Radiation Exposure Of Workers Research Articles

Visualization software for radioactive contamination based on Compton camera: COMRIS.

Identifying and visualizing the radiation source location are important in reducing the radiation exposure of workers at the decommissioning site of the Fukushima Daiichi Nuclear Power Station and in improving the radiation protection functions in other sites where radiation sources are handled. In this paper, we developed the COMpton camera for Radiation Imaging System (COMRIS) to identify and visualize the radiation source location in 3D using output data from a Compton camera and a simultaneous localization and mapping (SLAM) device as input data. Here, we presented COMRIS to visualize a 137Cs-radiation source in a dark environment using data acquired by a commercial Compton camera and a LiDAR-based SLAM device mounted on a robot as input data. The radiation source image obtained using the Compton camera was drawn on the 3D work environment model acquired by the SLAM device, and the radiation source location was visible in 3D.

Tools for harmonized data collection at exposure situations with naturally occurring radioactive materials (NORM)

Naturally occurring radioactive materials (NORM) contribute to the dose arising from radiation exposure for workers, public and non-human biota in different working and environmental conditions. Within the EURATOM Horizon 2020 RadoNorm project, work is ongoing to identify NORM exposure situations and scenarios in European countries and to collect qualitative and quantitative data of relevance for radiation protection. The data obtained will contribute to improved understanding of the extent of activities involving NORM, radionuclide behaviours and the associated radiation exposure, and will provide an insight into related scientific, practical and regulatory challenges.The development of a tiered methodology for identification of NORM exposure situations and complementary tools to support uniform data collection were the first activities in the mentioned project NORM work. While NORM identification methodology is given in Michalik et al., 2023, in this paper, the main details of tools for NORM data collection are presented and they are made publicly available.The tools are a series of NORM registers in Microsoft Excel form, that have been comprehensively designed to help (a) identify the main NORM issues of radiation protection concern at given exposure situations, (b) gain an overview of materials involved (i.e., raw materials, products, by-products, residues, effluents), c) collect qualitative and quantitative data on NORM, and (d) characterise multiple hazards exposure scenarios and make further steps towards development of an integrated risk and exposure dose assessment for workers, public and non-human biota.Furthermore, the NORM registers ensure standardised and unified characterisation of NORM situations in a manner that supports and complements the effective management and regulatory control of NORM processes, products and wastes, and related exposures to natural radiation worldwide.

Occupational exposure to ionizing radiation in medical staff: trends during the 2009–2019 period in a multicentric study

ObjectivesHealth workers exposed to ionizing radiation account for + 50% of workers exposed to man-made radiation in France. Over the last decade, the use of radiation in medicine has increased due to the introduction of new practices. The EXposition des Professionnels de santE aux RayonnemenTs ioniSants study aims to evaluate and characterize the trends in radiation exposure of health workers in France between 2009 and 2019.MethodsThis retrospective study includes all health workers with at least one dosimetric record in the system for occupational dosimetry registration (Système d’information de la surveillance de l’exposition aux rayonnements ionisants) database for each of the years 2009, 2014, and 2019, in the hospitals included in the study. Individual external doses and socio-professional data were collected. Statistical analyses include descriptions, graphs, and logistic regressions.ResultsA total of 1457 workers were included (mean age: 39.8 years, 59% women). The average exposure significantly decreased between 2009 and 2019 (−0.008 mSv/year, p < 0.05). There were large discrepancies in trends according to professions, departments, hospitals, and gender. Over the 10-year study period, radiologic technologists and physicians were the most exposed (0.15 mSv (95%CI 0.14–0.16) and 0.13 mSv (0.06–0.21), respectively), but their exposure tended to decrease. Workers in nuclear medicine departments had the highest radiation exposure (0.36 mSv (0.33–0.39)), which remained stable over time. Thirty-eight percent of recorded doses were nonzero in 2009, decreasing to 20% in 2019.ConclusionsThis study allowed to identify physicians and radiologic technologists in nuclear medicine departments as the most exposed medical workers in France, and to show an overall decrease trend in radiation exposure. This should be instructive for radiation monitoring and safety of exposed medical workers.Key Points• Radiation exposure of healthcare workers in most medical departments has steadily decreased between 2009 and 2019 in several French hospitals.• The number of zero doses consistently increased during the study period.• Workers in nuclear medicine departments are the most exposed, especially radiologic technologists and physicians.

