Nuclear Agency Research Articles

Erythemal ultraviolet radiation exposure of high school rowers in Aotearoa/New Zealand.

Athletes who compete in outdoor sports can receive potentially harmful levels of solar ultraviolet radiation (UVR). Rowing is a popular outdoor sport that takes place during the peak UVR season. Using electronic dosimeters attached to the shoulder strap of the rower's uniform, this study aimed to quantify the real-time solar UVR exposure experienced by high school rowers during competition. We measured personal UVR exposure (PE) during the time spent on the water in order to compete in a single rowing-race (race-time), when rowing administrators are responsible for athletes' wellbeing. Data collection took place in Aotearoa (New Zealand) at Lake Ruataniwha (44.28°S, 170.07°E), during two consecutive rowing seasons (December-February 2018-19 and 2019-20). Analysis of dosimeter data generated from 56 race-times over five regattas revealed a median personal UVR exposure (PE) of 1.15 standard erythemal dose (SED), where 1 SED is defined as an effective radiant exposure of 100 Jm-2. Mean race-time was 46min. Over two-thirds of race-times (69.6%) exceeded the Australian Radiation Protection and Nuclear Safety Agency recommendation of 1 SED being considered safe for most people in a day. An exposure of 1.5-3.0 SED produces perceptible erythema for people with light coloured skin and the lower parameter of 1.5 SED was exceeded in 14 (25.0%) of the race-times. By regatta, the median SED/h ranged from 0.96-2.40 and the median percentage of total concurrent ambient UVR ranged from 17 to 31%. Our results indicate that rowing is a high UVR sport and that races outside of peak UVR times also warrant the use of sun protection even when the UVI<3. Given that acute and cumulative UVR exposure are recognised risk factors in the development of ocular diseases and skin cancers later in life, risk management guidelines for competitive school rowing will be incomplete until a long-term approach to well-being is considered and comprehensive sun protection measures adopted.

STATE'S READINESS MOBILITY IN APPLYING NUCLEAR TECHNOLOGY AS ENERY DEVELOPMENT IN LEGAL PERSPECTIVE

The states Nuclear Program is a program to build and utilize nuclear science and technology both in the non-energy sector and in the energy sector for peaceful purposes. Utilization of non-energy in Indonesia has developed quite advanced. The use of nuclear power in every countries covers various fields such as health, research and industry. Indonesia's readiness in implementing nuclear energy is carried out by ratifying international conventions, issuing laws, and issuing regulations from the Nuclear Energy Supervisory Agency, readiness in the field of infrastructure used to strengthen technology, and in Indonesia is committed to reducing 26% of greenhouse gas emissions in the year 2020. A nuclear power plant or nuclear power plant is a thermal power plant that uses one or more nuclear reactors as a heat source. The working principle of a nuclear power plant is almost the same as a steam power plant, using high pressure steam to turn a turbine. The rotation of the turbine is converted into electrical energy. The difference is the heat source used to generate heat. A nuclear power plant uses uranium as its heat source. The fission reaction (fission) of the uranium nucleus produces enormous heat energy. The power of a nuclear power plant ranges from 40 MWe to 2000 MWe, and a nuclear power plant built in 2005 has a power distribution from 600 MWe to 1200 MWe. As of 2015 there are 437 nuclear power plants operating in the world, which in total generate about 1/6 of the world's electrical energy. To date, around 66 nuclear power plants are being built in various countries, including China with 28 units, Russia with 11 units, India with 7 units, the United Arab Emirates with 4 units, South Korea with 4 units, Pakistan and Taiwan with 2 units each. Nuclear power plants are categorized based on the type of reactor used. However, in some plants that have several separate reactor units, it is possible to use reactor types that are fueled such as Uranium and Plutonium.

