National Atomic Energy Commission Research Articles

Design and simulation of sun position sensors for space applications: A comparative study.

Sun position sensors are used in space applications as part of the attitude determination and control system. The aim of this work is to describe the design process of single and dual axis sun position sensors based on a photodiode array detector and a window to limit and direct the light that reaches the detector. The design process involves choosing the sensor architecture, modeling its output, and then evaluating the model through simulation. Six architectures, with different configurations and geometries for both the detector and window, were modeled and compared. To evaluate the model and performance of the sensor, a program was developed, and simulations were made varying the window height and size as well as the photodiode size. From the simulations performed, we concluded that for each design, the key factors that influence the sensitivity and field of view performance are the window height and window or photodiode size, depending on the sensor configuration. From the comparison across architectures, the detector configuration, as well as the window geometry, influences the sensitivity and linearity of the response for similar conditions of operation. The two-quadrant detector configuration offers a better sensitivity than the triangular photodiode configuration. For a better linearity of the output, a square window is preferred. This comparative study is part of the development of new products for space applications by the National Atomic Energy Commission and contributes to the Argentinian National Space Plan.

National Atomic Energy Commission: a brief historical review

El presente artículo pretende realizar un breve recorrido de la historia de la Comisión Nacional de Energía Atómica que actualmente es una Institución dependiente de la Universidad Nacional de Asunción. Lleva trabajando en la promoción y el uso pacífico de la energía nuclear y de las radiaciones ionizantes en el país desde su creación. Se detalla sus funciones y los servicios especializados que brinda a la sociedad en la actualidad.

Thermal-hydraulic modeling of CAREM-25 advanced small modular reactor using the porous media approach and COBRA-EN modified code

Small Modular Reactors (SMRs) are compact nuclear reactors designed to generate electric power up to 300 MWe. They could be assembled in factory, and then transported to be directly installed on-stie. CAREM (Central Argentina de Elementos Modulares) is a national SMR development project, based on light water reactor technology supervised by Argentina's National Atomic Energy Commission (CNEA). It is a natural circulation-based SMR with an indirect-cycle, including specific items and parts that simplify the design and improve safety performance. In this paper, the thermal-hydraulic study of CAREM-25 advanced small modular reactor is conducted by using COBRA-EN modified code and the Porous Media Approach (PMA) for the first time. According to PMA approach, each fuel assembly is modeled and divided into a network of lumped regions. While complex geometries are defined, the thermal-hydraulic parameters such as temperature and density are calculated for coolant and fuel rods. The obtained results show that the temperature in the fuel center may reach a peak around 1280 K in the hottest fuel assembly. Finally, the comparison of results from both methods (modified COBRA-EN and PMA) presented an appropriate consistency.

The rise of the Argentine Nuclear Program and the thwarted dream of industrialization (1950-1984)

The rise of the Nuclear Program in Argentina took place during the second stage of the process of Import Substitution Industrialization, which encourage local industry and the development of metalworking and electronics. In this context, one of the central aims of the National Atomic Energy Commission (CNEA) was to improve the domestic industry of goods and services in order to supply future nuclear power plants and promote technological autonomy. However, this philosophy began to struggle with the neoliberal reforms that were implemented after 1976. The primary objective of this work is to draw and analyze the main strategies implemented by CNEA to promote local industry. In this sense, this paper will be focus in the creation of the Metallurgy Department (1955), the Technical Assistance Service to Industry (1962), the National Industry Group (1965) and the creation of an Industrial Architect, ENACE SA (1980).

Quality control in blood irradiation

Irradiation is a technique used in hemotherapy to functionally inactivateviable lymphocytes, in cellular blood components, to reduce the risk of Transfusion-associated Graft-versus-Host Disease (AT-GVHD), is rare but letal. One way to avoid it is to irradiate blood componentes in situations such as: intrauterine transfusion, newborns, patients receiving immunosuppressive therapy in bone marrow transplantation. Thus, it is extremely important that blood component is irradiated and, above all, ensure that the minimum dose is 25 Gy.The blood policy in Brazil is implemented through laws and normative decrees, giving rise to a legal system that underpins the actions of hemotherapy services. In order to correct verify absorbed doses and the quality assurance process as well as the safety for the irradiator operators we describe in this paper a several of physical measurements that is mandatory to support a physicist to evaluate the quality assurance during and after the irradiation process. The results obtained from this physical measurements provided a guarantee of proper radiation dose used in hemotherapy as well as methods and procedures applied to protect the patient, employees and general public due to procedure of blood irradiation accordling the Technical Regulation of Hemotherapy Procedures of the National Health Surveillance Agency (ANVISA) and safety regulations by National Nuclear Energy Commission (CNEN).

