insoluble particulate when these systems were opened lip for re-tubing at CANDU NPPs. As a part of the improvement of dosimetry program at Wolsong Nuclear Power Plants, the carbon-14 metabolism based on references was investigated and studied to setup the internal dosimetry program due to inhalation of carbon-14.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.93-100
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• 2004

The smear media possible to sampling and radiation detection was prepared and evaluated for the surface contamination using indirect method. The films were made by impregnating Cerium Activated Yttrium Silicate (CAYS) in a polysulfone membrane. The membranes used solution as a dimethylformamide (DMF) and methylene chloride (MC), polysulfone as a polymer matrix and CAYS as a inorganic scintillator. The proximity membranes were prepared with single- and double-layered structure. The solidified methods were immersion to the nonsolvent bath such at water and ethanol and solvent evaporation. The measurement of the photon produced by interaction with radiation and inorganic scintillator used a photomultiflier tube (PMT), amplifier, and counter. In the comparison with the low background alpha/beta counter, the counter rate using inorganic scintillator proximity membrane for the $\^$14/C surface contamination was about 50%. Also. the $^3$H counting results revealed that the prepared membranes were efficient to monitor the surface contaminated with the low energy be-ray emitter nuclides.

• Journal of IKEEE
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• v.11 no.1 s.20
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• pp.69-76
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• 2007

This paper presents the design of LVDS (Low-Voltage-Differential-Signaling) transmitter for Gb/s-per-pin operation. The proposed LVDS transmitter is designed using BiCMOS technology, which can be compatible with CMOS technology. To reduce chip area and enhance the robustness of LVDS transmitter, the MOS switches of transmitter are replaced with lateral bipolar transistor. The common emitter current gain($\beta$) of designed bipolar transistor is 20 and the cell size of LVDS transmitter is $0.01mm^2$. Also the proposed LVDS driver is operated at 1.8V and the maximum data rate is 2.8Gb/s approximately In addition, a novel ESD protection circuit is designed to protect the ESD phenomenon. This structure has low latch-up phenomenon by using turn on/off character of P-channel MOSFET and low triggering voltage by N-channel MOSFET in the SCR structure. The triggering voltage and holding voltage are simulated to 2.2V, 1.1V respectively.

• Journal of Radiation Protection and Research
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• v.34 no.2
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• pp.55-64
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• 2009

In a pressurized heavy water reactor (PHWR), radiation workers who have access to radiation controlled areas submit their urine samples to health physicists periodically; internal radiation exposure is evaluated by the monitoring of these urine samples. Internal radiation exposure at PHWRs accounts for approximately 20 $\sim$ 40% of total radiation exposure; most internal radiation exposure is attributed to tritium. Carbon-14 is not a dominant nuclide in the radiation exposure of workers, but it is one potential nuclide to be necessarily monitored. Carbon-14 is a low energy beta emitter and passes relatively easily into the body of workers by inhalation because its dominant chemical form is radioactive carbon dioxide ($^{14}CO_2$). Most inhaled carbon-14 is rapidly exhaled from the worker's body, but a small amount of carbon-14 remains inside the body and is excreted by urine. In this study, a method for dual analysis of tritium and carbon-14 in urine samples of workers at nuclear power plants is developed and a method for internal dose assessment using its excretion rate result is established. As a result of the developed dual analysis of tritium and carbon-14 in urine samples of radiation workers who entered the high radiation field area at a PHWR, it was found that internal exposure to carbon-14 is unlikely to occur. In addition, through the urine counting results of radiation workers who participated in the open process of steam generators, it was found that the likelihood of internal exposure to either tritium or carbon-14 is extremely low at pressurized water reactors (PWRs).

