1. Mild Environment Qualification and Maintenance
Marie Nemier, Seismic & EQ Manager - QualTech NP

2. Mild Environment Qualification and Maintenance
Outline
 Definition
Significant aging mechanisms
Example: Relay life extension program of naturally aged relays
Open Part 21 of relay
Importance of preventative maintenance / surveillance
Any actions required by SC-2

3. Definition IEEE 323-1983 IEEE 323-2003
An environment expected as s result of normal service conditions and extremes (abnormal) in service conditions where seismic is the only design basis event (DBE) of consequence.
IEEE
An environment that would at no time be significantly more severe than the environment that would occur during normal operation, including anticipated operational occurrence.

4. Definition (2) Significant aging mechanism definition
An aging mechanism that, under normal and abnormal service conditions, causes degradation of equipment that progressively and appreciably renders the equipment vulnerable to failure to perform its safety function(s) during the design basis conditions.

5. Significant aging mechanism examples
Pressure
Radiation
Operational cycles
Temperature
Humidity
Non-seismic vibration

6. Significant aging mechanism examples (2)
Normal state (i.e., Energized or De-Energized)
In–cabinet heat rise
In-cabinet air circulation
Proximity to other components

7. Relay Life Extension Test Program
Received over 100 relays from utility that were removed from service
Many relays were original equipment installed (~40yrs old)
Based number to test on the EPRI sampling plan

8. Relay Life Extension Test Program (2)
Types of relays:
Auxiliary
Control
Time Delay
Protective Over-voltage
Protective Over-current
Protective Differential
Lock-out

9. Relay Life Extension Test Program (3)
Program consisted of the following tasks:
Initial receipt inspection for any signs of deterioration
Functional test
Operational cycling -100 cycles at rated load
Seismic test
Final functional test
Evaluation

10. Relay Life Extension Test Program (4)
Relays were received with a great variability in condition
Most relays showed no signs of significant wear, degradation or damage
Common discovery – high contact resistance
Some relays were found with evidence of over-heating
Charred case
Cracked solder
Brittle case

11. Relay Life Extension Test Program (5)
Good Visual Condition with no Evidence of Degradation

12. Relay Life Extension Test Program (6)
Good Visual Condition with no Evidence of Degradation

13. Relay Life Extension Test Program (7)
Evidence of Over-Heating

14. Relay Life Extension Test Program (8)
Evidence of Over-Heating

15. Relay Life Extension Test Program (9)
Evidence of Over-Heating

16. Relay Life Extension Test Program (10)
Evidence of Brittle Plastic

17. Relay Life Extension Test Program (11)
Good Visual Condition with no Evidence of Degradation

18. Relay Life Extension Test Program (12)
Seismic Testing

19. Relay Life Extension Test Program (13)
Seismic Testing

20. Relay Life Extension Test Program (13)
Conclusions
Failures were not identified during preventative maintenance / surveillance
Significant aging mechanisms (in-cabinet heat rise and proximity to other components) impacted mild environment seismic qualification and the ability of the relay to perform its safety function during a DBE
The failures were not common mode – relays without significant aging mechanisms performed to original qualification levels or higher

21. Recently Issued Part 21 Event #49911 Docket #99901414
Filed by Waterford 3 on 3/13/14 regarding Allen Bradley 700RTC Timing Relays to QualTech NP supplied relays
Identified that the relays had a common mode failure causing the relay to spuriously de-energize
Failure investigated by SwRI and determined to be solder joint on control circuit and failed internal capacitor – failure unable to be replicated in the lab
Actions taken immediately: relays that are normally energized limited to 3 year qualified life

22. Recently Issued Part 21 (2)
QualTech NP Response
Part 21 did not draw a definitive conclusion that the failures were caused by manufacturing deficiency
Discussions with the plant found that the relays were installed in a fire rated cabinet with no ventilation or air flow
All 5 relays that failed were located in the top right of the panel
Normal temperature in the cabinet ºF
Relays are normally energized near maximum rated coil voltage (134Vdc vs Vdc)
Other relays installed at lower temperatures have had no failures

23. Recently Issued Part 21 (3)
QualTech NP Response
Inspection found localized discoloration of the relay
Tested the 700RTC relay at maximum coil voltage at 140ºF for several weeks with no failures
Internal gel inside capacitor had “dried out”
Although marginal solder joint and a degraded capacitor were found, there is no link to the reported failure
The failure is not caused by a defect but application specific conditions induced premature aging

24. Mild Environment Qualification Significant Aging Mechanisms
Summary
Requires evaluation of significant aging mechanisms to verify that there is no impact on ability of the component to perform its safety function during DBE
Mild Environment Qualification
Local conditions (i.e.; in-cabinet heat rise, normally energized, lack of air flow) need to be accounted for when qualifying
Significant Aging Mechanisms
White Paper
Annex Appendix in IEEE 323 or 344
Future actions?

25. http://qualtechnp.cwfc.com Marie Nemier 513.528.7900 ext.2137