Quantitative activation analysis of the target assemblies of a medical linear accelerator

Radioactive nuclides with relatively long half-lives in the target assemblies of medical accelerators were investigated. The samples were the target assembly of a 10 MV linear accelerator, a 20 MV microtron and screws of a cyclotron. Gamma-spectroscopy was performed with a high-purity germanium (HPGe) detector. Detected nuclides were ⁵¹Cr, ⁵⁴Mn, ⁵⁹Fe, ⁵⁷Co, ⁵⁸Co, ⁶⁰Co, ⁶⁵Zn, ^108mAg, and ^110mAg. As the half-lives of some generated nuclides are relatively long, it is difficult to adapt to decay-in-storage.     

Transfer of some selected radionuclides (Cs, Sr, Mn, Co, Zn and Ce) from soil to root vegetables

Transfer of radionuclides from soil to root vegetables (radish, carrot and turnip) has been studied by radiotracer experiments using Andosol, a typical soil type in Japan. The averages of the transfer factors of¹³⁷Cs,⁸⁵Sr,⁶⁰Co,⁵⁴Mn and⁶⁵Zn for edible parts of the three vegetables were 0.02, 0.14, 0.004, 0.09 and 0.13, respectively. The transfer factor of¹⁴¹Ce for the edible part of carrot was 0.0002. The transfer factors obtained for the edible part of root vegetables were markedly lower than those for leaf vegetables.     

Simultaneous biobehavior of trace elements, Sc, Mn, Fe, Co, Zn, Se, Rb and Zr in the brain and other organs of C57BL/6N mice

The radioactive multitracer technique was applied to a study on the uptake of trace elements in normal C57BL/6N mice. Comparative uptake behavior of⁴⁶Sc,⁵⁴Mn,⁵⁹Fe,⁵⁸Co,⁶⁵Se,⁸³Rb and⁸⁸Zr tracers was examined among 11 organs (brain, cardiac muscle, lung, liver, spleen, pancreas, kidneys, bone, muscle, eyeballs and testes) and blood, and evaluated in terms of the “tissue uptake rate (the radioactivity percentage of injected dose per gram of tissue, %dose/g)”. The multitracer technique revealed reliable data demonstrating characteristic uptake of the 8 trace elements, Sc, Mn, Fe, Co, Zn, Se, Rb and Zr by the brain and other organs, as well as the distinctive features of the accumulation and retention of each element in the brain.     

Effect of humic acid on the bioavailability of radionuclides to rice plants

We investigated the effect of humic acid and solution pH on the uptake of the radionuclides, (83)Rb, (137)Cs, (54)Mn, (65)Zn, (88)Y, (102)Rh, and (75)Se in rice plants by the multitracer technique. The addition of humic acid to a culture medium containing SiO(2) increased the uptake of Mn and Zn at pH 4.3, whereas their uptake was decreased at pH 5.3. Humic acid depressed the uptake of Y at both pHs. The uptake of Se, which does not interact with humic acid, was not affected by its presence. These results suggest that uptake of the radionuclides by the rice plant is regulated by the affinity of radioactive nuclides for humic acid, as well as by the soil solution's pH.     

Cesium,manganese and cobalt water–sediment transfer kinetics and diffusion into mangrove sediments inferred by radiotracer experiments

A study on the trace elements transfer from tidal water to mangrove sediments from Guanabara Bay (southeastern Brazil) was performed in laboratory microcosms. Sediment cores were covered with tidal water spiked with ¹³⁷Cs, ⁵⁴Mn and ⁵⁷Co during 5-h experiments, and water samples were taken at regular intervals to measure uptake kinetics at the sediment–water interface. At the end of the experiments, the uptake and diffusional penetration into the sediments was evaluated. Half-removal times from water to sediments were slightly higher for ¹³⁷Cs (3.4 ± 1.7 h) than observed for ⁵⁴Mn (2.3 ± 0.2 h) and ⁵⁷Co (2.6 ± 1.1 h). After these experiments, all radioisotopes presented decreasing activities with increasing sediment depth, being the distribution of ¹³⁷Cs indicative of higher diffusion within the upper 2 cm. This study on the removal of ¹³⁷Cs, ⁵⁴Mn and ⁵⁷Co from tidal water by mangrove sediments suggests that while ⁵⁷Co and ⁵⁴Mn presented closer behaviors, there was a slightly higher mobility of ¹³⁷Cs.     