• Journal of Radiation Protection and Research
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• v.45 no.2
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• pp.76-80
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• 2020

Background: To improve the measurement accuracy of liquid-scintillation counting for activity standardization, it is necessary to significantly reduce the background caused by thermal noise or after-pulses. We have therefore improved a movable 3 photomultiplier (3PM)-γ coincidence-counting method using the logical sum of three double coincidences for β events. Materials and Methods: We designed a new data-acquisition system in which β events are obtained by counting the logical sum of three double coincidences. The change in β-detection efficiency can be derived by moving three photomultiplier tubes sequentially from the liquid-scintillation vial. The validity of the method was investigated by activity measurement of ¹³⁴Cs calibrated at the Korea Research Institute of Standards and Science (KRISS) with 4π(PC)β-γ(NaI(Tl)) coincidence counting using a proportional counter (PC) for the β detector. Results and Discussion: Measurements were taken over 14 counting intervals for each liquidscintillation sample by displacing three photomultiplier tubes up to 45 mm from the sample. The dead time in each β- and γ-counting channel was adjusted to be a non-extending type of 20 ㎲. The background ranged about 1.2-3.3 s^-1, such that the contributions of thermal noise or after-pulses were negligible. As the β-detection unit was moved away from the sample, the β-detection efficiencies varied between 0.54 and 0.81. The result obtained by the method at the reference date was 396.3 ± 1.7 kBq/g. This is consistent with the KRISS-certified value of 396.0 ± 2.0 kBq/g within the uncertainty range. Conclusion: The movable 3PM-γ method developed in the present work not only succeeded in reducing background counts to negligible levels but enabled β-detection efficiency to be varied by a geometrical method to apply the efficiency extrapolation method. Compared with our earlier work shown in the study of Hwang et al. [2], the measurement accuracy has much improved. Consequently, the method developed in this study is an improved method suitable for activity standardization of β-γ emitters.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.213-219
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• 2013

Currently, about 35 cyclotrons have been operating in South Korea. Most of them are mainly used for the synthesis of radiopharmaceuticals such as $^{18}FDG$, which is a cancer tracer for nuclear medicine. Highly enriched $H_2{^{18}}O$ containing up to 98% of $^{18}O/O$ isotope ratio is used as the target for $^{18}F$ production. The price of the highly enriched $H_2{^{18}}O$ ranges 60~70 USD/g, and all of them have been imported from foreign country in spite of the very expensive price. The target (enriched $H_2{^{18}}O$) is non-radioactive before the proton beam irradiation. But, the post-irradiation target (used $H_2{^{18}}O$) must be managed following the National Radiation Safety Regulations, because it turns into radioactive by the radioactivation of the impurities within the target. Recently, nevertheless of the fast increasing amount of used $H_2{^{18}}O$ in accordance with the increasing number of nuclear medicine cases, any activation analysis on the used $H_2{^{18}}O$ have been conducted yet in Korea. In this research, activation analysis have been conducted to confirm the specific radioactivity(Bq/g) of each radioisotopes within the used $H_2{^{18}}O$. The analysis have been done on the 3 of 20g samples collected from the used $H_2{^{18}}O$ storages at different cyclotron centers. Based on the results, it was confirmed that the "used $H_2{^{18}}O$" contains gamma emitters such as $^{56}Co$, $^{57}Co$, $^{58}Co$, and $^{54}Mn$ as well as the considerable amount of beta emitter $^3H$. It was also confirmed that the only one sample contained over exemption level of gamma emitters while the specific activity of tritium was lower than the exemption level in all samples. The specific activity of radioisotopes were measured different levels in the samples depending on the elapsed time after irradiation. Further study on the activation of the "used $H_2{^{18}}O$" is definitely necessary, nevertheless the as-is results of this research must be useful in establishing a rational "used $H_2{^{18}}O$" management protocol.