Assessment of radiation exposure in a nuclear medicine department of an oncology hospital

BackgroundMedical personnel in nuclear medicine departments are exposed to ionizing radiation which is associated with cancer induction and mortality risks. Examples of such personnel are those working in the hot-areas where radioisotopes for nuclear medicine examinations are prepared. This work aims to estimate the occupational radiation exposure for workers at the Nuclear Medicine department in Da Nang Oncology Hospital, Vietnam. Materials and methodsThe study was conducted from 2020 to 2021. The personal dose equivalents (Hp) were quantified for soft tissues for deep dose (Hp(10)), eye lens dose (Hp(3)), skin dose (and Hp(0.07)) were quantified utilizing optically stimulated luminescence dosimeters (OSLD) crystals. In this study, the dose equivalent at the hot area is measured by 9 OSLD, while that for staff was measured using 16 OSLD. ResultsIn 2020, the annual average Hp(10) was (0.38 mSv ± 1.39); in 2021 Hp(10) was (0.25 mSv ± 1.27). The average Hp(10) was well below the annual occupational dose limits (20 mSv.year−1). Regarding the annual dose, all recorded values were quite low compared to the annual radiation dose limits for radiation staff (20 mSv annual ∼ 1.67 mSv.month−1). Nevertheless, some points of measurement revealed a high-value dose of 5.69 mSv ± 2.83. This suggests that rigorous evaluation of the workplace is essential to ensuring workers' exposure is kept within safe levels. ConclusionsIt is concluded that the Hp(10) and Hp(0.07) for the working environment and radiation workers were below the dose limits from ICRP. In addition, it is recommended that continuous monitoring of the occupational dose in nuclear medicine department is essential to reduce the dosimetric hazards of personnel working in the department.

Assessment of hOGG1 Genetic Polymorphism (rs1052133) and DNA Damage in Radiation-Exposed Workers

The aim of this study was to assess the effect of radiation exposure, human 8-oxoguanine DNA N-glycosylase-1 (hOGG1) exon 7 genetic polymorphism and confounding factors on DNA damage response. Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and alkaline Comet assay method were applied to determine the hOGG1 genetic polymorphisms and DNA damage response. A total of 80 participants were enrolled in this study, consisting of 40 radiation-exposed workers as a case group and 40 non-radiation workers as a control group. The genotypes frequencies for controls were Ser/Ser (35%), Ser/Cys (32.5%), and Cys/Cys (32.5%), with frequencies of alleles being 326Ser (0.52) and 326Cys (0.48), whereas the genotypes frequencies for radiation-exposed workers (cases group) were Ser/Ser (17.5%), Ser/Cys (57.5%), and Cys/Cys (25%), with frequencies of alleles being 326Ser (0.46) and 326Cys (0.54). The results indicated that DNA damage response were not significantly higher in the exposed workers than in controls (22.55 ± 6.02 versus 21.72 ± 7.14; P=0.58). The time of exposure has a significantly negative correlation with comet tail length value among radiation workers. In addition, it was found that the DNA damage response was strongly associated with age and time of exposure with a decrease of 0.6 percent (P-value: 0.008) and 0.58 percent (P-value: 0.009), respectively. Whereas gender, smoking habit, and equivalent dose were not correlated with DNA damage. The single-nucleotide polymorphism of hOGG1 exon 7 (rs1052133) demonstrated no association with the extent of DNA damage in radiation-exposed workers.