Radioiodine therapy during the COVID-19 pandemic in a public reference hospital in Brazil: an experience report.

COVID-2019 has resulted in an emerging respiratory infection that has spread as a pandemic since January 2020. Nuclear Medicine Services and its workers experienced a dramatic change in their clinical routine. They were required to adjust protocols for this new health condition. Regarding radioiodine therapy (RIT), initial orientations were to postpone treatments. In Brazil, National Nuclear Energy Commission prepared guidelines. It authorized RIT to employ activities over 1850MBq in an outpatient setting on an exceptional basis. This study reports the RIT experience of a Brazilian hospital during the COVID-19 pandemic, intending to evaluate the applicability of outpatient treatment employing over 1850MBq of I-131 on a large scale. During referred period, 106 patients at our service had an indication for RIT, of which 58 agreed to participate in the research and provided informed consent. Majority of patients did not meet the minimum requirements for outpatient treatment using doses>1850MBq.

Technical specialization in Nuclear Medicine: an analysis of courses in Brazil and a proposal for a basic curriculum

Nuclear Medicine (NM) is a medical specialty that, through non-invasive methods, uses radioactive materials for diagnostic and therapeutic purposes. According to Standard NN 3.05 of the Brazilian National Nuclear Energy Commission (CNEN), a Nuclear Medicine System (NMS) must be composed of, at least, a Holder, a Nuclear Physician, a Radiation Protection Supervisor and higher and mid-level professionals, duly qualified for the performance of their duties, which may be exercised, in this case, by a radiology technician. Thus, in 2009, the National Council of Radiology Technicians (CONTER) granted a period of 5 (five) years for radiology technicians who work in the NM and Radiotherapy specialties to specialize in their areas of expertise, a period that was extended for another 5 (five) years. In this sense, this paper aims to carry out a survey of the Technical Specialization courses in NM offered in Brazil, considering that almost 10 years have passed since the CONTER Resolution No. 17, of 2014, verifying aspects such as structure and workload, based on the requirements of the Ministry of Education (MEC), in order to suggest a core curriculum for courses in NM. It was found that, with the legal requirement of this training, these courses began to be offered, but in a reduced number and only in some regions of Brazil, despite the existence of courses in the distance modality. It is understood, therefore, that an expansion of courses in the area is necessary, in view of the relevance of the service for NM.

Proposal for a professional qualification course in radiation protection to obtain the registration of Radiation Protection Supervisor to work at teaching and research laboratories

According to the CNEN Standard NN 6.01, aiming at professional registration for the preparation, use and handling of radioactive sources in teaching and research (T&R), the candidate must submit to the National Nuclear Energy Commission (CNEN), in addition to the registration professional or diploma recognized by the Ministry of Education (MEC) and the application for registration, proof of radiation protection course, with a minimum load of forty (40) hours. In this sense, the present paper aims to present a proposal and an experience report of a training course. The course, developed in conjunction with the rectory of the State University of West Paraná (UNIOESTE) / Cascavel campus, was directed to 12 professionals (teachers and technicians of the Chemistry and Biology courses), and carried out at the Fine Equipment Laboratory, in 2020. After the training, individuals were registered for the preparation, use and handling of radioactive sources with all the documentation proposed in Standard NN6.01 to obtain the registration and title of Radiation Protection Supervisor at T&R institutions issued by CNEN . With this certification, the professional will have a record valid for 05 years in low-risk installations, classified according to Standard NN 6.02. It is understood that the professional qualification course, with the objective of being certified by CNEN, is of great importance for T&R institutions that use radioactive material, in view of the lack of qualified professionals, and can be applied in other T&R institutions.

Licensing Approach Applicable to Land Facilities Supporting Nuclear-Powered Submarines

