2026-09-20T10:43:29Zhttps://dspace.mit.edu/server/oai/request

oai:dspace.mit.edu:1721.1/1036542022-01-13T07:54:05Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023

Richard Lanza. Root, Margaret Ann Massachusetts Institute of Technology. Department of Nuclear Science and Engineering. Massachusetts Institute of Technology. Department of Nuclear Science and Engineering 2016-07-18T19:10:17Z 2016-07-18T19:10:17Z 2014 2015 http://hdl.handle.net/1721.1/103654 953278141 Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, September 2015. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Cataloged from student-submitted PDF version of thesis. Includes bibliographical references (pages 100-101). Nuclear nonproliferation efforts rely on a variety of safeguards to protect sensitive materials in nuclear facilities. The enrichment of fresh light-water-reactor fuel assemblies is verified by several inspectorates using the uranium neutron coincidence collar (UNCL), which uses neutrons from an americium lithium (241AmLi) source to interrogate the assemblies from one side. Eighteen 3He tubes on the other three sides are used to count the coincidence neutrons from the induced fission reactions. Experiments have shown that 252Cf could also be used to complete these measurements, providing several benefits over the use of the standard 241AmLi source. The UNCL is one of the many instruments that will be available for training purposes in the China Center of Excellence for Nuclear Security (COE), which is located in Beijing, China. This thesis contains a detailed characterization of the response of this detector with 252Cf as compared with 241AmLi and an analysis of the technical basis for the use of 252Cf in place of 241AmLi in the Antech N2071 Neutron Coincidence Collar. This thesis (1) discusses the development a benchmarked, high-fidelity model of the UNCL using Monte Carlo N-Particle Extended (MCNPX), version 2.7.4.a; (2) fully characterizes the detection parameters, including the efficiency profile, die-away time, and deadtime parameters; and (3) demonstrates the technical basis for the replacement of 241AmLi sources with 252Cf sources by assessing the penetrability of neutrons from each source, evaluating the statistical uncertainty in the measurements incurred by each source, and investigating the possibility of a higher effective average number of neutrons produced per fission using 252Cf rather than 241AmLi. This work demonstrates the suitability of 252Cf as a substitute for 241AmLi and in fact shows approximately a 7.5% improvement in counting statistics over the traditional interrogation source at 4% enrichment. by Margaret Ann Root. S.M. 112 pages eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Nuclear Science and Engineering. Technical basis for use of a correlated neutron source in the uranium neutron coincidence collar Thesis application/pdf Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="4249d1ea-7fa5-470b-b832-ed953acabdb1"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Technical basis for use of a correlated neutron source in the uranium neutron coincidence collar</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2015</PublicationDate> <Authors> <Author> <DisplayName>Root, Margaret Ann</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Nuclear Science and Engineering.</Keyword> <Abstract>Nuclear nonproliferation efforts rely on a variety of safeguards to protect sensitive materials in nuclear facilities. The enrichment of fresh light-water-reactor fuel assemblies is verified by several inspectorates using the uranium neutron coincidence collar (UNCL), which uses neutrons from an americium lithium (241AmLi) source to interrogate the assemblies from one side. Eighteen 3He tubes on the other three sides are used to count the coincidence neutrons from the induced fission reactions. Experiments have shown that 252Cf could also be used to complete these measurements, providing several benefits over the use of the standard 241AmLi source. The UNCL is one of the many instruments that will be available for training purposes in the China Center of Excellence for Nuclear Security (COE), which is located in Beijing, China. This thesis contains a detailed characterization of the response of this detector with 252Cf as compared with 241AmLi and an analysis of the technical basis for the use of 252Cf in place of 241AmLi in the Antech N2071 Neutron Coincidence Collar. This thesis (1) discusses the development a benchmarked, high-fidelity model of the UNCL using Monte Carlo N-Particle Extended (MCNPX), version 2.7.4.a; (2) fully characterizes the detection parameters, including the efficiency profile, die-away time, and deadtime parameters; and (3) demonstrates the technical basis for the replacement of 241AmLi sources with 252Cf sources by assessing the penetrability of neutrons from each source, evaluating the statistical uncertainty in the measurements incurred by each source, and investigating the possibility of a higher effective average number of neutrons produced per fission using 252Cf rather than 241AmLi. This work demonstrates the suitability of 252Cf as a substitute for 241AmLi and in fact shows approximately a 7.5% improvement in counting statistics over the traditional interrogation source at 4% enrichment.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>