Separation of boron in Zr-Nb alloys by pyrohydrolysis followed by its determination with ion chromatography

Advanced nuclear reactors use boron doped Zr-Nb alloy as neutron control rods. Fabrication of boron doped Zr-Nb alloy demands the determination of B content in the alloy as well as its distribution across the control rod. The method being followed for the determination of B in the Zr-Nb matrix involves its dissolution (concentrated H₂SO₄ and NH₄(SO₄)₂ mixture) followed by determination using either spectrophotometry or ion selective electrodes. Pyrohydrolysis (solid samples are heated in a moist carrier gas at high temperature to release F, Cl and B as their respective acids) is a separation technique capable of separating boron directly from a solid matrix and provides a clean interference free sample for further analysis. However, the pyrohydrolytic behavior of Zr-Nb alloy and separation of B is not much studied. In view of this, pyrohydrolysis behavior of Zr-Nb alloy was investigated with a view to achieve complete recovery of boron from the alloy