Multitracer screening for in vivo element-element interrelations

Radioactive multitracer technique was applied to study the screening of in vivo interrelations between radioactive tracers (⁴⁶Sc, ⁵⁴Mn, ⁵⁸Co, ⁶⁵Zn, ⁷⁵Se, ⁸³Rb, ⁸⁵Sr and ⁸⁸Zr) and stable Zn species. Comparative uptake rates were examined in the blood, nine organs (thymus, lung, cardiac muscle, spleen, pancreas, kidney, liver, testes and bone) and eight brain regions (cerebral cortex, striatum, hippocampus, thalamus and hypothalamus, midbrain, cerebellum, pons and medulla, olfactory bulb) using 3-week-old mice fed by four kinds of Zn-deficient, -adequate and -excessive diets with Zn content from 0.7 to 3520 ppm. As a result, no significant difference between the dietary Zn-deficient state (Zn content: 3.6 ppm) and Zn-adequate state (Zn content: 36 ppm) was observed in the uptake rates of ⁶⁵Zn and other ⁴⁶Sc, ⁵⁴Mn, ⁵⁸Co and ⁷⁵Se, except for ⁸³Rb. In addition, significant differences among the organ and brain regional uptakes of ⁴⁶Sc, ⁵⁴Mn, ⁵⁸Co, ⁷⁵Se and ⁸³Rb were found in the dietary Zn-excessive state (Zn content: 3520 ppm). These results indicate that the organ and brain regional uptakes of tracers in Zn-deficient and excessive mice are strongly correlated with the blood uptakes and retentions of the tracers. Furthermore, the multitracer screening gives us new findings concerning the diet-related element-element interrelations in living bodies.     

Uptake and Distribution of Trace Elements in Growing Cucumber

Multitracer technique was used to study the uptake and distribution of some relatively long half-life radionuclides Be, Na, Mn, Co, Sc to growing cucumber (Cucumis Sativus L.) with two different treatments. In Hoagland solution, only ⁵⁴Mn and ⁶⁰Co accumulated in the every part of plants. ⁵⁴Mn, ⁶⁰Co and other radionuclides were absorbed in distilled water. The results indicate that there were major differences in the accumulation of trace elements between the two different treatments.     

Multitracer screening for in vivo element-element interrelations

Radioactive multitracer technique was applied to study the screening of in vivo interrelations between radioactive tracers (⁴⁶Sc, ⁵⁹Fe, ⁵⁸Co, ⁶⁵Zn, ⁷⁵Se, ⁸³Rb, ⁸⁵Sr and ⁸⁸Zr) and stable Mn species. Comparative uptake rates were examined in the blood, 9 organs (thymus, lung, cardiac muscle, spleen, pancreas, kidney, liver, testes and bone) and 8 brain regions (cerebral cortex, striatum, hippocampus, thalamus and hypothalamus, midbrain, cerebellum, pons and medulla, olfactory bulb) using the 3-weeks-old mice fed the Mn-deficient, -adequate or -excessive diets with Mn concentration from 0.4 to 300.4 ppm. Significant diet-related differences were found for ⁶⁵Zn uptake in some organs. The dietary Mn-deficient state induced increase Zn absorption in thymus and lung in short-time span (during 48 hours after injection). On the other hand, no significant diet-related differences were observed in any brain regional uptake rates except for ⁵⁴Mn uptake rate. The screening results are expected to give us new findings concerning the diet-related element-element interrelations in living bodies.     

Anthropogenic radiotracers assessment as tool to environmental compliance rules and management

A framework, within models and studies can be applied, to develop coherent and logical environmental impact management methodologies for ionizing radiation, is essential. A number of components, which form the basis for such a system, included the dilution factor for radioactive liquid effluent releases. In this study we established a strategic, fast and cheap methodology to estimate the dilution factor for the release of liquid radioactive effluents at IPEN. The radioisotopes ³H, ⁵⁴Mn, ⁶⁰Co, ⁶⁵Zn, and ¹³⁷Cs, generated in the routine operation of the Research Reactor IEA-R1, were used as radiotracers. The generated liquid radioactive effluent was stored in a 300 m³ capacity tank. The initial concentration of its present radioisotopes were determined. A planned release of effluent from the storage tank was carried-out. Simultaneously, the sampling was made upstream of the storage tank discharge point and the concentration ³H, ⁵⁴Mn, ⁶⁰Co, ⁶⁵Zn and ¹³⁷Cs in the mix sewerage system discharge point E1 at IPEN were monitored. The estimated dilution factor of discharge point of the aqueous effluent for ³H was 4.3 and 7.4, ⁵⁴Mn was12 and 16.1, ⁶⁰Co was 12.6 and 14.2, ⁶⁵Zn was 12 and 27.9 and ¹³⁷Cs was 6.2 and 13.9, respectively.     

