The Woodruff School

SUMMARY

In this thesis the history and technical details of isotopic (a,n) neutrons sources are discussed. The use of U-232 as part of dirty uranium was proposed as a new isotope for use in beryllium (a,n) neutron sources. A [U-232]UBe13 neutron source was designed and modeled and the fluence and flux distributions were calculated. The U-232 decay chain emits six high energy alpha particles in quick succession and is ideal for use in a beryllium (a,n) neutron source. U-232 is an undesirable byproduct in the production of U-233 in the thorium fuel cycle; its concentrations can vary from 5-3000 ppm in bred U-233. A 1.1018-cm diameter by 1.1018-cm tall cylinder of [U-233]UBe13 with 300ppm U-232 at 0.74 GBq (20 mCi) was modeled and found to have a peak yield of 3.5*(10^5) n/s after 10.17 years. At this peak yield, the [U-232]UBe13 source has better neutron production efficiency per initial alpha emission activity than other beryllide neutron sources.

SUBJECT:	M.S. Thesis Presentation

BY:	Ryan Bechtel

TIME:	Thursday, June 8, 2006, 2:00 p.m.

PLACE:	Neely Building, 118

TITLE:	Uranium-232 Beryllide Neutron Source

COMMITTEE:	Dr. Nolan Hertel, Chair (NRE) Dr. Chris Wang (NRE) Dr. Daniel Tedder (ChBE)

SUMMARY In this thesis the history and technical details of isotopic (a,n) neutrons sources are discussed. The use of U-232 as part of dirty uranium was proposed as a new isotope for use in beryllium (a,n) neutron sources. A [U-232]UBe13 neutron source was designed and modeled and the fluence and flux distributions were calculated. The U-232 decay chain emits six high energy alpha particles in quick succession and is ideal for use in a beryllium (a,n) neutron source. U-232 is an undesirable byproduct in the production of U-233 in the thorium fuel cycle; its concentrations can vary from 5-3000 ppm in bred U-233. A 1.1018-cm diameter by 1.1018-cm tall cylinder of [U-233]UBe13 with 300ppm U-232 at 0.74 GBq (20 mCi) was modeled and found to have a peak yield of 3.5*(10^5) n/s after 10.17 years. At this peak yield, the [U-232]UBe13 source has better neutron production efficiency per initial alpha emission activity than other beryllide neutron sources.