Lessons Learned from Guy Wire and Anchor Replacement

Lessons Learned from Guy Wire and Anchor Replacement at Sequoyah Nuclear Plant by Doyle Pittman 12 th NUMUG Meeting - 2008 EPRI 2008 International LLW Conference

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 $$ 12 th NUMUG Meeting - 2008 2

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 12 th NUMUG Meeting - 2008 3

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 12 th NUMUG Meeting - 2008 4

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 12 th NUMUG Meeting - 2008 5

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 12 th NUMUG Meeting - 2008 6

Getting Closer! 12 th NUMUG Meeting - 2008 7

New Guy Wire and Anchor 12 th NUMUG Meeting - 2008 8

12 th NUMUG Meeting - 2008 9

Success!!! 12 th NUMUG Meeting - 2008 10