Database of the Cohort of Workers of the Siberian Chemical Plant Exposed to Uranium Compounds

Introduction: Uranium, the basic raw material of the nuclear industry, poses health risks to people occupationally exposed to its compounds. Studies of adverse effects of radiation exposure in workers of nuclear facilities necessitate a cohort of employees handling uranium compounds. Objective: To form a historic cohort and create a database of the personnel of the Siberian Chemical Plant exposed to uranium compounds at workplaces in 1953–2000. Materials and methods: The source of information was the Regional Health and Dosimetry Register of the Seversk Biophysical Research Center, containing data on all current and former employees of the Siberian Chemical Plant (ca. 65,000 people) from the date of establishment of the company to the present. Results: We have created and described a cohort of 1,484 workers (898 men and 586 women) exposed to uranium compounds at the Siberian Chemical Plant in 1953–2000. Health and dosimetry information of the cohort members was entered in a specially developed database of the personnel of the Siberian Chemical Plant engaged in works with uranium compounds during that time period. Conclusion: Both the retrospective cohort and the detailed database allow epidemiological studies of cancer incidence and mortality in the industry workers and evidence-based conclusions about the contribution of occupational exposure to uranium compounds. The cohort of employees of the Siberian Chemical Plant meets all the requirements of up-to-date epidemiological studies in terms of its size and completeness of health and exposure data.

ПРИМЕНЕНИЕ НОВЫХ РЕКОМЕНДАЦИЙ МКРЗ ДЛЯ РАСЧЕТА ДОЗ ПЕРСОНАЛА ПРИ ИНГАЛЯЦИОННОМ ПОСТУПЛЕНИИ РАДИОНУКЛИДОВ УРАНА

Purpose: Harmonization and improvement of the system for regulating the internal radiation exposure of workers and the basic requirements for ensuring radiation safety, taking into account the application of new international requirements and recommendations. Material and methods: A brief description of the procedure for calculating absorbed and equivalent doses in organs and tissues after the intake of radionuclides into the human body is presented, using the biokinetic and dosimetric models adopted in the new ICRP recommendations, as well as a discussion of the impact of these changes on the results of calculating dose coefficients for the case of inhalation intake of uranium-235 radionuclide. Results: The effective dose values and equivalent doses to organs and tissues for workers were calculated depending on the time after a single inhalation intake of uranium-235 aerosol, according to new models [1–12] and according to previous ICRP models [15, 16]. The calculation of the effective dose according to the new models included calculations of equivalent doses for 14 main organs and tissues and 13 organs and tissues classified as “remainder tissues” as described in ICRP Publication 103 [3]. The committed effective dose was then calculated according to the new approach using the average of the equivalent doses for the reference adult male, HTM, and the reference adult female, HTF, as well as the tissue and organ weighting factors, WT, adopted in ICRP Publication 103. The values of the effective dose and equivalent doses on the red bone marrow, lungs and remainder tissues vs time in the range from several days to 18250 days (50 years) after a single inhalation intake of an aerosol of uranium-235 for standard value AMAD=5 µm and types of compounds F, M, S, F/M and M/S are presented according to new and previous ICRP models. It is shown that the value of the dose coefficient for type F, calculated by new models, is 2.6 times (2.3E-07÷6.0E-07) less than that calculated by previous ICRP models, and the value of the dose coefficient for type F/M calculated by new models is 1.6 times (3.8E-07÷6.0E-07) less than the value of the dose coefficient for type F calculated by previous ICRP models. For uranium trioxide UO3, taking into account its transition from compound type M to F/M, the value of the dose coefficient for committed effective dose according to the updated model of the respiratory tract is 4.7 times (3.8E-07÷1.8E-06) less than the corresponding value for the previous model of the type M respiratory tract. The committed effective dose value for compound type M, calculated using the new models, is 1.4 times (1.3E-06÷1.8E-06) less than the same value calculated using the previous ICRP models. The value of the committed effective dose for type M/S compounds (which, according to the new model of the respiratory tract, include uranium oxide U3O8 and dioxide UO2), calculated according to new models, is 1.2 times (5.1E-06÷6.1E-06) less than the value calculated from previous ICRP models for type S compounds (which included U3O8 and UO2 in the previous respiratory tract model). Conclusion: From the above data it follows that in case of the adoption of national radiation safety standards to new ICRP models, differences in the values of dose coefficients will result in a change of annual limits of intake (ALI) in the corresponding proportion for the types of uranium aerosol compounds noted above.

