Example of method 2 "Retrieving fuel debris from the top (mobile platform)”

Index > Considerations - 1. Dose reduction|Example of method 2 "Retrieving fuel debris from the top (mobile platform)”

ⅱ) Considerations - 1. Dose reduction

Issues to be noted for the proposing method in terms of safety are explained below.

  • Clarification of objects for mote and close oprations
  • Method to minimize the workers' exposure

Issues requiring special attention 1. Dose reduction

(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

(1) Prior preparation

  • Dose reduction for workers when transporting/installing equipment and removing it
  • Dose reduction for workers when investigating

(2) Install barrier

  • Dose reduction for workers when installing barrier

(3) Remove shield plug

  • Dose reduction for workers when removing shield plug
  • Dose rate reduction for external environment when removing shield plug

(4) Remove PCV/RPV upper head

  • Dose reduction for workers when removing PCV lid/RPV head
  • Dose reduction for external environment when removing upper head

(5) Install equipment and access

(6) Dismantle and remove internal structures

  • Dose reduction for workers and external environment when dismantling and removing internal structures

(7) Retrieve fuel debris

  • Exposure of workers when cutting fuel debris
  • Dose reduction for external environment when cutting and storing fuel debris

(8) Collect fuel debris and transfer canisters

  • Dose reduction for workers when storing fuel debris
  • Dose reduction for external environment when storing fuel debris and transferring canisters
  • Dose reduction for external environment affected by the radiation from temporary storage area

(9) Clean-up equipment

  • Dose reduction for external environment when removing equipment
Plant information>
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