The nuclear licensing process is a fundamental stage for the design and deployment of a nuclear facility. In Brazil, the licensing process of Central Nuclear Almirante Álvaro Alberto (CNAAA) nuclear power plants, in Angra dos Reis - RJ, was established mainly based on the U.S. Nuclear Regulatory Commission (U.S.NRC) guidelines. However, for each purpose specific requirements are established which promote a standardisation appropriate to the type of installation in question. Thus, not every nuclear installation can be adequately framed in the standards and requirements established for the licensing of a nuclear power plant, especially when considering nuclear facilities for strategic and defense purposes. For instance, the Specialized Maintenance Complex (CME) project that is being developed by the Brazilian Navy and aims to offer all the structure and systems for support on land to the first Brazilian nuclear-powered submarine. Therefore, when considering the interfaces between maritime/naval systems and operations, the purpose and specificity of installations such as CME extrapolate the commonly established nuclear normative framework. Due to the innovation of this type of installation in Brazil, there is no specific regulation for its licensing, constituting a unique situation for both the Brazilian Navy (applicant) and the National Nuclear Energy Commission - CNEN (Brazilian Nuclear Licensing Agency, which, in the near future, will have its function incorporated into the National Nuclear Safety Authority, ANSN). Even when researching standards and other guides in ostensible sources of nations that holds nuclear reactor technology for naval propulsion (and land support facilities), no normative guidance dealing specifically with the safety analysis and licensing of this type of installation has been identified. Thus, this paper proposes a first approach and analysis of the standards used by the U.S. Department of Defense (U.S.DOE) comparing them to the standards of the U.S. Nuclear Regulatory Commission (U.S.NRC) aiming to compose a specific normative proposition to carry out the safety analysis and licensing of a nuclear-powered submarines land support facility.

Evaluation of “Safety Related” and “Important to Safety” terminology for safety classification of nuclear installation items in Brazil

In general terms, safety demonstration of nuclear installations is carried out through an assessment of compliance with design criteria and safety requirements established in national and international codes and standards applicable to each type of installation. In addition, a safety analysis consisting of installation behavior study during its useful lifetime, shall be developed considering normal operating conditions, transients, and postulated accidents, to determine safety margins and verify the adequacy of items designed to prevent accidents or mitigate their consequences. Also, design requirements applicable to each installation item depend on its classification with respect to safety. Thus, safety classification of structures, systems, and components (SSCs) must be performed based on adequate methods and clear and consistent criteria to ensure that an overall safety level expected for the installation is achieved. It is worth emphasizing the importance of the terminology adopted and the understanding of concepts definitions used in a safety classification process. The objective of this paper is to present a review of the application of “safety related item” and “item important to safety” terminology, evaluating definitions and interpretations given by the International Atomic Energy Agency (IAEA), the United States Nuclear Regulatory Commission (U.S.NRC) and the National Nuclear Energy Commission (CNEN) of Brazil. In this work, this subject is raised to demonstrate that divergent definitions and misinterpretations of concepts may result in inconsistencies in SSCs safety classification.

Characterization of expanded vermiculite to use as natural barrier in repository

Brazilian National Nuclear Energy Commission – CNEN – is responsible to build a repository for the low and intermediate--level radioactive wastes generated in Brazil. In accordance of Brazilian legislation it will be a near surface one. In the repository, treated waste will be stored, which will be surrounded by engineering and natural barriers, in order to prevent the release of radionuclides, during the required time to their decay to the limit levels. The focus of this study is to characterize the expanded vermiculite, which can be used as a natural barriers, over and under the engineering barriers and also as a backfill. They have the function of limiting water infiltration and stabilizing the disposal system, filling the empty spaces, controlling the gases and delaying the release of radionuclides. In this paper is presented the characterization of an expanded vermiculite. The tests to determine its physical chemical properties were based on a clay characterization Protocol. The granulometric analysis was performed using a sieving method. The moisture content was established by the gravimetric method of weight loss, and the specific surface area by the BET method. The helium ultrapicnometer method was used to determine the density. The microstructure was analyzed by X-ray diffraction and scanning electron microscopy. The results indicate that the studied vermiculite would be efficient as a natural barrier of the Brazilian surface repository, as the it presented a stable structure.

The Direction Team at the Argentine Laboratory of Neutron Beams: Leaving a High-Heel Footprint

In 2015, the National Atomic Energy Commission (CNEA) of Argentina launched a project for a large-scale neutron facility: the Argentine Laboratory of Neutron Beams (LAHN). Rolando Granada was appoi...

