In-situ Testing Technique for On-Going Cable Aging Assessments at Oyster Creek

Transcription

1 In-situ Testing Technique for On-Going Cable Aging Assessments at Oyster Creek Presented by: Chad Kiger EMC Engineering Manager AMS Corporation

2 Background Information Oyster Creek had experienced multiple low voltage cable degradation issues Established a strategy to address cable aging in adverse environments Engineering Team identified critical cables Developed a plan for inspection, testing, replacement, and contingencies Original plan would have required scaffolding in Condenser Bay and multiple contingency conduit runs Wished to identify an alternative/supplemental approach Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 2 of 17

3 EAB is the Acceptable Method for the Determination of Cable Life Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 3 of 17

4 Traditional In-situ Cable Aging Assessment Methods Elongation at Break (%) Indenter Modulus (N/mm) CABLE Visual Inspections Indenter Measurements 500 EAB End-of-Life Indenter Hours Aged Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 4 of 17

5 Visual Inspection Photographs Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 5 of 17

6 FDR is an In-Situ Electrical Method Sensitive to Degradation in Cable Insulation 0.46 Analysis Window Trending Aging Degradation 0 hours CAK FDR Signal (Rho) hours 2105 hours 3309 hours 5282 hours 8999 hours Distance (ft) CHALLENGE: Correlating results to objective aging criteria Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 6 of 17

7 Frequency Domain Reflectometry (FDR) Test Overview Incident FDR Signal Performed remotely with end device connected Inject a series of discrete sine waves (low voltage, non-destructive) Measure Return Loss (Frequency Domain) Perform Inverse FFT (Time Domain) Evaluate Rho value at different distances along the length of the cable Directional Coupler FDR Test System Insulation Damage Signal Source Reflected FDR Data Acquisition System and Analysis Distance Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 7 of 17

8 Why Reflectometry Tests Identify and Locate Changes in Cable Impedance Reflectometry Tests Measure Characteristic Impedance of Cables Z 0 Z 0 = 120 E r ln 2s d Permittivity (E r ) - measure of resistance encountered when forming electric field in a medium. FDR detects smaller changes in E r than other electrical test methods Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 8 of 17

9 Our Challenge: Develop Correlations Between EAB and FDR One year of accelerated aging of LV XLPE and EPR (thermal and radiation) cables Periodically performed EAB, FDR, Indenter Modulus, and others lab measurements Developed empirical correlations between EAB and FDR Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 9 of 17

10 EAB and FDR correlations from 10,000 Aging Hours XLPE Insulation Aged at 135 C Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 10 of 17

11 Acceptance Criteria to Quantify Cable Aging Degradation FDR Category % Aged Comments Little to no indication of age related degradation Initial indication that age related degradation has occurred >99 Cable insulation has significant aging but is expected to function normally Cable insulation is at or near its end-of-life condition as defined by 50% EAB Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 11 of 17

12 Cable Testing performed at Oyster Creek Cable ID Function Number of Conductors Number of Conductors Tested Turbine Control Cables Turbine Control: Vacuum Trip No Turbine Control: Vacuum Trip No Turbine Control: Backup Overspeed Trip Turbine Control: Main Trip Solenoid Turbine Control: Bypass Opening Jacking Motor Turbine Control: Load Limit Motor Turbine Control: Main Pressure Regulator Motor Turbine Control: Emergency Governor Trip Turbine Control: Governor Motor Turbine Control: Thrust Bearing Wear Test and Trip Condensate Pump 1A Control Condensate Pump 1B Control Condensate Pump 1C Control Reactor Feedwater Pump 1A Control Reactor Feedwater Pump 1B Control Reactor Feedwater Pump 1C Control Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 12 of 17

13 FDR Results of Turbine Control Cables Test results show that the cable falls into a Category 2 CABLE Turbine Front Standard Control Room Approx. Distance =120 Turbine Front Standard End of Cable Cable Spreading Room Control Room is one floor above Cable Spreading Room Control Room Total Approx. Distance = 120 All of the results (LCR, TDR, IR) do not indicate issues that would affect normal operation (i.e. nf capacitance, GΩ IR) Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 13 of 17

14 Rho Rho Delta Rho is much larger for a Turbine Control Category 3 Cable m FDR CAK m 400m 200m Feet 0 FDR Gate 1-50m -100m -110m Cable Category 3 Feet Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 14 of 17

15 Elongation at Break (%) Did you see the pictures of the cables? Accelerated Aging Time (Hours) Neoprene XLPE CSPE (Hypalon) Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 15 of 17

16 Conclusions FDR testing showed various levels of cable aging Jacket material may have degraded but the insulation material was still in good condition No cables had reached their end-of-life criteria (Category 4) Data significantly reduced scaffolding and conduit installation as well as visual inspections Enhanced personnel safety Reduced radiation exposure 14 days to 4 days total time Site estimated $3.7 million in outage savings Proprietary / Duplication Prohibited / Copyright 2017 by AMS Corporation Slide 16 of 17

17 Thank You!