Non-radioactive Substances Research Articles

EVAPORATION OF METHYLATED SPIRIT AS AN ALTERNATIVE METHOD OF RADIOACTIVITY DEMONSTRATION IN PHYSICS AND CHEMISTRY AT SECONDARY SCHOOL LEVELS

Practical demonstrations by teacher and learner, especially in Science Education, make teaching-learning process pragmatic, learner-centred, easier to understand, and more appreciated. Also, it has been observed that radioactivity is one of the important topics in Physics and Chemistry at Secondary School levels. Unfortunately, its concept appears abstract and illusion in the minds of the learners due to lack of practical demonstrations or experimentation of the theory. The reason for such deficiency may be attributed to hazardous nature of radioactive substances, strict legal regulations on their exposures (both at the international and domestic levels), associated risk during transportation and handling, etc. The essence of this research is to devise a way of practically demonstrating radioactivity by utilising a non-radioactive substance that is cheaply available with high level of sustainability and potential to exhibit decay. Specifically, methylated spirit was used as the non-radioactive substance in this study. It was put in a syringe clamped vertically with an open end facing up and timing of its evaporation was performed separately for intervals of 10 minutes and 15 minutes. In each case, the volume of the methylated spirit left was recorded and the data obtained were analysed It was observed that the volume – time relationships were of exponential decay characteristic supported by empirical formula governing radioactivity, notwithstanding the time intervals considered. For 10 minutes interval consideration, the results showed evaporation constant (which is analogous to decay constant), and half-life to be 8.14 x 10-4 min-1, and 851.4 minutes respectively whereas in the case of 15 minutes interval, they were found to be 8.40 x 10-4 min-1, and 825.0 minutes respectively. Hence, it could be adjudged that methylated spirit is a promising non-radioactive substance for practical experiment/demonstration to make teaching and learning of radioactivity learner-centred for a better understanding of the topic in Physics and Chemistry at Secondary School levels.

Oscillation-free source term inversion of atmospheric radionuclide releases with joint model bias corrections and non-smooth competing priors

The source term of atmospheric radionuclide releases is essential for the hazardous consequence assessment and emergency response. However, the artificial release oscillations in the source term estimate remain a fundamental challenge and may deliver misleading information, because of the unavoidable model biases and observation uncertainties. We propose a new method that removes oscillations while recovering the release details. This method explicitly corrects the model biases using the joint correction model and compensates the observation uncertainties through non-smooth competing priors that involve two rival functions. The new priors better model the unsteady feature of the radionuclide releases and distinguish the true releases from oscillations, enabling release-preserving oscillation removal. We extend the projected alternating minimization algorithm for an efficient solution. The method achieves oscillation-free and nearly perfect profiles for real releases of the Perfluoro-Methyl-Cyclo-Hexane on continental and regional scales, and the radionuclide 41Ar on a local scale, outperforming state-of-the-art and very recent methods. The sensitivities to model inputs and key parameters are also investigated. Robust performance is exhibited under emissions of both radioactive and non-radioactive substances, different meteorological inputs and numbers of observations, paving the way for identifying dynamic atmospheric radionuclide releases at multiple scales, especially when the release status is unknown.

О необходимости корректировки НРБ-99/2009 и ОСПОРБ-99/2010

Purpose: The Basic Sanitary Rules (OSPORB-99/2010) and the Standards of Radiation Safety (NRB-99/2009) contain requirements on the treatment of radionuclide contaminated materials and waste, but non-radioactive substances and radioactive waste. The aim of this work is to develop recommendations for adjustment of OSPORB-99/2010 and NRB-99/2009 for radiation safety of current and future generations of people. 
 Results: Identified and justified by the shortcomings of NRB-99/2009 and OSPORB-99/2010 governing the treatment of materials and waste contaminated by radionuclides, but non-radioactive substances and radioactive waste, which can lead to overexposure of present and future generations of people. Developed and justified proposals for adjustments to NRB-99/2009 and OSPORB-99/2010.
 Conclusions: It was proposed adjustment of NRB-99/2009 and OSPORB-99-2010:
 in NRB-99/2009 it was proposed to delete from paragraph 5.3.4 the provisions regulating the use of materials for road construction; 
 in OSPORB-99/2010 the return to OSPORB-99 on establishment of the lower border of wastes and materials of limited use on total alpha and beta-activity is offered.

