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Showing papers by "Atomic Energy of Canada Limited published in 2014"


Journal ArticleDOI
TL;DR: In this article, a fuel-assembly simulator with four heated rods was installed inside a square channel with rounded corner, and the experimental data indicated a non-uniform circumferential wall-temperature distribution around the heated rod.

68 citations


Journal ArticleDOI
TL;DR: In this paper, the materials requirements of various supercritical water-cooled nuclear power plants are introduced, with a focus on the European Union pressure vessel concept and the Canadian pressure tube concept.

66 citations


Journal ArticleDOI
TL;DR: The Supercritical Water-Cooled Reactor (SCWR) is a high temperature, high pressure water-cooled reactor that operates above the thermodynamic critical point (374°C, 22.1MPa) of water as mentioned in this paper.

39 citations


Journal ArticleDOI
TL;DR: A new method using five-column chromatography separation has been developed for the simultaneous determination of Pu, Np, Th, U, Am, Cm, Pm, Y, and Sr isotopes, as well as iron-55, by inductively coupled mass spectrometry (ICPMS), α spectromaetry, Čerenkov and liquid scintillation (LS) counting.
Abstract: There is a growing demand for the rapid determination of hard-to-detect radionuclides in environmental and biological samples for environmental monitoring, radiological protection, and nuclear forensic reasons. A new method using five-column chromatography separation has been developed for the simultaneous determination of Pu, Np, Th, U, Am, Cm, Pm, Y, and Sr isotopes, as well as iron-55, by inductively coupled mass spectrometry (ICPMS), α spectrometry, Cerenkov and liquid scintillation (LS) counting. Spiked swipe and water samples as well as proficient testing water standards were analyzed to validate the separation procedure, and the results are in good agreement with the expected values. The method provides quick sample turnaround time and high analysis throughput with low analysis cost. The flexibility of the method also allows for its easy adaptation to various emergency and routine radioassays.

36 citations


Journal ArticleDOI
TL;DR: In this paper, a 5 × 5 rod assembly with a split-type spacer grid is simulated with ANSYS Fluent 14 using unsteady simulations with a fully conformal hybrid mesh (wall y + ∼30).

34 citations


Journal ArticleDOI
TL;DR: The most recent version, ASSERT-PV 3.2, has enhanced phenomenon models for improved predictions of flow distribution, dryout power and CHF location, and post-dryout (PDO) sheath temperature in horizontal CANDU fuel bundles as mentioned in this paper.

33 citations


Journal ArticleDOI
TL;DR: In this article, the p-type or n-type semiconductivity of the passive film depended significantly on the solution chemistries, and the competitive adsorption of these two ions was believed to determine the type of passive film.

30 citations


Journal ArticleDOI
TL;DR: In this article, a rapid procedure for sequential separation of Strontium-90 ( 90 Sr) was developed and tested in groundwater samples col- lected from an area of riverbed affected by a 90 Sr groundwater plume.
Abstract: Strontium-90 ( 90 Sr) is a ubiquitous contaminant at nuclear facilities, found at high concentrations in spent nuclear fuel and radioactive waste. Due to its long half-life and ability to be transported in groundwater, an accurate method for measuring 90 Sr in water samples is critical to the monitoring program of any nuclear facility. To address this need, a rapid procedure for sequential separation of Sr/ Y was developed and tested in groundwater samples col- lected from an area of riverbed affected by a 90 Sr groundwater plume. Sixteen samples, plus spike and water blanks, were analyzed. Five different measurements were performed to determine the 90 Sr and yttrium-90 ( 90 Y) activities in the samples: direct triple-to-double-coin- cidence ratio (TDCR) Cherenkov counting of 90 Y, liquid scintillation (LS) counting for 90 Sr following radiochemi- cal separation, LS counting for 90 Y following radiochem- ical separation, Cherenkov counting for 90 Y following radiochemical separation and LS counting of the Sr sam- ples for 90 Y in-growth. The counting was done using a low- level Hidex 300SL TDCR counter. Each measurement method was compared for accuracy, sensitivity and effi- ciency. The results following Cherenkov counting and radiochemical separation were in very good agreement with one another.

29 citations


Journal ArticleDOI
TL;DR: In this paper, the authors highlight and discuss the recent advances in thermochemical hydrogen production with the copper-chlorine (Cu-Cl) cycle, and their performance assessment is conducted.

