Download ppt - Lessons Learned from Guy Wire and Anchor Replacement at Sequoyah Nuclear Plant by Doyle Pittman 12th NUMUG Meeting - 2008

Lessons Learned from Guy Wire and Anchor Replacement at Sequoyah

Nuclear Plant

by Doyle Pittman

12th NUMUG Meeting - 2008

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Background

• 91-m tower erected in 1970

• Advance 33 in. triangular, galvanized tower

• Instrumented at 3 levels

• 18, 3/8 in. guy wires

• 6 guy anchors

• 2003 and 2004 inspections:

– Replace guy wires

– Replace two guy anchors

– Install new grounding

• Work order but no $$


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Background Continued

• Guy wire tension checked every 3-years

• Self assessment in 2006 found no tolerance limit for tension

• Acceptable range = 1050 to 2250 pounds per square inch

• Six wires outside range

• Declared tower unsafe to climb March 2007

• Investigated alternative ways to reach instruments – mobile crane with basket


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Lesson 1- Need Civil Engineer Support

• Maintain tower specifications

• Perform structural analysis– replace or repair tower – wind load less than design

• Guy anchor placement– slope– clearance– ground disturbance

• Tower condition


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Lesson 2 – Need for Workplan

• Training

• Forms/approvals

– crane operation

– digging permit

– NEPA review

– job safety analysis

– rigging planning

• Pre-job brief

– weather conditions

• Contingencies

– concrete drying


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Lesson 3 – Regulatory Implications

• Degraded condition determination

• Calibration due dates– Tolerance

– Tracking

• Data recoverability

• Limiting Condition for Operation – Moved to technical requirements manual

– Any two of three wind levels

– One of three temperature differences


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Getting Closer!


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New Guy Wire and Anchor


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Success!!!
