Improved activity standardization of 90Sr/90Y by means of liquid scintillation counting.

Radioactive strontium isotopes play an important role in environmental radioactivity. Reliable activity standards are required in order to validate radioanalytical techniques and related measurements. In this paper, improved methods for the primary activity standardization of 90Sr/90Y based on liquid scintillation counting are presented. To this end, two methods were used: the CIEMAT/NIST efficiency tracing technique with 3H as a tracer and the triple-to-double coincidence ratio method. Non-negligible discrepancies between the two methods were found when applying existing analysis techniques. A detailed study was carried out to identify and eliminate the causes of these discrepancies. Eventually, excellent agreement between the two methods was obtained. This required advanced beta spectrum calculations which were carried out with a specific version of the BetaShape program taking the atomic exchange effect into account. In addition, it was found that the quench-indicating parameters determined in commercial liquid scintillation counters are biased, which can cause significant problems for the CIEMAT/NIST efficiency tracing method. The effect depends on the counting rate and can be explained by a superposition of the LS spectra generated by 90Sr/90Y and the external standard source.

An Automated SeaFAST ICP-DRC-MS Method for the Determination of 90Sr in Spent Nuclear Fuel Leachates.

To reduce uncertainties in determining the source term and evolving condition of spent nuclear fuel is fundamental to the safety assessment. ß-emitting nuclides pose a challenging task for reliable, quantitative determination because both radiometric and mass spectrometric methodologies require prior chemical purification for the removal of interfering activity and isobars, respectively. A method for the determination of 90Sr at trace levels in nuclear spent fuel leachate samples without sophisticated and time-consuming procedures has been established. The analytical approach uses a commercially available automated pre-concentration device (SeaFAST) coupled to an ICP-DRC-MS. The method shows good performances with regard to reproducibility, precision, and LOD reducing the total time of analysis for each sample to 12.5 min. The comparison between the developed method and the classical radiochemical method shows a good agreement when taking into account the associated uncertainties.

Beta-ray imaging system with γ-ray coincidence for multiple-tracer imaging.

PURPOSE: Beta-ray imaging systems are widely used for various biological objects to obtain a two-dimensional (2D) distribution of ß-ray emitting radioisotopes. However, a conventional ß-ray imaging system is unsuitable for multiple-tracer imaging, because the continuous energy distribution of ß-rays complicates distinguishing among different tracers by energy information. Therefore, we developed a new type of ß-ray imaging system, which is useful for multiple tracers by detecting coincidence γ-rays with ß-rays, and evaluated its imaging performance. METHODS: Our system is composed of position-sensitive ß-ray and γ-ray detectors. The former is a 35 × 35 × 1-mm3 Ce-Doped((La, Gd)2 Si2 O7 ) (La-GPS) scintillation detector, which has a 300-µm pitch of pixels. The latter is a 43 × 43 × 16-mm3 bismuth germanium oxide (BGO) scintillation detector. Both detectors are mounted on a flexible frame and placed in a user-selectable position. We experimentally evaluated the performance of the ß-ray detector and the γ-ray efficiencies of the γ-ray detector with different energies, positions, and distances. We also conducted point sources and phantom measurements with dual isotopes to evaluate the system performance of multiple-tracer imaging. RESULTS: For the ß-ray detector, the ß-ray detection efficiencies for 45 Ca (245-keV maximum energy) and 90 Sr/90 Y (545 and 2280-keV maximum energy) were 14.3% and 21.9%, respectively. The total γ-ray detection efficiency of the γ-ray detector for all γ-rays from 22 Na (511-keV annihilation γ-rays and a 1275-keV γ-ray) in the center position with a detector distance of 20 mm was 17.5%. From a point-source measurement using 22 Na and 90 Sr/90 Y, we successfully extracted the position of a positron-γ emitter 22 Na. Furthermore, for a phantom experiment using 45 Ca and 18 F or 18 F and 22 Na, we successfully extracted the distribution of the second tracer using the annihilation γ-ray or de-excitation γ-ray coincidence. In all the imaging experiments, the event counts of the extracted images were consistent with the counts estimated by the measured γ-ray efficiencies. CONCLUSIONS: We successfully demonstrated the feasibility of our ß-ray autoradiography system for imaging multiple isotopes. Since our system can identify not only a ß-γ emitter but also a positron emitter using the coincidence detection of annihilation γ-rays, it is useful for PET tracers and various new applications that are otherwise impractical.

