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[en] The National Ionizing Radiation Metrology Laboratory (LNMRI / IRD / CNEN) is responsible for producing and maintaining the national radionuclide standards, used to guarantee the quality of services in various applications of nuclear energy in the country. Therefore, it makes use of absolute and relative methods of measurement, such as 4πβ-γ coincidence systems, 4πβ-γ anticoincidence and ionization chambers traceable to the BIPM international metrological chain. Aiming to contribute to the optimization of processes and improvement in the quality of services provided, this article presents a proposal for integration of measurement, source control and management systems through the implementation of a single repository for results storage, support data, charts of control, among others. (author)
[en] Dose measurements in radiodiagnostic services are easier and practical to perform with ionization chambers, however protocols for measurements differ from those applied in instrument calibration. The entrance surface air kerma is obtained from the application of a backscatter factor to the incident air kerma, but differences between the positioning of the X-ray tube, chamber and examination table implies an increase of the measurements, being necessary to application of an appropriate backscatter factor, dependent on the mass energy transfer coefficient for each material. The literature presents coefficients that diverge from the interaction behavior of the radiation with matter. The objective was to determine mass-transfer energy coefficients for calibration of dose measuring instruments and radiological protection. The results were able to determine mass transfer coefficients for calibration purposes showed a greater variance, being the lowest 1.9393E2 cm2/g to 40 kVp and the highest of 3.0133E3 cm2/g to 60 kVp
[en] The quest for seamless measurement has led metrology labs around the world to spend millions on system and device research and development to obtain new technologies and new methodologies that provide the least possible uncertainty associated with the measurement result. Becoming a reference laboratory is everyone's goal. In Brazil there are several metrology laboratories, among them ionizing radiations, which have in their measurement systems several measurement quantities. Many of these quantities are characterized and are part of the traceability chain. Others are overestimated or even underestimated because the laboratory lacks the technical resources to characterize them. One of these greatness is time. Acquiring equipment in time and frequency to be used in metrological processes in a laboratory is expensive. Thus, the temporal and low-cost reference used by the laboratory is most often the computer's own time. When collecting data or measuring records, most laboratories use computers that, through embedded programs, obey pre-established time intervals based on the computer's internal clock. The computer has basically two time references: the reference provided by the software clocks and the one provided by the hardware clock. Both are used as the computer's time reference. The objective of this work was to create methodological procedures to evaluate the software clock time behavior of the computers used in the ionizing radiation metrology laboratories, ensuring the traceability of the Time quantity and its associated uncertainty. But for that, it was necessary to develop an electronic device based on an ATMEL microcontroller that connects to the computer's RS232 / USB communication port. Upon connection, the device receives digital information generated by an embedded program and outputs a frequency signal of 1 Hz or one pulse per second (PPS) to the metering system. Two measurement methods were used to evaluate the clock time of the computer. The Totalizer Method, used for reference only, and the PPS difference method. The results obtained in the comparison between the time deviation values dt / t of the computer clock in relation to the stable time base of a reference standard, presented final values of (10.82 ± 0.11) μs- 1 for the PPS difference method and (10.91 ± 0.11) μs.s-1 for the Totalizer Method. The percentage difference between the two method is 0.82%. The instant that the computer has the most reliable time deviation values dt / t was from 10 hours of measurement. In the comparison between the duration of the PPS pulses provided by two separate computers, both of them being at rest, and being manipulated during data acquisition, considering 1 hour of acquisition, was (-6.24 ± 1.98) μs-1 and (-15.18 ± 93.80) μs-1. A substantial increase of approximately 59%. (author)
[en] In the latest revision of ISO / IEC 17025: 2017, General Requirements for the Competence of Testing and Calibration Laboratories, the concept of risk mentality was introduced in its management system requirements, leading laboratories to establish and document a formal process management of risks and opportunities in order to meet the new requirements. This work describes the procedure adopted by the Central Calibration Laboratory of SISMETRA (LCC) for the implementation of risk and opportunity management based on the guidelines of the ISO 31000: 2018 standard. (author)
[en] The dissemination of the activity is performed from radionuclide sources prepared in a dilution and weighing sequence, in this process, the activity of the source can be estimated from the deposited mass and the activity concentration of the master solution. After preparation, the activity is obtained from measurement methods. In this work, Bayesian estimates for the relative deviation of activities and their uncertainty were obtained in order to evaluate the performance of the sources’ preparation. The result (0.74 ± 0.23) %, although close to zero, shows one should investigate possible effects affecting the preparation and measurement of the sources. (author)
[en] Some modification in elimination weighing method for radioactive source allowed correcting weighing results without non-linearity problems assign a uncertainty contribution for the correction of the same order of the mass of drop uncertainty and check weighing variability in series source preparation. This analysis has focused in knowing the achievable weighing accuracy and the uncertainty estimated by Monte Carlo method for a mass of a 20 mg drop was at maximum of 0.06%. (author)
[en] Highlights: • The CCRI is expanding the usefulness of the CIPM MRA the international measurement system in radionuclide metrology. • The CCRI has revised its Strategy to better reflect impacts to its members and stakeholders. • The CCRI Strategy addresses improvements in the state-of-the-art in radionuclide metrology. • The CCRI is optimizing CMC claims in radionuclide metrology. - Abstract: The Consultative Committee for Ionizing Radiation (CCRI) has coordinated the development of a long-term strategy to support the international measurement system for radionuclide metrology. Supported by the Bureau International des Poids et Mesures (BIPM) and its associated institutional members, the CCRI strategy captures how an NMI/DI can demonstrate capability in radionuclide metrology with the support that is available through the CCRI and the BIPM. The CCRI strategy, specifically the aspects with direct impact on radionuclide metrology, is described. Various projects to ensure that the international measurement system for radioactivity can be sustained in the short and long term will also be outlined.
[en] The construction of a nuclear medicine service within the standards of radioprotection is a challenge from the point of view of cost optimization and containment of exposure. Assessing the impact of shielding thicknesses so that radiation levels are as low as reasonably achievable for both workers and the public is a crucial part in deciding which conduct to follow. In the analysis of the weekly limits, in S1 each of the groups contributed 50% of the recommended weekly dose limit, S2: 80% of the weekly dose limit and in S3 the dose contribution of each of the radionuclides individually. The results evidenced that the choice of situation 1, 2 or 3 in the methodology of the calculation of shielding impact in different thicknesses of barriers. It is concluded that the optimization of the thickness of the barriers can be obtained by adopting the situation that best describes the expected operating conditions of the installation. (author)
[en] The Monte Carlo simulation technique is a fundamental approach to the study of complex modeling, specifically in radiation physics. The study of half value layers is a fundamental topic in metrology and radiodiagnostic works, allowing the analysis and determination of parameters and physical processes involved. The objective of this research is the study of half value layers through Monte Carlo simulation, highlighting the gain that can be obtained with this technique. Because it was already practical and efficient, the code chosen was Geant4. (author)
[en] The safe and cost-effective decommissioning of legacy nuclear sites relies on accurate measurement of the radioactivity content of the waste materials, so that the waste can be assigned to the most appropriate disposal route. Such measurements are a new challenge for the science of radionuclide metrology which was established largely to support routine measurements on operating nuclear sites and other applications such as nuclear medicine. In this paper, we provide a brief summary of the international measurement system that is established to enable nuclear site operators to demonstrate that measurements are accurate, independent and fit for purpose, and highlight some of the projects that are underway to adapt the measurement system to meet the changing demands from the industry. - Highlights: • How the international measurement system operates. • The new demands from the nuclear industry. • National and international projects to meet these demands.