29 citations


Journal ArticleDOI
TL;DR: New fuel bundle and lattice concepts to implement thorium-based fuel cycles in pressure tube heavy water reactors (PT-HWRs) have been explored to achieve maximum resource utilization.
Abstract: New fuel bundle and lattice concepts to implement thorium-based fuel cycles in pressure tube heavy water reactors (PT-HWRs) have been explored to achieve maximum resource utilization. As an existin...

26 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a selection of recent work performed by Severe Accident Research Network (SARNET) members regarding iodine-paint interactions and paint aging in order to better define what has still to be done in this area.

Journal ArticleDOI
TL;DR: In this paper, the authors present a set of benchmarking activities for steam condensation in conditions of interest for nuclear reactor containment in the presence of non-condensable gases, with the goal of providing needed awareness about the capabilities of condensation models, at least in the simple configuration involved by the benchmark exercises.

Journal ArticleDOI
TL;DR: A prototype software system with sufficient capacity and speed to estimate radiation exposures in a mass casualty event by counting dicentric chromosomes (DCs) in metaphase cells from many individuals is presented.
Abstract: We present a prototype software system with sufficient capacity and speed to estimate radiation exposures in a mass casualty event by counting dicentric chromosomes (DCs) in metaphase cells from many individuals. Top-ranked metaphase cell images are segmented by classifying and defining chromosomes with an active contour gradient vector field (GVF) and by determining centromere locations along the centreline. The centreline is extracted by discrete curve evolution (DCE) skeleton branch pruning and curve interpolation. Centromere detection minimises the global width and DAPI-staining intensity profiles along the centreline. A second centromere is identified by reapplying this procedure after masking the first. Dicentrics can be identified from features that capture width and intensity profile characteristics as well as local shape features of the object contour at candidate pixel locations. The correct location of the centromere is also refined in chromosomes with sister chromatid separation. The overall algorithm has both high sensitivity (85 %) and specificity (94 %). Results are independent of the shape and structure of chromosomes in different cells, or the laboratory preparation protocol followed. The prototype software was recoded in C++/OpenCV; image processing was accelerated by data and task parallelisation with Message Passaging Interface and Intel Threading Building Blocks and an asynchronous non-blocking I/O strategy. Relative to a serial process, metaphase ranking, GVF and DCE are, respectively, 100 and 300-fold faster on an 8-core desktop and 64-core cluster computers. The software was then ported to a 1024-core supercomputer, which processed 200 metaphase images each from 1025 specimens in 1.4 h.

Journal ArticleDOI
TL;DR: In this paper, both the bare-rod and wire-wrapped bundle geometries were tested for the proposed fuel bundle design at 25MPa using STAR-CCM+CFD code to predict the sheath temperature variation along the axial direction.

Journal ArticleDOI
TL;DR: The results indicate that radiation adaptive responses at systemic levels, such as increases in the tumor latency times in aging mice, may not be mediated by modulated DNA repair, and that the genetic background may affect expression of a radioadaptive response.
Abstract: In this study, we sought to determine whether low-dose ionizing radiation, previously shown to induce a systemic adaptive response in C57BL/6J mice, is capable of enhancing the rate of DNA double-strand break repair. Repair capacity was determined by measuring γ-H2AX levels in splenic and thymic lymphocytes, using flow cytometry, at different times after a challenge irradiation (2 Gy, 60Co). Irradiation with low doses (20 and 100 mGy) was conducted in vivo, whereas the challenge dose was applied to primary cultures of splenocytes and thymocytes in vitro 24 h later. Obtained kinetics curves of formation and loss of γ-H2AX indicated that cells from low-dose irradiated mice did not express more efficient DNA double-strand break repair compared to controls. Immunoblot analysis of γ-H2AX and Phospho-Ser-1981 ATM confirmed that DNA damage signaling was not modulated by preliminary low-dose radiation. Mouse embryonic fibroblasts of C57BL genetic background failed to show clonogenic survival radioadaptive respons...

Journal ArticleDOI
TL;DR: The data suggest that the majority of DNA single-strand breaks and alkali-labile sites after exposure of human lymphocytes to UVA are produced by reactive oxygen species (the hydroxyl radical and singlet oxygen) and that the state of chromatin may substantially contribute to the outcome of such exposures.

