Advances in the Theory of Persistent Neutron Chains

The probability of initiating a persistent neutron chain in a multiplying assembly is calculated by solving the trunking problem associated with the Markov process of nuclear fission. For half a century, this problem has been solved by truncating fission multiplicities at two, an action known to reduce accuracy for both uranium and plutonium, which typically release between two and three neutrons per fission on average, with more possible for increasing neutron energy. The contributions of fission reactions which release larger number of neutrons are thus underestimated. This work extends the fission multiplicity up to fifth order, demonstrates that that upper limit is sufficient to provide confident estimates of initiation probabilities, extends Bell theory to allow for multiple neutron release in a single source event, provides estimates of the errors in current predictive models, and suggests an alternative method of extracting information from a probability distribution function.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nuclear Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Hill, James Lloyd

Contributors dc:contributor

• Axford, Roy A.

• Engineering, Nuclear

Language dc:language

eng

Identifier

(MiAaPQ)AAI9834689

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85938