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

ⅰ) Challenges and reference information : (2) Install barrier

Task(s): Installation of barrier based on the dose rate and allowable load of the floor, and equipment specification inside the barrier.

Arrangement of work environment to install barrier for preventing leakage of radioactive substance
Condition of damage and difference in level on operation floor and allowable load of operation floor
Design of areas for barrier assembly and temporary storage of materials on operating floor
Monitoring of radiation after installing barrier

Plant information	Atmospheric environment inside PCV (temp, dose rate, etc.) Plain view (Unit 1) Plain view (Unit 2) Plain view (Unit 3)

Assumptions and prerequisites	Assume that the rubbles are removed and decontamination work proceeds in 2020 when fuel debris retrieval starts No shielding or air tight function for boundary by the container covering operation floor is counted Effective dose rate outside the PCV - Operation floor : 1mSv/h - Operation areas except for operation floor : 3mSv/h - Passageway inside the building : 5mSv/h

Transportation of barrier (Disassemble into the parts to be transferred)
Assembly and installation of barrier
Weight reduction of barrier with shielding function
Design of transportation, shielding equipment, ventilation facility, etc. inside the barrier
Installation of ventilation facilities
Maintenancing boundary when carrying in and out equipment from/to the barrier etc.

Plant information	Work space on the operation floor (Plain view)

Assumptions and prerequisites	Allowable load of operation floor and passageway : 1.2t/㎡ Size of equipment which should be transported through passageway : Width 1.2m, Height 3m or less Overhead crane specification (Rated load 100t） Use existing opening, hatch, and stairs inside the reactor building for accessing each floor and delivering the equipment to each floor. No new openings, in principle, shall be created on the outer wall of the building　(Seismic resistance and leakage prevention of radioactive materials shall be considered when creating new openings)

Assumptions and prerequisites

Allowable load of operation floor and passageway : 1.2t/㎡
Size of equipment which should be transported through passageway : Width 1.2m, Height 3m or less
Overhead crane specification (Rated load 100t）
Use existing opening, hatch, and stairs inside the reactor building for accessing each floor and delivering the equipment to each floor. No new openings, in principle, shall be created on the outer wall of the building　(Seismic resistance and leakage prevention of radioactive materials shall be considered when creating new openings)