We report testing of the 3M Empore Tc-99 solid phase extraction Rad-Disk for capacity and selectivity of extraction of Tc-99. The disk was tested with U.S. Department of Energy Savannah River high-level waste. The radioactive species Cs-137, Sr-90, and Pu-238,241 were tested. We observed measurable interference with Tc-99 selectivity from SR-90 and Pu-238,241.
Analysis data of global fallout {sup 99}Tc in environmental samples should give useful information for predicting the nuclide's behavior. However, due to its low concentration and analytical difficulties with environmental samples, there are not many data. The authors improved a simple separation method, which had been previously reported for Tc in soil samples and used a combustion apparatus. In this study, two fundamental experiments were performed; one clarified the possibility of using deionized water for a trap solution instead of an alkaline solution, and the other checked for differences in Tc volatilities between 1-y-aged {sup 99}Tc and freshly added {sup 95m}Tc in a soil sample. The results showed that deionized water can trap volatilized Tc as well as alkaline solution, and the volatilities of aged {sup 99}Tc and freshly added {sup 95m}Tc from the soil sample do not differ. The procedure proposed is as follows: Tc in a soil sample is volatilized in a combustion apparatus for 3 h at 1000{degree}C and trapped in deionized water. Then the trap solution is passed through an extraction chromatographic resin (TEVA {center{underscore}dot} Spec{trademark} resin). After the eluate (ca. 8 M HNO{sub 3}) is evaporated to dryness and dissolved in a 2% HNO{sub 3}more » solution, the {sup 99}Tc concentration in the solution is measured by inductively coupled plasma mass spectrometry (ICP-MS). This method was employed to measure three environmental soil samples collected in Japan. The recoveries and {sup 99}Tc concentrations were 62--73% and 5--30 mB1/kg dry basis, respectively.« less
Decay corrections for mixed sources of genetically related {sup 95}Zr and {sup 95}Nb may appear to be more complex than those usually required for routine radionuclidic assays. The complexity arises because of the existence of a sufficiently long-lived {sup 95m}Nb metastable state in the decay series, and because both {sup 95}Zr and {sup 95m}Nb exhibit multi-branched decay. The necessary corrections are presented here in straightforward algebraic expressions. For sources in which {sup 95m}Nb is in secular equilibrium with {sup 95}Zr, the decay correction for {sup 95}Nb reduces to the simple form for a parent-to-child genetic relation, in which the presence of the intermediate {sup 95m}Nb state in the decay sequence can be ignored.
Technetium-99 is an artificial radionuclide with a long half-life of 2.1 x 10{sup 5} y. The main sources of environmental {sup 99}Tc are nuclear weapons tests and nuclear industries such as nuclear fuel processing plants and waste disposal facilities. Due to its high mobility in the terrestrial environment, it is one of the most important radionuclides for does assessment. In this study, the authors propose a separation procedure for Tc in environmental waters using a resin, after which samples can be measured by ICP-MS. Tracer experiments were carried out to determine a suitable concentration of HNO{sub 3} for separation of Tc from Ru in environmental waters on TECA{center{underscore}dot}Spec{sup {trademark}} resin. This was necessary, because, with a common procedure, a small amount of Ru was found in the eluate of 12 M HNO{sub 3} solution. Ruthenium has an isotopic abundance of 12.7% at mass 99 which interferes with Tc counting by ICP-MS. Most of the Ru sorbed on the resin was desorbed by 40 mL of 2 M HNO{sub 3}. Sorbed Tc was readily recovered using 4 mL of 8 M HNO{sub 3}. No Ru was found in the eluate of 9 M HNO{sub 3} solution. The authors also checked themore » concentrations of major elements, such as Mg, Na and Ca, in the eluates passing through the resin column by ICP=AES. It was clear that most of the major elements in the environmental waters, adjusted to 0.1 M HNO{sub 3}, passed through the resin column and, subsequently, concentration of each coexisting element in the strip solution by 8 M HNO{sub 3} was lower than 20 ppm. The procedure was applied to 2 L each for both river water and seawater. The recoveries of Tc for both waters in 4 mL of the strip solution by 8 M HNO{sub 3} were more than 98% and the detection limit of {sup 99}Tc by this procedure with ICP-MS measurement was 0.3 mB1 L{sup {minus}1}.« less
In the Netherlands the National Institute of Public Health and the Environment (RIVM) provides and manages technical information in the early phase of a nuclear accident. The RIVM measuring-strategy focuses on the direct exposure pathways of external irradiation and inhalation. This implies measuring ambient dose rate, surface contamination and activity concentrations in air. The measuring facilities consist of: two monitoring vans, a monitoring plane, the National Radioactivity Monitoring Network (NRM), extensive laboratory facilities for gross- and nuclide-specific analysis of radioactivity in air, water, soil and (food) products and measuring facilities of eight so-called contracted partner institutes (CPI). These institutes, geographically distributed throughout the country, are instructed to sample air and deposition, and to analyze the samples using gamma-ray spectroscopy. This paper focuses on the functionality of the eight CPI`s. Organization, measuring facilities and procedures are described and the results of intercomparisons are discussed.
