Studies on U-Zr and U-Pu-Zr alloys for determination of Cl and F using pyrohydrolysis

Pyrohydrolysis method was studied for the separation of Cl and F from U-Zr and U-Pu-Zr alloy nuclear fuels and determination by ion chromatography. A detailed study was performed on pyrohydrolysed products of U-Zr alloy, obtained on heating in moist argon and oxygen atmospheres using X-ray powder diffraction (XRD) and thermogravimetric methods. Using oxygen as the carrier gas pyrohydrolysis performed at 900 C was complete within 30 min. It was found that, moist oxygen as carrier gas only could open the matrix completely within stipulated time. This was attributed to the formation of α-U3O8, which was not possible in moist argon heating for 30 min. The pyrohydrolysis in moist Ar required 60-90 min for complete removal of halides. The method was then successfully extrapolated to U-Pu-Zr alloys. The results showed recovery up to 90% or above for the optimized conditions.