The most promising applications for targeted alpha-therapy with astatine-211 (At-211) include treatments of disseminated microscopic disease, the major medical problem for cancer treatment. The primary advantages of targeted alpha-therapy with At-211 are that the alpha-particle radiation is densely ionizing, translating to high relative biological effectiveness (RBE), and short-range, minimizing damage to surrounding healthy tissues. In addition, theranostic imaging with I-123 surrogates has shown promise for developing new therapies with At-211 and translating them to the clinic. Currently, Canada does not have a way of producing At-211 by conventional methods because it lacks alpha-particle accelerators with necessary beam energy and intensity. The work presented here was aimed at studying the Rn-211/At-211 generator system as an alternative production strategy by leveraging TRIUMF's ability to produce rare isotopes. Recognizing that TRIUMF provided production opportunities for a variety of astatine isotopes, this work also originally hypothesized and evaluated the use of At-209 as a novel isotope for preclinical Single Photon Emission Computed Tomography (SPECT) with applications to At-211 therapy research. At TRIUMF's Isotope Separator and Accelerator (ISAC) facility, mass separated ion beams of short­-lived francium isotopes were implanted into NaCl targets where Rn-211 or At-209 were produced by radioactive decay, in situ. This effort required methodological developments for safely relocating the implanted radioactivity to the radiochemistry laboratory for recovery in solution. For multiple production runs, Rn-211 was quantitatively transferred from solid NaCl to solution (dodecane) from which At-211 was efficiently extracted and evaluated for clinical applicability. This validated the use of dodecane for capturing Rn-211 as an elegant approach to storing and shipping Rn-211/At-211 in the future. Po-207 contamination (also produced by Rn-211 decay) was removed using a granular tellurium (Te) column before proceeding with biomolecule labelling. Although the produced quantities were small, the pure At-211 samples demonstrated these efforts to have a clear path of translation to animal studies. For the first time in history, SPECT/CT was evaluated for measuring At-209 radioactivity distributions using high energy collimation. The spectrum detected for At-209 by the SPECT camera presented several photopeaks (energy windows) for reconstruction. The 77-90 Po X­-ray photopeak reconstructions were found to provide the best images overall, in terms of resolution/contrast and uniformity. Collectively, these experiments helped establish guidelines for determining the optimal injected radioactivity, depending on scan parameters. Moreover, At-209-based SPECT demonstrated potential for pursuing image-­based dosimetry in mouse tumour models, in the future. Simultaneous SPECT imaging with At-209 and I-123 was demonstrated to be feasible, supporting the future evaluation of At-209 for studying/validating I-123 surrogates for clinical image-based At-211 dosimetry. This work also pursued a novel strategy for labelling cancer targeting peptides with At-211, using octreotate (TATE, a somatostatin analogue for targeting tumour cells, mostly neuroendocrine tumours) prepared with or without N-terminus PEGylation (PEG2), followed by conjugation with a closo-decaborate linking moiety (B10) for attaching At-211. Binding affinity and in vivo biodistributions for the modified peptides were determined using iodine surrogates. The results indicated that B10-PEG2-TATE retained target binding affinity but that the labelling reaction with iodine degraded this binding affinity significantly, and although having high in vivo stability, no I-123-B10-PEG2-TATE tumour uptake was observed by SPECT in a mouse tumour model positive for the somatostatin receptor (sstr2a). This suggested that further improvements are required for labelling. A new method for producing At-211 at TRIUMF is established, and At-209-­based SPECT imaging is now demonstrated as a new preclinical technology to measure astatine biodistributions in vivo for developing new radiopharmaceuticals with At-211. Combined with the theranostic peptide labelling efforts with iodine, these efforts provide a foundation for future endeavours with At-211-­based alpha-therapy at TRIUMF. All procedures were performed safely and rapidly, suitable for preclinical evaluations. All animal studies received institutional ethics approval from the University of British Columbia (UBC). / Graduate

