Radiolytic Degradation Studies on N,N‐dihexyloctanamide (DHOA) under PUREX Process Conditions

The radiolytic stability of DHOA, a high molecular weight N,N‐dialkyl amide has been investigated to evaluate its performance under PUREX process conditions vis–a–vis TBP. Gas chromatographic studies revealed the presence of caprylic acid, dihexylamine and dihexylketone in irradiated DHOA. Batch distribution studies of Pu, U, and fission products (¹⁴⁴Ce, ^103,106Ru, and ¹³⁷Cs) were carried out using the irradiated samples of 1.1 M DHOA and TBP in n‐dodecane, which showed significant retention of Pu, U, and fission products in the irradiated TBP as compared to that of DHOA even after successive contacts with the stripping solutions. Typically at 60 M Rad dose, the Pu content for DHOA was 1.4 mg/L after three contacts with 0.5 M HNO₃, and that for TBP was ～24 mg/L. White precipitate was observed at the interface during the stripping of Pu (with 0.5 M HNO₃) from the loaded irradiated TBP phase. The DHOA system, on the other hand showed no such problem during the stripping cycle but there was an increase in the density and viscosity for the irradiated DHOA.