Isoconcentration principle – an effective tool of (radio) analysis in environmental protection

The paper brings two determination methods for non-radioactive analytes based on isoconcentration principle. The first method represents a determination procedure for a non-radioactive substance by use of its radio-labelled form of known concentration by help of a (non-quantitative, but selective) separation method. The main advantage of this method consists in the fact, that the determination is executable only by the detection of radioactivity. The second described procedure enables the determination of the chosen analyte without requirement of radioactive form of the substance to be determinate.

Diffuse Vacuum Arc on the Nonthermionic Lead Cathode

Experimental study of the diffuse vacuum arc discharge on the nonthermionic lead cathode is presented. At the working cathode temperatures of 1.2–1.6-kK current–voltage characteristic of the discharge, cathode heat operation regime and its erosion rate were measured. Using probe methods, electron temperature (0.3–1.2 eV) and heavy particles (atoms and ions) mean charge (0.17–0.28 e) were determined in after-anode plasma. Evaluated current densities on the cathode are in agreement with a hypothesis on the ion mechanism of charge transfer on its surface. Parameters of the obtained discharge have been compared with the characteristics of the earlier investigated diffuse vacuum arcs on nonthermionic chromium and on thermionic gadolinium cathodes. The obtained data might be useful when creating plasma sources for verifying the plasma separation method of the spent nuclear fuel using the nonradioactive substances.

Prompt gamma neutron activation analysis of a 200 L steel drum homogeneously filled with concrete

In order to determine nonradioactive substances in radioactive waste packages an innovative method based on prompt gamma neutron activation analysis was developed. The methodology was verified through the analysis of a 200 L steel drum homogeneously filled with concrete. The results obtained for the elemental composition of concrete are in good agreement with the expected values, the differences lying between −9 and +5 %. The limits of detection for the toxic elements cadmium and mercury are 4 and 145 mg/kg, respectively for an assay time of 2000s.

Nuclide separation modeling through reverse osmosis membranes in radioactive liquid waste

The aim of this work is to investigate the transport mechanism of radioactive nuclides through the reverse osmosis (RO) membrane and to estimate its effectiveness for nuclide separation from radioactive liquid waste. An analytical model is developed to simulate the RO separation, and a series of experiments are set up to confirm its estimated separation behavior. The model is based on the extended NernstePlank equation, which handles the convective flux, diffusive flux, and electromigration flux under electroneutrality and zero electric current conditions. The distribution coefficient which arises due to ion interactions with the membrane material and the electric potential jump at the membrane interface are included as boundary conditions in solving the equation. A high Peclet approximation is adopted to simplify the calculation, but the effect of concentration polarization is included for a more accurate prediction of separation. Cobalt and cesium are specifically selected for the experiments in order to check the separation mechanism from liquid waste composed of various radioactive nuclides and nonradioactive substances, and the results are compared with the estimated cobalt and cesium rejections of the RO membrane using the model. Experimental and calculated results are shown to be in excellent agreement. The proposed model will be very useful for the prediction of separation behavior of various radioactive nuclides by the RO membrane.

Experience with Nuclear Medicine Information System

Objective: Radiology information system (RIS) is basically evolved for the need of radiologists and ignores the vital steps needed for a proper work flow of Nuclear Medicine Department. Moreover, CT/MRI oriented classical PACS systems are far from satisfying Nuclear Physicians like storing dynamic data for reprocessing and quantitative analysis of colored images. Our purpose was to develop a workflow based Nuclear Medicine Information System (NMIS) that fulfills the needs of Nuclear Medicine Department and its integration to hospital PACS system. Material and Methods: Workflow in NMIS uses HL7 (health level seven) and steps include, patient scheduling and retrieving information from HIS (hospital information system), radiopharmacy, acquisition, digital reporting and approval of the reports using Nuclear Medicine specific diagnostic codes. Images and dynamic data from cameras of are sent to and retrieved from PACS system (Corttex©) for reprocessing and quantitative analysis. Results: NMIS has additional functions to the RIS such as radiopharmaceutical management program which includes stock recording of both radioactive and non-radioactive substances, calculation of the radiopharmaceutical dose for individual patient according to body weight and maximum permissible activity, and calculation of radioactivity left per unit volume for each radionuclide according their half lives. Patient scheduling and gamma camera patient work list settings were arranged according to specific Nuclear Medicine procedures. Nuclear Medicine images and reports can be retrieved and viewed from HIS.Conclusion: NMIS provides functionality to standard RIS and PACS system according to the needs of Nuclear Medicine. Conflict of interest:None declared.