Assessment of thyroid gland hormones and ultrasonographic abnormalities in medical staff occupationally exposed to ionizing radiation

BackgroundIonizing radiation (IR) is high-energy radiation that has the potential to displace electrons from atoms and break chemical bonds. It has the ability to introduce mutations, DNA strand breakage, and cell death. Being a radiosensitive organ, exposure of the thyroid gland to IR can lead to significant changes in its function.Aim of the workWas to measure the levels of thyroid hormones panel and ultrasonography abnormalities in medical staff occupationally exposed to IR.Subjects and methodsA total of 120 subjects were divided into three main groups: Group I: radiation-exposed workers occupationally exposed to radioiodine (131I) (n = 40), Group II: radiation-exposed workers occupationally exposed to X-ray (n = 40), and Group III: non-exposed healthy professionals matched in age and sex with the previous groups (n = 40). Thyroid hormones panel including free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), anti-thyroperoxidase antibodies (anti-TPO), and thyroglobulin (Tg) were measured. Thyroid ultrasonography was performed. Oxidative stress markers such as malondialdehyde (MDA), hydrogen peroxide (H2O2), and total antioxidant capacity (TAC) were measured.ResultsGroup I had significantly higher fT3 levels than the control group. fT3 levels were considerably higher, while TSH was substantially lower in group II participants than in the control group. Tg was markedly lower in radiation-exposed workers. However, anti-TPO levels in radiation-exposed workers were significantly higher than in the control group. MDA and H2O2 were substantially higher; TAC was significantly lower in radiation-exposed workers compared to the control group. According to ultrasonographic examination, thyroid volume and the percentage of thyroid nodules in all radiation workers were significantly higher than in the control group.ConclusionDespite low exposure doses, occupational exposure to IR affects the thyroid hormones and links with a higher likelihood of developing thyroid immune diseases.

Application of a semi-automated dicentric scoring system in triage and monitoring occupational radiation exposure.

The dicentric chromosome assay (DCA) is considered the gold standard for radiation biodosimetry, but it is limited by its long dicentric scoring time and need for skilled scorers. The automation of scoring dicentrics has been considered a strategy to overcome the constraints of DCA. However, the studies on automated scoring methods are limited compared to those on conventional manual DCA. Our study aims to assess the performance of a semi-automated scoring method for DCA using ex vivo and in vivo irradiated samples. Dose estimations of 39 blind samples irradiated ex vivo and 35 industrial radiographers occupationally exposed in vivo were estimated using the manual and semi-automated scoring methods and subsequently compared. The semi-automated scoring method, which removed the false positives of automated scoring using the dicentric chromosome (DC) scoring algorithm, had an accuracy of 94.9% in the ex vivo irradiated samples. It also had more than 90% accuracy, sensitivity, and specificity to distinguish binary dose categories reflecting clinical, diagnostic, and epidemiological significance. These data were comparable to those of manual DCA. Moreover, Cohen's kappa statistic and McNemar's test showed a substantial agreement between the two methods for categorizing in vivo samples into never and ever radiation exposure. There was also a significant correlation between the two methods. Despite of comparable results with two methods, lower sensitivity of semi-automated scoring method could be limited to assess various radiation exposures. Taken together, our findings show the semi-automated scoring method can provide accurate dose estimation rapidly, and can be useful as an alternative to manual DCA for biodosimetry in large-scale accidents or cases to monitor radiation exposure of radiation workers.

