• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.154-159
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• 2011

To evaluate the radiation exposure of workers participating in task where high radiation exposure is expected, two-dosimeter is typically provided radiation workers, one on the chest and the other on the back, at Korean nuclear power plants (NPPs). In a previous study, the NCRP (55:50) algorithm was selected as the optimal two-dosimeter algorithm (TDA) with various field tests and this TDA has been applied to all Korean NPPs since 2006. In 2007, the International Commission on Radiological Protection (ICRP) published the new ICRP recommendation, ICRP 103, which provides the revised weighting factors for both radiation and tissues and the new reference phantom. In this study, the applicability of current NCRP (55:50) algorithm at Korean NPPs for ICRP 103 was analyzed. As a result, it was found that the NCRP (55:50) algorithm is still effective to estimate the effective dose of workers under ICRP 103.

• Journal of Radiation Protection and Research
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• v.15 no.1
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• pp.29-32
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• 1990

• Journal of Radiation Protection and Research
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• v.27 no.2
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• pp.77-80
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• 2002

A more practice approach for the determination of monetary values of the unit collective dose for intervention against long-term exposure following a nuclear accident was proposed. In addition, she monetary values of the unit collective dose estimated from the proposed approach were compared with those estimated from the previous model, which are derived from assumptions of routine exposure and the same values are applied in a nuclear accident without modification, using Korean economic data. The monetary values based on the proposed approach showed a distinct difference depending on inequity in the distribution of individual doses. The discounting rate was also an important factor in determination of monetary values of the unit collective dose.

• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.215-223
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• 1999

Characteristics of radiation field in the steam generator(S/G) water chamber of a PWR were investigated and the anticipated effective dose rates to the worker in the S/G chamber were evaluated by Monte Carlo simulation. The results of crud analysis in the S/G of the Kori nuclear power plant unit 1 were adopted for the source term. The MCNP4A code was used with the MIRD type anthropomorphic sex-specific mathematical phantoms for the calculation of effective doses. The radiation field intensity is dominated by downward rays, from the U-tube region, having approximate cosine distribution with respect to the polar angle. The effective dose rates to adults of nominal body size and of small body size(The phantom for a 15 year-old person was applied for this purpose) appeared to be 36.22 and 37.06 $mSvh^{-1}$) respectively, which implies that the body size effect is negligible. Meanwhile, the equivalent dose rates at three representative positions corresponding to head, chest and lower abdomen of the phantom, calculated using the estimated exposure rates, the energy spectrum and the conversion coefficients given in ICRU47, were 118, 71 and 57 $mSvh^{-1}$, respectively. This implies that the deep dose equivalent or the effective dose obtained from the personal dosimeter reading would be the over-estimate the effective dose by about two times. This justifies, with possible under- or over- response of the dosimeters to radiation of slant incidence, necessity of very careful planning and interpretation for the dosimetry of workers exposed to a non-regular radiation field of high intensity.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.555-564
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• 2017

The current radiation risk assessment for occupational exposure is based on the measured exposure dose and health checkups of workers. This people-centered risk assessment may occur errors because absence of using personal dosimeter or unrelated health symptoms of individuals lead to difficulties in obtaining accurate data from workers. In addition, although the established legal upper dose limit was used as a reference for the assessment, it does not imply that this limit is the optimal dose of radiation workers should get; ALARA principle should always be appreciated. Therefore, a new risk assessment model that can take account of all the important factors and implement optimization of radiation protection is required at the national level. In this paper, based on the KOSHA Risk Assessment, we studied on the workplace-centered risk assessment model for radiation field rather than the people-centered. The result of the study derived a right model for radiation field through the analysis of the risk assessment methods in various fields and also found data acquisition methods and procedures for applying to the model. Multidimensional model centering on the workplace will enables more accurate radiation risk assessment by using a risk index and radar plot, and consequently contribute to the efficient worker management, preemptive worker protection and implementation of optimization of radiation protection.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.179-186
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• 2004

A single-dosimeter worn on the anterior surface of body of a worker was found to provide significant underestimation of dose to the worker when radiation comes from behind of the human body. Recently, several researchers suggested that this kind of underestimation can be corrected to a certain extent by using an extra dosimeter on the back. But this multiple dosimetry also has the disadvantages like overestimation lowering work efficiency or cost burden. In this study, a single dosimeter introducing asymmetric filters enabled to identify PA exposure was designed by monte-carlo simulation and experiments and its dose evaluation algorithm for AP-PA mixed radiation field was established. This algorithm was applicable to penetrating radiation which had the effective energy more than 100 keV. Besides, the dosimeter and algorithm in this study were possible to be applied to near PA exposure.

