Determination of La in U3Si/Al spent nuclear fuel by ion chromatography-inductively coupled plasma-mass spectrometry

Lanthanum has been used as one of the burnup monitor in spent nuclear fuel. U3Si/Al spent nuclear fuel contains small amount of La in high concentration of U and Al. Therefore, chemical separation of La is required to remove matrix elements. At first, ion chromatography (IC) and inductively coupled plasma systems were installed in radiation shielded glove box to handle the radioactive samples. Retention behavior of uranium, aluminum, lanthanum and some interesting fission products (Sr, Zr, Y, Mo, Ru, Pd, Rh, Cs, Ba, Ce, Pr, Nd, Sm, Eu, and Gd) was investigated using the CG10 column and α-HiBA eluent. As all elements were eluted earlier than lanthanum in 0.2 M α-HiBA eluent, a portion of U and Al was directly passed to waste using a three way valve between the column and the nebulizer. Thus it was possible to determine the lanthanum in a high concentration of U and Al matrix. Retention time of La was about 12 minutes in this separation condition. Optimum range for the determination of La in U3Si/Al spent nuclear fuel was 1-10 μg/L(ppb) with this system and detection limit was 0.25 μg/L in case of 200 μL of sample volume. (author)