Task(s): Retrieval method, considering post processes and prevention of dose rate increase.

(3) Remove shield plug - Major challenges on the actual method

Transport / install equipment

• Places to assemble and install equipment for removing shield plug, if necessary
  
• Equipment to be used for assembly
• Maintenance of equipment and actions to trouble

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） Effective dose rate outside the PCV - Operation floor : 1mSv/h - Operation areas except for operation floor : 3mSv/h - Passageway inside the building : 5mSv/h

Removal

• Method for removing shield plug, considering possible deformation, and sticking and biting of the shield plug
• Preparation of temporary storage, and method for temporary placement of the removed shield plug
• Method for transportation of shield plug to the temporary storage
• Method for temporary placement of shield plug
• Method for transporting removed shield plug to another temporary storage

Plant information	Work space on the operation floor (Plain view) Dimension of shield plug

Countermeasures on dose increase

• Management of dose rate increase when removing shield plug
• Consideration of shielding substitutes for the shield plug

→(4) Remove PCV/RPV upper head