Task(s): Method for removing PCV/RPV upper head, considering deformation and dose rate increase.

(4) Remove PCV/RPV upper head - Major challenges on the actual method

Removal

• Method for removing PCV/RPV upper head considering deformation, and sticking and biting of PCV/RPV upper head
• Management of the dose rate increase when removing PCV/RPV upper head
• Preparation of temporary storage
• Method for transportation of PCV/RPV upper head to the temporary storage
• Method for temporary placement of PCV/RPV upper head
• Method for transporting removed PCV/RPV upper head to another temporary storage
• Control method of atmospheric environment inside PCV after removing PCV/RPV upper

Plant information	Work space on the operation floor (Plain view) Dimension of RPV upper head Atmospheric environment inside PCV (temp, dose rate, etc.) Injection of nitrogen gas and gas control system

Prevention of dose rate increment

• Management of the dose rate increase when removing PCV/RPV upper head

Assumptions and prerequisites	Air dose rate inside the PCV/RPV - Dose rate inside the PCV 100Gy/h - Dose rate inside the RPV 1kGy/h Effective dose rate outside the PCV - Operation floor : 1mSv/h - Operation areas except for operation floor : 3mSv/h - Passageway inside the building : 5mSv/h Overhead crane specification (Rated load 100t）

→(5) Install equipment and access