Environmental dependence of geometrical efficiency for the scintillation cell in radon and thoron measurement.

222Rn is recognized as a matter of international concern for human health risk. Because 220Rn as well as 222Rn coexist in the natural environment, thoron sometimes influences the experiment for radon measurement. It is important to measure radon and thoron separately to evaluate the risk of the exposure to 222Rn.

Calibration experiments for radon in drinking water measurements using portable-type electrostatic-collection radon monitors.

Portable-type electrostatic-collection radon monitors (RAD7) are often used for in-situ measurements of radon in water. In this study, we evaluated the calibration factors and their uncertainties for two RAD7 monitors based on comparative measurements with the liquid scintillation counting method. In the first experiment, we found that both RAD7 monitors had relatively large uncertainties due to leakage of radon gas that bubbled from the gaps between the lids of the desiccant container and the glass vial.

Site-specific dose conversion factors for radon progeny based on ambient aerosol characteristics in an outdoor environment and a tourist cave.

Site-specific Dose Conversion Factors (DCFs) for radon progeny were estimated based on the aerosol measurement results in an outdoor environment and a tourist cave. The Activity Median Diameter (AMD) and unattached fraction were measured and used to calculate the effective dose per unit intake of radon progeny. The AMDs in the outdoor environment was in the range of 0.

Development of calculation tool for iodine 131 biodistribution depending on the aerosol particle distribution.

Radiation damage to tissues depends on radiation exposure levels. Therefore, we have studied accurate estimations of radiation exposure levels so far. Recently, we developed a tool that can calculate the respiratory tract deposition of radionuclides based on polydisperse particle size distribution.

Effectiveness of simplified dose estimation equations for triage after criticality accident-a case study of dose assessment in the JCO criticality accident.

The dosimetry for the triage of personnel encountering a criticality accident was investigated. The JCO criticality accident of 1999 was selected as a case study, and attention was paid to the identification and the segregation of severely exposed personnel. A series of Monte Carlo calculations revealed that simplified equations proposed by ANSI to estimate dose with respect to distance work well to determine the region of interest for triage.

Development of a new integrated IN-VIVO counting system at the QST.

A new in-vivo counting system that functions as both a whole-body counter (WBC) and a lung counter (LC) was developed at the QST to enhance its dose assessment capability. This paper presents an overview of this system and the results of its performance tests. For use of the system as a WBC, three high purity germanium (HPGe) detectors installed in a 20-cm-thick iron shielding chamber are linearly arrayed over a subject lying on the bed, whereas two of the three HPGe detectors are placed over the subject's chest from side to side when using the system as an LC.

Oxidative Modification Status of Human Serum Albumin Caused by Chronic Low-Dose Radiation Exposure in Mamuju, Sulawesi, Indonesia.

The recently discovered high-level natural background radiation area (HBRA) of Mamuju in Indonesia provides a unique opportunity to study the biological effects of chronic low-dose radiation exposure on a human population. The mean total effective dose in the HBRA was approximately 69.6 mSv y (range: 47.

INFLUENCE OF SAMPLING FLOW RATE ON THORON EXHALATION RATE MEASUREMENTS BY THE CIRCULATION METHOD.

Researchers have used various methods to obtain the exhalation rates of radon and thoron from soil and building materials. One of the typical methods for radon exhalation rate is the circulation method using an accumulation container, an external or internal sampling pump and a continuous radon monitor. However, it is necessary to consider sampling flow rate if this method is applied to exhalation rate measurement for thoron due to its short half-life.

Detection of biological responses to low-dose radiation in humans.

It has been considered difficult to detect the biological effects of low-dose radiation exposure below approximately 100 mSv in humans. Serum proteomic analysis and oxidative modification profiling were conducted with blood samples collected from residents of a newly discovered high-level natural background radiation area (annual effective dose approximately 50 mSv y) and normal-level area (1.22 mSv y) in Mamuju, Indonesia, where many people have been living for generations.

Rn and Ra Concentrations in Spring Water and Their Dose Assessment Due to Ingestion Intake.

Rn and Ra concentrations of less than a few to several thousands of Bq L have been observed in several underground bodies of water around the world. Although regulations for these concentrations in water have been implemented internationally, there are currently no regulations in place in Japan. However, concentrations that exceed these internationally recognized regulatory values have also been observed in Japan.

Comprehensive exposure assessments from the viewpoint of health in a unique high natural background radiation area, Mamuju, Indonesia.

Mamuju is one of the regions in Indonesia which retains natural conditions but has relatively high exposure to natural radiation. The goals of the present study were to characterize exposure of the entire Mamuju region as a high natural background radiation area (HNBRA) and to assess the existing exposure as a means for radiation protection of the public and the environment. A cross-sectional study method was used with cluster sampling areas by measuring all parameters that contribute to external and internal radiation exposures.

