According to the International Atomic Energy Agency (IAEA), a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS) in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry.
The ICRP Statement on Tissue Reactions (2011), based on epidemiological evidence, recommended a reduction for the eye lens equivalent dose limit from 150 to 20 mSv per year. This paper presents mainly the dose estimations received by industrial gamma radiography workers, during planned or accidental exposure to the eye lens, Hp(10) and effective dose. A Brazilian Visual Monte Carlo Dose Calculation program was used and two relevant scenarios were considered. For the planned exposure situation, twelve radiographic exposures per day for 250 days per year, which leads to a direct exposure of 10 h per year, were considered. The simulation was carried out using a Ir source with 1.0 TBq of activity; a source/operator distance between 5 and 10 m and placed at heights of 0.02 m, 1 m and 2 m, and an exposure time of 12 s. Using a standard height of 1 m, the eye lens doses were estimated as being between 16.3 and 60.3 mGy per year. For the accidental exposure situation, the same radionuclide and activity were used, but in this case the doses were calculated with and without a collimator. The heights above ground considered were 1.0 m, 1.5 m and 2.0 m; the source/operator distance was 40 cm, and the exposure time 74 s. The eye lens doses at 1.5 m were 12.3 and 0.28 mGy without and with a collimator, respectively. The conclusions were that: (1) the estimated doses show that the 20 mSv annual limit for eye lens equivalent dose can directly impact industrial gamma radiography activities, mainly in industries with high number of radiographic exposures per year; (2) the risk of lens opacity has a low probability for a single accident, but depending on the number of accidental exposures and the dose levels found in planned exposures, the threshold dose can easily be exceeded during the professional career of an industrial radiography operator, and; (3) in a first approximation, Hp(10) can be used to estimate the equivalent dose to the eye lens.
A ameaça de "terrorismo radiológico" foi reconhecida mundialmente após o evento de 11 de setembro de 2001.Fontes radioativas podem ser utilizadas para construção de DDR -Dispositivos de Dispersão Radiológica ("bomba suja"). Estudos demonstram que o uso de um DDR poderia causar danos à saúde, psicossociais e prejuízos econômicos e ambientais. O Brasil acompanha essa preocupação mundial, pois possui amplo parque médicoindustrial que utiliza fontes radioativas. Este trabalho apresenta um panorama sobre a segurança física de fontes radioativas no país, baseado no inventário de instalações radiativas, comparando os requisitos regulatórios nacionais às recomendações internacionais. No Brasil existem aproximadamente 2.500 instalações radiativas, com cerca de 500 fontes radioativas Categoria 1 e 2, que são a maior preocupação em termos de segurança física. A norma brasileira de licenciamento aborda somente alguns aspectos de proteção física, não apresentando orientação clara para elaboração e implantação de sistemas de proteção física, não atendendo às recomendações internacionais. Para o Brasil se inserir no cenário mundial de segurança física de fontes radioativas torna-se premente a elaboração de legislação específica, com critérios regulatórios bem definidos. A falta de requisitos mais detalhados dificulta avaliação regulatória mais criteriosa sobre as condições de proteção física das instalações, seja por meio da avaliação de planos e demais documentos de proteção física ou pela realização de inspeções regulatórias.Palavras-chave: segurança física, terrorismo radiológico, bomba suja.
The Physical Protection System is based on the five basic security functions (deterrence, detection, delay, response, and security management), all of which are required to protect a radiological facility against malicious acts. Evaluating the performance of PPS, including the security procedures and their implementation, is a way to engage with staff, raise their awareness on the importance of security. This article presents a new effectiveness evaluation model of the PPS administrative structure through qualitative analysis, which is appropriate for the security management evaluation of low-consequence radiological facilities, to protect them against malicious acts. This model was developed in five stages to obtain a structured process for conducting the PPS administrative structure evaluation, based on the security management function, consisting of 11 topics and 89 qualitative questions to determine the Relative Robustness Index of this function. Model topics were classified with distinct relative weights based on their relevance to the PPS. For testing and validation of the model, 6 industrial radiological facilities classified in different security levels were selected. The results showed that the self-assessment model proposed in this article is viable, considering its simplicity, promptness, and applicability in identifying and analyzing the strengths and weaknesses of the PPS security management function. The new model made possible the effectiveness evaluation of the PPS globally and punctually, making it possible to identify which topics of security management are above, or below, the minimum required for the current security level.
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