Manufacturing of miniaturized high activity 192Ir sources have been made a market preference in modern brachytherapy. The smaller dimensions of the sources are flexible for smaller diameter of the applicators and it is also suitable for interstitial implants. Presently, miniaturized 60Co HDR sources have been made available with identical dimensions to those of 192Ir sources. 60Co sources have an advantage of longer half life while comparing with 192Ir source. High dose rate brachytherapy sources with longer half life are logically pragmatic solution for developing country in economic point of view. This study is aimed to compare the TG-43U1 dosimetric parameters for new BEBIG 60Co HDR and new microSelectron 192Ir HDR sources. Dosimetric parameters are calculated using EGSnrc-based Monte Carlo simulation code accordance with the AAPM TG-43 formalism for microSlectron HDR 192Ir v2 and new BEBIG 60Co HDR sources. Air-kerma strength per unit source activity, calculated in dry air are 9.698×10-8 ± 0.55% U Bq-1 and 3.039×10-7 ± 0.41% U Bq-1 for the above mentioned two sources, respectively. The calculated dose rate constants per unit air-kerma strength in water medium are 1.116±0.12% cGy h-1U-1 and 1.097±0.12% cGy h-1U-1, respectively, for the two sources. The values of radial dose function for distances up to 1 cm and more than 22 cm for BEBIG 60Co HDR source are higher than that of other source. The anisotropic values are sharply increased to the longitudinal sides of the BEBIG 60Co source and the rise is comparatively sharper than that of the other source. Tissue dependence of the absorbed dose has been investigated with vacuum phantom for breast, compact bone, blood, lung, thyroid, soft tissue, testis, and muscle. No significant variation is noted at 5 cm of radial distance in this regard while comparing the two sources except for lung tissues. The true dose rates are calculated with considering photon as well as electron transport using appropriate cut-off energy. No significant advantages or disadvantages are found in dosimetric aspect comparing with two sources.

A hypothetical accidental case of a 3-MW TRIGA Mark-II research reactor has been assumed to assess the radiological consequences due to the deposition of 137Cs and 90Sr on ground, vegetation, milk and meat. The air concentrations in sixteen cardinal directions have been estimated where the maximum concentration has been found to be at 110 m distance from the core of the reactor for all the directions. Calculated maximum doses of 137Cs, 90Sr and both 137Cs and 90Sr have been found to be within the ranges of 0.005-0.014 μSv hr–1, 0.013-0.036 μSv hr–1 and 0.018-0.05 μSv hr–1, respectively for all the directions, which are below the measured background dose limit 0.25 μSv hr–1 and also within the IAEA acceptable dose rate limit of 0.5 μSv hr–1. The calculated low doses due to the aforementioned radionuclides can be considered negligible with regard to the radiation hazards. The relationship between total effective dose rate for various pathways (i.e. immersion, inhalation, ground deposition, and ingestion of contaminated vegetation, milk, meat) and air concentration in all the directions has been established. Obtained relation reveals that the total effective dose rate is directly proportional to the air concentration, and the overall proportionality constants for 137Cs and 90Sr radionuclides have been obtained as 0.57 and 0.28, respectively. This study might provide information on the radiological safety required for the radiation protection purposes of the people living in the vicinity of the reactor site.

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A hypothetical accidental case of a 3-MW TRIGA Mark-II research reactor has been assumed to assess the radiological consequences due to the deposition of 137 Cs and Sr have been found to be within the ranges of 0.005-0.014 µSv hr -1 , 0.013-0.036 µSv hr -1 and 0.018-0.05 µSv hr -1 , respectively for all the directions, which are below the measured background dose limit 0.25 µSv hr -1 and also within the IAEA acceptable dose rate limit of 0.5 µSv hr -1 . The calculated low doses due to the aforementioned radionuclides can be considered negligible with regard to the radiation hazards. The relationship between total effective dose rate for various pathways (i.e. immersion, inhalation, ground deposition, and ingestion of contaminated vegetation, milk, meat) and air concentration in all the directions has been established. Obtained relation reveals that the total effective dose rate is directly proportional to the air concentration, and the overall proportionality constants for 137 Cs and 90 Sr radionuclides have been obtained as 0.57 and 0.28, respectively. This study might provide information on the radiological safety required for the radiation protection purposes of the people living in the vicinity of the reactor site.

In this study, a systematic analysis of fresh and sea water fishes, poultry and their feeds and sediments was conducted using research reactor based neutron activation analysis (NAA) technique with the aim to determine elemental status with special emphasis on arsenic and chromium contamination. Sixty nine samples in different categories (fresh water fishes from three ponds, and corresponding sediments, sea water fishes from Bay of Bengal, chicken from five farms, their feeds) were analyzed through a series of NAA experiments to determine the translocations of toxic elements from feed to fish, sediments and birds and their excretion through litters. The analytical results revealed that some of the locally produced feeds for poultry and fish are highly contaminated with chromium. The flesh of both the fresh water fish and poultry are free from arsenic contamination. The sea fish contains high arsenic concentration. However, the major form of seafood arsenic as arsenobetaine that is completely harmless and its occurrence in seafood presented no human health concerns. The present study will certainly help to the Food Controlling Authority in Bangladesh to produce fish and poultry in a controlled sustainable manner and will also create public awareness.