Journal ArticleDOI
TL;DR: The fate of colored natural organic matter (CNOM) was investigated for a period of 16 months at a municipal wastewater treatment plant of a mid-sized city in Northern Ontario, Canada, using fluorescence spectroscopy as mentioned in this paper.
Abstract: The fate of colored natural organic matter (CNOM) was investigated for a period of 16 months at a municipal wastewater treatment plant of a mid-sized city in Northern Ontario, Canada, using fluorescence spectroscopy. Our objectives were to assess the changes of CNOM at the inlet and outlet of the plant and to determine if these changes were correlated with parameters routinely measured at the plant. The fluorescence signals were spectrally resolved into humic-like, fulvic-like, and protein-like components using a parallel factor analysis (PARAFAC) routine. We found that the signals of the CNOM components in the raw sewage had protein-like characteristics, followed by fulvic-like and humic-like characteristics. Conversely, after treatment, the CNOM signals were dominated by fulvic-like components, followed by approximately equal signals of humic-like and protein-like components. The fluorescence signals were, on average, ∼60 % lower in the effluent for the protein-like components and ∼28 % lower for the humic-like components, suggesting a decomposition of these CNOM materials. The fluorescence signals showed a small apparent increase of fulvic-like components, by ∼4 %, suggesting that the material showing this signal is recalcitrant to decomposition, or it could be potentially produced in the process. We found weak but statistically significant correlations (R 2 > 0.3) between the total fluorescence signals and total carbon (TC), the flow rate through the plant, and rainfall in the raw sewage. Similarly, correlations were found between protein-like fluorescence of the protein-like components and total Kjeldahl nitrogen (TKN) and ammonium at the effluent (R 2 > 0.3).


Journal ArticleDOI
TL;DR: It is shown, for the first time, that DNA comets can be visualized and analyzed using Giemsa staining and the unexpectedly high sensitivity of GiemsA staining for the comet assay is due to the Romanowsky-Giemsa effect, the stain photo-stability and the higher resolution of bright-field imaging compared to fluorescence imaging.
Abstract: This study was undertaken to evaluate the compatibility of Giemsa staining protocol with the comet assay. We showed, for the first time, that DNA comets can be visualized and analyzed using Giemsa staining. We generated DNA damage dose response curves for human peripheral blood lymphocytes exposed to X-ray radiation using the comet assay with either SybrGreen I or Giemsa stain. The dose response curves were fitted by linear regressions (R2 > 0.977). The SybrGreen I results showed only ~1.2-fold higher slope coefficient (method sensitivity) compared to the Giemsa results. The unexpectedly high sensitivity of Giemsa staining for the comet assay is due to the Romanowsky-Giemsa effect, the stain photo-stability and the higher resolution of bright-field imaging compared to fluorescence imaging. Our results demonstrate that Giemsa staining can effectively be used for measuring DNA damage by the comet assay. The low cost and availability of Giemsa stain makes this method affordable for any low budget research and will facilitate new applications of the comet assay in biology and medicine.

Journal ArticleDOI
TL;DR: In this paper, conditions affecting the determination of 90Sr/90Y activities in liquid samples by the triple-to-double coincidence ratio (TDCR) Cherenkov counting technique were conducted.
Abstract: A study to evaluate conditions affecting the determination of 90Sr/90Y activities in liquid samples by the triple-to-double coincidence ratio (TDCR) Cherenkov counting technique was conducted. The Cherenkov radiation produced by the 90Y beta decay was determined using a commercially available Hidex 300 SL liquid scintillation counter. The interferences of sample geometry, including sample counting vial type and volume composition, and sample colour on the TDCR were investigated. The effects of potentially interfering beta and mixed beta–gamma emitters on the TDCR Cherenkov counting of 90Sr/90Y activities were also examined. The TDCR values were used to quantify counting efficiencies of 90Y under different experimental conditions. The results demonstrated that the Cherenkov counting efficiency of 90Y is independent of sample volume and counting vial size. The effect of colour quenching was examined using yellow and brown food-grade dyes. The TDCR correction for colour quenching was found to be effective. An evaluation of counting efficiency of different beta-emitting radionuclides demonstrated that strong gamma emissions can contribute to the Cherenkov counting efficiency. Overall, measured radioactivity values deviated from reference values by ≤7.5 %, which is acceptable for screening applications in emergency situations.