MELCOR steady state calculation of the generic PWR of 40MWth

After the two most significant nuclear accidents in history – the Chernobyl Reactor Four explosion in Ukraine(1986) and the Fukushima Daiichi accident in Japan (2011) –, the Final Safety Analysis Report (FSAR) included a new chapter (19) dedicated to the Probabilistic Safety Assessment (PSA) and Severe Accident Analysis (SAA), covering accidents with core melting. FSAR is the most important document for licensing of siting, construction, commissioning and operation of a nuclear power plant. In the USA, the elaboration of the FSAR chapter 19 is according to the review and acceptance criteria described in the NUREG-0800 and U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide (RG) 1.200. The same approach is being adopted in Brazil by National Nuclear Energy Commission (CNEN). Therefore, the FSAR elaboration requires a detailed knowledge of severe accident phenomena and an analysis of the design vulnerabilities to the severe accidents, as provided in a PSA – e.g., the identification of the initiating events involving significant Core Damage Frequency (CDF) are made in the PSA Level 1. As part of the design and certification activities of a plant of reference, the Laboratory of Risk Analysis, Evaluating and Management (LabRisco), located in the University of São Paulo (USP), Brazil, has been preparing a group of specialists to model the progression of severe accidents in Pressurized Water Reactors (PWR), to support the CNEN regulatory expectation – since Brazilian Nuclear Power Plants (NPP), i.e., Angra 1, 2 and 3, have PWR type, the efforts of the CNEN are concentrated on accidents at this type of reactor. The initial investigation objectives were on completing the detailed input data for a PWR cooling system model using the U.S. NRC MELCOR 2.2 code, and on the study of the reference plant equipment behavior – by comparing this model results and the reference plant normal operation main parameters, as modeled with RELAP5/MOD2 code.

Management of solid waste from health services according to the National Solid Waste Policy: a study conducted in the South of the Brazil

Abstract: The management of waste from health services is considered an extremely controversial topic and widely discussed because it is mainly about contaminated materials. This study aims to analyze the waste management of health services in hospitals in a southern region of Brazil, identifying the final disposal processes, in accordance with the National Solid Waste Policy, describing the management and practices in each link of the final destination chains and estimation of the volume of post-consumer waste generated. For this, it was necessary to describe the management and practices in each link of the chains, estimate the volume of waste generated, identify the reverse logistics chains and the final destination of the post-consumer waste from the health services. In addition to evaluating the feasibility of reusing hospital waste, taking into account the technical standards and legislation present in the National Solid Waste Policy and in organizations such as the National Agency for Health Surveillance, the Brazilian Association of Technical Standards, the National Council of the Environment and the National Nuclear Energy Commission. The National Solid Waste Policy brought an information framework already contained in other norms and resolutions in force, before its publications, determining the objectives that have not yet been fully met in the investigated region.

Comparative analysis of equipment performance in nuclear medicine

To ensure satisfactory equipment performance, image reliability and accurate diagnosis a set of measurements and analysis named as quality control (QC) has to be established. QC is a routine practice where the essential quipment performance or procedure is evaluated by comparing the results to a predefined acceptable range. Currently there are 448 Nuclear Medicine Services (NMS) in Brazil that have to comply with the standards and regulations stablished by Brazilian regulatory agencies the National Nuclear Energy Commission (CNEN) and the National Health Surveillance Agency (ANVISA). Both regualtory bodies have power to control and ensure compliance with their national regulations including quality control tests of equipments to be fulfilled by all NMS operating in Brazil. However, these standards do not establish minimum performance requirements for the most tests and do not guarantee the quality to the population health care. This paper aims to evaluate and analyze the performance limits of the quality control tests in nuclear medicine practice requested in Brazilian standards and compare them with available requirements addressed in international recommendations. Regarding performance limit evaluation many of the requested tests do not address a methodology or minimum performance values to ensure what is considered satisfactory in a quality control test. It was found that Brazilian NMS standards need revision when compared to international recommendations.

A comparison of quality assurance standards: Correlation of the USA and Brazilian codes for the construction of an ISFSI

As the spent fuel pools of Angra 1 and Angra 2 nuclear power plants are near their capacity limits, Eletronuclear of Brazil has begun its plans to the first independent spent fuel storage installation in Brazil. However, the lack of a domestic safety standard for an ISFSI* has forced the Brazilian National Nuclear Energy Commission to adopt the United States Nuclear Regulatory Commission requirements for the preparation of an ISFSI Safety Analysis Report. Consequently, the need for a comparison and gap analysis of the regulatory requirements for quality assurance systems in USNRC 10CFR Part72 Subpart G with the Brazilian standard CNEN–NN–1.16, became timely and necessary. The main purpose of this research is to establish the correlation of requirements between USNRC 10CFR Part72 Subpart G with the Brazilian standard CNEN–NN–1.16 for the effective implementation of a quality assurance system and its role in the nuclear license process of an ISFSI. In light of this goal, this research has been developed based on the characterization of the normative bases and the elaboration of a correlation matrix of similar requirements. The results of this research, document that there is harmonization and coherence between both normative codes, and further establishes that in the area of QAS requirements, both approaches are acceptable.