Complexation of europium and uranium by humic acids analyzed by capillary electrophoresis‐inductively coupled plasma mass spectrometry

Investigations of the mobility of radioactive and nonradioactive substances in the environment are important tasks for the development of a future disposal in deep geological formations. Dissolved organic matter (DOM) can play an important role in the mobilization of metal ions due to complexation. In this study, we investigate the complexation behavior of humic acid (HA) as a model substance for DOM and its influence on the migration of europium as homologue for the actinide americium and uranium as the principal component of nuclear fuel. As speciation technique, capillary electrophoresis (CE) was hyphenated with inductively coupled plasma mass spectrometry (ICP-MS). For the study, 0.5 mg·L⁻¹ of the metals and 25 mg·L⁻¹ of (purified Aldrich) HA and an aqueous solution sodium-perchlorate with an ionic strength of 10 mM at pH 5 were used. CE-ICP-MS clearly shows the different speciation of the triple positively charged europium and the double positively charged uranyl cation with HA.

Pure zircon process for removing radionuclides from zircon concentrates

The presence of U and Th as impurities in zircon makes it radioactive. Provided the U and Th levels are below 500 ppm, or 70 Bq g-1 activity, the limits that allow transportation of the material as a non-radioactive substance, it is acceptable as a commercial product. However, some zircon sands contain radioactivity levels well above this limit. A new process (the pure zircon process) is described for the removal of radioactivity from zircon. Tests to identify the best flux addition, calcination temperature and time, and leaching conditions indicated that by grinding a zircon sample containing 1059 ppm U + Th to a particle size of about 15–20 μm, calcining it with 15 wt-% calcium borate (colemanite) at 1200°C for 4 h and leaching the calcine with up to 1M HCl at 80°C for 30 min gave a product with <500 ppm U + Th. While the grade of Zr of the final product was slightly increased, the levels of major impurities, Al, Fe, Ti and P were decreased. Operating costs for the pure zircon process using the optimum conditions were estimated to be A$243/t leach product.

On the identification of representative samples from large data sets, with application to synoptic climatology

The analysis of large data sets in meteorological and air quality studies is often made though the examination of specific case studies, especially when time-consuming computational models are employed. This paper presents the development of a tool to identify specific case studies, termed as representative days, that would subsequently be modelled. The success of such tools should be judged on the discrimination between the specified cases: and the degree to which they capture and recreate historical characteristics of the original data set. The developed approach utilises a principal component algorithm with varimax rotation (r-PCA) and the subtractive clustering algorithm coupled with a cluster validity criterion. In this paper, the developed tool is applied to a data set from the North Sea, utilizing two years worth of data from the DNMI operational forecasting model. The results will be subsequently used in photochemical and radiative forcing modelling tools as part of the EC funded project AEOLOS, with the ultimate goal to estimate the global warming potential of non-radioactive tracing substances such as SF6 and PFCs, which are heavily used in the oil industry.

Prediction of impacts of Temelín NPP on hydrosphere

Problems associated with possible impacts of Temelin Nuclear Power Plant (NPP) on the environment are being studied under supervision of the Czech Ministry of Environment. The objective of ongoing studies is to examine a reference level (conditions prior to the plant operation) in terms of concentrations of radioactive and non-radioactive polluting substances in the environment. Special attention paid to the hydrosphere is associated with requirements for protection of water quality in the Vltava River and its use to supply Prague capital, outdoor recreation, and other purposes. It is also important that the Vltava affects water quality in the Elbe as the main Czech-German transboundary river. Relevant attention is paid also to protection of groundwater resources in use for water supply purposes in wide environs of the plant. Possible impacts on hydrosphere are being predicted for standard operation of the plant and also for accidental conditions. The monitoring and research are intended to be continued during the pre-operational period and additional three years during the operation. The main interim results are presented in this paper.