• Journal of Radiation Protection and Research
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• v.32 no.1
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• pp.27-34
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• 2007

In this paper, We are evaluated about bio-signal between general workers and nuclear medicine workers which is more radiation exposure relatively. In order to reciprocal evaluated two group, we experimented nuclear medicine workers in Chung-Buk National University Hospital at department of nuclear medicine and worker in Chon-Nam National University Hospital at CT room, general radiographic room, medical recording room, receipt room, general office room. Used of experimental Equipments as follows, for a level of radiation measurement by pocket dosimeter which made by Arrow-Tech company, for heart rate and blood pressure measurement by TONOPORT V which made by GE medical systems company, for heat flux and skin temperature and energy expenditure measurement by Armband senseware 2000 which made by Bodymedia company. Result of experiment obtains as follows: 1) Individual radiation exposure is recorded 3.05 uSv at department of nuclear medicine and order as follows CT room, general radiograpic room, medical recording room, receipt room, general office room. Department of nuclear medicine more 1.5 times than other places. 2) Radiation accumulated dose is not related to Heat flux, Skin temperature, Energy expenditure. 3) Blood pressure is recorded equal to nuclear medical workers, general officer, general people about systolic blood pressure and diastolic blood pressure. Compared to blood pressure between nuclear medical works which is more radiation exposure and other workers was not changed. Consequently, more radiation exposed workers at nuclear medicine field doesn't have hazard.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.161-170
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• 1997

Theoretical and experimental determination of the lower limits of detection (LLD) of C-300-A $CaSO_4$:Dy TL dosimeters which are currently used for the personnel monitoring in Korea Atomic Energy Research Institute(KAERI) are described with a critical level which is defined as the signal level above which a result has a probability of being due to a fluctuation of the background. The personnel monitoring processors can derived easily the LLD of their system using this method with the background readings of their service interval and the irradiation readings of the known doses. Experimental studies were also conducted for the fading rates of the dosimeters with the temperatures and humidities for 3 months. Finally sensitivity changes in repeat uses were measured for 40 times consecutive uses of the dosimeters. The applications of the experimental results of fading rates and sensitivity changes in real personnel monitoring services are discussed briefly.

• Journal of Radiation Protection and Research
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• v.22 no.2
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• pp.85-95
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• 1997

TLD and film badges have been traditionally used as formal dosimeters in personal monitoring and are still most widely used. Recently, electronic personal dosimeters based upon Si diode or miniature G-M tube were developed and are getting attractions due to their merits of active nature ; indication of dose rates and the commutative dose, and facilitation of record keeping and radiological control. Response characteristics of the electronic dosimeters including reproducibility, accuracy, linearity, energy and angular dependencies, detection threshold, and response time were examined for three commercial types ; EPD2, STEPHEN6000, and PD-3i. The results were compared with the relevant requirements of IEC standards and Ontario Hydro standards to conclude that their general performances were good. Some specific deficiencies, e.g. incapability of shallow dose measurement of STEPHEN6000, and PD-3i, however, should be corrected to be used as a formal dosimeter.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.2
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• pp.107-114
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• 2012

Purpose: Unlike the existing linear accelerator with photon, proton therapy produces a number of second radiation due to the kinds of nuclide including neutron that is produced from the interaction with matter, and more attention must be paid on the exposure level of radiation workers for this reason. Therefore, thermoluminescence dosimeter (TLD) that is being widely used to measure radiation was utilized to analyze the exposure level of the radiation workers and propose a basic data about the radiation exposure level during the proton therapy. Materials and Methods: The subjects were radiation workers who worked at the proton therapy center of National Cancer Center and TLD Badge was used to compare the measured data of exposure level. In order to check the dispersion of exposure dose on body parts from the second radiation coming out surrounding the beam line of proton, TLD (width and length: 3 mm each) was attached to on the body spots (lateral canthi, neck, nipples, umbilicus, back, wrists) and retained them for 8 working hours, and the average data was obtained after measuring them for 80 hours. Moreover, in order to look into the dispersion of spatial exposure in the treatment room, TLD was attached on the snout, PPS (Patient Positioning System), Pendant, block closet, DIPS (Digital Image Positioning System), Console, doors and measured its exposure dose level during the working hours per day. Results: As a result of measuring exposure level of TLD Badge of radiation workers, quarterly average was 0.174 mSv, yearly average was 0.543 mSv, and after measuring the exposure level of body spots, it showed that the highest exposed body spot was neck and the lowest exposed body spot was back (the middle point of a line connecting both scapula superior angles). Investigation into the spatial exposure according to the workers' movement revealed that the exposure level was highest near the snout and as the distance becomes distant, it went lower. Conclusion: Even a small amount of exposure will eventually increase cumulative dose and exposure dose on a specific body part can bring health risks if one works in a same location for a long period. Therefore, radiation workers must thoroughly manage exposure dose and try their best to minimize it according to ALARA (As Low As Reasonably Achievable) as the International Commission on Radiological Protection (ICRP) recommends.