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Time dependent non-extinction probability for fast burst reactors


Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/9319

Time dependent non-extinction probability for fast burst reactors

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dc.contributor.author Gregson, Michael
dc.date.accessioned 2009-07-08T22:52:27Z
dc.date.available 2009-07-08T22:52:27Z
dc.date.issued 2009-07-08T22:52:27Z
dc.date.submitted May 2009
dc.identifier.uri http://hdl.handle.net/1928/9319
dc.description.abstract Sandia National Laboratories has successfully operated fast burst reactors over the past four decades. Fast burst reactors refer to a type of reactor that is able to achieve intense neutron pulses in very short periods of time using fissile material. Typically these systems are comprised of enriched metallic uranium fuel. During operation of a fast burst reactor, a phenomena known as a pre-initiation has been known to take place. A pre-initiation occurs when the neutron population exceeds some fiducial prior to achieving the final reactivity state in a pulse operation. Reactivity is determined from the physical configuration of the reactor and governs the average neutron population behavior. The purpose of this study is to examine the probability of initiation (or the pre-initiation probability) for a fast burst type of system, with emphasis on the Sandia Pulse Reactor-III (SPR-III) for physics parameters. The magnitude of the pre-initiation problem for SPR-III was examined to establish the magnitude of the phenomena. This work focuses on developing and numerically solving an equation that describes the non-extinction probability in a prompt critical assembly when the population is so low that it deviates from the average behavior. A zero dimensional (0-D) model is derived to describe the neutron non-extinction probability in a system where the reactivity is changing as a function of time. Analytical solutions to the model are provided where solutions could be found. Numerical solutions were obtained for a variety of cases applicable to fast burst reactor operation. Use of 0-D Monte Carlo techniques is also presented as a means to examine the low population stochastic behavior and for comparison to the deterministic solution. The 1-D time dependent equation for slab geometry was evaluated to highlight the importance of neutron leakage. The non-extinction probability equation was solved using a modified form of the standard fixed point iteration method. Other iteration techniques were also analyzed. Particular emphasis was extended to a linearized routine since the performance can be analyzed analytically and it allows for development of acceleration techniques. An accelerated routine was then developed and analyzed. The numerical performance between the iteration routines was thoroughly investigated. The impact of the acceleration routine on the iteration count and the associated decrease in runtime was evaluated. en_US
dc.description.sponsorship Sandia National Laboratories en_US
dc.language.iso en_US en_US
dc.subject stochastic en_US
dc.subject non-extinction en_US
dc.subject fast burst reactor en_US
dc.subject.lcsh Pulsed reactors--Mathematical models.
dc.subject.lcsh Nuclear reactors--Reactivity--Mathematical models.
dc.subject.lcsh Nuclear reactor kinetics--Mathematical models.
dc.title Time dependent non-extinction probability for fast burst reactors en_US
dc.type Dissertation en_US
dc.description.degree Doctor of Engineering en_US
dc.description.level Doctoral en_US
dc.description.department University of New Mexico. Dept. of Chemical and Nuclear Engineering en_US
dc.description.advisor Prinja, Anil
dc.description.committee-member Cooper, Gary
dc.description.committee-member Ueki, Taro
dc.description.committee-member Coutsias, Evangelos

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