Support activities in Namie Town, Fukushima undertaken by Hirosaki University.

This paper does not necessarily reflect the views of the International Commission on Radiological Protection.Several radiation monitoring research projects are underway on dose assessment, biological analysis, and risk communication under an agreement with Namie Town. Indoor radon and thoron progeny concentrations have been measured using passive-type monitors to estimate internal doses due to inhalation.

Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations.

A long-term measurement technique of radon exhalation rate was previously developed using a passive type radon and thoron discriminative monitor and a ventilated type accumulation chamber. In the present study, this technique was applied to evaluate the thoron exhalation rate as well, and long-term measurements of radon and thoron exhalation rates were conducted for four years in Gifu Prefecture. The ventilated type accumulation chamber (0.

Discriminative Measurement of Absorbed Dose Rates in Air from Natural and Artificial Radionuclides in Namie Town, Fukushima Prefecture.

Ten years have elapsed since the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, and the relative contribution of natural radiation is increasing in Fukushima Prefecture due to the reduced dose of artificial radiation. In order to accurately determine the effective dose of exposure to artificial radiation, it is necessary to evaluate the effective dose of natural as well as artificial components. In this study, we measured the gamma-ray pulse-height distribution over the accessible area of Namie Town, Fukushima Prefecture, and evaluated the annual effective dose of external exposure by distinguishing between natural and artificial radionuclides.

Radon Activity Concentrations in Natural Hot Spring Water: Dose Assessment and Health Perspective.

The world community has long used natural hot springs for tourist and medicinal purposes. In Indonesia, the province of West Java, which is naturally surrounded by volcanoes, is the main destination for hot spring tourism. This paper is the first report on radon measurements in tourism natural hot spring water in Indonesia as part of radiation protection for public health.

A unique high natural background radiation area - Dose assessment and perspectives.

The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures.

CAESIUM RETENTION CHARACTERISTICS OF KNIFC-PAN RESIN FROM RIVER WATER.

The caesium retention characteristics of a potassium-nickel hexacyanoferrate resin in a polyacrylnitrile (KNiFC-PAN) matrix were tested in fresh water over the range of 2.5-400 mL min-1. The experimental setup used 2 mL resin and 4-L aliquots of freshwater samples.

Passive-Type Radon Monitor Constructed Using a Small Container for Personal Dosimetry.

The International Commission on Radiological Protection (ICRP) recently recommended a new dose conversion factor for radon based on the latest epidemiological studies and dosimetric model. It is important to evaluate an inhalation dose from radon and its progeny. In the present study, a passive radon personal monitor was designed using a small container for storing contact lenses and its performance was evaluated.

Importance of Discriminative Measurement for Radon Isotopes and Its Utilization in the Environment and Lessons Learned from Using the RADUET Monitor.

Radon (Rn) and thoron (Rn), sources of natural background radiation, have been the subjects of long-standing studies, including research into radon and thoron as major causes of lung cancer at domestic and international levels. In this regard, radon and thoron measurement studies have been widely conducted all over the world. Generally, the techniques used relate to passive nuclear track detectors.

Impact of Wind Speed on Response of Diffusion-Type Radon-Thoron Detectors to Thoron.

Air exchange through a porous medium depends partly on a pressure gradient induced in it, i.e., air-flow conditions of the outer air.

COMPARATIVE STUDY ON PERFORMANCE OF VARIOUS ENVIRONMENTAL RADIATION MONITORS.

After the Fukushima Daiichi Nuclear Power Plant accident, the radiation dose for first responders was not evaluated accurately due to lack of the monitoring data. It has been important to evaluate a radiation dose for workers in emergency response at a nuclear accident. In this study, a new device which can evaluate both of external and internal exposure doses was developed and the performance of various environmental radiation monitors including commercially available monitors were tested and compared from the viewpoint of an environmental monitoring at emergency situation.

INVESTIGATION OF EXTERNAL RADIATION DOSES DURING RESIDENTS' TEMPORAL STAY TO NAMIE TOWN, FUKUSHIMA PREFECTURE.

Namie Town in Fukushima Prefecture, the majority of which was an evacuation area as a result of the effects of the Fukushima Daiichi Nuclear Power Plant accident, carried out a 'temporal stay' in September 2016 so that residents could check their houses. Therefore, in cooperation with the town authorities, the authors distributed personal dosemeters and behaviour record forms to record the personal dose equivalent rate and investigate the relationship between residents' external radiation dose and their behaviour. When the personal dose equivalent rate was calculated from the measured personal dose equivalent per hour, the median was 0.