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 thermogravimtric methods. Using oxygen as the carrier gas pyrohydrolysis performed at 900 degrees 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 alpha-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.