• Journal of Radiation Protection and Research
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• v.32 no.4
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• pp.190-193
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• 2007

The objective of this study is to recommend the radiation protection design parameters from the shielding point of view for concrete wall between the decay tank room and the primary pump room in TRIGA Mark-II Research Reactor Facility. The shield design for this concrete wall has been performed with the help of Point-kernel Shielding Code Micro-Shield 5.05 and this design was also validated based on the measured dose rate values with Radiation Survey Meter (G-M Counter) considering the ICRP-60 (1990) recommendations for occupational dose rate limit ($10{\mu}Sv/hr$). The recommended shield design parameters are: (i) thickness of 114.3 cm Ilmenite-Magnetite Concrete (IMC) or 129.54 cm Ordinary Reinforced Concrete (ORC) for concrete wall A (ii) thickness of 66.04 cm Ilmenite-Magnetite Concrete (IMC) or 78.74 cm Ordinary Reinforced Concrete (ORC) for concrete wall B and (iii) door thickness of 3.175 cm Mild Steel (MS) on the entrance of decay tank room. In shielding efficiency analysis, the use of I-M concrete in the design of this concrete wall shows that it reduced the dose rate by a factor of at least 3.52 times approximately compared to ordinary reinforced concrete.

• Journal of radiological science and technology
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• v.42 no.6
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• pp.477-482
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• 2019

Recently, due to the increased use of medical radiation, the radiation exposure of radiation workers should be considered as well as medical exposure of patients. And it is recommended to close the door during radiography. however, In this study, when the door was inevitably opened for radiography, the proposed method was to install the shield as a method of reducing the exposure dose. And its efficiency was analyzed. In simple chest radiography, the measurement point was changed according to the measurement location. Dose rate were measured 10 times for each condition using a dosimeter. And the average value was derived. Using this, the change of dose according to the opening and closing of the door and the installation of the shield was analyzed. Using this, we compared and analyzed the dose change according to the door opening and closing and the installation of the shield, and significance was verified through the SPSS ver. 24. Depending on whether the door was opened or closed, 11,215.35%, 159.0%, 101.9% increased in front of the door in the consol room, behind the wall and behind the lead glass. Depending on the installing of the shield, the 49.2%, 29.6%, 19.9%, 30.6% decrease in front of the door in the examination and consol room, behind the wall and lead glass. In addition, statistical analysis was showed that there were significant differences in both the results according to whether the door was opened or closed and shielding(p<.05). Close the door during radiography. However, when the door should be opened, it was confirmed that the dose rate were reduced by installing the shield. Therefore, to optimize radiation protection, it is recommended to install shields when opening the door.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.350-353
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• 2009

The shielding enclosure is very essential device to test the electromagnetic wave power generated by various RF equipments. Some standards for the shielding enclosures were established to test them in right method. Generally, There are IEEE-STD-299 and MIL-STD-285 and NSA-65-6 of the method for measuring the effectiveness of shielding enclosures, the IEEE-STD-299 combined MIL-STD-285 and NSA-65-6 about the method for measuring shielding effectiveness(SE) about 1969 years, but, the measurement point of 299 proposal is many points(including shielding wall, seam, coner beat, shielding door, etc) and demand long time of measurement. To improve SE test method for shielding enclosures was studied and suggested to develop a proper test procedure. First, we measure reference level as frequency range and H/V polarization, secondly, measure leakage point, and finally, measure shield effect and calculate SE. Our method has a merit of the less measurement point than IEEE-STD-299, and shorten time than 299, and define representation SE of shielding enclosure effectively.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.45-47
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• 2001

The function of the thermal shield(TS) is to eliminate the thermal radiation from the room temperature side to the coil temperature(4.5K) region so as to reduce the thermal load on the He refrigerator. The TS is composed of multilayer insulation(MLI) which is coated very thin aluminum on the insulating material, cryopanel which is cooled by cold gaseous He, and supports which stand the cryopanel and MLI on the room temperature part. The thermal shield for the TF coils and PF coils has been located between the coils and vacuum vessel. The thermal shielding cryopanel is cooled under 80 K by a forced flow of helium gas using cooling pipes on the cryopanel.

• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.130-141
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• 2020

Background: Concrete activation in cyclotron vaults is a major concern associated with their decommissioning because a considerable amount of activated concrete is generated by secondary neutrons during the operation of cyclotrons. Reducing the amount of activated concrete is important because of the high cost associated with radioactive waste management. This study aims to investigate the capability of the neutron absorbing materials to reduce concrete activation. Materials and Methods: The Particle and Heavy Ion Transport code System (PHITS) code was used to simulate a cyclotron target and room. The dimensions of the room were 457 cm (length), 470 cm (width), and 320 cm (height). Gd₂O₃, B₄C, polyethylene (PE), and borated (5 wt% ^natB) PE with thicknesses of 5, 10, and 15 cm and their different combinations were selected as neutron absorbing materials. They were placed on the concrete walls to determine their effects on thermal neutrons. Thin B₄C and Gd₂O₃ were placed between the concrete wall and additional PE shield separately to decrease the required thickness of the additional shield, and the thermal neutron flux at certain depths inside the concrete was calculated for each condition. Subsequently, the optimum combination was determined with respect to radioactive waste reduction, price, and availability, and the total reduced radioactive concrete waste was estimated. Results and Discussion: In the specific conditions considered in this study, the front wall with respect to the proton beam contained radioactive waste with a depth of up to 64 cm without any additional shield. A single layer of additional shield was inefficient because a thick shield was required. Two-layer combinations comprising 0.1- or 0.4-cm-thick B₄C or Gd₂O₃ behind 10 cm-thick PE were studied to verify whether the appropriate thickness of the additional shield could be maintained. The number of transmitted thermal neutrons reduced to 30% in case of 0.1 cm-thick Gd₂O₃+10 cm-thick PE or 0.1 cm-thick B₄C+10 cm-thick PE. Thus, the thickness of the radioactive waste in the front wall was reduced from 64 to 48 cm. Conclusion: Based on price and availability, the combination of the 10 cm-thick PE+0.1 cmthick B₄C was reasonable and could effectively reduce the number of thermal neutrons. The amount of radioactive concrete waste was reduced by factor of two when considering whole concrete walls of the PET cyclotron vault.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.65-76
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• 2010

Purpose: he use of PET scanners and the number of patient in Korea have been increased for recent several years dramatically. For this reason, technologists have more possibilities to be exposed to the radiation. The hospitals using PET scanners should make an effort to reduce the radiation exposure dose. The purpose of this study was to evaluate the radiation exposure does when using radiation shielding devices. The evaluation was performed through questionnaire survey and experiment. Materials and Methods: First, the technologists who had experience working in PET center in 2008-2009 were surveyed with questionnaire and TLD Figures, personal opinion of utilization of radiation shielding devices are analyzed. Second, we measured the shielding rate of shielding devices which have been using in PET study procedures. We divided the procedures into four steps; distribution, moving, injection of $^{18}F$-FDG and patient setup. Results: First, the results of this survey, using of L-block+Syringe shield, L-block, Syringe shield, No shield during the injection, were each 58.5%, 20%, 9%, 12.3%. The TLD values according to utilization of radiation shield, using both L-block+Syringe Shield and L-block showed the lower TLD values, and Syringe shield only or No shield showed the higher TLD values. Second, the results of experiments according to PET study procedures measured the shielding rates as follows. The shielding rates during the distribution using L-block, L-block+Apron shield were measured 97.4%, 97.7%. The shielding rates during the $^{18}F$-FDG delivery to the injection room using mobile Syringe shield, Syringe holder, Syringe shield carrier were each 81.7%, 98.9%, 99.7%. The shielding rates during the injection using Syringe shield, L-block, L-block+Syringe shield were measured each 51.9%, 98.3%, 98.7%. The shielding rates of Apron were measured in each 30, 60, 90, 120, 150 cm distance. The measurement were each 16.9%, 14.2%, 16.6%, 17.1%, 18.1%, 18.6%. Conclusion: The most effective method for radiation shielding is to using L-block during the $^{18}F$-FDG distribution and Syringe shield carrier during in moving $^{18}F$-FDG. For the $^{18}F$-FDG injection, L-block+Syringe shield have to be used. The shielding effect of Apron has shown average 16.4%. According to the survey of questionnaire, the operators recognized well risk of the radiation exposure but, tended ignore in working. The radiation dose according to recognition of radiation exposure risk was not relevant. but radiation dose according to utilization of radiation shield lower the more use it. The main reason of no use of shielding devices is cumbersome, 55% of the respondents answered. I'm sure, by use of radiation shield in all PET procedure, radiation exposure will be reduced considerably.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.895-908
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• 2018