Epidemiological study of health effects in Fukushima Emergency Workers: Progress report on the Health Examination Study, 2016-2019

• Summarized results of the first health examination conducted from January 2016 to March 2019. • Of the 19,808 emergency workers, 5,718 participated in the Health Examination Study until March 2019. • No health abnormalities were found among study participants, as a group. To clarify the long-term health effects from radiation exposure in emergency workers who responded to the radiation accident at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, which was hit by a tsunami caused by the 2011 off the Pacific coast of Tohoku earthquake, the Epidemiological Study of Health Effects in Fukushima Emergency Worker (currently, the Epidemiological Study on the Health Effects of Radiation Workers) was initiated in 2014. We aimed to compile the results of the Health Examination Study conducted from January 2016 to March 2019 to demonstrate the characteristics of the study participants during this period. We included individuals who completed the first health examination and provided consent to use their survey results in our study. A total of 5,718 people were included, among which 5,707 (99.8%) were men. The mean age of the study participants was 51.6 years at the time of the health examination. Compared to Japanese men, the study participants were more likely to have obesity, to be current smokers, and to consume alcohol at least once a month. There were no significant differences in the blood test results between the study participants and healthy Japanese men. To clarify the long-term health effects of radiation exposure on the emergency workers, it is important to make efforts to prevent the study participants from dropping out of the cohort over time and to keep them participating in the Health Examination Study.

Assessing the need for radiation protection measures in artisanal and small scale mining of tantalite in Oke-Ogun, Oyo State, Nigeria

There is concern that work scenarios on the tantalite mining sites in Oke-Ogun, Oyo State, Nigeria may cause occupational radiation exposure of workers due to enhanced concentrations of naturally occurring radionuclides in some process materials. A prior radiological assessment of the mining activities was carried out to determine if and which exposure scenarios may require radiation protection measures. Samples of the materials involved, comprising tantalite (tantalum ores), soil and waste rock were collected and analyzed for activity concentrations of 40K, 226Ra, 238U and 232Th using a hyper pure germanium detector gamma-ray spectrometer. Radon concentrations in the mines were also measured using a continuous radon monitor - Radon-Scout Plus (Sarad, GmbH). Activity concentrations of 40K are below 10 Bqg-1 in all the samples but all the tantalite samples contain more than 1 Bqg-1 of 226Ra and 238U. Hence tantalite is regarded as naturally occurring radioactive material (NORM) and the mining activity as a practice. The requirements for planned exposure situations apply to all the mining sites but, on the basis of graded approach, the optimum radiation protection measures vary from one mine to another, ranging from exemption to authorization. Exposures to radon in the underground mines pose the greatest radiological risks and portend the greatest need for regulatory control in the mining operations. The results further underscore the need to integrate radiation protection with the other health and safety measures in the mining sector.

Characterization of Thermoluminescent Dosimeters for Neutron Dosimetry at High Altitudes.

Neutrons constitute a significant component of the secondary cosmic rays and are one of the most important contributors to natural cosmic ray radiation background dose. The study of the cosmic ray neutrons’ contribution to the dose equivalent received by humans is an interesting and challenging task for the scientific community. In addition, international regulations demand assessing the biological risk due to radiation exposure for both workers and the general population. Because the dose rate due to cosmic radiation increases significantly with altitude, the objective of this work was to characterize the thermoluminescent dosimeter (TLDs) from the perspective of exposing them at high altitudes for longtime neutron dose monitoring. The pair of TLD-700 and TLD-600 is amply used to obtain the information on gamma and neutron dose in mixed neutron-gamma fields due to the present difference in 6Li isotope concentration. A thermoluminescence dosimeter system based on pair of TLD-600/700 was characterized to enable it for neutron dosimetry in the thermal energy range. The system was calibrated in terms of neutron ambient dose equivalent in an experimental setup using a 241Am-B radionuclide neutron source coated by a moderator material, polyethylene, creating a thermalized neutron field. Afterward, the pair of TLD-600/700 was exposed at the CERN-EU High-Energy Reference Field (CERF) facility in Geneva, which delivers a neutron field with a spectrum similar to that of secondary cosmic rays. The dosimetric system provided a dose value comparable with the calculated one demonstrating a good performance for neutron dosimetry.

