CANDU nuclear reactor designs, operation and fuel cycle

Boczar, P.G.

doi:10.1533/9780857096388.3.278

Cited by 3 publications

(3 citation statements)

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“…Considerable experimental evidence exists to show that fission product and actinide-lanthanide doping have a significant effect on the kinetics of air oxidation of the fuel, [10][11][12][13] and preliminary electrochemical experiments on SIMFUEL suggest a similar influence in aqueous environments. 6 Since there has been a continuous trend toward higher in-reactor fuel burn-up, [14][15][16] the extent of doping and its influence on reactivity are becoming more important. Both the mechanism and the rate of oxidation are influenced by the presence of dopants.…”

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confidence: 99%

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO₂)

Razdan

Shoesmith

2013

J. Electrochem. Soc.

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The influence of trivalent dopants (rare-earths, RE) on the structure, composition and electrochemical reactivity of UO 2 has been investigated using scanning electron microscopy (SEM/XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and cyclic voltammetry (CV). This was achieved by comparing the behavior of undoped UO 2.002 , a slightly doped 1.5 at% SIMFUEL, and two rare-earth doped UO 2 (6 wt% Gd-UO 2 and 12.9 wt% Dy-UO 2 ) specimens. The reactivity decreased in the order UO 2.002 > SIMFUEL > Dy-UO 2 > Gd-UO 2 , showing that this decrease is a consequence of RE III doping. Raman spectroscopy showed this could be attributed to the formation of RE III -oxygen vacancy clusters whose formation decreases the availability of the vacancies required to accommodate the injection of oxygen interstitials during anodic oxidation. The behavior of SIMFUEL is complicated by the simultaneous formation of RE III -oxygen vacancy clusters and Zr-O 8 clusters.The safe disposal of spent nuclear fuel (SNF) is one of the key issues facing the modern nuclear power industry, and a major international effort is underway to develop safe management and disposal procedures. One potential management strategy in Canada is permanent disposal in a deep geologic repository. 1 The spent fuel would be sealed in metallic containers, emplaced in a repository and surrounded with compacted clay. The prospects for long term containment using copper containers are very good and corrosion models predict only minimal corrosion damage should be sustained. 2,3 However, if failure were to occur, contact of the fuel wasteform (uranium dioxide (UO 2 )) with groundwater would become possible. Although the solubility of UO 2 is very low under the anticipated anoxic conditions, radiolysis of the groundwater, due to the inherent radioactivity of the spent fuel, could lead to fuel corrosion, the U(IV) in the fuel being oxidized to the significantly more soluble U(VI) state. 4 This would make radionuclide release to the groundwater possible.Spent fuel is mainly UO 2 (> 95%), the remainder being the radioactive fission products and actinides produced during the in-reactor process. The inventory of radionuclides within the fuel depends on in-reactor burn-up and the linear power rating of the fuel. 5 Formation of these products leads to many physical and chemical changes within the fuel, 5 and post irradiation inspection of the fuel shows the presence of both volatile and non-volatile fission products. While volatile products may escape to the fuel-cladding gap, the non volatile products remain fixed within the fuel matrix in three distinct phases: the lanthanides in the fcc-fluorite lattice; the noble metals in metallic precipitates; and radionuclides unstable in the fluorite matrix in mixed metal oxides (perovskites). 6 The key changes likely to influence the chemical reactivity of the UO 2 matrix are the rare earth (RE) doping of the matrix and the development of non-stoichiometry. 7 Micro Raman spectroscopic studies show that non-stoichiometry lead...

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confidence: 99%

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO₂)

Razdan

Shoesmith

2013

J. Electrochem. Soc.

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“…Measurement of a LEU reactor spectrum with the superior energy resolution of the PROSPECT AD-I would supplement current statistically precise measurements [6][7][8], improve the knowledge of n e spectra from fission of 238 U, 239 Pu and 241 Pu, and reduce systematic uncertainties in the comparison of LEU and HEU n e spectra through use of a common detector for both measurements. Measurement of a CANDU reactor [49,50], in which frequent refueling maintains a static fuel mixture of 235 U, 238 U, 239 Pu, and 241 Pu, would further improve the determination of each spectral component. The ratio of a PROSPECT measurement at a CANDU reactor compared to an HEU reactor is demonstrated in figure 10.…”