Bioaccumulation of gamma emitting radionuclides in Polysiphonia fucoides

The article presents the results of a study on the bioaccumulation abilities of Polysiphonia fucoides, a red algae specific to the southern Baltic Sea, towards (of) gamma emitting isotopes. A laboratory experiment was carried out to determine changes in the activities of some isotopes—⁵⁴Mn, ⁵⁷Co, ⁶⁵Zn, ^110mAg,¹¹³Sn, ¹³⁴Cs, ¹³⁷Cs and ²⁴¹Am—occurring in P. fucoides exposed to a seawater medium containing these isotopes over the course of 1 month. All analyzed isotopes showed the greatest increase of radioactive activity in plant tissue in the first 24 h of exposure. The temporary concentration factors of cesium isotopes were increasing linearly during the experiment from 114 to 274 in the case of ¹³⁷Cs, and from 144 to 351 in the case of ¹³⁴Cs. The level of the initial concentration factor of cesium isotopes in the plant proved to be independent of the initial concentration of the isotope in seawater and it took the lowest (125 dm³ kg^?1) level among the studied isotopes. In the case of a mixture of gamma emitting isotopes, a linear relation between the individual isotope activity in P. fucoides and its initial concentration in seawater was established after the first day of exposure; the isotopes initial concentration factors ranged from 767 to 874 dm³ kg^?1. Having reached the maximal concentration level, a statistically significant decline in radioactivity concentrations of the five isotopes in the plant tissue was observed. A half-life of biological removal of the isotopes from the plant tissue was established at: 3.8 days in the case of ⁵⁴Mn, 4 days—⁵⁷Co, 4 days—⁶⁰Co, 4.2 days—¹³⁷Cs and ²⁴¹Am—3.5 days.     

Characterization of strong complexing agents in natural waters by liquid-liquid extraction

The solvent extraction method for characterization of strong complexing agents in natural waters has been developed. The titration curve the relationship between the concentration of a metal added in a sample solution and that of the metal in the organic phase after extraction, has been modelled on the basis of Ringbom's theory. The concentration of the metal in the organic phase is easily calibrated by the activities of the radioisotopic spike. The conditional stability products for complexation of natural ligands with cobalt (⁵⁷Co), manganese (⁵⁴Mn) and zinc (⁶⁵Zn) were calculated from the titration curves.     

A method for assessing and correcting coincidence summing effects for germanium detector efficiency calibrations

The addition of⁵⁴Mn and⁶⁵Zn to a nine-radionuclide standard (containing²⁴¹Am.,¹⁰⁹Cd.⁵⁷Co,¹³⁹Ce,²⁰³Hg.¹¹³Sn,¹³⁷Cs,⁸⁸Y, and⁶⁰Co) provides the capability to determine the extent of coincidence summing for gamma rays from⁸⁸Y and⁶⁰Co. A method for correcting the efficiency points at 1332 keV (⁶⁰Co) and 1836 keV (⁸⁸Y) for coincidence summing is presented.     

Influence of plant roots upon the mobility of radionuclides in soil, with respect to location of contamination below the surface

The movement of⁸⁵Sr,¹³⁷Cs,⁵⁴Mn and⁶⁰Co in the 50 cm soil profile was studied with and without the presence of plant roots (triticum aestivum) in order to investigate the influence of roots and depth contamination upon the migration of radionuclides. The water table was maintained manually at 3 cm from the bottom. The physiochemical characteristics (E_h Fe^–2, NH ₄ ⁺ , pH and moisture content) as well as the total and extractable radioactivity were investigated. In the discrete contamination, where the location of contamination varied within the soil profile (0–5, 25–30 or 45–50 cm from the top), the influence of location upon the movement of these radionuclides was also studied. It was found that the changes in the soil physicochemical characteristics influenced the mobility of the four radionuclides. The extractability of⁵⁴Mn and⁶⁰Co was significantly increased in the reducing region of the soil, whereas that of⁸⁵Sr,¹³⁷Cs was not. Plant roots excerted significant effects upon the soil characteristics, via, reducing the E_h pH and moisture content of the soil; increasing the extractability of both⁵⁴Mn and⁶⁰Co from the depth of 35 cm downwards. Radionuclide migration occurred via physicochemical and biological transport. The biological transport via plant roots was of particular importance for¹³⁷Cs. Location of contamination had a significant influence upon the mobility of radionuclides. The migration of radionuclides was in the sequence of contamination in middle>bottom>top. The degree of the influence varied with radionuclides concemed. In the top layer contamination, the rank of the migration from the contamination layers, on the other hand⁵⁴Mn,⁶⁰Co and¹³⁷Cs were more mobile and the movement was:⁸⁵Sr⁵⁴Mn⁶⁰Co>¹³⁷Cs. In the middle and bottom contamination layers, on the other hand,⁵⁴Mn and⁶⁰Co and¹³⁷Cs were more mobile and the movement was⁸⁵Sr⁵⁴Mn⁶⁰Co>¹³⁷Cs. The results provide evidence conceming the soil-root interaction influencing the transfer efficiency of radionuclides from below the soil surface into the human food chain.     