• Biomolecules & Therapeutics
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• v.5 no.1
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• pp.100-105
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• 1997

DW-166HC ($^{166}$Holmium-chitosan) is a complex of $^{166}$Ho, $\beta$- and $\gamma$-ray emitter, and chitosan, a polymer of glucosamine, with radiotherapeutic potential. The current study was performed to determine the acute toxicities of $^{165}$Ho-chitosan in mice by two different routes of administration. The both sex mice were given a single intravenous bolus injection of $^{165}$Ho-chitosan complex at doses of 12, 10, 6, 5 and 4 mg/kg or subcutaneous administration at doses of 600, 500, 400 and 300 mg/kg. Chitosan was dosed to control animals as 16 and 800 mg/kg, intravenously and subcutaneously, respectively. The doses of $_{165}$Ho-chitosan complex were expressed as $_{165}$holmium nitrate pentahydrate and the ratio of $^{165}$Ho$(NO_3)_3$).$5H_2O$ to chitosan was 3/4 Severe convulsion and respiratory failure were followed by death within 10 min after intravenous dosing. Transient unilateral hindlimb hypokinesias were found in two mice of 5 mg/kg dosing group during the study period. No abnormalities were observed during the necropsy of survived animals in intravenous dosing group. Only one male animal was found dead in 500 mg/kg subcutaneously dosed group. Alopecia with or without cutaneous ulcer were found in most mice including control animals. During necropsy, omental adhesion was observed in all dose ranges and enlarged spleen was found in several animals including control group. It is suggested that the acute intravenous >).$LD_{50}s$ for male and female mice were 4.90 and 6.03 mg/kg, respectively. The lowest lethal dose in male was 500 mg/kg by subcutaneous administration.

• The Korean Journal of Nuclear Medicine
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• v.30 no.3
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• pp.351-360
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• 1996

Chitosan is a polysaccharide of natural orgin obtained by full or partial deacetylation of chitin, a very abudant natural polymer, which has the properties of biocompatibilities, bioaffinities, and biodegradabilities. The free amino group of chitosan should be participated in forming chelate with holmium (${\beta}$-emitter). $^{166}Ho(NO_3)_3\;5H_2O$ of high radionuclidic purity of upto 99.9% was made by neutron irradiation of naturally occuring $^{166}Ho(NO_3)_3\;5H_2O$, and then reacted with the prepared chitosan solution. The effect of pH, reaction time, the concentration and viscosity of chitosan and the amount of $^{166}Ho$ on forming $^{166}Ho$-chitosan complex ($^{166}Ho$-CHICO) were investigated. $^{166}Ho$-chitosan macroaggregate($^{166}Ho$-CHIMA) was made from $^{166}Ho$-CHICO. Their physical properties such as radionuclidic purity, particle size distribution, stability in vitro and vivo were examined. Their high in vitro and vivo stability makes them attractive agents for internal radiotherapy by local administeration.

• The Korean Journal of Nuclear Medicine
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• v.33 no.2
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• pp.163-171
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• 1999

Purpose: Liquid beta emitter filled in angioplasty balloon could be used to perform endovascular balloon brachytherapy to prevent coronary artery restenosis. We investigated the dosimetry for Re-188-DTPA liquid-filled balloon and medical internal radiation dosimetry in case of balloon leakage. Materials and Methods: We estimated radiation dose from an angioplasty balloon (20 mm length, 3 mm diameter cylinder) to the adjacent vessel wall using Monte Carlo EGS4 code. We obtained time-activity curves of kidneys in normal dog and calculated $T_{max},\;T_{1/2}$. Using MIRDOSE3 program, we estimated absorbed doses to the major organs (kidneys, bladder) and the whole body when we assumed that balloon leaked all the isotope contained. Results: The radiation dose was 17.5 Gy at the balloon surface when we applied 3,700 MBq/ml of Re-188 for 100 seconds, Fifty percent of the energy deposited within 1 mm from the balloon surface. The estimated internal dose to the whole body was 0.005 mGy/MBq and 18.5 mGy for the spillage of 3,700 MBq of Re-188. Conclusion: We suggest that Re-188-DTPA can be used for endovascular balloon brachytherapy to inhibit coronary artery restenosis after angioplasty with tolerable whole body radiation dose in case of balloon rupture.