Risk of occupational radiation exposure for radiation workers involved in interventional endourology in Saudi Arabia

In recent years, fluoroscopically-guided interventional procedures have become an essential part of endourology practices and widely performed around the world. Despite the many clinical benefits of these procedures, they expose patients and workers to a significant amount of radiation. Thus, this study aimed to estimate the mean annual occupational radiation dose for interventional endourology workers in Saudi Arabia. During the five-year period from 2017 to 2021, 262 interventional endourology workers were monitored to estimate the radiation effective dose during their work routine in 28 Saudi Ministry of Health healthcare facilities. To estimate the radiation effective doses for workers, thermoluminescent dosimeters (TLD) were used on a quarterly basis. The interventional endourology workers were asked to operate the TLD-100 device using a lead apron, a thyroid protective collar and leaded protective eyewear to protect most parts of their body. The mean annual effective dose (mSv) was used as an indicator of the overall occupational exposure for the workers. Analysis of the occupational dose data showed that the mean annual effective dose for all workers, averaged over the study period, was 0.70 mSv (0.12–3.18 mSv). The results indicate a safe environment in terms of radiation protection with no single dose exceeding the recommended occupational dose limits. However, optimisation of radiation protection practices is always advised to facilitate a reduction in the occupational exposure to the radiation dose.

Occupational radiation exposure for various medical radiation workers, especially the dental radiation workers, in Taiwan from 2013 to 2020

Background/purposeThe development of dental radiology in Taiwan has been over a century. This study explored mainly the profile of dental radiation workers and their occupational radiation exposure in Taiwan from 2013 to 2020. Materials and methodsThis study used the secondary data analysis to survey mainly the changes of manpower of the dental radiation workers and their occupational radiation exposure in Taiwan from 2013 to 2020. ResultsThe number of monitored dental radiation workers increased from 678 in 2013 to 770 in 2020. However, the proportion of monitored dental radiation workers to the total monitored medical radiation workers decreased from 4.29% in 2013 to 3.67% in 2020. Although the number of monitored dental radiation workers increased, the number of the measurably exposed dental radiation workers decreased from 2013 to 2020. The annual collective exposure dose fluctuated from 5.21 man-Sv to 15.47 man-Sv, but it showed a decreasing trend. Furthermore, the mean annual effective exposure dose of total monitored dental radiation workers (0.01–0.02 mSv) and that of the measurably exposed dental radiation workers (0.15–1.11 mSv) were relatively low among various medical radiation workers. In overall, the proportion of medical radiation technologists to dentists varied from 0.41 to 0.45. ConclusionAlthough the number of monitored dental radiation workers increase, the number of the measurably exposed dental radiation workers, the proportion of the measurably exposed dental radiation workers to the total monitored dental radiation workers, and the annual collective exposure dose for monitored dental radiation workers decrease from 2013 to 2020.

Does occupational ionizing radiation exposure in healthcare workers affect their hematological parameters?

Blood cells are used as the most sensitive marker to determine the effects and intensity of ionizing radiation. This descriptive study aimed to evaluate the effect of radiation exposure on hematological parameters in healthcare workers who were exposed to radiation in a university hospital between May and June 2021. A total of 339 participants were included, of which 169 (49.9%) were radiation workers and 170 (50.1%) were in the control group. A decrease was observed in white blood cell and neutrophil counts in those exposed to ionizing radiation for less than 10 years; however, white blood cell, neutrophil, hemoglobin levels decreased, and red cell distribution width (RDW) levels increased in those exposed to ionizing radiation for 10 years or more (p < 0.005). A statistically significant increase was observed in the RDW and lymphocyte levels as the years of work experience in the profession increase in the group exposed to IR. The findings indicate that the effect of low-dose ionizing radiation on the hematopoietic system is related to the frequency and duration of the dose. Hematological parameters can be sensitive biomarkers of low-dose ionizing radiation; possible disturbances in the hematopoietic system can be recognized before the onset of symptoms, and necessary precautions can be taken promptly.

