By using HR-ICP-MS, the isotopic ratios of neodymium isotopes (
142 Nd,
143
Nd,
144 Nd,
145
Nd,
146 Nd,
148 Nd, and
150 Nd), samarium isotopes (
147 Sm,
148 Sm,
149 Sm,
150 Sm,
151 Sm,
152 Sm, and
154 Sm), europium isotopes (
151 Eu and
153 Eu), and
gadolinium isotopes (
152 Gd,
154 Gd,
155 Gd,
156 Gd,
157 Gd,
158 Gd, and
160 Gd) in
spent fuels were determined. The concentrations of
97 Mo,
99 Tc,
101 Ru,
103 Ru, and
109 Ag in the residue solution were analyzed by HR-ICP-MS by adopting the
calibration curve method.
This new measurement method has the following merits.
1. It requires a sample of 10 μg, one-tenth of the amount required for use of TIMS.
2. We need 5 days to obtain results, which is one-sixth of the time required by the
previous method using TIMS.
3. Obtained accuracy (1s) is approximately 1 %, which is sufficient considering the
required measurement error.
Figures 6.6, 6.7, and 6.8 are examples of measurement results for
101
Ru,
103 Rh,
and
150 Sm, respectively.
Fig. 6.2 Position of
samples taken from ZN3
fuel assemblies (average
burn-up, 53.5 GWd/t) [4]
6 Development of the Method to Assay Barely Measurable Elements in Spent. . .
51