Subtraction of high background due to fast neutrons in determining boron distribution by neutron induced autoradiography

Neutron induced autoradiography is known to be a powerful tool for the study of distribution of boron due to its extremely high cross section with thermal neutrons. The method is based on the detection of 10B(n, α)7Li reaction products with plastic track detector (CR-39) exposed to the neutron flux with a sample analyzed. The experiments were performed at the UVA Research Reactor in the thermal pneumatic irradiation tube with a cadmium ratio of ∼25 at the irradiation position. The radiograms were analyzed with the UTCHSA Image Tool software developed at the University of Texas Health Science Center. The method was developed and applied for the study of boron distribution in the nickel base alloy samples of Inconel 718 and Inconel 690 with ∼4 ppm of boron concentration, respectively. (A.A.D.)