A new method for quantifying ⁶⁴Cu in nuclear debris samples

Quantifying ⁶⁴Cu in post-detonation nuclear debris samples can provide important diagnostic information regarding the structural materials used within a nuclear device. However, this task is challenging due to the weak gamma emissions associated with the decay of ⁶⁴Cu, its short half-life (12.701 h), and the presence of interfering fission product radioisotopes. Large quantities of debris sample are generally needed to accurately quantify ⁶⁴Cu, which can be problematic in sample-limited scenarios where other radiometric analyses are required. Herein, we present a new method for the separation of ⁶⁴Cu from solutions of mixed fission products and demonstrate the quantification of its activity through use of gas-flow proportional beta counting. The new method was validated through a series of rigorous tests and was shown to improve the detection limit of ⁶⁴Cu by over two orders of magnitude, from 2.5 × 10⁶ to 1.3 × 10⁴ atoms/sample for 100 min measurements.