To investigate the applicability of the Feynman- (or variance-to-mean) and Rossi-α techniques to subcriticality monitoring of the future accelerator-driven subcritical reactor (ADSR), a series of experiments was performed at the Kyoto University Critical Assembly (KUCA). To simulate the pulse mode operation of the ADSR, a D-T pulsed neutron generator was employed. As a result, it was observed that the α-values measured by these techniques clearly depended on the subcriticality, ranging from $0.65 to $2.72. Furthermore, through measurements in transient states that were realised by operating control rods, it was found that one can detect subcriticality changes in quasi-real-time. © 2006 Inderscience Enterprises Ltd.