Military operations can present risks whose origins may be unconventional. As an example, we can mention those within the spectrum of chemical, biological, radiological, and nuclear (CBRN) defense. This study evaluates, through a computer simulation, an operation in which soldiers face radiological contamination after the triggering of a radiological dispersion device (RDD) in an inhabited urban area. The simulation of the Gaussian scattering (analytical) of the Cs-137 radionuclide is performed using the HotSpot Health Physics codes software. The results of the simulation are evaluated according to two radiological risk domains, referring to high (above 100 mSv) and low integrated radiation doses over 4 continuous days of operation. The radiological risk for developing solid cancer according to specific epidemiological models was estimated. This information served as a basis for estimating the future detriment, that is, the loss of life expectancy (LLE). In addition, the methodology may serve as an instructional resource for tabletop exercises contributing to develop leadership and preparation for decision-making in asymmetric environments.

Este trabalho descreve a modelagem computacional de dispersão atmosférica decorrente de acidente radiológico hipotético em reator modular de pequeno porte (SMR), cuja potência é de 16 MWe (50 MWt). Utilizou-se o software SCALE para modelar o núcleo com três regiões de enriquecimento do combustível, a 4%, 5% e 20%, e obter atividades dos radionuclídeos oriundos de reações nucleares durante o burnup, após 2 anos de operação. Foi escolhida uma localidade de interior para instalação do SMR, onde informações sobre condições meteorológicas foram coletadas para identificação da classe de estabilidade atmosférica predominante. Dentre os radionuclídeos do inventário, considerou-se a contribuição do Cs-137 para simulação, usando-se o código HotSpot, da concentração e das doses totais efetivas (TEDE) recebidas, ambas em função da distância do evento. Os resultados sugerem que a TEDE máxima calculada foi de 3,6 Sv, a 34 m do reator, diminuindo com o tempo e distância, e seguindo o modelo Gaussiano de dispersão, e que a pluma de contaminação é dependente dos critérios de Pasquill-Gifford e da atividade do Cs-137. Para doses entre 1 mSv e 10 mSv e entre 10 mSv e 50 mSv, sugere-se a abrigagem da população nas construções existentes na localidade, e para valores acima de 50 mSv, a abrigagem nessas condições ou a evacuação do pessoal das proximidades do reator em movimento contrário ao de propagação da pluma. A relevância dessa investigação mostra a importância do planejamento de respostas em situação de emergência e a influência das condições meteorológicas, considerando-se os dados assumidos na

This study describes the computational modeling of the atmospheric dispersion resulting from a postulated radiological accident in a small modular reactor (SMR), with a power of 16 MWe (50 MWt), and containing three fuel enrichment regions, at 4%, 5 % and 20%. Among the hypothetical inventory radionuclides, derived from nuclear reactions during fuel burnup after 2 years of operation, the contribution of Cs-137 was considered for simulation, using the HotSpot code, of the concentration and total effective doses (TEDE) received, both depending on the distance from the event. A locality in the interior of Brazil was chosen to install the SMR, where information on meteorological conditions was collected to identify the predominant atmospheric stability class. The results suggest that the maximum calculated TEDE was 3.6 Sv, 34 m from the reactor, decreasing with time and distance, and following the Gaussian dispersion model, and that the contamination plume is dependent on the Pasquill-Gifford criteria and Cs-137 activity. For doses between 1 mSv and 10 mSv and between 10 mSv and 50 mSv, it is suggested that the population be housed in existing buildings in the locality, and for values above 50 mSv, shelter in these conditions or the evacuation of people close to the reactor in movement contrary to the spread of the plume. The relevance of this investigation shows the importance of emergency response planning and the influence of meteorological conditions, considering the data assumed in the simulation.