Brain regional uptake of radioactive Sc, Mn, Zn, Se, Rb and Zr tracers into normal mice during aging

Radioactive multitracer technique was applied to study the brain regional uptake of trace elements by the normal mice during aging. The brain regional radioactivities of ⁴⁶Sc, ⁵⁴Mn, ⁶⁵Zn, ⁷⁵Se, ⁸³Rb and ⁸⁸Zr were measured 48 hours after intraperitoneal injection of a solution in normal mice aged 6 to 52 weeks to evaluate the brain regional (corpus striatum, cerebellum, cerebral cortex, hippocampus, and pons and medulla) uptakes. The radioactive distributions of ⁴⁶Sc, ⁵⁴Mn and ⁸⁸Zr tracers were variable and region-specific in the brain, while those of ⁶⁵Zn, ⁷⁵Se and ⁸³Rb tracers were comparable among all regions of interest. The brain regional uptakes of all tracers slightly increased with age from 10 to 28 weeks, and then remained constant during aging after 28 weeks. These uptake variations may be involved in the functional degenerative process of the blood-brain barrier during aging.     

Efficiency calibration of HPGe detector in far and close geometries

The absolute total and full-energy peak (FEP) efficiencies of a high purity germanium (HPGe) photon detector are measured in the energy range from 40 keV to 1500 keV. The functional parameters are fitted to the calibration points from 14 long-lived standard sources (¹²⁹I,²⁴¹Am,¹⁰⁹Cd,⁵⁷Co,¹³⁹Ce,¹³⁷Cs,⁵⁴Mn,⁶⁵Zn,⁶⁰Co,²²Na,¹³³Ba,¹⁵²Eu,¹⁵⁴Eu and^166mHo) within an accuracy better than the quoted uncertainty of the calibration sources. The efficiencies in far and close geometries are compared.     

Assessment of gamma emitting radionuclides in the aquatic ecosystem of Kakrapar Atomic Power Station and evaluation of radiological doses to aquatic plants

During operation and maintenance of Pressurised Heavy Water Reactors (PHWRs) at Kakrapar Atomic Power Station (KAPS), low level radioactive liquid waste is generated and released to the aquatic ecosystem (Moticher lake). The silt and aquatic weed (Hydrilla verticillata) samples collected from different locations in Moticher lake were analysed for ¹³⁷Cs, ¹³⁴Cs, ⁶⁵Zn, ⁶⁰Co, ⁵⁴Mn and ⁴⁰K during 2007–2008. A wide variation in activity levels of ¹³⁷Cs, ¹³⁴Cs, ⁶⁵Zn, ⁶⁰Co, ⁵⁴Mn and ⁴⁰K in silt and weed samples were observed in aquatic system of KAPS. The activity buildup in the silt is confined to a small area in the Moticher lake. The activity levels were found to be insignificant at 1 km away from discharge point (upstream and downstream). An attempt was made to evaluate the radiological dose to aquatic weed (Hydrilla verticillata), which was found to be well within the dose limit prescribed by US DOE. The total radiological dose due to the naturally occurring radionuclide (⁴⁰K) is comparatively higher than that of other reactor released gamma emitting radionuclides.     

