Ensuring alternative air supplies for safety relief valves(SRV) in the event of a station blackout (SBO) at a Nuclear Power Plant (NPP) .

摘要

In the event of a long-term station blackout (SBO) at BWR, Safety Relief Valve (SRV) would cease to operate through loss of electric current and/or loss of air supply. However, SRV need to continue to be operated to ensure the safe shut-down of the nuclear power plant in question. In order to solve this problem, it is necessary to devise effective strategies. Followings show our counter measure for this problem. Two sets of valves are connected to the exhaust line of the air supply solenoid valve by a three-way air valve which switches the flow path by internal pressure. This valve has three connection ports called the pressure port, the exhaust port, and the cylinder port. The valves facilitate the air flow through the actuator by receiving pressure from the pressure port. Valve disks can switch closed port from the pressure port to the exhaust port. By the use of a valve at the exhaust line of a solenoid valve of SRV, it is possible to; (1) Maintain the exhaust line from the actuator port during operation/standby time. (2) Activate the air-operated valve by receiving pressure from the exhaust port through solenoid valve in the event of SBO. This enables SRVs to be operated, even in the event of an unexpected and severe accident caused by a prolonged station blackout.