Section: Applied Physics Measurementsmentioning

confidence: 99%

The PROSPECT physics program

Ashenfelter¹,

Balantekin²,

Band³

et al. 2016

J. Phys. G: Nucl. Part. Phys.

105

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The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and probe eV-scale sterile neutrinos by searching for neutrino oscillations over meter-long distances. PROSPECT is conceived as a 2-phase experiment utilizing segmented 6 Li-doped liquid scintillator detectors for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT Phase I consists of a movable 3-ton antineutrino detector at distances of 7-12 m from the reactor core. It will probe the best-fit point of the ν e disappearance experiments at 4σ in 1 year and the favored region of the sterile neutrino parameter space at >3σ in 3 years. With a second antineutrino detector at 15-19 m from the reactor, Phase II of PROSPECT can probe the entire allowed parameter space below 10 eV 2 at 5σ in 3 additional years. The measurement of the reactor antineutrino spectrum and the search for short-baseline oscillations with PROSPECT will test the origin of the spectral deviations observed in recent θ 13 experiments, search for sterile neutrinos, and conclusively address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly.

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“…Other advantages of the thorium fuel cycle are: reduced generation of higher actinides with long radioactive life and attractive thermo physical properties of ThO 2 (ref. 1). Feasibility of the scheme of converting Th 232 to U 233 and subsequently fissioning U 233 to produce nuclear energy was demonstrated in several countries, a brief account of which is provided later in this article.…”

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Nuclear Power from Thorium:Different Options

2016

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Keywords: Accelerator-driven sub-critical systems, breed and burn reactors, fast reactors, light water reactors, molten salt breeder reactors, pressurized heavy water reactors, thorium fuel cycle.NATURE has provided only one fissile isotope, U 235 , splitting of which in fission chain reaction produces most of the present day nuclear energy. Natural uranium contains 0.7 wt% of U 235 , which is fissile material while the remaining 99.3 wt% U 238 is fertile. In contrast, natural thorium (Th 232 ) is only a fertile material with no fissile content in it. While examining the sustainability of nuclear power, the use of thorium was given due consideration from the early years of the nuclear power generation. In view of the fact that the total inventory of naturally available U 235 is inadequate to provide nuclear energy for a long period (beyond a century or two), the idea of utilizing fertile material by first converting them into fissile and subsequently fissioning them to produce energy was conceived way back in the 1950s. It was also recognized that the fertile to fissile conversion could be made possible only if a steady supply of neutrons can be made economically. The process of nuclear fission produces neutrons in excess of what is required for sustaining the chain reaction and these excess neutrons are utilized for the generation of fresh fissile nuclides. While the fast neutron spectrum fissioning of Pu 239 can generate more fissile nuclides than consumed, U 233 (derived from Th 232 by neutron absorption) can also do the same at a reduced level in a wide neutron energy spectrum from thermal to fast. It is this nuclear property, which was the main incentive of thorium utilization in the early years. Other advantages of the thorium fuel cycle are: reduced generation of higher actinides with long radioactive life and attractive thermo physical properties of ThO 2 (ref. and subsequently fissioning U 233 to produce nuclear energy was demonstrated in several countries, a brief account of which is provided later in this article. However no major power plant has been built with U 233 as the main fuel. This is primarily because driving a thorium-based reactor requires a driver fuel containing any of the fissile nuclides U 235 , U 233 or Pu 239 . The fissile fertile mix U 235 + U 238 in natural and enriched uranium is being used extensively over the last six decades for producing energy and generating fresh fissile nuclides. The capture crosssection of Th 232 is nearly thrice higher than that of U 238 in thermal neutron spectrum, therefore, introduction of thorium will invariably require larger fissile content in

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CANDU nuclear reactor designs, operation and fuel cycle

Cited by 3 publications

References 3 publications

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO₂)

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO₂)

The PROSPECT physics program

Nuclear Power from Thorium:Different Options

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CANDU nuclear reactor designs, operation and fuel cycle

Cited by 3 publications

References 3 publications

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO2)

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO2)

The PROSPECT physics program

Nuclear Power from Thorium:Different Options

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Product

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Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO₂)

Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO₂)