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

Index > ⅱ) Considerations - 3. Seismic safety｜Example of method 1 "Retrieving fuel debris from the top (fixed transporting equipment)”

ⅱ) Considerations - 2. Boundary

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

  • Method for maintaining boundary is important in terms of prevention of release of radioactive material during the operation period

Issues requiring special attention 2. Boundary

(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

  • Maintain boundary function to prevent dispersion of radioactive material when checking condition inside the PCV/RPV

(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

  • Maintain boundary function to prevent dispersion of radioactive material during the period between the start of removing shield plug and the end of retrieving fuel debris

(8) Collect fuel debris and Transfer canisters

(9) Clean-up 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
  • Allowable load of operation floor and passageway :1.2t/㎡
  • Dimensional limit of operation floor and passageway : Width 1.2m･Height 3m
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