Abstract: The test has been done for simulating the large current discharge of batterypackage, which may occur at the cut-ofi of mains for long-term while the reac-tor operates continuously at high power level in HWRR. The test was finished onthe aged battery package which was scheduled to be replaced. The test showed thebattery package system used as the. emergency power supply is effective for emer-gency cooling of the reactor core.