Herein, we employ the threshold energy neutron analysis (TENA) technique to introduce the world's first active interrogation system to detect special nuclear materials (SNMs), including U-235 and Pu-239. The system utilizes a DD neutron generator based on inertial electrostatic confinement (IEC) to interrogate suspicious objects. To detect secondary neutrons produced during fission reactions induced in SNMs, a tensioned metastable fluid detector (TMFD) is employed. The current status of the system's development is reported in this paper, accompanied by the results from experiments conducted to detect 10 g of highly enriched uranium (HEU). Notably, the experimental findings demonstrate a distinct difference in the count rates of measurements with and without HEU. This difference in count rates surpasses two times the standard deviation, indicating a confidence level of more than 96% for identifying the presence of HEU. The paper presents and extensively discusses the proof-of-principle experimental results, along with the system's planned trajectory.

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