Check valve test method for control rod drive.

摘要

In a hydraulic system of a control rod drive (D) for insertion of control rods (C), a test apparatus and test process is disclosed for determining the integrity of the hydraulic system check valve (22) for preventing inadvertent control rod ejection responsive to the reactor pressure. The check valve is located between a hydraulic valve (18) for causing rod insertion and a hydraulic cylinder containing an actuating piston (P). Downstream of the check valve, alteration is made to the hydraulic path by the installation of a conduit (40) with a quick disconnect (44,84) connected through an isolation valve (42). Test apparatus for temporary connection at the disconnect is disclosed consisting of a small positive displacement piston and cylinder (60) which connects to the quick disconnect through a rapidly opening toggle valve (71). Provision is made for timing the excursion of piston in the piston and cylinder preferably by end of stroke microswitches (66,74). When the quick opening valve (71) is opened, with resultant backflow from the hydraulic system through the check valve into the volume defined by the small displacement piston and cylinder (60), proper check valve operation and closure results in a long excursion time of the piston between the two microswitches: this indicates that the check valve seats and remains sealed to prevent control rod ejection. Control rod ejection is not permitted due to the small volume of the interrogating piston and cylinder. If the time of excursion of the piston between the two microswitches is short, there is an indication that the check valve has not properly seated and that control rod ejection is possible.