An Evaluation of Three Representative Multimedia Models Used to Support Cleanup Decision‐Making at Hazardous, Mixed, and Radioactive Waste Sites

The decision process involved in cleaning sites contaminated with hazardous, mixed, and radioactive materials is supported often by results obtained from computer models. These results provide limits within which a decision‐maker can judge the importance of individual transport and fate processes, and the likely outcome of alternative cleanup strategies. The transport of hazardous materials may occur predominately through one particular pathway but, more often, actual or potential transport must be evaluated across several pathways and media. Multimedia models are designed to simulate the transport of contaminants from a source to a receptor through more than one environmental pathway. Three such multimedia models are reviewed here: MEPAS, MMSOILS, and PRESTO‐EPA‐CPG. The reviews are based on documentation provided with the software, on published reviews, on personal interviews with the model developers, and on model summaries extracted from computer databases and expert systems. The three models are reviewed within the context of specific media components: air, surface water, ground water, and food chain. Additional sections evaluate the way that these three models calculate human exposure and dose and how they report uncertainty. Special emphasis is placed on how each model handles radio‐nuclide transport within specific media. For the purpose of simulating the transport, fate and effects of radioactive contaminants through more than one pathway, both MEPAS and PRESTO‐EPA‐CPG are adequate for screening studies; MMSOILS only handles nonradioactive substances and must be modified before it can be used in these same applications. Of the three models, MEPAS is the most versatile, especially if the user needs to model the transport, fate, and effects of hazardous and radioactive contaminants.

A generalized separation reaction scheme for assessment of the radioanalytical method of concentration dependent distribution

For the assessment of the analytical error of concentration dependent distribution (CDD), complex-forming separation reaction was proposed in a generalized form of equilibrium\(ML_{ } + + nL \rightleftarrows \overline {ML} _{ }\), where n is the effective stoichiometric coefficient, i.e. the difference of mean ligand numbers\( \) and of a mixture of complexes of analyte M with reagent L in the respective groups (distinguished by bars above the symbols) of the separation system. Calibration curve\(I = A/\bar A\) is derived from measurement of gross activity of complexes, A=A(ML ) and\(\bar A = A(\overline {ML} _{ } )\). Theoretical relative error is expressed as a product of three terms, δx/x=f1f2f3. The first term f1 depends on the degree of isotopic dilution, and the recommended ratio of amounts of nonradioactive (x) and radioactive (y) substance M is x/y∈(1;4). The second term f2 depends first of all on the slope of distribution ratio (yield of separation\(\bar R\)) vs. the analyte; reagent ratio, n(Z+1)/T. The form of slope is analyzed on the basis of the generalized separation reaction. Optimal conditions were discussed from this point of view and the ideal case is at f2=1. The third term f3 depends on the activities A and Ā, i.e. on the distribution ratio, sample volumes, and the manner of counting. The ideal ratio of sample activities is A=Ā and the optimal interval\(\bar R\) ∈ (0.2;0.8) is suggested

Application of Lung Deposition Models to Nonradioactive Substances

Application of Lung Deposition Models to Nonradioactive Substances

The quantitative binding of tetracycline to dentin

Unerupted human third molar crown segments were used to measure the change in the concentration of various substances which occurs when they move across dentin from pulpal to occlusal surfaces. The chemicals used were technetium-99m (99mTc), 45Ca, and [3H]-labeled tetracycline. When solutions of these isotopes were filtered across dentin at flow rates of 1 μl per min to 14 μl per min, 45Ca was almost completely removed, 99mTc showed no change in concentration, and 65 to 75% of the [3H]-labeled tetracycline was removed at a flow rate of 1 μl per min. This increased to a removal of 99% at 14 μl per min. 45Ca, 99mTc, or [3H]-labeled tetracycline were preloaded into dentinal tubules and eluted with nonradioactive substances or water. 45Ca was eluted with CaCl2 but not with water; 99mTc was rapidly removed with water; [3H]-labeled tetracycline was readily removed, but more slowly, with either tetracycline base or water. These data suggest that 45Ca ionically binds to dentin and 99mTc does not. The binding of 3H]-labeled tetracycline was flow rate dependent and it seemed to bind nonspecifically and reversibly. Unerupted human third molar crown segments were used to measure the change in the concentration of various substances which occurs when they move across dentin from pulpal to occlusal surfaces. The chemicals used were technetium-99m (99mTc), 45Ca, and [3H]-labeled tetracycline. When solutions of these isotopes were filtered across dentin at flow rates of 1 μl per min to 14 μl per min, 45Ca was almost completely removed, 99mTc showed no change in concentration, and 65 to 75% of the [3H]-labeled tetracycline was removed at a flow rate of 1 μl per min. This increased to a removal of 99% at 14 μl per min. 45Ca, 99mTc, or [3H]-labeled tetracycline were preloaded into dentinal tubules and eluted with nonradioactive substances or water. 45Ca was eluted with CaCl2 but not with water; 99mTc was rapidly removed with water; [3H]-labeled tetracycline was readily removed, but more slowly, with either tetracycline base or water. These data suggest that 45Ca ionically binds to dentin and 99mTc does not. The binding of 3H]-labeled tetracycline was flow rate dependent and it seemed to bind nonspecifically and reversibly.

