Example of method 1 "Retrieving fuel debris from the top (fixed transporting equipment)”

ⅰ) Challenges and reference information : (4) Remove PCV/RPV upper head

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

(1)Prior preparation (2)Install barrier (3) Remove shield plug (4) Remove PCV/RPV upper head (5) Install equipment and access (6) Dismantle and remove internal structures (7)Retrieve fuel debris (8) Collect fuel debris and Transfer canister (9) Clean-up equipment

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

 

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)