Journal ArticleDOI
TL;DR: In this paper, pressure tube heavy water reactors (PT-HWRs) are used to implement thorium-based fuel cycles to achieve maximum resource utilization, which is highly advantageous for impl...
Abstract: New reactor concepts to implement thorium-based fuel cycles have been explored to achieve maximum resource utilization. Pressure tube heavy water reactors (PT-HWRs) are highly advantageous for impl...

Journal ArticleDOI
TL;DR: In this article, an anaerobic bioreactor system was used to treat coal mine effluent containing 85μg/L of selenium in a lake near Grande Cache, AB, Canada.
Abstract: Selenium (Se) contamination of aquatic resources and its mitigation is of global concern. Anaerobic bioreactors are the most promising method for treating Se-laden water in end-pit lakes resulting from intensive coal mining and waste rock leachate in the Canadian Rockies. This study assessed the suitability of a bioreactor system to treat non-acidic, coal mine effluent containing 85 μg/L of Se, near Grande Cache, AB, Canada, while making the system as cheap as possible using locally available materials. We successfully used a sediment inoculum from the same end-pit lake as the effluent source to obtain sulfur/Se-reducing bacteria and mixed the inoculum with mulch, manure, gravel, limestone, and bone meal to comprise the ‘active substrate’ for the bioreactors. The anaerobic bioreactors reduced >95 % of the total Se in the inflow water with a flow rate of ≈0.2 m3/h. Se removal was not related to water temperature, which declined from 17 to ≈2 °C in November, suggesting water can be treated regardless of temperature. The use of manure as a bacterial carbon/nitrogen source introduced Escherichia coli into the downstream environment, but after a short elevated concentration, the abundance of E. coli dropped below water quality guidelines. We were able to show that successful Se reduction can be achieved using an anaerobic bioreactor design and locally available material. This design kept the building and maintenance price lower than previous reactors, making the approach promising for larger scale applications and making bioreactors a more cost accessible remediation technology for non-acidic end-pit lakes.

Journal ArticleDOI
TL;DR: The developed methods fulfill the requirements for emergency and routine radioassays and the efficiency and reliability of the procedures were confirmed using spiked samples.
Abstract: Polonium-210 (210Po) can be rapidly determined in drinking water and urine samples by alpha spectrometry using copper sulfide (CuS) microprecipitation. For drinking water, Po in 10 mL samples was d...

Journal ArticleDOI
TL;DR: In this article, the stability of suspended floors and their mega supporting structures is discussed in relation to P-delta effect and the storey-based stability method for assessing the critical load multipliers to be applied to the supporting frames.
Abstract: Buildings designed with floors suspended on mega supporting structures (core tubes/frames) are referred to as suspended buildings. Such buildings can meet some practical requirements such as the gaining of large open spaces. Some aspects, including seismic performance and structural stability, however, are not completely understood by the engineering community. This motivated an investigation into the performance of suspended buildings subjected to gravity and ground earthquake motion. The stability of suspended floors and their mega supporting structures is discussed in relation to P-delta effect. A suspended-floor section is able to gain stiffness from gravity, but the stability of its mega supporting structure may be a problem due to the up-shifted gravity. This leads to a discussion of the storey-based stability method for assessing the critical load multipliers to be applied to the supporting frames. In view of the pros and cons of suspended buildings, a passive control system with three-performance ...

Journal ArticleDOI
TL;DR: In this article, a Ni-20Cr-5Al model alloy is tested in supercritical water cooled nuclear reactors (SWCR) for over 6000h and the long term corrosion behavior of the samples with various surface preparations is evaluated by measuring weight change and examining surface microstructure and oxide formation.

Journal ArticleDOI
TL;DR: In this article, the mass transfer behavior of oxygen and ferricyanide in dilute aqueous solutions was investigated using a rotating cylinder electrode under bulk boiling condition, and a correlation was developed to predict the reaction of dissolved oxygen below boiling condition.

Journal ArticleDOI
TL;DR: An ICP-MS method using a micro-flow injection (μ-FI) sample introduction system was developed for measuring 237Np and 239,240,241Pu in urine samples for sensitive and rapid population monitoring following a radiological or nuclear accident as discussed by the authors.
Abstract: An ICP-MS method using a micro-flow injection (μ-FI) sample introduction system was developed for measuring 237Np and 239,240,241Pu in urine samples for sensitive and rapid population monitoring following a radiological or nuclear accident. Good selectivity from the chemical separation method allowed the determination of 237Np together with Pu isotopes using 242Pu as a tracer. Significant improvements in ICP-MS sensitivity and detection limit were achieved using the μ-FI sample introduction and the desolvation techniques. The method developed has been successfully applied to a set of human urine samples spiked with Pu isotopes and a set of rat urine samples with metabolized Pu isotopes from research experiments.