Effect of kGy neutron doses on polymer composite consists of poly (vinylidene difluoride)–lithium bis(oxalato)borate

Present work is aimed to explore the electrical and structural behavior of polymer composite consists of poly (vinylidene difluoride)–lithium bis(oxalato)borate under tens of kGy neutron dose. PVDF-LiBOB samples were prepared via solution casting method. The samples were irradiated with neutron doses of 15, 23, 31, 39 and 47 kGy using Reaktor TRIGA PUSPATI at Malaysian Nuclear Agency. X-ray diffraction analysis reveals an increase of crystallinity with the neutron doses, which indicates an improvement of the mechanical strength of the material. Deconvolution of Fourier transform infrared spectra from 1830 to 1760 cm−1 confirms a reduction of free ions following the radiation dose. Electrochemical impedance spectroscopy showed a decrease in ionic conductivity with an increase in neutron dose, which indicates the non-conducting/radiation resistant behavior of the studied polymer composite. Furthermore, the dielectric constant shows an inverse behavior with the relaxation time following the increase of neutron dose until 47 kGy. Key transport parameters such as mobile charge concentration, mobile ion mobility and mobile ion diffusion coefficient supports the evidence to the increased radiation resistant behavior of PVDF-LiBOB with the increase of neutron doses. As such, the studied low-cost polymer composite (PVDF-LiBOB) has the potential to be used as a radiation resistant coating materials for protecting of sophisticated industrial devices (e.g., energy storage devices) which may provide a better device stability.

X-RAY RADIATION MONITORING IN THE CLINIC HEALTH SERVICE ENVIRONMENT TO PATIENT ABSORPTION DOSAGE WITH AGE GROUP END TEENAGES, EARLY ADULT, END ADULT

A study on patient absorption dose according to age group was carried out. The amount of absorbed A study on patient absorption dose according to age group was carried out. The amount of absorbed dose of X-ray radiation affect the body cells. Health care hospitals such as clinics, environments that use ionizing radiation. Based on the procedure for using ionizing radiation for medical purposes, the Indonesian Nuclear Energy Supervisory Agency recommends monitoring radiation doses for health workers on health service environment. Likewise with the patient, because the patient is directly exposed to the ionizing radiation. Some researh explained that the probability of the greatest stochastic effect on interventional cardiology procedures with X-rays of young patients whose radiation dose has been measured is the occurrence of leukemia, in other research found on baby and toddler patient that there was a significant difference in the absorbed dose in each patient's age group. This study aims to determine the comparison of the absorbed X-ray doses on thorax examination received by patients in the three youngest and oldest age groups. The data that support the calculation of the absorbed dose first find the exposure dose calculation by set value on the control panel of the X-ray machine to each patient is checked are the voltage, current, focal length of the patient's X-ray field, and the age of the patient. Determination of the absorbed dose was carried out using an equation, namely the milliroentgen unit. The exposure dose, milliRoentgen, was converted to an absorbable dose unit, mGy. Average absorption dose per age was compared by one-way ANOVA statistical analysis. The results showed that the absorbed dose of X-rays of patients at the Quantum Diagnostic Clinic for each age group had an insignificant comparison value. The absorbed dose in late adolescence and early adulthood did not have a significant difference. Dosage between early adolescence and late adulthood also did not have a significant difference. Thus, at the Denpasar Quantum Clinic, the absorbed dose of radiation received on young patients is relatively safe compared to the older age group. There was no significant difference in the value of the absorbed dose between one age group and another.

Dilematics and Challenges of Nuclear Regulatory Control During the Pandemic of Covid-19

Dilematics and Challenges of Nuclear Regulatory Control During the Pandemic of Covid-19. Any activity using nuclear energy must be controlled by the Nuclear Energy Regulatory Agency (BAPETEN). The regulatory control is aimed at protecting the health and safety of working personnel, public and environment from the potential hazards arising from nuclear activities. In the implementation of regulatory control, it often needs to do activity involving a number of people, such as meeting to discuss regulation or to clarify some issues of licensing. In many cases, it needs also to do licensing verification and regulatory inspection to the nuclear/radiation facilities to ensure their safety conditions. However, since the outbreak of COVID-19, activities that involve many people such as meetings and visits must be reduced. This has created some regulatory dilemmas and challenges. Therefore, it is necessary to conduct a study to analyze these dilemmas/challenges to find their solutions. Present study using analytical descriptive method was performed to answer such problems. This paper presents results of the study in the form of analysis of the regulatory dilemmas/challenges, and recommends some solutions.¬

Radiation Exposure Study on Cathlab Radiation Workers Using My Dose Mini as a Radiation Safety Effort at Adam Malik Hospital Medan