Ensuring radiation safety in medical institutions of the dental profile

The analysis of indicators of radiation exposure of medical workers of the dental profile of the Samara region during medical procedures for the period from 2004 to 2019 is carried out in comparison with the quantitative dynamics of X-ray diagnostic studies. The main directions of occupational safety indicators of medical workers of the dental profile when working with X-ray diagnostic equipment have been determined. The purpose was to conduct a comparative analysis of the radiation exposure indicators of medical workers of the dental profile of the Samara region during medical procedures for the period from 2004 to 2019, to characterize the radiation safety of personnel. An analytical work was carried out on the indicators of the average radiation dose of medical workers of the dental profile of the Samara region during medical procedures according to the data of radiation and hygienic certification of the territory of the Samara region for the period from 2004 to 2019. In the framework of this study, the number and demand for X-ray diagnostic procedures in medical institutions of the dental profile among the population. A retrospective analysis of the dynamics of X-ray studies and the values of the average individual dose of radiation for personnel working with X-ray dental devices in 10 large medical institutions of the dental profile of various forms of ownership in the territory of Samara and the Samara region (C1-C10) for the period from 2004 to 2019 was carried out…. on the basis of the annual forms of statistical reporting of the radiation-hygienic passport of the organization (RGPO). The decrease in radiation exposure is due to the replacement of outdated equipment with more modern ones, the transition from film types of research to digital ones, an increase in personnel literacy in the field of radiation safety, which characterizes the improvement of radiation safety indicators for dental personnel in Samara and the Samara region.

An assessment of radiation exposure of workers during decommissioning of reactor vessel at Kori #1 unit

This study is for assessment and optimization of workers' radiation exposure for decommissioning Reactor Vessel (RV) at Kori #1 unit in connection with its dismantling process for the purpose of establishing Radiation Safety Management Plan. The basis of radiological conditions of this assessment is supposed to be those of 10 years after the permanent shutdown of Kori #1 unit when dismantling work of Reactor Vessel would suppose to be started. Dose rates of work areas were evaluated on the basis of spatial dose rate derived from activation level calculated by MCNP(Monte Carlo N-Particle Transport) and ORIGEN-S code. The dismantling process of Kori #1 RV was developed based on in-situ execution in atmospheric environment as the following steps of Preparation, Dismantling of Peripheral Structures, Dismantling of RV and Finishing Work. For assessment of exposure of RV dismantling work, those processes of each steps are correlated with spatial dose rates of each work areas where the jobs being done. Results of the assessment show that workers' collective dose for RV dismantling work would be in the range of 536 man- mSv ∼ 778 man- mSv. The most critical process would be dismantling of upper connecting parts of RV with 170 man- mSv ∼ 256 man- mSv while among the working groups, the expert group performing dismantling of ICI (In-core instrumentation) nozzles and handling & packaging of cut-off pieces is evaluated as the most significantly affected group with 37.5 man- mSv ∼ 39.4 man- mSv. Based on the assessment, improvement plan for better working conditions of the most critical process and the most affected workers in terms of radiation safety were suggested.