RESUMOA crescente demanda de estudos voltados para o setor petrolífero vem da preocupação com o NORM (Natural Occurring Radioactive Material) presente nas incrustações e borras, proveniente das atividades de extração de petróleo, que pode prejudicar os trabalhadores, caso esses, sejam expostos a quantidades significativas dessa radiação. Sendo assim, este trabalho tem como objetivo determinar as atividades específicas dos isótopos de Ra, em amostras de incrustações e borras, utilizando um detector semicondutor de germânio de alta pureza -HPGe coaxial, com tempo de aquisição de 86400 s; e avaliar, utilizando um identificador radiológico portátil -IRP com cintilador de NaI(Tl) e tempo de aquisição de 180 s, as taxas de dose associadas a essas amostras e sua eficiência na identificação rápida, "in situ", do NORM presente nas mesmas. A geometria de medição foi padronizada a uma distância de 5 cm amostra-detector. Foram analisadas três amostras de incrustação e uma de borra, retiradas de diferentes pontos da linha de retorno de água produzida do tanque de despejo de um navio plataforma do tipo FPSO. Os resultados mostraram uma variação das atividades específicas de

This paper presents a study on the implementation of nuclear security’s knowledge in the brazilian reality, sharing the promotion of nuclear security education, aligned to guidelines and orientations of the IAEA, and covering fields such as The Regulatory Area and The Non- Regulatory Area. The study takes into account the acts of terrorism that indicate the use or threat of use of radioactive material, radiological weapons or even nuclear weapons, including local attacks where such materials are present. The Nuclear Security planning in a country includes everything. From planning a safety project from a core of a nuclear reactor to planning a gym's safety. It also includes physical security plan, safeguards plan, information security, the society's alert about any risk and actions to prevent and detect the different types of threats, such as the risk of sabotage, illegal transfer of radioactive material, among others.

This study establishes a quantitative analysis protocol of radionuclides in a radiological and nuclear mobile laboratory of the Brazilian Army's Institute of Chemical, Biological, Radiological and Nuclear Defense. The gamma spectrometry technique was used, by a HPGe detector, to identify certified gamma-emitting radioactive sources (Am-241, Cs-137 and Co-60) present in a standard solution diluted in a Marinelli flask of 4L. Energy, resolution and efficiency calibration curves were determined using the LabFit software, for this detector, in the considered geometry. The results show to be satisfactory the linear adjustment (Channel versus Energy) of set points have been obtained experimentally which was confirmed by the determination coefficient achieved (). Besides that, it could be also verified that the exponential function was the mathematical model that best represented the answer of the HPGe detector energy resolution and that the mathematical adjustment options provided by LabFit which allowed to correlate the counting efficiency with the energy of each photopeak, despite the lack of a greater amount of energy. To define specific activities, the measurement errors between theoretical and experimental values were less than 4%, evidencing the reasonable responsiveness of the measurement system.

The provision for the Brazilian Army of equipment that provides reliable and safe measurements, enabling decision-making based on radioprotection parameters, leads to the need to investigate the metrology of the calibration system used in the Radiation Monitor Calibration Laboratory (LabCal) of the Institute of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN). To this end, the commissioning in cesium-137 is of primary importance in this process. In order to check the conformity of the radiator system, in this work, the ambient dose equivalent rate, , was obtained experimentally for several configurations to compare them with the appropriate theoretical concepts. For this, the distance between the source of Cesium-137 (36.9 GBq in 01/22/2015) and the ionization chamber was varied from 500 to 3000 mm at 250mm intervals. To obtain lower ambient dose equivalent rates, 15 and 32 mm thick lead attenuators were used. The mathematical model that best fit the experimental values was analyzed. In all cases, the potential function offers better fit, since the coefficients of determination obtained are approximately equal to 1, obeying the Law of the Inverse Square of the Distance, according to theoretical foundation. Moreover, it was evaluated that the relative deviations are below the limits established by the relevant standard.

The provision for the Brazilian Army of equipment that provides reliable and safe measurements leads to the need  for a metrology study of the calibration system used in the Institute's Radiation Monitor Calibration Laboratory (LabCal) of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN). In order  to verify the stability of dosimetry in Cesium-137, the ambient dose equivalent rate, H*(10), was experimentally obtained for certain distance settings and lead attenuators at different dates in order to compare them. To this end, the distance between the source of Cesium-137 and the ionization chamber was varied from 1000, 2000 and 3000 mm without attenuator and with lead attenuators with 15 and 32 mm. In this work, the reproducibility of the system was analyzed by comparing the scenario of equal distance and attenuator, but with a different test date. For this purpose, the correction due to the radioactive decay of the source up to a reference date was used for comparison.Furthermore,the stability of the LabCal in Cesium-137 was verified in the light of the relevant standards for exposures without attenuators and with select attenuators for the tested distances.