Cathlab radiation workers, when performing interventional procedures, are at high risk of the effects of radiation exposure. The risk of radiation exposure is deterministic and stochastic biological effects. Therefore, radiation exposure studies of radiation workers at the cath lab were conducted to determine the value of radiation exposure received. This radiation exposure study was conducted by measuring and recording radiation exposure doses received by radiation workers. Measurements are made when the radiation officer performs the intervention procedure. The research was carried out for one month in the cath lab room of the Adam Malik General Hospital, Medan. The modalities used are GE Medical System Interventional Fluoroscopy and Phillips Allura Xper FD20. The dosimeter used is “my dose mini”, which is placed inside a shield or apron worn by radiation workers. The size of the apron shield used is 0.50 mm Pb at the front and 0.25 mm Pb at the rear. Radiation officers whose radiation exposure dose was measured consisted of 10 doctors, 11 nurses, and one radiographer. Each inspection procedure of each radiation worker has a different distance, time, and shield from the radiation source. The measurement of radiation exposure dose is (1-59 μSv) for doctors, (1-58 μSv) for nurses, and 1 μSv for radiographers. To protect against radiation must pay attention to the factors of time, distance, and shielding. Ways that can do are to avoid being close to radiation sources for too long, keep a space at a safe level from radiation, and use shields such as Pb-coated aprons, use Pb gloves, Pb goggles, and thyroid protectors. The amount of radiation exposure dose received by each radiation worker at the time of measurement is still within the tolerance limit. The Nuclear Energy Regulatory Agency (BAPETEN) regulation, which the International Commission recommends on Radiological Protection (ICRP), is 20 mSv/year. The results of this study are expected to be used as input for improving the quality of service for monitoring radiation exposure doses in the Cathlab and as reference material for further research.

Agro-morphological response of rice (Oryza sativa L.) (cv MR 284) to chronic gamma irradiation

An experiment to study the effect of cobalt 60 gamma irradiation on agronomic traits of Malaysian rice variety, MR284, was performed by using randomized complete block design (RCBD) with three replications in Gamma Green House (GGH) located at Malaysia Nuclear Agency. The GGH facility can produce a low dose rate of chronic gamma-ray which causes less damage to the plant cell and eliminate undesirable traits as well as produce wide mutation spectrum. Seedlings in pots at the age of 14 days were exposed to gamma rayS in GGH at different dose rate from 0.03 Gy/hour to 0.66 Gy/hour for 77 days (flowering stage). Data on survival rate and growth performance such as plant height and tiller number were recorded every 7th day. The result showed that, chronically irradiated MR284 plant exhibited various significant responses of agronomic characteristic against different doses of chronic gamma irradiation. Based on the survival curve, growth reduction (GD50) for MR284 was recoded at 318.63 Gy based on filled grain per plant trait. At cumulative doses of 68.87 Gy and 167.25 Gy (0.07 and 0.17 Gy/hour, respectively), the rice seedlings demonstrated the highest plant height with maximum tillering and highest number of filled grains. Those rates are stimulating to the growth and development of the plants. This study helps explicate the dose-response on local rice varieties through chronic radiation in a Gamma Green House facility in Malaysia.

Laboratory facilities for nuclear forensic investigation in Malaysian Nuclear Agency

Nuclear forensic is a new field and a key element in nuclear security in any country. The purpose of nuclear forensic investigation is to establish the history of nuclear material of unknown origin by analysing the nuclear material in the laboratories. Hence, the results of the nuclear forensic examination will provide the evidence to support law enforcement or nuclear security investigation in the country. The typical analysis used in nuclear forensic investigation is radiological assessment, physical characterization, isotope analysis, elemental/chemical analysis and traditional forensic analysis. This paper will discuss the capability of laboratories in the Malaysian Nuclear Agency and internal arrangement in handling nuclear forensic analysis.

Determination of the legal framework for localization science and technology valleys and technology incubators in nuclear activitiesys and technology incubators in nuclear activities

