Effective methods for monitoring internal contamination among workers handling radioactive materials in various fields.

This study aimed to develop effective methods for monitoring internal contamination among workers handling radioactive materials in various fields. A total of 160 workers from nuclear power plants, medical institutions, military units, and educational/research institutions were included in the study. The monitoring methods included urinalysis and whole-body counting (WBC) using a mobile radio bioassay laboratory (MRL). Gamma-emitting radionuclides were monitored using the MRL WBC system, and a separate pretreatment procedure was used for tritium measurement in urine samples. Gross beta-screening was performed using a liquid scintillation counting system. The results were evaluated on the basis of the established screening criteria and compared with the dose limits. Additionally, tritium concentrations in the bodies of workers in the vicinity of a heavy-water reactor was analysed to assess the association between tritium concentration and occupation. The results showed a wide distribution of tritium concentrations. Workers involved in fuel and maintenance tasks demonstrated the maximum exposure. Workers in medical facilities showed low levels of internal contamination, which was primarily related to tasks involving radioactive isotopes. Military personnel involved in equipment repair showed significant tritium contamination due to damage during repairs. Workers in educational and research institutions in general had low levels of internal contamination.

Neonatal Abusive Head Trauma without External Injuries: Suspicion Improves Diagnosis.

The term "shaken baby syndrome" has been replaced by "abusive head trauma (AHT)" based on the mechanism of injury. The reported mortality rate of AHT ranges from 10% to 30%. Up to two-thirds of survivors suffer from serious long-term disabilities. Thus, an expeditious and accurate diagnosis is crucial to prevent further abuse that might result in death or serious disabilities. It remains a challenge for physicians to diagnose AHT when parents do not give a history of trauma in preverbal infants without any external signs. Here, we report a case of a 14-day-old boy who presented with a febrile convulsion without evident external injuries nor history of trauma according to his parents. He was diagnosed with AHT based on MRI findings of subacute subdural hemorrhage, multiple cortical hemorrhages, cerebral edema, and diffuse axonal injury. In conclusion, health care providers should keep in mind that the history of trauma provided by the parents or caregivers might not always be true and that reasonable suspicion of abuse is the most important in the diagnosis of AHT, although neuroimaging plays a pivotal role. Reasonable suspicion of AHT in combination with a thorough physical examination, neuroimaging, and skilled neuroradiologist can improve diagnosis and help victims in a timely manner.

Screening Criteria for the General Public in Radiation Emergencies From Liquid Scintillation Urinalysis.

Gross alpha/beta screening of urine samples was performed to evaluate internal contamination and dose assessment. Data on background radioactivity concentration were extracted by analyzing the urine samples of non-contaminated individuals who had visited a radiation effect medical clinic since 2012. Screening criteria were studied and established for radiation emergencies based on these results. In particular, pure beta-emitting radionuclides (H and Sr) with a high dose conversion factor were considered to be the source of contamination. Moreover, the screening criteria for the general public were determined based on age groups. The liquid scintillation counting method was used for gross alpha/beta radiation counting. A standardized procedure of correction for chemical and color quenching was performed and validated. The gross beta counting method was validated by analyzing standard urine samples. The fluctuation of the screening criteria was large, based on the time elapsed after intake. A screening criterion of 150 Bq L can be applied within 5 d after intake considering the minimum detectable activity. A standard screening criterion set to 250 Bq L will be used as an important reference for decision making and additional monitoring. Although early evaluation and accurate identification of contaminated radionuclides is preferred, these relatively simple criteria were proposed to address radiation emergency situations involving several casualties.

The Effects of Occupational Stress, Work-Centrality, Self-Efficacy, and Job Satisfaction on Intent to Quit Among Long-Term Care Workers in Korea.

A large and growing population of elderly Koreans with chronic conditions necessitates an increase in long-term care. This study is aimed at investigating the effects of occupational stress, work-centrality, self-efficacy, and job satisfaction on intent to leave among long-term care workers in Korea. We tested the hypothesized structural equation model predicting the intention to quit among long-term care workers in Korea. Survey data were collected from 532 long-term care workers in Seoul, Korea. Results showed that occupational stress was positively associated with intention to leave the job. The study also identified several possible mediators (self-efficacy, work-centrality, job satisfaction) in the relationship between stress and intent to quit. Evidence-based stress management interventions are suggested to help the workers better cope with stressors. Mentoring programs should also be considered for new workers.

Rapid Analysis of 239,238Pu, 241Am, and 90Sr for Nasal Smear Samples in Radiation Emergency and Evaluation of Intake Retention Fraction.

The efficiency of the nasal smear method was reviewed to perform a method of sample collection, analysis and initial dose estimation. The screening method of alpha-emitting radionuclides using chemical separation and alpha spectrometry was also studied. To rapidly conduct the appropriate response to victims, special monitoring for Pu, Am, and Sr using sequential analysis was established, and the method was successfully validated through participation in an international inter-comparison program. The duration of the analysis method was evaluated with regard to application in emergency situations because of its relatively rapid treatment and counting time. The intake retention fraction was calculated and evaluated to review the characteristics of each radionuclide in the anterior nasal passage of the extra-thoracic region. No large difference was observed among the four radionuclides. However, the values of the intake retention fraction were affected by age groups because of the different respiratory rates. The effects of the Y ingrowth and particle size were also discussed.

