Measure to solve technical subjects in MARICO-2 subassembly retrieval. Experimental Fast Reactor Joyo Oarai R&D Center, JAEA

Transcription

1 Measure to solve technical subjects in MARICO-2 subassembly retrieval Experimental Fast Reactor Joyo Oarai R&D Center, JAEA 1

2 Status of MARICO-2 test subassembly (S/A) Rotating Plug Hold-down shaft Hold-down shaft MARICO-2 Holding Mechanism Reactor Vessel UCS core In-vessel storage rack MARICO-2 S/A Approx.90mm Bent MARICO-2 S/A Hold-down shaft Transfer pot UCS R-15 R-16 Approx. 200mm MARICO-2 S/A Transfer pot Image of in-vessel Results of in-vessel observation 2

3 Status of MARICO-2 test subassembly (S/A) A handling head has come out from S/A. S/A cannot be gripped by the ordinary refueling machine. Test S/A The length of the bent part of S/A is more than 200 mm. It cannot pass through the fuel exchange hole. Transfer pot A degree of mechanical interaction between S/A and the transfer pot should be taken into consideration in the design of a retrieval device. The bent S/A is losing its balance. Normal state State of MARICO-2(S/A) 3

4 Development of gripper mechanism for retrieving MARICO-2 S/A 4

5 Development of gripper mechanism possible possible 1 st Plan Gripping & retrieving S/A singly impossible impossible S/A is bent onto the in-vessel storage rack impossible possible 2 nd Plan Gripping pot and retrieving together 3 rd Plan Gripping both of pot and S/A Retrieving together 5

6 Handle Preliminary in-vessel test(1) MARICO-2 S/A lift-up test Two Claws Type Gripper Transfer pot Inspection hole(a) Rotating Plug Gripper Transfer pot (Dummy) MARICO-2 S/A Two Claws Type Gripper It is confirmed that MARICO-2 S/A is stuck in transfer pot owing to its deformation. Equipment to retrieve MARICO-2 S/A together with transfer pot is required. Lift-up equipment MARICO-2 S/A (Dummy) to grip and lift up the transfer pot is required. 6

7 Gripping position of transfer pot and gripper structure The observed gap between MARICO-2 S/A and a pot is narrow. It was uncertain whether a single hook type gripper could insert. Estimated outline of S/A Inner diameter of opening of a transfer pot (107mmφ) Expected Space which can insert a single hook (30mm X 30mm) Image of Single hook type gripper (Latch finger) Na level 7

8 Preliminary in-vessel test(2) Preliminary in-vessel test was conducted to demonstrate latch finger performance. Latch finger Latch finger UCS Holddown shaft Dummy transfer pot Dummy S/A Fiberscope Latch finger MARICO-2 S/A Latch finger MARICO-2 S/A MARICO-2 S/A Latch finger Transfer pot 70mm Insertion of latch finger Lifting up MARICO-2 S/A 8

9 Decision of gripper mechanism Preliminary in-vessel tests show; - Detachment of S/A from pot is impossible - Grip and Lift of transfer pot are possible by the latch finger possible possible 1 st Plan Gripping & retrieving S/A singly impossible impossible S/A is bent onto the in-vessel storage rack impossible possible 2 nd Plan Gripping pot and retrieving together 3 rd Plan Gripping both of pot and S/A Retrieving together 9

10 Basic structure of gripper mechanism Transfer pot Wire rope Latch finger MARICO-2 S/A Spring Latch finger Pot supporting nose Outline of gripper mechanism Design point - Shape of latch finger is based on the fuel exchange machine which handles transfer pot normally - Single latch finger is improved its reliability through changing to the higher strength material. 10