Radiochemical precipitation studies for separation of iodine from tellurium and other trace impurities

Precipitation of radiotellurium, containing trace radioimpurities, has been carried out from sulfate media at different pH-values. The highest precipitation yield was achieved at the region of pH ~4–6. Quantitative uptake by the formed precipitate was noticed for (i) ⁵⁴Mn, ^110mAg and ¹²⁵Sb over all the pH-range of study (pH 1.7–9.2), (ii) for ⁶⁵Zn and ⁶⁰Co in the regions of pH ~6–8 and pH 6–8.8, respectively, and (iii) for ¹³⁴Cs in the region of pH 1.7–2.8, while its percent uptake fluctuated around 60.5 % in the region of pH 4.4–6.4. Further precipitation studies have been conducted for a mixture of ¹²⁵I and radiotellurium from sulfate, nitrate and chloride media at pH-values of 6.0 and 7.5. The highest ¹²⁵I recovery yield in the obtained supernatant was 95.0 ± 1.3 %, which was achieved with sulfate medium at pH 6.0 with percent uptake values of 5.0 ± 1.3, 98.9 ± 0.9 and 62.0 ± 4.6 % of ¹²⁵I, ^123mTe and ¹³⁴Cs, respectively, and quantitative uptake of ⁵⁴Mn, ^110mAg, ¹²⁵Sb, ⁶⁰Co and ⁶⁵Zn by the precipitated tellurium. Thereafter, the supernatant was further acidified with H₂SO₄ and boiled, after adding H₂O₂, for 3 h. >99 % of ¹²⁵I was distilled off from the acidified supernatant. The distilled of ¹²⁵I was received in 0.1 M NaOH + 1 % Na₂S₂O₃ solution, with a radionuclidic purity of >99.99 %, radiochemical purity of >99.8 % as I^? and pH ~13.     

Establishment of reference materials for Nigeria using instrumental neutron activation analysis

This work has been motivated by the need to establish reference materials from locally available sources. Neutron Activation Analysis (NAA) with Ge(Li) detector has been used to determine 26 elements in seven homogeneous clay samples with a wide range of composition. Short half-life nuclides (10s-10 m) were used to assay Na, Mg, K, Tl, Al, V, Mn, Ba, Dy, Ca and U by a fast rabbit transfer system. The long-lived nuclides were used to assay Sc, Sm, Cr, Eu, Ce, Cs, La, Fe, Lu, Hf, Co, Rb, Ta, Sb, and Pa(Th) after decay of²⁴Na. The approach was purely instrumental. The accuracy of the resutls was tested by atomic absorption spectrometriy (AAS).     

Application of instrumental neutron activation analysis to plant medicines in Ghana: A review

Some essential elements in eleven plant medicines used at the Center for Scientific Research into Plant Medicine (CSRPM), Mampong-Akwapim, Ghana, for the management and cure of various diseases were determined by instrumental neutron activation analysis (INAA), using thermal neutrons at a flux of 5^.10¹¹ n^.s^-1.cm^-2. The plant medicines were: Sirappac powder-E, Tina-A powder, Blighia powder, Aphrodisiac powder, Ninga powder and Lippia tea. The others are Olax powder, Ritchiea powder, Momordica powder, Kenken and Fefe powder. Concentrations of seventeen elements namely Al, Br, Ca, Cl, Co, Cu, Cr, K, Mn, Mg, Na, Rb, Sb, Sc, Ta, V, and Zn have been determined by short, medium and long irradiation times. Of these elements Co, Sb, and Sc are found to be present at the trace level, Br, Cu, Cr, Mn, Rb, Ta, V and Zn at the minor level, while Al, Ca, Cl, K, Mg and Na were generally at major level. The differences in the concentration of the elements are attributed mainly to soil composition and climate in which the plants grow. Standard reference material NIST SRM-1571 (Orchard Leaf) was analyzed simultaneously with the samples. The precision and accuracy of the method were evaluated using real samples and the standard reference material. It was found that the elemental concentrations measured in the NIST SRM-1571 were within ±10% of the reported values. The importance of these elements as related to human health and nutrition has been discussed.     

Determination of 32 elements in rocks by neutron activation analysis and high resolution gamma-ray spectroscopy

Neutron activation analysis and Ge(Li) spectroscopy was used to determine 32 elements in seven U.S.G.S. standard rocks of a wide range of composition. Short half-life nuclides (10 sec-10 min) were used to measure Sc, Hf, Dy, Mg, Al, Ca, Ti, V (and Na) in an automated rabbit Ge(Li) detector system. The elements K, Cu, Zn, Ga, Sr, Ba, La, Eu, Sm (and Mn) were determined by dissolution of the irradiated sample followed by removal of²⁴Na on hydrated antimony pentoxide (HAP). Long-lived nuclides were used to measure Sc, Cr, Fe, Co, Zr, Rb, Sb, Cs, Ba, Ce, Eu, Yb, Tb, Lu, Hf, Ta and Th after decay of²⁴Na. The method involves little radiochemistry and the separation is selective for²⁴Na under the experimental conditions used. Elemental concentrations determined agree well with previously published data.