Uptake of 137Cs and 85Sr onto thermally treated forms of bentonite.

This study focuses on the structural changes of bentonite upon thermal treatment at various temperatures, i.e. 150, 300 and 600, and their effect on the sorption behaviour for 137Cs and 85Sr. Thermal treatment caused gradual disappearance of the major peak of montmorillonite (at 15.15 Å) and minimization of calcite as observed by powder x-ray diffraction, in addition thermal gravimetric analysis indicated the occurrence of dehydration and dehydroxylation of the materials upon heating. Sorption experiments were carried out by batch-method and data were expressed in terms of distribution coefficients (Kd). Contact time, solution-solid ratio and radionuclide activity concentration were investigated in order to determine the optimal conditions and speculate the mechanism of the uptake. Sorption data revealed that the heated forms had lower selectivity for 137Cs than the original bentonite, while B-150 and B-300 were the best sorbents when 137Cs presents in salt media. In either case, ion exchange process of 137Cs with the crystal lattice cations (i.e. Ca2+ and Mg2+) was the governing mechanism. Contrarily, bentonite heated forms are recommended sorbents for 85Sr, especially B-600. The outperformance of thermally treated bentonites reflected chemical bonding reaction with the surface OH groups as well as precipitation of Sr(OH)2.

Automated 90Sr Separation and Preconcentration in a Lab-on-Valve System at Ppq Level.

A quick, automated and portable system for the separation and determination of radiostrontium in aqueous samples, using Sr-resin and multi sequential flow injection analysis, has been developed. The concentrations of radioactive strontium were determined by flow scintillation counting, allowing for on-line and also on-site determination. The proposed system can determine radioactive strontium at industrial relevant levels without further modification using overall analysis time of less than 10 min per aqueous sample. The limit of the detection is 320 fg·g-1 (1.7 Bq/g).

Effect of humic acid & bacterial exudates on sorption-desorption interactions of 90Sr with brucite.

One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility. Understanding the chemical interactions of these components is important to inform ongoing sludge retrievals and effluent management. Additionally, interactions of radionuclides with organics at high pH will be an important consideration for the evolution of cementitious backfilled disposal sites in the UK. Batch sorption-desorption experiments were performed with brucite, 90Sr and natural organic matter (NOM) (humic acid (HA) and Pseudanabaena catenata cyanobacterial growth supernatant) in both binary and ternary systems at high pH. Ionic strength, pH and order of addition of components were varied. 90Sr was shown not to interact strongly with the bulk brucite surface in binary systems under pH conditions relevant to the pond. HA in both binary and ternary systems demonstrated a strong affinity for the brucite surface. Ternary systems containing HA demonstrated enhanced sorption of 90Sr at pH 11.5 and vice versa, likely via formation of strontium-humate complexes regardless of the order of addition of components. The distribution coefficients show HA sorption to be reversible at all pH values studied, and it appeared to control 90Sr behaviour at pH 11.5. Ternary systems containing cyanobacterial supernatant demonstrated a difference in 90Sr behaviour when the culture had been subjected to irradiation in the first stages of its growth.

Hematological indicators in pygmy wood mouse Apodemus uralensis (Muridae, Rodentia) populations as markers of the environmental radiation exposure: East Urals radioactive trace (Russia).

