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Introduction Alternative methods for producing the medical imaging isotope 99mTc are actively being developed around the world in anticipation of the imminent shutdown of the National Research Universal (NRU) reactor in Chalk River, Ontario, Canada and the high flux reactor (HFR) in Petten, Holland that together currently produce up to 80 % of the world’s supply through fission. The most promising alternative methods involve accelerators that focus Bremsstrahlung radiation or protons on metallic targets comprised of 100Mo and a supporting material used to conduct heat away during irradiation. As an example, the reaction 100Mo(p,2n)99mTc provides a direct route that can be incorporated into routine production in regional nuclear medicine centers that possess medical cyclotrons for production of other isotopes, such as those used for Positron Emission Tomography (PET). The targets used to produce 99mTc are subject to a number of operational constraints. They must withstand the temperatures generated by the irradiation and be fashioned to accommodate temperature gradients from in situ cooling. The targets must be resilient, which means they cannot disintegrate during irradiation or post processing, because of the radioactive nature of the products. Yet, the targets must be easily post-processed to separate the 99mTc. In addition, the method used to manufacture the targets must not be wasteful of the 100Mo, because of its cost (~$2/mg). Any manufacturing process should be able to function remotely in a shielded space to accommodate the possibility of radioactive recycled target feedstock. There are a number of methods that have been proposed for large-scale target manufacturing including electrophoretic deposition, pressing and sinter-ing, electroplating and carburization [1]. How to develop these methods for routine production is an active business [2,3]. From the industrial perspective, plasma spraying showed promising results initially [4], but the process became ver

Thermal separation is defined as a mass transfer process driven by molecular forces. The process involves the heat transfer between two phases with different composition. In general, thermal separation occurs when heat is generated in the system additionally to the already existing phases. In a second phase the mass is transferred in the system (adsorption) and at the end of this step the separation is completed. The thermal separation can be achieved in temperature or concentration gradient function of system configuration [1]. Thermo-chromatography is a process in which the separation occurs in gase-ous phase. By passing a heated gas through a column a thermal gradient is created with a continuously decreasing temperature along the column. The separation occurs based on the different volatilization temperatures, the less volatile species will condense on the column walls at the higher temperatures and the highly volatile compounds will condense at lower temperatures. Parameters like temperature, carrier flow rate, column geometry and length have impact on the absorption of the compound on the column material affecting the separation efficiency. The thermal separation has been used for separation of Molybdenum (Mo) and Technetium (Tc) by either sublimation in the case of 94mTc {2,3,4] or dry distillation in the case of 99mTc from neutron irradiated MoO3 [5]. The thermal separation process has been used in the development of a new type of Mo/Tc generators starting from the MoO3 as target material for production of 99mTc in linear accelerators [6]. Dry distillation has become a standard procedure for separation of radioiodine from tellurium targets [7]. The present paper describes the thermal separation of a three component system (Cu/Mo/Tc) used as a target in the production of 99mTc through the 100Mo(p,2n) reaction. Material and Methods The separation method involves the use of oxygen as a carrier gas and oxidation agent. The method is based on the different volati

Introduction Alternative methods for producing the medical imaging isotope 99mTc are actively being developed around the world in anticipation of the imminent shutdown of the National Research Universal (NRU) reactor in Chalk River, Ontario, Canada and the high flux reactor (HFR) in Petten, Holland that together currently produce up to 80 % of the world’s supply through fission. The most promising alternative methods involve accelerators that focus Bremsstrahlung radiation or protons on metallic targets comprised of 100Mo and a supporting material used to conduct heat away during irradiation. As an example, the reaction 100Mo(p,2n)99mTc provides a direct route that can be incorporated into routine production in regional nuclear medicine centers that possess medical cyclotrons for production of other isotopes, such as those used for Positron Emission Tomography (PET). The targets used to produce 99mTc are subject to a number of operational constraints. They must withstand the temperatures generated by the irradiation and be fashioned to accommodate temperature gradients from in situ cooling. The targets must be resilient, which means they cannot disintegrate during irradiation or post processing, because of the radioactive nature of the products. Yet, the targets must be easily post-processed to separate the 99mTc. In addition, the method used to manufacture the targets must not be wasteful of the 100Mo, because of its cost (~$2/mg). Any manufacturing process should be able to function remotely in a shielded space to accommodate the possibility of radioactive recycled target feedstock. There are a number of methods that have been proposed for large-scale target manufacturing including electrophoretic deposition, pressing and sinter-ing, electroplating and carburization [1]. How to develop these methods for routine production is an active business [2,3]. From the industrial perspective, plasma spraying showed promising results initially [4], but the process became ver