Welding of duplex stainless steel pipeline material for the oil and gas industry is now common practice. To date, research has been conducted primarily on the parent material and heat affected zones in terms of its susceptibility to various forms of corrosion. However, there has been little research conducted on the degree of sensitisation of the various successive weld layers, namely the root, fill and cap layers. The focus of this research study was to: (i) provide an in-depth microstructural analysis of the various weld passes, (ii) study the mechanical properties of the weld regions; (iii) determine degree of sensitisation of the various weld passes; and (iv) investigate the residual stress levels within the various regions/ phases of the welds. Four test conditions were prepared using manual Gas Tungsten Arc Welding with 'V' and 'U' bevel configuration. Structural analysis consisted of (i) optical microscopy, scanning electron microscopy and magnetic force microscopy; (ii) ferrite determination using Magna-Gauge, Fischer Ferrite-scope and Point Count method. Mechanical testing consisted of Vickers hardness measurements, Charpy impact studies and transverse tensile testing. The degree of sensitisation was determined by three test methods: a modified ASTM A262, ASTM A923 and a modified Double Loop Electrochemical Potentiodynamic Reactivation (DL-EPR) test. Residual stress levels were determined using two neutron diffraction techniques: a reactor source and a time of flight spallation source. Microstructure observed by optical microscopy and magnetic force microscopy shows the formation of both fine and coarse structures within the weld metal. There was no evidence of secondary austenite, being present in any of the weld metal conditions examined. In addition, no detrimental intermetallic phases or carbides were present. The DL-EPR test results revealed that the fill layer regions for all four conditions and the base material showed the highest values for Ir/Ia and Qr/Qa. All four test conditions passed the ASTM A262 and A923 qualitative type tests, even under restricted and modified conditions. Residual stress measurements by neutron diffraction conducted at Lucas Heights Hi-Flux Reactor revealed that the ferrite phase stress was tensile in the heat affected zones and weld, and appeared to be balanced by a local compressive austenite phase stresses in the normal and transverse directions. Residual stress measurements by neutron diffraction conducted at Los Alamos Nuclear Science Centre revealed that in the hoop direction, ferrite (211) and austenite (311) exhibit tensile strains in the weld. In the axial and radial direction, the strains for both phases were more compressive. Correlations between the degree of sensitization and microstructural changes / ferrite content were observed. Higher degrees of sensitization (Ir/Ia and Qr/Qa) were associated with reduced ferrite (increased austenite) content. Correlations between the stresses generated, the evolved microstructures and degree of sensitization were evident. Stresses within the cap region were generally shown to be of a tensile nature in the transverse and longitudinal direction. In summary, the study has shown that correlations exist between the weld microstructure, susceptibility to sensitisation and levels / distribution of internal stresses within the weld regions.

Thesis (Ph.D.); Submitted to North Carolina State Univ., Raleigh, NC (US); 6 Apr 2005. / Published through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-211400" Dashdorj, D. 04/06/2005. Report is also available in paper and microfiche from NTIS.

This dissertation focuses on irradiations of a spallation set-up consisting of more than half a ton of natural uranium that were executed by a 660 MeV proton beam at the Joint Institute for Nuclear Reserch in Dubna. Two types of irradiations were arranged: with and without lead shielding. Both types were arranged with threshold activation detectors (Al-27, Mn-55, Co-59, and In-nat) located throughout the whole set-up both in horizontal and vertical positions and activated by secondary neutrons produced by spallation reaction. The threshold activation detectors were analysed by the method of gamma-ray spectroscopy. Radionuclides found in the threshold detectors were analysed and reaction rates were determined for each radionuclide. Ratios of the reaction rates were determined from irradiation of the set-up with and without lead shielding. Subsequently, the neutron spectra generated inside the spallation target at different positions were calculated using Co-59 detector. The experimental results were compared with Monte Carlo simulations performed using MCNPX 2.7.0.

Urychlovačem řízené podkritické systémy (ADS) se schopností transmutovat dlouhodobě žijící radionuklidy mohou vyřešit problematiku použitého jaderného paliva z aktuálních jaderných reaktorů. Stejně tak i potenciální problém s nedostatkem dnes používaného paliva, U-235, jelikož jsou schopny energeticky využít U-238 nebo i hojný izotop thoria Th-232. Tato disertační práce se v rámci základního ADS výzkumu zabývá spalačními reakcemi a produkcí tepla různých experimentálních terčů. Experimentální měření bylo provedeno ve Spojeném ústavu jaderných výzkumů v Dubně v Ruské federaci. V rámci doktorského studia bylo v průběhu let 2015-2019 provedeno 13 experimentů. Během výzkumu byly na urychlovači Fázotron ozařovány různé terče protony s energií 660 MeV. Nejdříve spalační terč QUINTA složený z 512 kg přírodního uranu, následně pak experimentální terče z olova a uhlíku nebo terč složený z olověných cihel. Byl proveden také speciální experiment zaměřený na detailní výzkum dvou protony ozařovaných uranových válečků, z nichž je složen spalační terč QUINTA. Výzkum byl především zaměřen na monitorování uvolňovaného tepla ze zpomalovaných protonů, spalační reakce a štěpení, způsobeného neutrony produkovanými spalační reakcí. Dále se na uvolňování tepla podílely piony a fotony. Teplota byla experimentálně měřena pomocí přesných termočlánků se speciální kalibrací. Rozdíly teplot byly monitorovány jak na povrchu, tak uvnitř terčů. Další výzkum byl zaměřený na monitorování unikajících neutronů z terče porovnávací metodou mezi dvěma detektory. První obsahoval malé množství štěpného materiálu s teplotním čidlem. Druhý byl složený z neštěpného materiálu (W nebo Ta), avšak s podobnými materiálovými vlastnostmi se stejnými rozměry. Unik neutronů (resp. neutronový tok mimo experimentální terč) byl detekován uvolněnou energií ze štěpné reakce. Tato práce se zabývá přesným měřením změny teploty pomocí termočlánků, s využitím elekroniky od National Instrument a softwaru LabView pro sběr dat. Pro práci s daty, analýzu a vizualizaci dat byl použit skriptovací jazyk Python 3.7. (s využitím několika knihoven). Přenos částic by simulován pomocí MCNPX 2.7.0., a konečně simulace přenosu tepla a určení povrchové teploty simulovaného modelu bylo provedeno v programu ANSYS Fluent (pro jednodušší výpočty ANSYS Transient Thermal).

