In the Core Shroud Replacement Program, other RPV internal components (Noted * in the above figure) are removed to reduce the radiation source, to eliminate interference's and ultimately to replace other SCC susceptible components made of 304 stainless steel.
Toshiba has made it possible for human access into the RPV in order to perform core shroud replacement. This was accomplished through a very effective Chemical Decontamination and installation of In-vessel Shielding. Radiation exposure was further minimized by the application of remote automated tooling and mockup training.
Replacement Sequence
After chemical decontamination, the existing Core Shroud and other components are cut out underwater and removed. Then In-vessel shields are installed and finally, Jet Pumps, Core Shroud and other components are installed in turn.
