• Analytical Science and Technology
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• v.5 no.1
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• pp.57-61
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• 1992

For the neutron spectrum measurement, $^6Li$ neutron spectrometer system is installed. The characteristic of the $^6Li$ detector are investigated using a $^{137}Cs$ and $^{207}Bi$ point source, and the neutron capture peaks and the pulse height spectrum using an $^{214}Am-Be$ neutron source are measured. Furthermore, the pulse height spectrum for the irradiation time variation from the (214)^Am-Be neutron source, and for the distance variation between detector and source, and the threshold variation of discriminator are measured.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.185-189
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• 2011

As nuclear industry has been developed, a various types of radiological contamination has occurred. After 9.11 terror in U.S.A., it has been concerned that terrorists' active area has been enlarged to use nuclear or radioactive substance. Recently, the most powerful earth-quake stroke, which triggered a massive tsunami in Japan and then Fukushima nuclear power plant reactor has suffered from a serious accident in history. The Fukushima reactor accident has occurred an anxiety of radiation leaks and about 170,000 people have been evacuated from the accidental area near the nuclear power plant. For these reasons, a social chaos can be occurred if radiological contamination occurs to the supply system for the drinking water. As such, the establishment of the radiation monitoring system for the city main water system is compelling for the national security. In this study, a feasibility test of radiation monitoring system which consists of unified hybrid-type radiation detectors was experimented for multi detection system by using gamma-ray imaging. The hybrid-type radiation sensors were fabricated with CsI(Tl) scintillators and photodiodes. A preamplifier and amplifier was also fabricated and assembled with the sensor in the shielding case. For the preliminary test of detection of radiological contamination in the river, multi CsI(Tl)-PIN photodiode radiation detectors and $^{137}Cs$ gamma-ray source were used. The DAQ was done by Linux based ROOT program and NI DAQ system with Labview program. The simulated contamination was assumed to be occurred at Gapcheon river in Daejeon city. Multi CsI(Tl)-PIN photodiode radiation detectors were positioned at the Gapcheon river side. Assuming that the radiological contaminations flows in the river the $^{137}Cs$ gamma-ray source has been moved and then, the contamination region was reconstructed.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.123-131
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• 2018

This study compared PENELOPE with measured values from low energy peak to high energy peak to reduce peak to compton ratio and continuum background spectrum using $^{60}Co$, $^{137}Cs$ and mixed volume source. In addition, the change in backscattering and compton edge efficiency was compared with that of PENELOPE through changes in the vicinity of low energy. The results from the mixed volume source are applied to the soil samples to determine how much the minimum detection limits of the soil samples are reduced in the suppression and unsuppressed mode. The compton suppression of the low energy region of $^{60}CO$ (1,173 keV) was considerable, and the Compton edge RF for the $^{137}Cs$ (661 keV) peak was 2.8. In particular, the $^{60}Co$ source emits coincidence gamma rays of 1,173.2 keV and 1,332.5 keV, so compton inhibition was reduced by approximately 21%. RF of compton edges of 1,173 keV and 1,332 keV emitted from a $^{60}Co$ source was 3.2 and 3.4, and the peak to compton edge ratio was improved to 8: 1. And Compared with Penelope, the uncertainty was well within 2%. In compton unsuppressed mode, MDA values of 661 keV, 1,173 keV and 1,332 keV were 0.535, 0.173 and 0.136 Bq/kg, respectively, but decreased in compton suppressed mode to 0.121, 0.00826 and 0.00728 Bq/kg. Thus, Compton suppressed could reduce the background radioactivity and the radioactivity contained in the detector itself.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2640-2645
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• 2021

We report the development of a gamma-ray imaging device, named Large-Area Hybrid Gamma Imager (LAHGI), featuring high imaging sensitivity and good imaging resolution over a broad energy range. A hybrid collimation method, which combines mechanical and electronic collimation, is employed for a stable imaging performance based on large-area scintillation detectors for high imaging sensitivity. The system comprises two monolithic position-sensitive NaI(Tl) scintillation detectors with a crystal area of 27 × 27 cm² and a tungsten coded aperture mask with a modified uniformly redundant array (MURA) pattern. The performance of the system was evaluated under several source conditions. The system showed good imaging resolution (i.e., 6.0-8.9° FWHM) for the entire energy range of 59.5-1330 keV considered in the present study. It also showed very high imaging sensitivity, successfully imaging a 253 µCi ¹³⁷Cs source located 15 m away in 1 min; this performance is notable considering that the dose rate at the front surface of the system, due to the existence of the ¹³⁷Cs source, was only 0.003 µSv/h, which corresponds to ~3% of the background level.