The hematological effects of chronic radiation exposure in males of the pygmy wood mouse (Apodemus uralensis Pall., 1811) from the East Urals radioactive trace (EURT) area were assessed, taking into account population abundance and reproductive status (immature, ripening, and mature yearlings). For this purpose, we analyzed the morpho-functional characteristics of erythrocytes (red cell indices [MCV, MCH, MCHC], red cell count, activity of antioxidant enzymes [GSH-Px, CAT], lipid peroxidation, glycolysis, osmotic resistance, methaemoglobin content) and blood plasma components (free hemoglobin, total lipids, total cholesterol, and glucose) in the background territory and the EURT area; these areas have a density of soil contamination with 90Sr of 12,851 and 198 kBq × m-2, respectively (four and two order of magnitude higher than the background value). The data indicate the "hyperfunctional" state of the erythrocyte, aimed at activation of the gas transport function of blood in the radioactive environment. This, as a consequence, determines the insufficiency of energy supply of the cell defense system necessary to maintain the structural integrity of the membrane. Intensification of membrane lipid peroxidation, reduction of osmotic resistance and GSH-Px activity in red cells, an increase in the degree of intravascular hemolysis, and tendency towards erythropenia indicate the processes of accelerated aging of erythrocytes and their more pronounced destruction in the circulatory bed. The level of the hematological response increased with increasing radiation burden and was more pronounced with a large population size. The interaction effect of "overpopulation" and "radioactive pollution" was observed to a lesser degree for ripening males, and was very small for sexually mature animals. Immature males from the EURT head part with internal whole-body radiation doses of 0.0045-0.35 mGy/day can be considered as the most sensitive group to the factors synergy, including radiation damage and overabundance population.

Mesenchymal stem and progenitor cells of rats' bone marrow under chronic action of ionizing radiation. / MEZENKhIMAL'NI STOVBUROVI KLITYNY TA KLITYNY POPEREDNYKY KISTKOVOGO MOZKU ShchURIV V UMOVAKh KhRONIChNOÏ DIÏ IONIZUIuChOÏ RADIATsIÏ.

Under the influence of ionizing radiation on hematopoietic system, the level of its injury is determined not only by the radiosensitivity of hematopoietic stem cells, but also by radiation induced changes in microenvironment func tioning, in particular, mesenchymal stem cells as its components. OBJECTIVE: to define functioning characteristics of mesenchymal stem and progenitor cells of rats' bone marrow under prolonged action of ionizing radiation as a result of 90Sr incorporation. MATERIALS AND METHODS: We applied the model of Wistar rats' internal irradiation with 90Sr radionuclide and per formed the in vitro cultivation of their bone marrow mesenchymal cells. Colony forming efficiency in the in vitro cell culture was determined, as well as the possibility of these cells to form feeder layers and to support rat bone mar row hematopoietic cells in the culture of diffusion chambers in vitro. RESULTS AND CONCLUSIONS: We established that chronic action of incorporated 90Sr radionuclide induced considerable decrease in proliferative activity of mesenchymal stem cells comparing to control, as well as the inhibition of the capability to prolonged support of hematopoietic processes in vitro by their feeder layers.Thus, bone marrow mesenchymal stem cells and their closest progeny - progenitor cells were characterized by rather high radiosensitivity under the influence of ionizing radiation, which was revealed in considerable decline of their functional activity in cell culture in vitro comparing to control indices as a result of irradiation.

Adsorption Kinetics of 137Cs+/90Sr2+ on Ca-Bentonite.

137Cs+/90Sr2+ adsorption kinetics on natural Ca-bentonite under the impact of different adsorption conditions was examined in detail. The results indicate that natural Ca-bentonite shows a strong adsorption capacity for Cs+/Sr2+. The adsorption reached at equilibrium after 2 hours for Cs+. Cs+/Sr2+removal efficiency reaches the highest when the pH value is 5 to 8 and increases with the increase of Ca-bentonite adding amount. Cs+ removal efficiency increases with the increase of Cs+ initial concentration, while Sr2+ removal efficiency slightly varies around 70%. The adsorption of Cs+/Sr2+ by Ca-bentonite follows the pseudo-second-order model and is controlled by chemical adsorption. Meanwhile, the results of intraparticle diffusion modelling indicate that intraparticle diffusion is a kinetics controlling step, besides surface adsorption and liquid film diffusion.

Forage grasses with lower uptake of caesium and strontium could provide 'safer' crops for radiologically contaminated areas.

