Gas escape pressure testing device and method

A gas escape pressure testing device and a testing method, pertaining to the technical field of high-level radioactive waste disposal. The testing device comprises a cylindrical body (6) used to contain a sample (5). A sealing segment is formed on an inner wall of the cylindrical body (6). One end of the cylindrical body (6) is a gas inlet end and another end of the cylindrical body (6) is a gas discharge end. A gas delivery device is connected to the gas inlet end, and a gas monitoring device is connected to the gas discharge end. The sealing segment is fabricated on the inner wall of the cylindrical body (6), so as to enable the expansible sample (5) to expand after absorbing water in order to block the sealing segment and to achieve a seal, such that a contact surface in a vertical direction between the sample (5) and the cylindrical body (6) is no longer smooth, thereby preventing gas from escaping from the interface between the sample (5) and the cylindrical body (6), and effectively improving the accuracy of a gas escape pressure testing result.