Journal ArticleDOI
TL;DR: In this article, the results showed that when tested under high density supercritical water, the bare IN625 sample suffered from intergranular attacking while low density super critical water did not have the same effect.
Abstract: In this study, IN625 and a NiCrAlY coated IN625 were tested in high density and low density supercritical water for 500 h. The NiCrAlY coating was applied using plasma spray method. The surfaces were finely polished before testing to assist microstructure observation after testing. The NiCrAlY coated samples were additionally heat treated in air furnace to encourage alumina formation. SEM and XRD analyses were carried out to determine surface microstructure changes, particularly oxide formation. The results showed that when tested under high density supercritical water, the bare IN625 sample suffered from intergranular attacking while low density supercritical water did not have the same effect. Both as-sprayed NiCrAlY and heat treated NiCrAlY did not show any signs of intergranular attack or pitting after being tested in high density and low density supercritical water.

Journal ArticleDOI
TL;DR: In this article, Monte Carlo track chemistry simulations were used to determine the yields (or G-values) of hydrogen peroxide in the radiolysis of neutral water and dilute aqueous bromide solutions by low linear energy transfer (LET ∼ 0.3 keV μm−1) radiation (e.g., γ-rays from 60Co, fast electrons or high-energy protons).
Abstract: Monte Carlo track chemistry simulations were used to determine the yields (or G-values) of hydrogen peroxide in the radiolysis of neutral water and dilute aqueous bromide solutions by low linear energy transfer (LET ∼ 0.3 keV μm−1) radiation (e.g., γ-rays from 60Co, fast electrons or high-energy protons) and tritium β-particles (mean LET ∼ 6 keV μm−1) at 25 °C. We investigated the influence of Br− ions, as selective scavengers of ˙OH radical precursors of H2O2, on the inhibition of G(H2O2) for these two types of radiation. Studying this system under a wide range of Br− concentrations (5 × 10−7 to 0.2 M) and using a well-accepted mechanism for radiolysis in the presence or absence of air, we examined the chemical changes in the scavengeability of H2O2 produced by 300 MeV irradiating protons (used in this work to reproduce the effects of 60Co γ/fast electron radiolysis) and tritium β-electron radiolysis. We found that these changes could be related to differences in the initial spatial distributions of radiolytic species (i.e., the structure of the electron tracks, the low-energy β-electrons of tritium depositing their energy almost entirely as cylindrical “short tracks” and the energetic Compton electrons produced by γ-radiolysis forming mainly spherical “spurs”), in full agreement with previous experimental and theoretical work. Simulations showed that the short track geometry of higher LET tritium β-electrons in both water and aqueous bromide solutions favored a clear increase in G(H2O2) compared to 60Co γ-rays. Moreover, the presence of oxygen was seen to scavenge hydrated electrons (eaq−) and H˙ atoms on the ∼10−7 s time scale, thereby protecting H2O2 from further reactions with these species in the homogeneous stage of radiolysis. This protection against eaq− and H˙ atoms therefore led to an increase in the long time H2O2 yields, as seen experimentally. Finally, for both deaerated and aerated solutions, the H2O2 yield in tritium β-radiolysis was found to be more easily suppressed than in the case of cobalt γ-radiolysis, and interpreted by the quantitatively different chemistry between spurs and short tracks. These differences in the scavengeability of H2O2 precursors in passing from 300 MeV irradiating protons to tritium β-electron irradiation were in good agreement with experimental data, thereby lending strong support to the picture of tritium β-radiolysis in terms of short tracks of high local LET.

Journal ArticleDOI
TL;DR: The obtained results indicate that the lung cancer could be treated by BNCT under the assumptions of calculations.
Abstract: Monte Carlo simulations were performed to evaluate dose for possible treatment of cancers by boron neutron capture therapy (BNCT). The computational model of male Oak Ridge National Laboratory (ORNL) phantom was used to simulate tumours in the lung. Calculations have been performed by means of the MCNP5/X code. In this simulation, two opposite neutron beams were considered, in order to obtain uniform neutron flux distribution inside the lung. The obtained results indicate that the lung cancer could be treated by BNCT under the assumptions of calculations.