11 Access to MARICO-2 S/A position 11

12 Large R/P Small R/P Access route for retrieval Fuel handling hole (φ164mm) (Largest route in existing penetration holes) In-vessel inspection hole (B) (Φ110mm) Geometric condition The length of bent part of MARICO-2 S/A > 200mm Transfer pot MARICO-2 Approx. 200mm 1m Access route to retrieve MARICO-2 is UCS hole (1m) by geometric size MARICO-2 UCS UCS MARICO-2 In-vessel inspection hole (A) (Φ110mm) Approx. 70mm Approx. 90mm UCS cannot be positioned right above MARICO-2 to avoid a contact with it. The retrieval device employs offset configuration 12

13 Pantograph mechanism and manner of retrieving A hole where the UCS was extracted Thermal insulating plate Ex-vessel test Offset Upper arm Lower arm 1) Extending arms to right above position of MARICO-2 and lift up the pot 2) Avoiding the in-vessel thermal insulating plate by folding upper arm 3) pulling up to diagonally upward 4) Folding lower arm and Storing MARICO-2 to a guide sleeve Movement of each component such a hoist mechanism and a pantograph mechanism were carefully checked by ex-vessel test. 13

14 Image of MARICO-2 retrieval 14

15 Guide tube Transfer pot Design for reliable gripper mechanism 3.2)Lock pin 4) Break of hoist wire 4.1) Enough strength wire 4.2) Backup by wire operating latch finger Guide rail Gripper mechanism Front view 3.1) Lock lever 3) Trip of latch finger 2) Break of latch finger Side view 1) Failure in gripping operation 1) In-vessel observation Causes of failure 1) Failure in gripping operation 2) Break of latch finger 3) Trip of latch finger 2) Enough strength material 4) Break of hoist wire Measures 1) In-vessel observation device is prepared to monitor the gripping operation. 2) Enough strength material which has 7 times strength of the maximum stress. 3.1) Lock lever When pot is lifted up by hoist wire, the lock lever makes grip tight by weight of pot 3.2) Lock pin When pot is lifted to upper position, lock pin is push on lock lever. 4.1) Enough strength wire which has 13 times strength of the maximum stress. 4.2) Backup by wire operating latch finger which is designed as same diameter with the hoist wire. 15

16 Maintain of boundary of MARICO-2 retrieval device 16

17 Boundary structure of MARICO-2 retrieval device Main boundary is formed by steel wall. Manual handles in the boundary is needed to stretch the pantograph. Install of Glove box Upper guide sleeve and bellows (Steel boundary) Lower guide sleeve (Steel glove box) Handles to stretch Pantograph mechanism Hoist handle 17

18 Safety measures for work in glove box Ventilation of Argon Argon gas blow-down Upper guide sleeve (Steel boundary) Lower guide sleeve (Steel glove box) Polycarbonate window Working pressure range : Pa (Design pressure: 1000Pa) Open and Close dependent on situation Lid Glove Small R/P Main boundary is formed by steel wall. A steel lid is installed to shut convection of Ar cover gas. By appropriate Argon gas blow-down, convection of Ar cover gas is prevented. In-vessel Argon cover gas Glove port cover (to close port when glove is not used) 18

19 Measure for unexpected incident - Safety measures against falling accident of transfer pot - Provision for unexpected incident in MARICO-2 retrieval work 19

20 Safety measures against falling of transfer pot (1) Stopper mechanism of falling pot Wedge Cotter Roller (2) Shock absorber Shock absorber at bottom Large dia. Small dia. Unlocking In lifting operation Roller rides up along the wedge of in mobile space in housing. In falling accident Roller slips down along the wedge and constrict the pot. Unlocking The stopper is unlocked by a lift of the cotter. 20

21 Provision for unexpected incident in MARICO-2 retrieval work Unexpected incident Return of the pot to the initial position Preparation of operation manual including the initial response in unexpected incident Full mockup test in manufacturer s factory - Confirmation of operation procedures including return to initial position - Careful checking and revising manual - Training of operators Investigation of incident and its cause Measure based on the cause analysis Fiberscope type observation device monitors and records in-vessel status during retrieval work Preparation of the inspection work area The equipment pit is available as inspection area in the reactor containment vessel Retry 21