A new measurement of the neutron electric dipole moment (nEDM) is being developed at TRIUMF, where a high density source of ultra cold neutrons (UCN) is currently under construction. A fast, high-efficiency UCN detector is needed for the experiment, and a 6-Li doped glass scintillation detector is being explored for this purpose. In this work, simulations and test measurements were carried out to optimize the light guide design for the new UCN detector. Acrylic and air-core light guides, the latter with two different reflecting surfaces, were considered. Three prototype light guides were constructed and tested, and results were compared with simulations. The best solution was found to be an acrylic guide, wrapped with mylar foil. For a guide 12 cm in length as required by the experimental layout, a lower limit of approximately 25 photoelectrons per neutron capture was established for the proposed geometry and photomultiplier configuration. / May 2016

<p>Accelerator-driven systems for transmutation of nuclear waste have been suggested as a means for dealing with spent fuel components that pose potential radiological hazard for long periods of time. While not entirely removing the need for underground waste repositories, this nuclear waste incineration technology provides a viable method for reducing both waste volumes and storage times. Potentially, the time spans could be diminished from hundreds of thousand years to merely 1.000 years or even less. A central aspect for accelerator-driven systems design is the prediction of safety parameters and fuel economy. The simulations performed rely heavily on nuclear data and especially on the precision of the neutron cross section representations of essential nuclides over a wide energy range, from the thermal to the fast energy regime. In combination with a more demanding neutron flux distribution as compared with ordinary light-water reactors, the expanded nuclear data energy regime makes exploration of the cross section sensitivity for simulations of accelerator-driven systems a necessity. This fact was observed throughout the work and a significant portion of the study is devoted to investigations of nuclear data related effects. The computer code package EA-MC, based on 3-D Monte Carlo techniques, is the main computational tool employed for the analyses presented. Directly related to the development of the code is the extensive IAEA ADS Benchmark 3.2, and an account of the results of the benchmark exercises as implemented with EA-MC is given. CERN's Energy Amplifier prototype is studied from the perspectives of neutron source types, nuclear data sensitivity and transmutation. The commissioning of the n_TOF experiment, which is a neutron cross section measurement project at CERN, is also described.</p>

Accelerator-driven systems for transmutation of nuclear waste have been suggested as a means for dealing with spent fuel components that pose potential radiological hazard for long periods of time. While not entirely removing the need for underground waste repositories, this nuclear waste incineration technology provides a viable method for reducing both waste volumes and storage times. Potentially, the time spans could be diminished from hundreds of thousand years to merely 1.000 years or even less. A central aspect for accelerator-driven systems design is the prediction of safety parameters and fuel economy. The simulations performed rely heavily on nuclear data and especially on the precision of the neutron cross section representations of essential nuclides over a wide energy range, from the thermal to the fast energy regime. In combination with a more demanding neutron flux distribution as compared with ordinary light-water reactors, the expanded nuclear data energy regime makes exploration of the cross section sensitivity for simulations of accelerator-driven systems a necessity. This fact was observed throughout the work and a significant portion of the study is devoted to investigations of nuclear data related effects. The computer code package EA-MC, based on 3-D Monte Carlo techniques, is the main computational tool employed for the analyses presented. Directly related to the development of the code is the extensive IAEA ADS Benchmark 3.2, and an account of the results of the benchmark exercises as implemented with EA-MC is given. CERN's Energy Amplifier prototype is studied from the perspectives of neutron source types, nuclear data sensitivity and transmutation. The commissioning of the n_TOF experiment, which is a neutron cross section measurement project at CERN, is also described.

This master’s thesis deals with usage of burn-up (spent) nuclear fuel in nuclear power plants of next generation – accelerator driven transmutation plants which is produced in current nuclear power plants. This system could significantly reduce the volume of dangerous long-lived radioisotopes and moreover they would be able to take advantage of its great energy potential due to fast neutron spectrum. In the introduction are listed basic knowledge and aspects of spent nuclear fuel along with its reprocessing and the possibility of further use while minimizing environmental impact. As another point detailed description of accelerator driven systems is described together with its basic components. In addition this search is followed by individual chronological enumeration of projects of global significance concerning their current development. Emphasis is placed on SAD and MYRRHA projects, which are used like base for calculations. This last, computational part, deals with the creation of the geometry of subcritical transmutation reactor driven by accelerator and subsequent evaluation which assembly is the most effective for transmutation and energy purposes along with changing of target, nuclear fuel and coolant/moderator.