Binding of [ 3H]substance P to putative substance P receptors in rat brain membranes

[ 3H]Substance P was used to label putative substance P receptors in rat brain membranes. [ 3H]Substance P binding was saturable, reversible, and displaceable by non-radioactive substance P. A ssociation, dissociation and saturation experiments suggest a single site interaction of [ 3H]substance P to its binding site(k −1/k +1=0.56 nM; K D=0.9 nM, B max 86.5 fmol/mg protein.

Skin decontamination—a comparison of four methods

Many hospital laboratories and departments now handle large quantities of radioactive nuclides—commonly ∼ 100 GBq (several curies) per day. Despite strict adherence to clearly defined safety procedures the risk of accidental contamination of skin cannot be entirely eliminated, particularly when high specific activities are used. For example many procedures require the administration of solutions containing 370 MBq (10 mCi) per ml of an isotope such as 99Tcm. A spill or spray of 0.1 μ1 would contain 37 kBq (1 μCi), which if spread over 1 cm2 of skin and left to decay would give a local absorbed dose of 3 cGy (rads) (calculated from the data of Henson (1972)). Even in departments which are not handling radioactive substances substantial risks to staff arise by contamination of the skin by drugs, many of which are sensitizing agents. Trace residues of these non-radioactive substances are difficult or impossible to measure accurately in vivo. The only satisfactory technique of assessing the effectiveness of decontaminating procedures is therefore to generalize from measurements made using γ ray emitting nuclides. We have compared soap and water with two detergents recommended for the removal of radioactive contamination from skin, and with a mildly abrasive skin cleanser. Three radioactive tracers were used, 99Tcm pertechnetate (because it is the commonest radionuclide used in large quantities), 123I sodium iodide and 51Cr in the form of chromic chloride. Both these latter can react chemically with proteins and may therefore become firmly attached to skin.

Dose assessment analogies.

Assessments of radiation detriment are based on the absorbed dose in the organs and tissues of interest, assuming a linear, nonthreshold dose--response relationship for the induction of cancer or genetic effects at low doses. Similar assessments may be made for nonradioactive, mutagenic, or carcinogenic substances, in which case the time integral of the local tissue concentration of the substance may be the quantity which would correspond to the radiation dose. It can be shown that the assessment then involves calculations which are very similar to those made in the assessment of radiation detriment. It is suggested that an attempt should be made to make such assessments for nonradioactive pollutants, in order to provide a more appropriate basis for comparisons with radiation detriments. In the assessment of the detriment from inhaled substances, the overall collective intake commitment is simply the total amount of each substance ever to be inhaled, irrespective of when or where. This quantity might be assumed to be proportional to the total detriment in form of lung cancer.

Clear evidence for the presence of β-alanine as a constituent of papiliochrome II

1. 1. From the crude extract of the wings of Papilio xuthus labelled with [1- 14C]β-alanine, the decomposition-product SN-1 of Papiliochrome II was purified and hydrolyzed. Of two main hydrolysates, one was identified as [ 14C]β-alanine, and the other was the non-radioactive substance SN-1a. 2. 2. The above results were confirmed by the decomposition of purified Papiliochrome II and by the autoradiograph of thin-layer chromatograms of Papiliochrome II and its decomposition-products. 3. 3. It was also proved using [1- 14C]DOPAmine that SN-1a is a DOPAmine derivative. 4. 4. From the previous and present results, it is evident that Papiliochrome II contains, as constituents, both kynurenine and a DOPAmine derivative containing β-alanine.