The authors have developed a semiautomatic procedure for determination of {sup 226}Ra in environmental samples. The methodology is based upon automatic isotope separation and preconcentration using a sequential injection procedure. Once the sample to be analyzed has been prepared, its {sup 226}Ra concentration is obtained by means of a low background proportional counter. Before the series reaches the equilibrium the determination can be carried out simultaneously for several samples by using a multiple-sample proportional counter, or consecutively with a simple counter if the function of activity vs. time is known. By using an autosampler, a sampling rate of 3 h{sup {minus}1} with a 40-mL initial sample volume is achieved. This is an important improvement regarding the non-automatic method (0.5 h{sup {minus}1}). The LLD of the procedure is 0.012 Bq with a relative standard deviation of 6.9% (number of samples = 4) for a {sup 226}Ra activity of 1.0 Bq/L.
Environmental monitoring procedures have been introduced which are designed to provide a rapid response by the nuclear industry in the event of a nuclear emergency. Within three hours of sample receipt the laboratory is now capable of screening up to 80 samples by total alpha/beta determination and gamma spectrometry. This rapid screening would enable the identification of samples of particular interest. Radiochemical analytical methodology is in place which would then enable the determination of transuranic radioisotopes and radiostrontium ({sup 89}Sr and {sup 90}Sr) within a period of 24 hours from sample receipt to reporting of results. The Limit of Detection achievable via this methodology is of the order of 10% of the Commission for the European Communities restriction level. Typically, the 2{sigma}-counting uncertainty associated with these measurements is in the range 10--50%. As such, this methodology is appropriate for the urgent provision of reassurance or informed advice in the event of radionuclide release. Improvements in batch analysis time have been achieved by the use of microwave enhanced sample digestion techniques, commercially available extraction resins, optimization of conventional radiochemistry procedures and the utilization of combined Cerenkov and triple channel liquid scintillation counting techniques. Sample calculation and management is facilitated by amore » computerized Laboratory Information Management System (LIMS).« less
The capabilities of a Quantulus{trademark} model 1220 Liquid Scintillation Counter (LSC) for rapidly analyzing alpha-particle emitters and {sup 90}Sr on air filters and swipe samples have been studied. Counting conditions were established and the instrument was calibrated using quench standards of {sup 90}Sr/Y and {sup 241}Am prepared on membrane filters. A LOTUS{trademark} template was developed to analyze the spectra. The data were used to develop a method for estimating the optimum pulse-shape analysis parameter based on linear fits to the quench parameter. Linear fits were also used to estimate window settings for {sup 90}Sr and {sup 90}Y, the Sr/Y ratio and the counting efficiencies. The linear fits have been incorporated into the template so that they are all done automatically when the quench parameter is entered. Analysis of the spectra from a sample can be done in a matter of minutes. Sample preparation simply involves transferring the filter to a scintillation vial and adding cocktail. Since the counting efficiencies of the LSC are high, counting times of an hour or less can be employed. The study showed that the method produces results that are sufficiently reliable for air filters and swipe samples. This methodology was used to analyze swipe samplesmore » from CANDU{reg_sign} nuclear stations. The results revealed complex beta-particle spectra with a number of components present. However, {sup 90}Y could be estimated from the high-energy component, which was less abundant than the low and intermediate energy components. The swipe samples contained much less alpha- than beta-particle activity.« less
A method for actinide determinations has been established which has considerable advantages over currently described procedures. The benefits are rapid sample throughput, good safety features with no compromise in data quality. A borate fusion is used for the sample digestion. Chemical separation is optimized by using a column of anion-exchange resin column stacked on a UTEVA column. Uranium was measured using thermal ionization mass spectrometry with a precision of 0.2% 2 sigma. Pu measurements were made using alpha-particle spectrometry. The procedure has been applied successfully to a wide range of sample types and other actinide elements (Th, Am, etc.) could also be included in the analytical scheme. The method has been thoroughly evaluated by measuring international reference samples. The method lends itself very well to large-scale environmental surveys.
This paper summarizes the results of three previous studies determining real counting efficiencies of a proportional counter for the determination of the activity of alpha- and beta-particle-emitting radionuclides on wipe-test samples. Application of the results of the previous studies to air-filter analysis is discussed. Counting efficiencies obtained from Mylar-covered, activity-certified standards and counting efficiencies obtained from electroplated, emission-rate-certified standards are compared with the counting efficiencies determined from actual wipe samples. A serious potential for under-reporting of alpha/beta activity on wipes and air-filter samples is addressed.
