Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 24 for “"U-235"”.
-
Measurement of energies of gamma-rays following the decay of Np-239 and fission products of U-235
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1961.
-
Radial power flattening in sodium fast reactors
… by varying the fuel volume fraction at a fixed U-235 enrichment of 18.5%. Of particular interest was how best to reduce the radial power peaking at the center of the reactor. Two cores were modeled: one with a uniform fuel volume fraction of 37% and one with fuel volume fractions which increased …
-
Dependence of transuranic content in spent fuel on fuel burnup
… and simulated with a three batch fuel cycle. U-235 enrichment was adjusted to achieve fuel burnups of 30, 50, 70 and 100 MWD per kg of initial uranium. These burnups demanded reload enrichments of 3.15%, 4.63%, 6.26% and 9.01% U-235 w/o respectively. The resultant spent fuel transuranic isotopic …
-
A one-dimensional fuel burnup model of a PWR
… a time interval. The isotopes considered were U-235, Pu-239, U-238, Xe-135, I-135, Sm-149, Pm-149 and the lumped burnable poison isotope. The flux was approximated by the sum of two trigonometric functions. The magnitude and shape of the flux were determined by holding power constant, …
-
Proliferation Resistance of Utilizing Enriched Reprocessed Uranium
… used fuel and its further enhancement after U-235 re-enrichment) compared to natural or reprocessed uranium. U-236, one of Pu-238 precursors, can enhance intrinsic barriers against Pu proliferation while practicing the recycling of used fuel. Until this time, the verification of the …
-
Helium-Air mixing in simulated reactor cavities of Very High Temperature Reactors
… gas-cooled reactors use graphite containing U-235 TRISO fuel particles in their core, as a moderator to slow down neutrons for fission chain reactions and for general core support. In the event of a primary circuit pipe break, the coolant gas escapes into the surrounding reactor cavity until …
-
Development of a 37-element fuel bundle for the production of molybdenum-99 in CANDU power reactors.
… Since Mo-99 is generated by the fission of U-235 with a fission yield of 6.1%, the proposed designs use enriched uranium in the Mo-99 producing fuel pins. The challenge lies in designing a fuel that is able to produce significant quantities of Mo-99 while having similar neutronics and …
-
Neutronic evaluation of GCFR core diluents and reflectors
… void reactivity than those started up using U-235 as the fissile material. While there are no ideal candidates that are superior in all respects, considering only neutronic performance, the following appear worthy of further investgation: Metallic fuel diluents or matrices (eg. CERMET or …
-
LEU-HEU Mixed Core Conversion Thermal-hydraulic Analysis and Coolant System Upgrade Assessment for the MIT Research Reactor
… of converting from the current 93%-enriched U-235 highly-enriched uranium (HEU) fuel to the low enriched uranium (LEU, <20%-enriched U-235) fuel, as part of the global non-proliferation initiatives. A high-density, monolithic uraniummolybdenum (U-10Mo) fuel matrix is chosen. The fuel element …
-
Micro-heterogeneous thorium based fuel concepts for pressurized water reactions
… configurations are as follows: (1) For a given U-235 inventory, a 20% to 30% increase in fuel cycle achievable bumup above the homogeneous case is possible, therefore 10% to 15% above the all-UO2 fuel; (2) For certain axially heterogeneous configurations, a "burnable poison" reactivity suppression …
-
Estimating warhead design properties from multiple resonances in physical cryptographic warhead verification
… the areal densities of the fissile isotopes U-235 and Pu-239 are virtually always estimated with less than 100% error. By adjusting the beam endpoint energy to 2.16 MeV, the error on the plutonium estimators is shown to increase substantially. The effect of isotopic enrichment on the quality of …
-
Optimal initial fuel distribution in a thermal reactor for maximum energy production
… to a reflected cylindrical reactor using U-235 as fuel and light water as moderator and reflector. Fissions in both fast and thermal groups are considered. The reactor is divided into several annular regions, and the constant flux approximation in each depletion step is then used to solve …
-
Analysis of in-core experiment activities for the MIT Research Reactor using the ORIGEN computer code
… analyses for ten individual elements (plus U-235 and U-238) that are commonly found in MITR in-core experiment (ICE) assemblies. The ORIGEN-S analyses for the ACI, HTIF, and EPRI ECP experiments produced results that were relatively similar to the results produced by previous analyses that …
-
Investigation of a direct method for measuring the resonance escape probability in thorium-water lattices
… consisted of a fission plate made of a disc of U-235 (0.900 inch in diameter, 5 mgs in weight) mounted at the end of a Cd-covered aluminum tube which conducted a beam of neutrons from inside the thermal column of the VPI reactor into the lattice. Cd-covered indium foils were used to measure. flux …
-
ADVANCED APPLICATIONS OF COSMIC-RAY MUON RADIOGRAPHY
… Provided that there is sufficient mass, U-235 could be differentiated from U-238 through muon induced fission.
-
Optimization and analysis of the laser isotope separation technique SILEX and ensuing proliferation ramifications
… to produce greater than 50% enriched U-235. A rigorous and holistic view of the technology will better inform policy by improving the accuracy of claims and identifying realistic solutions to problems the technology may pose. This thesis will seek to provide this deeply technical and …
-
The Design of Reactor Cores for Civil Nuclear Marine Propulsion
… propulsion core design, this study uses 18% U-235 enriched micro-heterogeneous ThO2-UO2 duplex fuel. To provide a basis for comparison we also evaluate the performance of homogeneously mixed 15% U-235 enriched all-UO2 fuel. This research also attempts to design a high power density core with 14 …
-
Nuclear Electric Propulsion with Low Enriched Uranium
… (HEU). Using low enriched uranium (LEU, 20% U-235 by mass) avoids many of the security costs and public perception issues associated with HEU but has implications for the power system design. The core will require more fuel and/or a moderator, increasing its size and mass. The use of a …
-
Feasibility Assessment of Adopting the ADDER Computer Code for the MIT Research Reactor Fuel Management
… to ± 100 pcm critical search tolerance, and U-235 mass differences remaining below 0.5 g per fuel element at end of cycle. Differences for other result types remain low enough to show the potential of transitioning to ADDER, with higher differences located near control blades when using the …
-
Impact of nuclear data libraries for criticality calculation of HTGR
… data because of larger thermal covariance of U-235 ̅_ data in ENDF/B-VIII.1. In addition, HTR-10 uncertainty is larger than HTTR uncertainty for both libraries. This could be attributed to smaller fuel volume ratio in the active core (V_fule/V_active core) of the HTR-10, therefore softer …
Page 1 of 2