The object of research in science and technology valleys and technology incubators, which for governments are the best investment of the scientific energies of scientists and innovators. As they are a link between research institutions and the industrial and service sectors, and as they transfer ideas and research results to different markets. This research aims to highlight the importance of Localization science and technology valleys and technological incubators related to nuclear activities, as they are one of the important tributaries to support the owners of the ideas of ambitious nuclear projects. The research also aims to shed light on the problems and obstacles that hinder the achievement of the desired goals of nuclear activities, such as: – the lack of information in the fields related to it; – the scarcity of expertise needed to implement it; – the lack of funding; – the absence of investors in this highly specific «nuclear» sector. The research presents the extent of the possibility of Localization those nuclear activities in Egypt through establishment valleys and incubators so that through this Localization there is an integrated environment of services and support that will ensure their development, raise their growth rates, and increase their efficiency. It is will lead to an increase in the chances of their success and sustainability, especially since Nuclear technology is used in many fields of industry, medicine, and agriculture. The research highlight the provisions of Egyptian Law regarding science, technology, and innovation incentives, as well as Egyptian Law establishing the Innovators Care Fund, to determine the possibility of establishing these valleys and incubators through the provisions of Egyptian legislation. Obtained results will have reached a great impact in encouraging investors and financiers to enter into technological partnerships with nuclear agencies in Egypt for the sake of safe investment in the elements associated with nuclear materials.

Human Consequences of Multiple Nuclear Detonations in New Delhi (India): Interdisciplinary Requirements in Triage Management.

The human casualties from simulated nuclear detonation scenarios in New Delhi, India are analyzed, with a focus on the distribution of casualties in urban environments and the theoretical application of a nuclear-specific triage system with significant innovation in interdisciplinary disaster management applicable generally to urban nuclear detonation medical response. Model estimates of nuclear war casualties employed ESRI’s ArcGIS 9.3, blast and prompt radiation were calculated using the Defense Nuclear Agency’s WE program, and fallout radiation was calculated using the Defense Threat Reduction Agency’s (DTRA’s) Hazard Prediction and Assessment Capability (HPAC) V404SP4, as well as custom GIS and database software applications. ESRI ArcGISTM programs were used to calculate affected populations from the Oak Ridge National Laboratory’s LandScanTM 2007 Global Population Dataset for areas affected by thermal, blast and radiation data. Trauma, thermal burn, and radiation casualties were thus estimated on a geographic basis for New Delhi, India for single and multiple (six) 25 kt detonations and a single 1 mt (1000 kt) detonation. Major issues related to the emergency management of a nuclear incident are discussed with specific recommendations for improvement. The consequences for health management of thermal burn and radiation patients is the worst, as burn patients require enormous resources to treat, and there will be little to no familiarity with the treatment of radiation victims. Of particular importance is the interdisciplinary cooperation necessary for such a large-scale emergency response event, which would be exemplified by efforts such as the application of a Nuclear Global Health Workforce.

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the ARPANSA, Australia and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for air kerma of the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Australia and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in November 2020. The comparison result, based on the calibration coefficients for two transfer chambers and expressed as a ratio of the ARPANSA and the BIPM standards for air kerma, is 0.9986 with a combined standard uncertainty of 2.7 parts in 103. The result agrees within the uncertainties with the indirect comparison carried out in 2010. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the ARPANSA, Australia and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for absorbed dose to water of the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Australia and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in November 2020. The comparison result, based on the calibration coefficients for two transfer chambers and evaluated as a ratio of the ARPANSA and the BIPM standards for absorbed dose to water, is 0.9995 with a combined standard uncertainty of 5.1 parts in 103. The result agrees within the uncertainties with the comparison carried out in 2010. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Calibration of whole body counter for assessment of internal dose in the human body

In the Malaysian Nuclear Agency (Nuklear Malaysia), the ORTEC Whole Body Counter System, bed type was used for assessing internal dose due to intake of gamma radionuclides in the human body. In this study, the performance of ORTEC Whole Body Counter System includes energy calibration, counting efficiency, validation test and minimum detectable activity (MDA) for the radionuclides of interest (ROI) has been investigated using ORTEC whole body counter phantom and mixed standard sources having gamma energies between 59.5 keV and 1836.2 keV. Later, the whole body counting was performed to determine the existence of any gamma radionuclides in the body. The result of the energy calibration was within the tolerance limit of ± 5%. The counting efficiency varies between 0.0000881 cps/Bq and 0.000332 cps/Bq. The results of the validation test show that the bias (Br) and repeatability (SBr) are within the acceptable range of -0.25 ≤ Br ≤ +0.50 and SBr ≤ 0.40, respectively. The MDA for each ROI of I-131, Cs-137 and Co-60 were 165.4 ± 10.0 Bq, 144.6 ± 11.5 Bq and 167.3 ± 30.5 Bq, respectively. A total of 14 volunteers from Postgraduate Educational Course in Radiation Protection and Safety of Radioactive Sources (PGEC-16) were invited to perform the whole body counting. Each volunteer was scanned for 1200 s with the bed speed of 0.065 inch/s. The results show that there is no internal exposure found for all monitored person. Consequently, it can be concluded that the ORTEC Whole Body Counter System (WBC) is now ready to be used for internal dose assessment.