Effective dose evaluation of NORM-added consumer products using Monte Carlo simulations and the ICRP computational human phantoms.

The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1mSv y(-1) for 44 products. It was demonstrated that NORM-added consumer products could be quantitatively assessed for the safety regulation.

Feasibility study for the assessment of the exposed dose with TENORM added in consumer products.

Consumer products including naturally occurring radioactive material have been distributed widely in human life. The potential hazard of the excessively added technically enhanced naturally occurring radioactive material (TENORM) in consumer products should be assessed. The aim of this study is to evaluate the organ equivalent dose and the annual effective dose with the usage of the TENORM added in paints. The activities of gammas emitted from natural radionuclides in the five types of paints were measured with the high-purity germanium detector, and the annual effective dose was assessed with the computational human phantom and the Monte Carlo method. The results show that uranium and thorium series were mainly measured over the five paints. Based on the exposure scenario of the paints in the room, the highest effective dose was evaluated as <1 mSv y(-1) of the public dose limit.

Screening of alpha- and beta-emitting radionuclides using liquid scintillation counting and monitoring procedures in radiation emergencies.

Urine gross alpha and beta activity analysis was conducted, and an internal contamination screening method was adopted to monitor visitors to Japan after the Fukushima accident. In particular, spot urine samples were used to evaluate internal contamination for 16 mo, and a total of 90 people participated in gross alpha and beta emitter screening. An ultra-low-background liquid scintillation counter was used for measurement, and optimal pulse shape analysis values were determined by measuring alpha- and beta-emitting certified reference materials. Moreover, linearity and reproducibility were assessed to validate the adopted methods, and international intercomparison was conducted using synthetic urine samples by measuring alpha- and beta-emitting radionuclides in multi-contaminated samples. Here, the measurement results of visitors to Japan are discussed, and a screening procedure is established for gross alpha and beta activity analysis during radiation emergencies.

32P measurement and dose conversion factor evaluation of activated human hair by criticality accident.

In order to conduct dose assessment of victims in criticality accidents, a method of fast neutron capture-activated (32)P measurement of hair in which samples are treated by a chemical and analytical procedure that takes 9 h and measurement is conducted by liquid scintillation counting is presented. To validate this measurement method, hair samples spiked with a (32)P reference source were measured and the results analysed and the optimal sample mass and detection efficiency were determined. To verify the correlation between (32)P-specific activity and absorbed dose for spectra with two neutron mean energies, samples collected from three normal individuals were irradiated at various neutron energies and irradiation times using the MC50 Cyclotron of the Korea Institute of Radiological and Medical Sciences. The (32)P-specific activity trend of the irradiated hair agreed well with the absorbed doses. Based on the results, dose conversion factors, which were 0.67 ± 0.15 and 0.59 ± 0.06 Gy (Bq g(-1))(-1) at neutron mean energies of 2.33 and 5.36 MeV, respectively, were calculated as a guide for medical treatment of criticality accident victims.

Evaluation of sodium activation distribution in the PMMA water phantom after fast neutron irradiation.

(24)Na produced by the neutron activation of stable sodium in the body is commonly used to assess neutron doses after criticality accidents. However, the (24)Na distribution is not uniform owing to the interaction with the human body. In this study, we experimentally evaluated the (24)Na distribution in a PMMA water phantom and 60 polyethylene vials. The vials were analyzed to evaluate the sodium activation distribution in the PMMA water phantom by employing a correction factor.

Tritium analysis of urine samples from the general Korean public.

The tritium concentrations of urine samples and the effective dose of the general Korean public were evaluated. To achieve accurate HTO analysis of urine samples, we established the optimal conditions for measuring the HTO content of urine samples. Urine samples from 50 Koreans who do not work at a nuclear facility were analyzed on the basis of the results. The average urine analysis result was 2.8 ±1 .4 Bq/L, and the range was 1.8-5.6 Bq/L. The measured values were lower than those reported for other countries. These results show that environmental factors and lifestyle differences are the main factors affecting the tritium level of the general public.

Radioactive contamination monitoring for the Korean public following Fukushima nuclear accident.

On March 11, 2011, as a result of the Great East Japan Earthquake, severe damage to the Fukushima nuclear power plant caused the release of radioactive materials. We conducted radioactive contamination monitoring for Korean residents in Japan and Korean travelers to East Japan after the accident. More than 800 members of the Korean public were surveyed for personal monitoring. Measured levels of external and internal contamination were within the screening levels for each monitoring method.

Indoor radon distribution of subway stations in a Korean major city.

The overall survey on indoor radon concentration was conducted at all subway stations in a major city, Daejeon in the central part of Korea. It was quarterly performed from September 2007 to August 2008. The annual arithmetic mean of indoor radon concentration of all the stations was 34.1+/-14.7 Bq m(-3), and the range of values was from 9.4 to 98.2 Bq m(-3). The radon concentrations in groundwater (average 31.0+/-0.8 Bq m(-3)) were not significantly high in most stations, but the concentration (177.9+/-2.3 Bq L(-1)) of one station was over the level of 148 Bq L(-1) in drinking water proposed by U.S. EPA. Based on indoor survey results, the approximate average of the annual effective dose by radon inhalation to the employees and passengers were 0.24 mSv y(-1), and 0.02 mSv y(-1), respectively. Although the effective dose based on the UNSCEAR report was potentially estimated, for more accurate assessment, the additional survey on the influence by indoor radon will be necessary.