The Japan Atomic Energy Agency uses criticality accident alarm systems to monitor the occurrence of any accidental criticality at the Tokai Reprocessing Plant (TRP). A total of six plastic scintillator-based detectors, newly purchased or developed for TRP, were tested by exposing them to pulsed radiation generated at the Transient Experiment Criticality Facility (TRACY), which is a pulse-type reactor that uses uranyl nitrate solution as fuel. All detectors tested responded properly to pulsed radiation that simulated an actual accidental criticality.