Substitution of a species or cultivar with higher uptake of an element by one with lower uptake has been proposed as a remediation strategy following accidental releases of radioactivity. However, despite the importance of pasture systems for radiological dose, species/cultivar substitution has not been thoroughly investigated for forage grasses. 397 cultivars from four forage grass species; hybrid ryegrass (Lolium perenne L. x Lolium multiflorum Lam.), perennial ryegrass (Lolium perenne L.), Italian ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Shreb.); were sampled from 19 field-based breeding experiments in Aberystwyth and Edinburgh (UK) in spring 2013 and analysed for caesium (Cs) and strontium (Sr) concentrations. In order to calculate concentration ratios (CRs; the concentration of an element in a plant in relation to the concentration in the soil), soils from the experiments were also analysed to calculate extractable concentrations of Cs and Sr. To test if cultivars have consistently low Cs and Sr concentration ratios, 17 hybrid ryegrass cultivars were sampled from both sites again in summer 2013 and spring and summer 2014. Tall fescue cultivars had lower Cs and Sr CRs than the other species. Three of the selected 17 hybrid ryegrass cultivars had consistently low Cs CRs, two had consistently low Sr CRs and one had consistently low Cs and Sr CRs. Cultivar substitution could reduce Cs CRs by up to 14-fold and Sr CRs by 4-fold in hybrid ryegrass. The identification of species and cultivars with consistently low CRs suggests that species or cultivar substitution could be an effective remediation strategy for contaminated areas.

A sequential determination of 90Sr and 210Po in food samples.

The latest EU Council Regulation 2016/52/Euratom updates the emergency limits on radionuclides in foods including 210Po and 90Sr, two of the most important radionuclides for radiological dose from the ingestion pathway. A novel and straightforward method has been developed for sequential determination of 90Sr and 210Po in food samples using ultra low-level liquid scintillation counting and alpha-particle spectrometry. For 90Sr analysis, the method makes use of stable strontium as yield tracer, and 210Po is determined through self-deposition using 209Po as a yield tracer. The quantification limit for this method is 25.0 and 2.0Bqkg-1 for 90Sr and 210Po, respectively. The proposed radiochemical separation can be completed within 2days for a batch of 12 samples. The radiochemical procedure was validated by its application for the measurement of IAEA certified reference materials, and through participation in a national intercomparison exercise. Results are also presented in seafood from the Mediterranean coast.

No effect of digestate amendment on Cs-137 and Sr-90 translocation in lysimeter experiments.

The soil-plant transfer of Cs-137 and Sr-90 in different crops was determined with respect to the present-day amendment practice of using digestate from biogas fermenters. The studies were performed using large lysimeters filled with undisturbed luvisol monoliths. In contrast to the conservative tracer, Br-, neither of the studied radionuclides showed a significant vertical translocation nor effect of the applied digestate amendment compared to a non-amended control was found. Furthermore, no significant plant uptake was measured for both nuclides in wheat or oat as indicated by the low transfer factors between soil-shoot for Cs-137 (TF 0.001-0.010) and for Sr-90 (0.10-0.51). The transfer into nutritionally relevant plant parts was even lower with transfer factors for soil-grain for Cs-137 (TF 0.000-0.001) and for Sr-90 (0.01-0.06). Hence, the amendment with biogas digestate is unfortunately not an option to further reduce plant uptake of these radionuclides in agricultural crops, but it does not increase plant uptake either.

[Application of the EPR and FISH Methods to Dose Reconstruction for People Exposed in the Techa River Area].

Release of liquid radioactive waste into the Techa River from the Mayak Production Association during 1949-1956 resulted in a significant exposure of about 30000 people who lived in downstream settlements. The residents were exposed to internal and external radiation. The article discusses the capability of two methods that were used 50 years after the termination of radioactive discharges for the dose reconstruction, namely EPR measurements of tooth enamel, and FISH measurements of stable chromosome aberrations in circulating lymphocytes. The Main issue in the application of these methods for the dose reconstruction was local irradiation from strontium radioisotopes incorporated in teeth and bones. The EPR and FISH assays were supported by measurements of the 90Sr content in the skeleton and teeth in order to estimate and subtract internal doses from incorporated 89, 90Sr. The resulting dose estimates obtained from EPR and FISH mea- surements were found to be consistent The settlement-averaged values in the upper-Techa Region varied from 550-570 mGy to 130-160 mGy and showed a reduction with the distance from the release site. The EPR- and FISH-based dose estimates were in agreement with the doses calculated with the dosimetry system TRDS that uses data on radionuclide contamination of the Techa River floodplain and individual residential histories.

Adsorptive Property of Food Materials and Chemicals to Cesium and Strontium.

