Attachment 1 bfnper 155668 reactor bldg crane main hoist brake study
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Attachment 1 BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study PowerPoint PPT Presentation


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Attachment 1 BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study. Page 1 of4. Attachment 1 BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study. Introduction:

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Attachment 1 BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study

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Attachment 1 bfnper 155668 reactor bldg crane main hoist brake study

Attachment 1BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study

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Attachment 1 bfnper 155668 reactor bldg crane main hoist brake study1

Attachment 1BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study

  • Introduction:

  • BFNPER155668, During U1C7 outage, when the vessel head was raised approximately 4 inches off the vessel flange, the lift was stopped to verify a level rig to prevent binding on the guide caps or thread protectors. During this level check, the head slowly lowered back down to the reactor vessel flange. This slow lowering of the head was not observed by any of the riggers associated with the lift. After a short discussion between the Person in Charge (established per MMTP-103), the Flagman and the Crane Operator, a decision was made to lift the head again. The Refuel Floor Supervisor / Task Manager and the Refuel Floor SRO were not informed or consulted. It is important to note that the only personnel with the proper vantage point to see that the head had slowly lowered were the Person In Charge and the two craft personnel checking the head level. The vessel head was lifted a second time to approximately 4 inches and, again, the head slowly lowered back to the vessel flange. The lift was secured and the Refuel Floor Supervisor / Task Manager and the Refuel Floor SRO were informed.

  • The Refuel Floor SRO reported that the reactor building crane main hoist brake is slipping (10/27/2008 23:10) and declared the reactor building crane inoperable. WO 08-720819-000 was used to troubleshoot the crane and PER 155668 was initiated. The troubleshooting revealed the reactor building crane main hoist brake was out of adjustment. The brake was adjusted and retested satisfactory in accordance with MPI-0-111-CRA001, Reactor Building Overhead Crane Inspection, Testing and Preventative Maintenance. The Unit 1 Reactor Pressure Vessel Head was then successfully rigged to the refueling floor. Interviews with the personnel assigned as the Refuel Floor Supervisor / Task Manager revealed that, if consulted, they would have made the same decision as the Person in Charge to lift the head again.

  • Industry Event:

  • SER 2-85, Similar incident at San Onofre Unit 2, during the refueling sequence for reactor vessel head removal, an attempted lift of the reactor vessel head with the polar crane resulted in an unanticipated head lowering of about one inch to the seated position. This lowering was caused by malfunctioning components in the crane control circuit. About fifteen seconds after reenergizing the crane, the operator started to lift the head. When he operated the controls to raise the head, it descended about one inch and came to rest in its normal position on the reactor vessel. The operator then pushed the emergency stop button to stop all crane motion. He then tried the unloaded auxiliary hook, and it exhibited the same downward travel when subjected to an "up hoist" command.

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Attachment 1 bfnper 155668 reactor bldg crane main hoist brake study2

Attachment 1BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study

  • Training:

  • Courses MTS037.002, Rigging Fundamentals, MTS037.005, Pendant Crane Training, and MTS037.001, Overhead Crane Operator Training, teach trainees that when rigging a load to hold the load for a period of time after picking it up a few inches to test the brake to ensure the brake will hold. This is especially relevant if the load weight is close to the capacity of the hoisting device.

  • Procedures Changes:

  • MSI-0-000-LFT001, Rev. 49

  • Since procedure was lacking instructional detail for testing the crane brake when making a lift, the following was added to procedure Precautions/Limitations.

  • Section 3.0

    N. When performing a lift, if a crane abnormality or unknown malfunction is

  • encountered the following minimum requirements apply prior to continued

  • operation (this includes continued operation for troubleshooting purposes):

    • Place the load in a safe condition. Consult with Supervision if necessary to determine the safe condition.

    • Inform Supervision.

    • Perform crane safety checks in accordance with applicable procedures.

  • O. The Crane Operator shall test the brakes each time a load equal to or greater than 90% of the cranes rated capacity is handled. The brakes shall be tested by raising the load a few inches and applying the hoist brakes to ensure the load is held.

  • EPI-0-111-CRA009, Rev.10

  • The following changes were made to the Electrical annual inspection procedure for the Reactor Building Crane:

  • As-Found, As-Left Tables were for Main & Aux. Hoist Electric Brakes and added signoffs for 1st/2nd party.

  • Page3of4


    Attachment 1 bfnper 155668 reactor bldg crane main hoist brake study3

    Attachment 1BFNPER 155668, Reactor Bldg. Crane Main Hoist Brake Study

    • Summary:

    • (During U1C7) After lifting the U1 RPV head was lifted approximately 4" above the vessel flange to check leveling, the RPV head slowly drifted back down onto the vessel flange. After two sequential lift attempts troubleshooting revealed that the reactor building crane main hoist magnetic brake coil air gap was out of tolerance. The air gap was reset per brake vendor nameplate, the brake tension was re-tested and the crane was returned to service. Involved personnel continued making the lift twice more and wrote a troubleshooting work order.

    • Focus Area:

    • What mistake(s) was made?

    • What should have been done at the first lift?

    • When should the notifications have been made?

    • What consequences could have taken place?

    • What would have been the conservative action to take in this situation?

    • Expectations for future Crane Operations:

    • When performing a lift, if a crane abnormality or unknown malfunction is encountered, always use conservative decisionmaking and apply the following minimum requirements prior to continued operation (this includes continued operation for troubleshooting purposes):

    • STOP the lifting activity and PLACE the load in a safe condition. Consult with Supervision if necessary to determine the safe condition.

    • INFORM Supervision of the problem.

    • PERFORM crane safety checks in accordance with applicable procedures. - performed by qualified Crane Personnel

    • Remember to Stop When Unsure

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