• Progress in Medical Physics
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• v.22 no.4
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• pp.198-205
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• 2011

Gamma irradiator is widely used for cell, animal experiment, irradiation for blood, dose measurement, and education. Biobeam8000 gamma irradiator (STS Steuerungstechnik &. Strahlenschutz GmbH, Braunschweig, Germany, Cs137, 81.4 TBq) that KIRAMS (Korea Institute of Radiological and Medical Science) has is a irradiation device that enables to be used in large-capacity of 7.5 L and extensive area. Cs-137 source moves range of 24 cm back-and-forth in a regular cycle in beaker for uniform irradiation and a beaker that puts a specimen like existing radiation irradiator such as Gammacell3000 rotates $360^{\circ}$ during irradiation. Precise dose information according to the location of radiation source would be needed because of the movement of radiation source, whereas radiation could be uniformly irradiated in comparison with existing gamma irradiator. In this study, dose distribution of the inside beaker located in Biomeam8000 gamma irradiator was measured using glass dosimeter, and dose evaluation and distribution regarding dose linearity and dose reproducibility were implemented based on measurement results. This aims to show guideline for efficient use of irradiator based on measurement result when doing experiment or radiation exposure.

• Journal of Radiation Protection and Research
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• v.15 no.2
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• pp.75-85
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• 1990

The dose calculations were carried out using environmental montoring data around Karlsruhe Nuclear Research Center(KfK). Ingestion of plant foods was the most important pathway, and the K-40 and Pb-210 natural radioisotopes in food were the most effective radiation source to man. The dose received from artificial nuclides were mostly emitted by gamma irradiation of Cs-134 and Cs-137 deposited on the ground. The effective dose equivalent in the KfK environment was far less than the dose equivalent limit recommended by ICRP.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.85-95
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• 1995

Radiation measuring system using wireless communication method with single channel has been diveloped and tested. In this system, radiation signals from GM tube are transformed into digital pulses in pulse processing circuit and modulated in FSK (frequency shift keying) circuit for digital communication and then wirelessly transmitted to a receiving unit. The digital pulses received are then demodulated in FSK circuit and converted into radiation dose/dose rate in the data acquisition unit to display on the screen of a personal computer. The performance of this system was evaluated by using both a pulse generator and a standard radiation source(Cs-137). In both cases, digital pulses with 5V were observed in pulse processing circuit without distortion of their shape through wireless communication system. The experimental results of radiation measurement by this system after several test-irradiation of GM detector to a standard radiation source(Cs-137), showed good agreement with irradiation dose rate within 10% difference, and proved that this system could be effectively utillized as radiation measuring instrument. It is expected that this wireless radiation measuring system developed for the first time in Korea, can be used as a radiation monitor as well as a personal dosimeter if we can further improve this system to adopt wireless multichannel communication system.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.293-299
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• 2014

Compton suppression device is a device by using the Compton scattering reaction and suppress the Compton continuum portion of the spectrum, so can be made more clear analysis of gamma ray peak in the Compton continuum region. Measurements above background occurs or, radioactivity counts of radioactivity concentration value of $^{40}K$ nuclides $^{137}Cs$ and natural radioactivity artificial radioactivity detected from the surface soil sample, unwanted non-target analysis and interference peak who dotted line you know the calibration of the measurement energy is allowed to apply the (Compton suppression) non-suppressed spectrum inhibition spectrum and (Compton Unsuppression) the background to the measured value of the activity concentration value of the standard-ray source is detected relative to the peak of By measuring according to the different distances cause $^{137}Cs$, and comparative analysis of the Monte Carlo simulation, in order to obtain a detection capability for efficient, looking at the Compton inhibitor, as the CSF value increases with increase in the distance, more It was found that the background due to Compton continuum of the measured spectrum suppression mode Compton unrestrained mode can know that the Compton suppression many were made, using a $^{137}Cs$ is reduced.

• Nuclear Engineering and Technology
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• v.22 no.4
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• pp.315-325
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• 1990

The analytical repository source term (REPS) computer code is developed for the safety assessment of radioactive waste geologic repository. For reliable prediction of the leach rates for various radionuclides, degradation of concrete structures, corrosion rate of waste container, degree of corrosion on the container surface, and the characteristics of radionuclides are considered in this REPS code. For the validation of the radionuclide leach rates predicted by the REPS model, the calculated leach rates of Cs-137, Sr-85, and Co-60 are compared with two reported leaching test results. Cesium and strontium leach congruently, and the leaching test results of these species can be reproduced by the congruent leaching model included in the REPS model. In case of cobalt, the solid diffusion model is in good agreement with the leaching test results.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.63-70
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• 1993

A simplified safety assessment is carried out on rock-cavern type disposal of LLW using the analytical repository source term (REPS) model. For reliable prediction of the leach rates for various radionuclides, degradation of concrete structures, corrosion rate of waste container, degree of corrosion on the container surface, and the characteristics of radionuclides are considered in the REPS model. The results of preliminary assessment show that Cs-137, Ni-63, and Sr-90 are dominant. For the parametric uncertainty and sensitivity analysis, Latin hypercube sampling technique and rank correlation technique are applied. The results of the potential public health impacts show that radiological dose to intruder in the worst case scenario will be negligible and that more attention should be given to near-field performance.