Mapping the Critical Intellectual Capital of IRD

Currently, several studies that dealing with the subject of knowledge management aiming the preservation and transfer of intellectual capital, leading to the retention of knowledge retention in an institution or organization. The National Nuclear Energy Commission (CNEN) of Brazil, the federal authority responsible for the national nuclear energy standards, research, development, and regulation, has been facing difficulties in human resources due to the increase in the number of retirements and the lack of replacement of people, especially with the scientific-technical profile, as a result of the cancelation of public employee hiring in the country.The purpose of this study is to map the critical technical areas at the Institute of Radiation Protection and Dosimetry (IRD), from CNEN. A model used by the International Atomic Energy Agency (IAEA) was adopted here, which takes into account the time for retirement, beyond the specificity and availability of knowledge.As a result of the study, it was possible to identify that in all end-areas, the IRD has employees that retain the critical knowledge, but they are hard to be replaced or transfer their knowledge. Therefore, a management plan should be implemented for the retention and transfer of knowledge specific to the nuclear area, which is essential for IRD to continue to meet its strategic objectives and that also contributes to minimize the impacts to the country generated by the loss of this sensitive and specialized knowledge.

Study of emission of radioactive gaseous effluents in the production of 18F-FDG

The number of units producing radiopharmaceuticals with a half-life of fewer than two hours has increased with the growth of PET technology in Brazil. In the production of such radiopharmaceuticals such as 18F-FDG or 11C-PIB, gaseous waste is formed. The International Atomic Energy Agency (IAEA) proposes a methodology that can be used to evaluate the dispersion of these gaseous effluents. This work has retrospectively evaluated the emission of radioactive gaseous effluents generated in the production of 18F-FDG, in order, to delimit yield values of radioactive waste in the gaseous form and to verify the effectiveness and the design of the safety elements of the exhaust system evaluated before the standards of the National Nuclear Energy Commission (CNEN) and IAEA recommendations. Thirty-six productions of 18F-FDG were found.

Nuclear Imaging Exams Authorized by the Brazilian Health Care System and Nuclear Imaging Equipment Distribution in the State of Rio Grande do Sul

Introduction: For nuclear imaging exams to be funded by the Brazilian public health care system (Sistema Único de Saúde, SUS), the institution must be first authorized by the National Nuclear Energy Commission (Comissão Nacional de Energia Nuclear, CNEN) to secure the safe use of radiation. Objective: To describe the distribution of equipment used in nuclear imaging exams and the quantity of exams funded by the SUS according to the macroregions defined by Rio Grande do Sul Health Department from 2013 to 2015. To check the consistency of data from the Department of Informatics of the Ministry of Health (Departamento de Informática do Sistema Único de Saúde, DATASUS) and the CNEN in November 2015. Methods: Secondary data from DATASUS and the CNEN were used. The region of health, the macroregion, and its respective estimated population were obtained from the Brazilian Institute of Geography and Statistics. Results: The Porto Alegre metropolitan area showed the largest concentration of gamma cameras. The number of exams was higher in philanthropic institutions with a valid register at the Brazilian Ministry of Health and federal funded organizations. Some regions had less CNEN-authorized institutions than SUS-authorized ones. Conclusion: The distribution of equipment and exams was uneven in the state.

Subsídios para o licenciamento nuclear para uma instalação independente de armazenamento complementar a seco de elementos combustíveis irradiados: correlação das bases normativas para um sistema de garantia da qualidade no Brasil

As Angra 1 and Angra 2 nuclear power plants’ spent fuel pools are near their capacity limits. The decision to construct the first independent spent fuel storage installation (ISFSI) in Brazil was taken by Eletronuclear. However, considering the lack of a specific safety standard for this installation, the Brazilian National Nuclear Energy Commission (or in Portuguese, Comissao Nacional de Energia Nuclear – CNEN) has recognized the United States Nuclear Regulatory Commission (USNRC) regulatory requirements for the preparation of the Safety Analysis Report. So, it was identified the importance of a gap analysis of regulatory requirements of a quality assurance system provided on USNRC 10 CFR 72 Subpart G with the Brazilian standard CNEN NN 1.16. The main purpose of this research was to establish the correlation of requirements of regulatory requirements of the USNRC 10 CFR 72 Subpart G with those of the Brazilian standard CNEN NN 1.16 for the effective implementation of a quality assurance system and provide support for nuclear license process of this installation. In light of this problem, this research has been developed based on some pillars, such as the characterization of the normative bases, the elaboration of a correlation matrix of requirements, which were validated with a group of specialists. Therefore, the results of this research contribute to the nuclear licensing process and also for the knowledge management of quality assurance systems, where it is possible to apply the available material for different stakeholders who need to understand the requirements for carrying out their activities.