As modern science is developed and advanced, examination and number of times using radiation are increasing daily. General diagnostic X-ray generator is installed on stationary form, But X-ray generator was developed because patient who is in the intensive care unit, operation room, emergency room can not move to general x-ray room. What we examine patient by x-ray generator is certainly necessary, So patient exposure is inevitable. but reducing radiation exposure is highly important matter about radiation technology, guardian, patient in the same hospital room, nurse etc. For this reason, rule regarding safety control of diagnostic x-ray generator revised for radiation worker, patient and protector proclaim that mobile diagnostic x-ray shield must placed in case of examine different location excluding operation room, emergency room, intensive care unit. But, radiogical technologist is having a lot of difficulties to examine with mobile x-ray generator, diagnostic x-ray shield partition, image plate and lead apron. So, when we use x-ray generator, we manufacture shield tools can be attached to the mobile x-ray generator On behalf of x-ray shield partition and conduct analysis and in comparison to part of body and distribution of dose rate and find way to reduce radiation exposure through distribution of dose rate of patient within the radiogical technologist, medical team. Mobile x-ray generator aimed at SHIMADZU inc. R-20, We manufactured equipment for shielding x-ray scattered x-ray by installing shielding wall from side to side based on support beam on the mobile x-ray generator. Shielding wall when moving can be folded and designed to expand when examine. Experiment measured five times in each by an angle for dose rate of eyes, thyroid, breast, abdomen and gonad on exposure condition of upper and lower extremity, chest, abdomen which is examined many times by mobile x-ray generator. We used dosimeter RSM-100 made by IJRAD and measured a horizontal dose rate by body part. The result of an experiment, shielding decreasing rate of the front and the rear showed 77 ~ 98.7%. Therefore using self-production shielding wall reduce scattered x-ray occurrence rate and confirm can decrease exposure dose consequently. Therefore, through this study, reduction result which is used shielding wall of self-production will be a role of shielding optimization and it could be answer about reduction of medical exposure recommended by ICRP 103.

• Journal of the Korea Safety Management & Science
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• v.19 no.2
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• pp.95-100
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• 2017

In this study, the bacterial contamination level of equipments and devices in the nuclear medicine department of a university hospital was investigated. CNS was detected from the sample collected from the door opening button of the nuclear medicine department. Bacillus sp. was detected from the table and CNS with Bacillus sp. were detected from the control button at the PET-CT room no.1. Also, CNS was detected from the table and the control button at the PET-CT room no.2. In the distribution room no.1, CNS and Bacillus sp. were detected while CNS being detected from the distribution room no.2 and CNS with Bacillus sp. being detected from the distribution room no.3. In the injection room, Enterrococcus faecium and Pontoea sp. were detected. On the table of the ecsomatics room, Pontoea sp. was detected. Bacillus sp. was detected from the inside of the syringe Pb shield and CNS was detected from the outside. Enterrococcus faecium was detected from the Gamma camera table and Bacillus sp. was detected from the door grip. On the chair at the patient waiting room, Pseudomonas aeruginosa abd Bacillus sp. were detected. Therefore, it was understood that infection should be prevented by securely sterilizing examination devices after each examination, maintaining cleanliness by regular sterilization of waiting chairs and such objects with a number of direct contacts with patients, and infection education for the features of nuclear department.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.414-417
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• 2006

Especially, the case which the facilities have been shielded in the building. In this case there must be suitable grounding system, and this case must be considered sufficiently to the one part of the design at the design. in addition there must be an electric leakage defense system and The case to be a criterion signal ground system. Rod type grounding electrodes is applied much and we studied the relation that rod type grounding method and shielding room as newly grounding object. in this paper, shield room is the object(target) to be established newly additionally, we try to describe about the flow of a grounding technology concept change and a ground facilities.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.144-146
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• 1995

A superconducting 2 tesla MRI magnet for the animal magnetic resonance imaging has been developed as a basic model for the application of the precise supercoducting magnet technology. MRI cryostat with 210mm room temperature bore was designed and manufactured for this magnet. The cryostat was designed basically not only to extract the principal design parameters at the performance test but also for the convenience of the manufacturing. The most extinct feacture of the cryostat is that it does not have $LN_{2}$ tank and the 77K thermal shield is cooled by circuling $LN_{2}$ through copper pipe which is welded around the shield plate. It results in reduction of the total cryostat size(about 30%).