Mechanical and neutronic properties of neutron absorbing materials

“The primary neutron absorbing material examined in this project was Boraflex™, which consists of a silicone polymer with boron carbide acting as the neutron absorber. Two aluminum based neutron absorbers, Boral™ and Al-B-Ten, were also examined. Both X-ray and neutron radiography were used to examine the Boraflex™. The neutron radiography gave better resolution in detecting fluctuations in the boron carbide distribution; however, X-ray radiography did perform better in detecting flaws in the base material. Tensile tests were performed to determine the uniformity of Boraflex™\u27s tensile properties. The average tensile strength was calculated to be 303 ± 15 psi. A small angular dependence was found in the material; however, the tensile properties were uniform as a whole. Neutron activation analysis was used to identify the presence of trace impurities in the Boraflex™ that could become radioactive after long exposures to neutrons. The elements identified were magnesium, manganese, zinc, dysprosium, and lanthanum. The total removal cross section for thermal neutrons, and the absorption cross sections were also determined. The total cross section for Boraflex™ was 14 ± 1 barn. This was compared to Boral™, which had a cross section of 220 ± 20 TM barn. The absorption cross section for the Boraflex was 12 ± 1 barn. This value was compared to the absorption cross section of Al-B-Ten, which was 4.8 ± 0.5 barn”--Abstract, page iii