Thermal separation is defined as a mass transfer process driven by molecular forces. The process involves the heat transfer between two phases with different composition. In general, thermal separation occurs when heat is generated in the system additionally to the already existing phases. In a second phase the mass is transferred in the system (adsorption) and at the end of this step the separation is completed. The thermal separation can be achieved in temperature or concentration gradient function of system configuration [1]. Thermo-chromatography is a process in which the separation occurs in gase-ous phase. By passing a heated gas through a column a thermal gradient is created with a continuously decreasing temperature along the column. The separation occurs based on the different volatilization temperatures, the less volatile species will condense on the column walls at the higher temperatures and the highly volatile compounds will condense at lower temperatures. Parameters like temperature, carrier flow rate, column geometry and length have impact on the absorption of the compound on the column material affecting the separation efficiency. The thermal separation has been used for separation of Molybdenum (Mo) and Technetium (Tc) by either sublimation in the case of 94mTc {2,3,4] or dry distillation in the case of 99mTc from neutron irradiated MoO3 [5]. The thermal separation process has been used in the development of a new type of Mo/Tc generators starting from the MoO3 as target material for production of 99mTc in linear accelerators [6]. Dry distillation has become a standard procedure for separation of radioiodine from tellurium targets [7]. The present paper describes the thermal separation of a three component system (Cu/Mo/Tc) used as a target in the production of 99mTc through the 100Mo(p,2n) reaction. Material and Methods The separation method involves the use of oxygen as a carrier gas and oxidation agent. The method is based on the different volati

Introduction Alternative methods for producing the medical imaging isotope 99mTc are actively being developed around the world in anticipation of the imminent shutdown of the National Research Universal (NRU) reactor in Chalk River, Ontario, Canada and the high flux reactor (HFR) in Petten, Holland that together currently produce up to 80 % of the world’s supply through fission. The most promising alternative methods involve accelerators that focus Bremsstrahlung radiation or protons on metallic targets comprised of 100Mo and a supporting material used to conduct heat away during irradiation. As an example, the reaction 100Mo(p,2n)99mTc provides a direct route that can be incorporated into routine production in regional nuclear medicine centers that possess medical cyclotrons for production of other isotopes, such as those used for Positron Emission Tomography (PET). The targets used to produce 99mTc are subject to a number of operational constraints. They must withstand the temperatures generated by the irradiation and be fashioned to accommodate temperature gradients from in situ cooling. The targets must be resilient, which means they cannot disintegrate during irradiation or post processing, because of the radioactive nature of the products. Yet, the targets must be easily post-processed to separate the 99mTc. In addition, the method used to manufacture the targets must not be wasteful of the 100Mo, because of its cost (~$2/mg). Any manufacturing process should be able to function remotely in a shielded space to accommodate the possibility of radioactive recycled target feedstock. There are a number of methods that have been proposed for large-scale target manufacturing including electrophoretic deposition, pressing and sinter-ing, electroplating and carburization [1]. How to develop these methods for routine production is an active business [2,3]. From the industrial perspective, plasma spraying showed promising results initially [4], but the process became ver

Thermal separation is defined as a mass transfer process driven by molecular forces. The process involves the heat transfer between two phases with different composition. In general, thermal separation occurs when heat is generated in the system additionally to the already existing phases. In a second phase the mass is transferred in the system (adsorption) and at the end of this step the separation is completed. The thermal separation can be achieved in temperature or concentration gradient function of system configuration [1]. Thermo-chromatography is a process in which the separation occurs in gase-ous phase. By passing a heated gas through a column a thermal gradient is created with a continuously decreasing temperature along the column. The separation occurs based on the different volatilization temperatures, the less volatile species will condense on the column walls at the higher temperatures and the highly volatile compounds will condense at lower temperatures. Parameters like temperature, carrier flow rate, column geometry and length have impact on the absorption of the compound on the column material affecting the separation efficiency. The thermal separation has been used for separation of Molybdenum (Mo) and Technetium (Tc) by either sublimation in the case of 94mTc {2,3,4] or dry distillation in the case of 99mTc from neutron irradiated MoO3 [5]. The thermal separation process has been used in the development of a new type of Mo/Tc generators starting from the MoO3 as target material for production of 99mTc in linear accelerators [6]. Dry distillation has become a standard procedure for separation of radioiodine from tellurium targets [7]. The present paper describes the thermal separation of a three component system (Cu/Mo/Tc) used as a target in the production of 99mTc through the 100Mo(p,2n) reaction. Material and Methods The separation method involves the use of oxygen as a carrier gas and oxidation agent. The method is based on the different volati

