Development of Sealing Structure of Control Rod Drive Mechanism and Its Prototype Test

In order to confirm the effectiveness of a newly designed seal structure of CRDM which will be applied on floating nuclear power plants (FNPP), a prototype of the seal structure was trial-manufactured. The prototype went through hydrostatic test, cyclic hydrostatic test, thermal test, cyclic thermal test and multiple installation-uninstallation tests. The tests followed the instructions of industrial standard, and the test condition was same as that of the primary loop of a typical FNPP. The prototype went through all the cold and hot fluid tests without visible leakage, abnormal sound, visible damage of all mechanical parts and other abnormities. The trapezoidal threads of the seal structure were still in good form after 60 times installations and uninstallations. In a word, the performance of the seal structure was successfully proved through the prototype test.