Improved estimation of density of boron carbide control rods using digital X-ray radiography

Abstract

We report a new procedure for the accurate estimation of the density of a vibro-compacted boron carbide (B₄C) capsule using digital X-ray radiography combined with suitable beam pre-hardening filters. Under identical radiography exposure conditions, the grey values of both the boron carbide capsule and a standard stainless steel (SS) step-wedge are compared and the variation of density along the length of the capsule is evaluated. Without filters, due to the continuous X-ray spectrum, the absorption of mass thickness is influenced by soft X-rays and characteristic peak energy. Compared to the results obtained without filters, a 6 improvement in the density measurements is achieved with SS and brass filters in B₄C. To validate the procedure, density estimation was carried out in a pellet of TiO₂ with known density. For the TiO₂ pellet, the average densities estimated without filter and with filter were 3.93 g/cm³ and 4.13 g/cm³, respectively, against the actual value of 4.20 g/cm³ measured by gas pycnometry. The beam hardening correction led to a 5 improvement in the density estimation due to flattening of the X-ray spectrum by the filters.