The results of an intercomparison of in situ gamma-ray spectrometers that was held at Brookhaven National Laboratory in the fall of 1997 are presented. Six different organizations participated in this intercomparison which involved simultaneous and sequential co-located field measurements at a site with typical background radiation and another site with elevated {sup 137}Cs concentrations in the soil. These field measurements were supplemented with laboratory-based measurements of point sources at three different energies and two different angles of irradiance. Among the participants, agreement in the field measurements results was generally within 15% of the group mean for each radionuclide. Comparisons to soil sample measurements at the background site show agreement of the group means to within 10% for the various radionuclides present after correcting for the effects of soil moisture. The point source measurement results indicate that the observed differences among groups may be related to systematic errors in their calibrations that result from uncertainty in the activities of the sources used, dissimilarities in the source-detector setup geometry, and inaccuracies in the detector model used in a theoretical calibration.
We have developed a method to separate anion complexes of radioactive sulfur, iodine, and phosphorus to enable determination by radiochemical techniques. This method involves ion-chromatographic separation of the anion complexes from other highly emitting radioactive species such as {sup 137}Cs and {sup 90}Sr which interfere with radiochemical analysis. We essentially use the ion chromatograph as a sample pretreatment method. The samples are injected onto a cation-exchange column which allows the anions to pass through while retaining the positively charged species. If more than one negatively charged radio nuclide is present, the sample is injected onto an anion-exchange column and the individual anions are separated from each other as well as from the cations. These anions are collected in the column effluent and measured by nuclear counting methods. The method was developed to enable measurement of trace radionuclides in radioactive waste and in environmental samples. Trace radionuclides that are present in concentrations of only a few hundred disintegrations-per-minute per milliliter can be separated and then analyzed using liquid scintillation counting analysis. This paper establishes the separation and collection protocol, collection efficiencies for sulfur, iodine, and phosphorus anion standards, and overall efficiencies and detection limits for the separation and subsequent radiochemical analysismore » of {sup 129}I from both environmental level and high-salt waste samples.« less
An analytical method based upon solid-phase extraction disks and applicable to the analysis of radium in aqueous samples (i.e., surface, ground, and drinking waters) is described. Radium is isolated by pulling an acidified sample aliquot through an Empore{trademark} Radium Rad Disk with a vacuum. The disk then may be directly assayed by the least-squares gamma-ray spectrometric method. Alternatively, the radium or daughter products may be eluted from the disk and further processed according to traditional EPA-prescribed methods. This method is efficient, safe, reliable, and potentially field deployable. Samples are easily processed in batches, and a 1-L sample may be prepared in as little as 20-30. Empore{trademark} Radium Rad Disks have been found to exhibit a large capacity for radium; over 74 Bq of {sup 226}Ra have been loaded onto a 25-mm disk. Quantitative recoveries of radium have been observed for sample volumes up to 3 L with a 47-mm disk.
Computerized alpha-particle spectroscopy is a convenience when the spectra do not require complicated mathematics to perform accurate analyses and a necessity when the spectra exhibits significant amounts of peak overlap. This paper describes an alpha-particle-spectroscopy software package that provides the capability to do both simple and more sophisticated analyses. The software has been tested against typical uranium, plutonium, americium, and thorium samples to verify its performance and validity. In addition, its performance in severe peak overlap situations has been evaluated by measuring one sample under low to very high absorption condition. The results of these tests indicate good performance and accuracy.
Previously, a system was developed at the INEL for measuring the gamma-ray-emitting radionuclides in small soil samples for the purpose of environmental monitoring. These samples were counted close to a {approx}20% thin-window n-type Ge detector and, therefore, it was necessary to take into account the coincidence summing that occurs for some radionuclides. In order to improve the technical basis for the coincidence summing corrections, the authors have carried out a study of the variation in the coincidence summing probability with position within the sample volume. A Monte Carlo electron and photon transport code (CYLTRAN) was used to compute peak and total efficiencies for various photon energies from 30 to 2000 keV at 30 points throughout the sample volume. The geometry for these calculations included the various components of the detector and source along with the shielding. The associated coincidence summing corrections were computed at these 30 positions in the sample volume and then averaged for the whole source. The influence of the soil and the detector shielding on the efficiencies was investigated.
A key objective at the Savannah River site is to obtain on-line or at-line analyses of special nuclear material. The capability to perform these analyses using NaI technology greatly reduces instrument maintenance problems compared to using cooled, high-resolution detectors. The instrument described here is an antiCompton spectrometer specifically designed to reduce the forward-angle Compton scatter continuum in order to improve the capability to measure {sup 235}U in the presence of the common gamma-ray-emitting fission products {sup 95}Zr/{sup 95}Nb, {sup 106}Ru, and {sup 137}Cs. The instrument consists of a thin, 8% resolution NaI detector backed by a 7.62-cm low-resolution NaI crystal to accomplish forward-angle antiCompton suppression.
