Abstract: A thermally actuated shutdown seal provides a shutdown seal usable in a pump having a primary seal assembly positioned circumferentially about a rotating shaft for separating a region of high pressure coolant fluid from the shaft. The shutdown seal includes a two-piece interlocked housing which encompasses carbon graphite ring segments positioned circumferentially about the shaft, a garter spring and a series of compression springs. The replaceable insert with machined recess contains the shutdown seal assembly and is biased axially with a wave spring and held with the annular recess by a closure ring. The seal is designed with coolant fluid flow directly in contact with such ring segments and specially designed paths around the ring segments during normal pump operation.