In March, 2011, large amounts of radioactive materials were released from the Fukushima Daiichi nuclear power plant after the nuclear accident. Especially, for humans, internal exposure to ¹³7Cs and 9°Sr radionuclides presents very high risks because of their very long physical half-lives (¹³7Cs: 30.2 years, 9°Sr: 28.9 years). Therefore, it is important to inhibit the absorption of radioactive materials and to promote the excretion of them from the body through feces. The aim of this.study was to explore foods, their components and various chemicals showing adsorption properties to Cs and Sr. Sodium alginate (ALA-Na) strongly adsorbed Cs and Sr compared with other samples. Chondroitin sulfate, carboxymethyl cellulose sodium (CMC-Na), methyl cellulose (MC) and apple polyphenols (AP; high molecule weight) also showed adsorption potency to Cs in that order. For Sr adsorption, kelp, CMC-Na, MC, AP (high molecule weight), laminaran and Jew's mallow exhibited adsorbing effects in that order. These samples might be useful and safe tools to protect from the adverse effects induced by internal exposure to these radioactive materials.

Highly stable and magnetically separable alginate/Fe3O4 composite for the removal of strontium (Sr) from seawater.

In this study, a highly stable alginate/Fe3O4 composite was synthesized, and systematically investigated for the practical application of strontium (Sr) removal in complex media, such as seawater and radioactive wastewater. To overcome the drawbacks of the use of alginate microspheres, high contents of alginic acid and Fe3O4 were used to provide a more rigid structure with little swelling and facile separation, respectively. The synthesized composite was optimized for particle sizes of <400 µm and 1% content of Fe3O4. The alginate/Fe3O4 composite showed excellent Sr uptake (≈400.0 mg/g) and exhibited outstanding selectivity for Sr among various cations (Na, Mg, Ca and K). However, in diluted Sr condition (50 mg/L), Ca significantly affected Sr adsorption, resulting in a decrease of Kd value from 3.7 to 2.4 at the 0.01 M Ca. The alginate/Fe3O4 composite could be completely regenerated using 0.1 M HCl and CaCl2. In real seawater spiked with 50 mg/L of Sr, the alginate/Fe3O4 composite showed 12.5 mg/g of Sr uptake, despite the highly concentrated ions in seawater. The adsorption experiment for radio-active 90Sr revealed a removal efficiency of 67% in real seawater, demonstrating the reliability of the alginate/Fe3O4 composite.

[Analysis of Microsatellite DNA in Rodents from Eastern Urals Radioactive Trace Zone and Contiguous Territories].

The variability of four microsatellite loci of rodents, caught from the head part of Eastern Urals Radioactive Trace (EURT), along with the rodents inhabiting contiguous zone with background radiation level and distant-reference territory, was analyzed forthe first time. Differences in the parameters of genetic diversity between northern red-backed voles from the EURT zone and from the reference population were detected. An increase in some indices of genetic diversity in animals from a contiguous to the EURT zone was found; this is probably associated with animal migration and configuration of the area of pollution. A transfer of radiation-induced effects to the contiguous territories and a decrease in the possibility of fixation of adaptations in a series of generations of mobile rodent species in the area of local radioactive pollution are consequences of migrations. The results of the study make it possible to recommend microsatellite markers for the analysis of radiation-induced effects in rodents as model objects of radioecological monitoring.

(90)Sr in teeth of cattle abandoned in evacuation zone: Record of pollution from the Fukushima-Daiichi Nuclear Power Plant accident.

Here we determined the (90)Sr concentrations in the teeth of cattle abandoned in the evacuation area of the Fukushima-Daiichi Nuclear Power Plant (FNPP) accident. (90)Sr activity concentrations in the teeth varied from 6-831 mBq (g Ca)(-1) and exhibited a positive relationship with the degree of radioactive contamination that the cattle experienced. Even within an individual animal, the specific activity of (90)Sr (Bq (g Sr)(-1)) varied depending on the development stage of the teeth during the FNPP accident: teeth that were early in development exhibited high (90)Sr specific activities, while teeth that were late in development exhibited low specific activities. These findings demonstrate that (90)Sr is incorporated into the teeth during tooth development; thus, tooth (90)Sr activity concentrations reflect environmental (90)Sr levels during tooth formation. Assessment of (90)Sr in teeth could provide useful information about internal exposure to (90)Sr radiation and allow for the measurement of time-course changes in the degree of environmental (90)Sr pollution.