Nuclear Restart Politics: How the ‘Nuclear Village’ Lost Policy Implementation Power

Abstract The March 2011 nuclear accident (3.11) shook Japan’s nuclear energy policy to its core. In 2012, the Liberal Democratic Party (LDP) returned to government with a pro-nuclear policy and the intention to swiftly restart nuclear power plants. In 2020, however, only six nuclear reactors were in operation. Why has the progress of nuclear restarts been so slow despite apparent political support? This article investigates the process of restarting nuclear power plants. The key finding is that the ‘nuclear village’, centered on the LDP, Ministry of Economy Trade and Industry, and the nuclear industry, which previously controlled both nuclear policy goal-setting and implementation, remained in charge of policy decision making, i.e. goal-setting, but lost policy implementation power to an extended conflict over nuclear reactor restarts. The main factors that changed the politics of nuclear reactor restarts are Japan’s new nuclear safety agency, the Nuclear Regulation Authority (NRA), and a substantial increase in the number of citizens’ class-action lawsuits against nuclear reactors. These findings highlight the importance of assessing both decision making and implementation in assessments of policy change.

Potenciando ideas: una propuesta de análisis para discutir el desarrollo de tecnología nuclear en Argentina y México (1950 – 1991)

Este artículo presenta un análisis comparativo basado en el método de rastreo de proceso de los programas nucleares de Argentina y México entre 1950 y 1991. Estudia los niveles de avance de cada caso con base en la posibilidad de implementación de ideas de autonomía tecnológica, de acuerdo con su capacidad de potenciación determinada por tres dimensiones: la autonomía lateral de la principal agencia nuclear, la formación de alianzas estratégicas con actores intermediarios clave y una política exterior en materia nuclear conducente a tal meta.

Position-Sensitive Detector in Neutron Tomography and Material Characterization

Position-sensitive detectors (PSDs) have been used in neutron tomography and nanostructural characterization of material using neutrons that scattered from a monochromator of highly oriented pyrolytic graphite type, placed directly in the neutron beam in the Small Angle Neutron Scattering (SANS) facility at the Malaysian Nuclear Agency. PSD uses the 3He(n,p) reaction to detect neutrons. Because of the 3He high neutron cross section of 5333 b at 25.3 meV, a PSD is suitable for neutron detection across its axial direction at a low neutron flux of 103 cm−2‧s−1. Because of its insensitivity toward gamma radiation, the signals from the PSD for real neutrons are relatively easy to analyze. This paper discusses the use of a PSD in neutron tomography and nanostructural characterization of material in the SANS facility at the Malaysian Nuclear Agency.

The Analysis of Loss of Forced Flow Event on the HTGR Type Experimental Power Reactor

Since 2014, Indonesia's National Atomic Energy Agency (BATAN) has been launching a plan to construct a 10 MWt Experimental Power Reactor (Reaktor Daya Eksperimental / RDE). The RDE design is based on the small-sized pebble-bed high-temperature gas-cooled reactor (HTGR) technology with TRISO fuels. By concept, HTR-10 design, which was developed by the INET of China, is used as the reference design. During the development process, a safety analysis report (SAR) of RDE design has to be prepared to be evaluated by the Indonesia Nuclear Regulatory Agency (BAPETEN). The report contains, among others the description of the RDE accident sequences, which can be only provided by simulations using a certain code. This paper emphasizes the transient analysis, which is simulated using RELAP5/SCDAP/Mod3.4 , which is a thermal-hydraulic code specified for light water coolant systems. The simulated event is the loss of primary coolant mass flow, which is caused by the failure of the primary gas blower motor. The methodology of simulation is first by modelling the RDE nuclear steam supply system to verify steady-state operational parameter of the RDE design. The second step is to simulate the event of loss of flow, which is followed by the failure to shut down the reactor. The simulation results in the decrease of the fuel pebble temperature during the event due to the negative fuel temperature reactivity coefficient and the core heat removal by the cavity cooling. Overall, the RELAP5 code has a limitation in the RDE simulation to define two different non-condensable gases, which reduces the accuracy of the simulation results.

