A comparison of radioactive waste from first generation fusion reactors and fast fission reactors with actinide recycling

Limitations of the fission fuel resources will presumably mandate the replacement of thermal fission reactors by fast fission reactors that operate on a self-sufficient closed fuel cycle. This replacement might take place within the next one hundred years, so the direct competitors of fusion reactors will be fission reactors of the latter rather than the former type. Also, fast fission reactors, in contrast to thermal fission reactors, have the potential for transmuting long-lived actinides into short-lived fission products. The associated reduction of the long-term activation of radioactive waste due to actinides makes the comparison of radioactive waste from fast fission reactors to that from fusion reactors more rewarding than the comparison of radioactive waste from thermal fission reactors to that from fusion reactors. Radioactive waste from an experimental and a commercial fast fission reactor and an experimental and a commercial fusion reactor has been characterized. The fast fission reactors chosen for this study were the Experimental Breeder Reactor 2 and the Integral Fast Reactor. The fusion reactors chosen for this study were the International Thermonuclear Experimental Reactor and a Reduced Activation Ferrite Helium Tokamak. The comparison of radioactive waste parameters shows that radioactive waste from the experimental fast fission reactor may be less hazardous than that from the experimental fusion reactor. Inclusion of the actinides would reverse this conclusion only in the long-term. Radioactive waste from the commercial fusion reactor may always be less hazardous than that from the commercial fast fission reactor, irrespective of the inclusion or exclusion of the actinides. The fusion waste would even be far less hazardous, if advanced structural materials, like silicon carbide or vanadium alloy, were employed

Experimental investigation of the thermal-hydraulics of gas jet expansion In a two-dimensional liquid pool

"October 1978."Also issued as an M.S. thesis by the first author and supervised by the second author, MIT Dept. of Nuclear Engineering, 1978Includes bibliographical references (pages 115-117)Gas jet blowdown in a two-dimensional liquid pool has been experimentally investigated. Two sets of experiments were performed: a set of hydrodynamic experiments, where a non-condensible gas is injected into a subcooled liquid pool; and a set of thermal-hydraulic experiments, where a non-condensible heated gas is injected into a near saturated liquid pool. Liquid entrainment by the gas, bubble growth characteristics, and the potential for vaporization, were investigated for a variety of experimental pressures (3 to 10 bars) and two liquid types (water and R-113). Liquid entrainment increased with increasing pressure. The fraction of the jet volume which is liquid is relatively the same for all pressures and decreases with time of expansion. A Taylor instability mechanism for entrainment is found to under predict the entrained volume. In the initial stages of the expansion, higher entrainment is experienced for more dense fluids. For the same fluid, the entrainment rate was slightly higher for the heated experiments compared to the unheated experiments. Both lateral and vertical growth rates increased with pressure. Vaporization may have occurred for the 4 bar initial pressure, 12 °C superheat condition in freon R-113.Report issues under contract with the U.S. Nuclear Regulatory Commission NRC-04-77-12

Failure of Buildings Founded on Fills

A number of cases have come to light in Delhi recently where partial or total failure of buildings has occurred. Two cases of failures due to excessive settlement are discussed. The nature of distress and the geotechnical factors leading to failures were investigated. It was found that in both cases the foundations were resting on fills, resulting in excessive settlement. Remedial measures were considered and in one case, these have been successfully implemented. A large number of structures were thus rehabilitated

Forced convection degraded core cooling in light water reactors

Includes bibliographical references (pages 135-141)Work performed with support from E.G. & Idaho, In

Modeling of fuel-to-steel heat transfer in core disruptive accidents

"June 1980."Also issued as a Ph. D. thesis by the first author, MIT Dept. of Nuclear Engineering, 1980Includes bibliographical references (pages 110-111)A mathematical model for direct-contact boiling heat transfer between immiscible fluids was developed and tested experimentally. The model describes heat transfer from a hot fluid bath to an ensemble of droplets of a cooler fluid that boils as it passes through the hot fluid. The mathematical model is based on single bubble correlations for the heat transfer and a drift-flux model for the fluid dynamics. The model yields a volumetric heat transfer coefficient as a function of the initial diameter, velocity and volume fraction of the dispersed component. An experiment was constructed to boil cyclopentane droplets in water. The mathematical and experimental results agreed reasonably well. The results were applied to investigate the possibility of steel vaporization during a hypothetical core disruptive accident in a liquid metal fast breeder reactor. The model predicts that substantial steel vaporization may occur in core disruptive accidents, if the steel reaches its saturation temperature rapidly enough. The potential importance of steel vaporization is dependent on the accident scenario.Report issued under contract with the U.S. Nuclear Regulatory Commission NRC-04-77-12

Theoretical studies on some aspects of molten fuel-coolant thermal interaction.

Massachusetts Institute of Technology. Dept. of Nuclear Engineering. Thesis. 1973. Ph.D.Includes bibliographical references.Ph.D

Harmonically Resonant Cavity as a Bunch-Length Monitor

A compact, harmonically resonant cavity with fundamental resonant frequency 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Electron Beam Accelerator Facility (CEBAF) photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM). A cavity antenna attached directly to a sampling oscilloscope detected the electron bunches as they passed through the cavity bore with a sensitivity of ∼1  mV/μA . The oscilloscope waveforms are a superposition of the harmonic modes excited by the beam, with each cavity mode representing a term of the Fourier series of the electron bunch train. Relatively straightforward post-processing of the waveforms provided a near-real time representation of the electron bunches revealing bunch-length and the relative phasing of interleaved beams. The noninvasive measurements from the harmonically resonant cavity were compared to measurements obtained using an invasive RF-deflector-cavity technique and to predictions from particle tracking simulations

Measuring and Controlling the Energy Spread in CEBAF

As compared to electron storage rings, one advantage of recirculating linear accelerators is that the beam properties at target are no longer dominated by the equilibrium between quantum radiative diffusion and radiation damping because new beam is continually injected into the accelerator. This allows the energy spread from a CEBAF-type machine to be relatively small; the measured energy spread from CEBAF at 4 GeV is less than 100 parts per million accumulated over times of order several days. In this paper, the various subsystems contributing to the energy spread of a CEBAF-type accelerator are reviewed, as well as the machine diagnostics and controls that are used in CEBAF to ensure that a small energy spread is provided during routine running. Examples of relevant developments are (1) stable short bunches emerging from the injector, (2) precision timing and phasing of the linacs with respect to the centroid of the beam bunches on all passes, (3) implementing 2 kHz sampling rate feedback systems for final energy stabilization, and (4) continuous beam energy spread monitoring with optical transition radiation devices. We present measurement results showing that small energy spreads are achieved over extended periods.Comment: 5 pages, 5 figures, Invited Paper TH205 at 2000 International Linac Conferenc