Biochemical and Molecular Characterization of Klebsiella species isolated from neoplastic patients under Irradiation therapy

Neoplastic radiation therapy was able to alter the microbial flora of patients' bodies, as well as the microbial flora of radiation-exposed workers, and provided control for possible infectious consequences. Klebsiella aerogenes was a non-fermentative aerobic gram negative bacteria that was widely distributed in nature, requiring species identification in up to 25% of cases in the lab. Antibiotic susceptibility of Klebsiella species multi-resistant isolates is common, and all isolates were characterized in all cases of clinically significant infections caused by these organisms. Only 15 isolates showed significant antimicrobial activities against at least one of the tested indicator bacteria. Vancomycin is an anti-Klebsiella species antibiotic to which resistance is rarely seen, their use should be reserved for the treatment of species infections resistant to all other antibiotics, the emergence of widespread antibiotic-resistant bacteria enhanced the need for new sources of antimicrobial agents, and isolate SHM4-1 was active against all of them, with IC60 values of 3.3 and 1.1 g/ml against HCT-116 and HepG-2 cell lines, respectively. It was genotypically identified as a species with the PKS 4 biosynthetic gene cluster present. To enhance the production, mannitol, ammonium sulphate, pH 7, 2% inoculum size, and 2 days at 37°C were utilized.

Chromosome Damage in Relation to Recent Radiation Exposure and Radiation Quality in Nuclear Power Plant Workers.

Ionizing radiation is a well-known carcinogen that causes genomic instability. However, the biological and carcinogenetic effects of occupational radiation exposure at low doses have not been extensively studied. The aim of this study was to assess chromosomal instability in power plant workers exposed to occupational radiation at low doses in South Korea. Chromosomal aberrations in the lymphocytes of 201 nuclear power plant workers and 59 sex-matched controls were measured. Chromosomal aberrations in the lymphocytes of 201 nuclear power plant workers (mean age: 41.4 ± 10.0 years) and 59 sex-matched controls (mean age: 47.2 ± 6.0 years) were measured. A total of 500 metaphases for each subject were scored randomly. The means of recent 1.5-year, recent 5.5-year, and cumulative exposed radiation doses among workers were 8.22 ± 7.0 mSv, 30.7 ± 22.0 mSv, and 158.8 ± 86.1 mSv, respectively. The frequency of chromosome-type and chromatid-type aberrations was significantly higher in workers than that in the control group (p < 0.001), and the frequency of chromosome-type aberrations among workers increased in a radiation dose-dependent manner (τ = 0.16, p = 0.005). Poisson regression analyses revealed that chromosome-type aberrations were significantly associated with recent 1.5-year dose after adjusting for confounding variables such as age, smoking, and alcohol intake, even when only the exposed worker was considered. Frequency of multi-aberrant cells (two or more chromosome aberrations within a cell) increased according to cumulative neutron exposure. Our study demonstrates that chromosome damage can be induced in nuclear power plant workers occupationally exposed to ionizing radiation at low doses below the occupational permissible dose limit. Furthermore, an increase in multi-aberrant cells may provide evidence for chronic neutron exposure in nuclear power plant workers. This study was performed to obtain baseline data for a surveillance program of workers occupationally exposed to ionizing radiation long-term.

A state-aware adaptive pathfinder for dynamic minimum dose path planning during an emergency in a complex radioactive environment

Optimal walking-path planning is one of the most effective measures to minimize radiation exposure of workers in radioactive environments. Several algorithms have been proposed to control workers' exposure especially during normal operations of a nuclear facility. However, when an emergency or accident occurs, the radioactive environment becomes dynamic and complex, rendering the conventional shortest path algorithms non-optimal and inefficient. This work presents a state-aware adaptive pathfinder (SAP), a method to solve the minimum dose path for an emergency worker in a dynamic nuclear environment. The algorithm dynamically tracks and updates the state of both the radiation source and the (human) target, and adaptively presents the minimum dose path based on the current state. The advantages of the proposed SAP approach are evaluated in two experiments with eight (8) different scenarios. In the first experiment, a minimum dose walking path is obtained for a worker in a static environment with three scenarios. In the second experiment, cumulative dose by the emergency worker along a path is dynamically computed in three scenarios that define both the worker and the radiation source moving in uniform and non-uniform speed. Compared with conventional methods, the results show that the proposed SAP is simpler, more flexible, and effective for path planning in a complex radioactive environment. The performance evaluation result of SAP in both static and dynamic environments, and during a nuclear emergency is discussed in this paper.