KERAGAAN KEDELAI (Glycine max (L) merril) GENERASI M1 VARIETAS ANJASMORO HASIL RADIASI SINAR GAMMA

The purpose of this research was to find out the diversity of Anjasmoro variety soybean of M1 generation resulted from gamma-ray radiation on its various phenotype characters. A total of 300 seeds were radiated with Isotope and Radiation Technology Application from National Nuclear Power Agency at Pasar Jumat, South Jakarta, then planted in the experimental garden of Agriculture Faculty, Riau University. The dosage of irradiation used was 100 Gy, 150 Gy, 200 Gy, and 250 Gy also M0 as an ancestor. The quantitative and qualitative observation was made as such flowering age, harvest age, plant height, amount of seeds per plant, seeds weight per plant and growth type. The data were analyzed with variance analysis then continued with Duncan’s New Multiple Range Test on a 5% level. The diversity component was analyzed with homogeneity of variance according to the Levene test procedure. The result shows gamma-ray radiation is causing diversity on Anjasmoro variety on quantitative characters such as flowering age, harvest age and seed weight per plant. The vast diversity has happened on irradiation dosage of 200Gy.

Results of the first national indoor radon survey performed in Serbia

The first step in every systematic approach to investigating population exposure to radon on a national level is to perform a comprehensive indoor radon survey. Based on general knowledge of the radon levels in Serbia and corresponding doses, the results obtained from a national indoor radon survey would allow policymakers to decide whether it is necessary to establish a national radon programme. For this reason, Serbia initiated work on a national radon action plan (RAP) in 2014 when it was decided to carry out the first national indoor radon survey. The responsibility for establishing the RAP in Serbia is that of the national regulatory body in the field of radiation protection—the Serbian Radiation and Nuclear Safety and Security Directorate (SRBATOM), formerly known as the Serbian Radiation Protection and Nuclear Safety Agency. The first national indoor radon survey was supported by the International Atomic Energy Agency (IAEA) through a Technical Cooperation Programme. Thanks to the IAEA, we received 6000 passive radon devices based on track-etched detectors. In addition, in order to ensure technical support for the project, SRBATOM formed a task force made up of expert radon representatives from national research institutions. This paper presents a thorough description of the sampling design of the first Serbian indoor radon survey. It also presents the results of the national indoor radon survey, including descriptive statistics and testing of the distribution of the obtained results for log-normality. Based on GPS coordinates, indoor radon data were projected onto a map of 10 km × 10 km grid cells. Two values were calculated for each cell to create two distinct maps. One map shows the arithmetic mean value of indoor radon concentration per grid cell, and the other map shows the number of radon detectors per grid cell used for the calculation of mean values.

Variabilities in X-ray diagnostic reference levels.

To estimate the variability of X-ray diagnostic reference levels (DRLs) depending on the number of X-ray devices and data per device. Dose-area products (DAP) were collected by the national nuclear control agency from the 590 devices installed in 345 medical centers in the country. From 2015 to 2017, the number of chest (postero-anterior (PA) view alone, and both postero-anterior and lateral views (PA/LAT)), abdomen, pelvis, and lumbar spine examinations collected in these centers ranged from 23,000 to 77,000. The impact of the number of devices and DAP data per device on DRLs' variabilities (95th confidence intervals divided by medians) is estimated using a bootstrapping method as a function of the number of devices and DAP per device. The DRLs' variabilities ranged from 30 to 200% depending on the number of devices and DAP data per device but stabilized at 30% when the number of devices was higher than 200 for chest PA and abdomen examinations, 300 for lumbar spine and pelvis examinations, and 400 for chest PA/LAT examinations, regardless of the number of DAP data per device. Extrapolations of our results suggest that thousands of devices are necessary to reduce DRLs' variabilities to 10%. DAP-related DRL variabilities are high but only moderately influenced by the number of DAP data per device and of devices provided this number is higher than 200 to 400 devices according to the type of examination. Harmonization of methods of data collection between the authorities of the EU states should be recommended. • DAP-related DRLs are not fixed values but ranges of values with at least 30% variability. • DAP-related DRLs strongly depend on the number of devices included when lower than 100. • If the number of devices included exceeds 200 to 400, the DRLs' variabilities do not depend on the number of DAP per device and should not exceed 30%.