Introduction Alternative methods for producing the medical imaging isotope 99mTc are actively being developed around the world in anticipation of the imminent shutdown of the National Research Universal (NRU) reactor in Chalk River, Ontario, Canada and the high flux reactor (HFR) in Petten, Holland that together currently produce up to 80 % of the world’s supply through fission. The most promising alternative methods involve accelerators that focus Bremsstrahlung radiation or protons on metallic targets comprised of 100Mo and a supporting material used to conduct heat away during irradiation. As an example, the reaction 100Mo(p,2n)99mTc provides a direct route that can be incorporated into routine production in regional nuclear medicine centers that possess medical cyclotrons for production of other isotopes, such as those used for Positron Emission Tomography (PET). The targets used to produce 99mTc are subject to a number of operational constraints. They must withstand the temperatures generated by the irradiation and be fashioned to accommodate temperature gradients from in situ cooling. The targets must be resilient, which means they cannot disintegrate during irradiation or post processing, because of the radioactive nature of the products. Yet, the targets must be easily post-processed to separate the 99mTc. In addition, the method used to manufacture the targets must not be wasteful of the 100Mo, because of its cost (~$2/mg). Any manufacturing process should be able to function remotely in a shielded space to accommodate the possibility of radioactive recycled target feedstock. There are a number of methods that have been proposed for large-scale target manufacturing including electrophoretic deposition, pressing and sinter-ing, electroplating and carburization [1]. How to develop these methods for routine production is an active business [2,3]. From the industrial perspective, plasma spraying showed promising results initially [4], but the process became ver

Thermal separation is defined as a mass transfer process driven by molecular forces. The process involves the heat transfer between two phases with different composition. In general, thermal separation occurs when heat is generated in the system additionally to the already existing phases. In a second phase the mass is transferred in the system (adsorption) and at the end of this step the separation is completed. The thermal separation can be achieved in temperature or concentration gradient function of system configuration [1]. Thermo-chromatography is a process in which the separation occurs in gase-ous phase. By passing a heated gas through a column a thermal gradient is created with a continuously decreasing temperature along the column. The separation occurs based on the different volatilization temperatures, the less volatile species will condense on the column walls at the higher temperatures and the highly volatile compounds will condense at lower temperatures. Parameters like temperature, carrier flow rate, column geometry and length have impact on the absorption of the compound on the column material affecting the separation efficiency. The thermal separation has been used for separation of Molybdenum (Mo) and Technetium (Tc) by either sublimation in the case of 94mTc {2,3,4] or dry distillation in the case of 99mTc from neutron irradiated MoO3 [5]. The thermal separation process has been used in the development of a new type of Mo/Tc generators starting from the MoO3 as target material for production of 99mTc in linear accelerators [6]. Dry distillation has become a standard procedure for separation of radioiodine from tellurium targets [7]. The present paper describes the thermal separation of a three component system (Cu/Mo/Tc) used as a target in the production of 99mTc through the 100Mo(p,2n) reaction. Material and Methods The separation method involves the use of oxygen as a carrier gas and oxidation agent. The method is based on the different volati

Effective evaluation of air pollution control strategies requires the use of validated and reliable mathematical models that can relate pollutant emissions to atmospheric air quality. The derivation and use of such models, at least for inert and linearly decaying pollutants such as CO and SO_2, has received a great deal of attention. Much less work has been devoted to assessing how the model predictions are related to actual atmospheric concentrations. The objectives of this paper are to formulate the concepts of validity and accuracy and to suggest and describe some experiments that can be performed to assess these features.

The complexity of systems of chemical reactions makes it difficult to determine the effect uncertainties in rate constants and other parameters have on the behavior of .the species concentrations. Mathematically, the sensitivity analysis of a system of chemical reactions consists in the problem of determining the effect of uncertainties in parameters and initial conditions on the solution of a set of ordinary differential equations. Sensitivity analysis procedures may be classed as deterministic or stochastic in nature. Currently available sensitivity analysis techniques are reviewed, and the entire problem is presented in a unified framework.