Palliative care of bone pain due to skeletal metastases: Exploring newer avenues using neutron activated (45)Ca.

INTRODUCTION: With an objective to develop a cost-effective radiochemical formulation for palliation of pain due to skeletal metastases, we have demonstrated a viable method for large-scale production of (45)Ca (t½=163 days, Eßmax=0.3MeV) using moderate flux research reactor, its purification from radionuclidic impurities adopting electrochemical approach and preclinical evaluation of (45)CaCl2. METHODS: Irradiation parameters were optimized by theoretical calculations for production of (45)Ca with highest possible specific activity along with minimum radionuclidic impurity burden. Based on this, the radioisotope was produced in reactor by irradiation of isotopically enriched (98% in (44)Ca) CaO target at a thermal neutron flux of ~1 × 10(14) n.cm(-2).s(-1) for 4 months. Scandium-46 impurity co-produced along with (45)Ca was efficiently removed adopting an electrochemical separation approach. The bone specificity of (45)CaCl2 was established by in vitro studies involving its uptake in hydroxyapatite (HA) particles and also evaluating its biodistribution pattern over a period of 2 weeks after in vivo administration in Wistar rats. RESULTS: Thermal neutron irradiation of 100mg of enriched (98% in (44)Ca) CaO target followed by radiochemical processing and electrochemical purification procedure yielded ~37 GBq of (45)Ca with a specific activity of ~370 MBq/mg and radionuclidic purity>99.99%. The reliability and reproducibility of this approach were amply demonstrated by process demonstration in several batches. In vitro studies indicated significant uptake of (45)CaCl2 (up to 65%) in HA particles. In vivo biodistribution studies in Wistar rats showed specific skeletal accumulation (40-46%ID) with good retention over a period of 2 weeks. CONCLUSIONS: To the best of our knowledge, this is the first study on utilization of (45)CaCl2 in the context of nuclear medicine. The results obtained in this study hold promise and warrant further investigations for future translation of (45)CaCl2 to the clinics, thereby potentially enabling a cost-effective approach for metastatic bone pain palliation especially in developing countries.

Contemporary Understanding of Radioactive Contamination of the Techa River in 1949-1956.

Analysis of recently available archive materials regarding the liquid radioactive waste storage and reprocessing at the "Mayak" Production Association in 1949-1956 has led to a more accurate reconstruction of radionuclide releases into the Techa River. Radionuclide concentrations in the Techa River water, bottom sediments and floodplain soils in 1949-1951 were reconstructed with the use of a purposely-developed Techa River model. Model calculations agree with the measurements of the specific activity in the river water and bottom sediments conducted since 1951. The model output for the (90)Sr concentration in the river water shows a good agreement with the retrospective estimates derived from (90)Sr measurements in teeth and the whole body of the Techa riverside residents. Modeled (137)Cs-contamination of the floodplain shows agreement with the values reconstructed from (137)Cs measurements in the floodplain soils obtained in later years. Reconstructed contamination levels by radionuclides in the Techa River water and floodplain are being used to refine internal and external doses and risk estimates of late effects in the population chronically exposed to radiation.

Cement As a Waste Form for Nuclear Fission Products: The Case of (90)Sr and Its Daughters.

One of the main challenges faced by the nuclear industry is the long-term confinement of nuclear waste. Because it is inexpensive and easy to manufacture, cement is the material of choice to store large volumes of radioactive materials, in particular the low-level medium-lived fission products. It is therefore of utmost importance to assess the chemical and structural stability of cement containing radioactive species. Here, we use ab initio calculations based on density functional theory (DFT) to study the effects of (90)Sr insertion and decay in C-S-H (calcium-silicate-hydrate) in order to test the ability of cement to trap and hold this radioactive fission product and to investigate the consequences of its ß-decay on the cement paste structure. We show that (90)Sr is stable when it substitutes the Ca(2+) ions in C-S-H, and so is its daughter nucleus (90)Y after ß-decay. Interestingly, (90)Zr, daughter of (90)Y and final product in the decay sequence, is found to be unstable compared to the bulk phase of the element at zero K but stable when compared to the solvated ion in water. Therefore, cement appears as a suitable waste form for (90)Sr storage.