ENS 53653
ENS Event | |
|---|---|
04:00 Aug 7, 2018 | |
| Title | Part 21 Notification - Namco Limit Switch Failed Test Due to Insufficient Lubrication |
| Event Description | The following information was received via email from Curtiss Wright:
Curtiss-Wright was notified on August 7, 2018 by Exelon's Dresden Plant that a Curtiss-Wright Supplied Namco Limit Switch, P/N: EA700-90964 had failed during a planned maintenance test. The switch contacts were found to be sluggish in returning to the normal shelf state after actuation, or would not return at all. The switch was identified as Curtiss-Wright Tag Number 5T34603 and was provided as a safety related component to Exelon in September 2005. According to Exelon, the item was stored for 8 years, then failure occurred approximately 5 years into service. The part has a manufacturer date coded as August 2005. The switch was subsequently sent to Exelon Powerlabs where a detailed failure evaluation was performed. Exelon Powerlabs confirmed the failure mode and determined that there was insufficient lubrication in place to support normal switch function. The switch was then sent to Namco for further evaluation and Namco confirmed the lack of lubricant was the likely cause of the failure. Curtiss-Wright is currently investigating this issue and will provide a follow up report by November 15, 2018.
The following information was received via E-mail: In reference to the Curtiss-Wright Interim Notification Report dated 10/8/2018 for an EA700-90964 limit switch failure, the following clarifications and updates are provided. The subject switch was originally supplied by Curtiss-Wright to Exelon's Dresden plant. Subsequently Dresden transferred the switch to Quad Cities where it was installed and found degraded and inoperable during a planned maintenance test. The initial notification of failure to Curtiss-Wright was by Quad Cities personnel, and not Dresden personnel. The switch was previously identified as Curtiss-Wright Tag Number 5T34603, which was incorrect. The actual Tag Number of the failed unit is 5T36403. The failure is still under investigation and Curtiss-Wright has been in communication with the manufacturer, Quad Cities personnel and Exelon Powerlabs personnel concerning the failure and application. A key factor in the failure appears to be heat related, specifically the switches operating temperature. As such, additional operating temperature data is being taken by Exelon personnel which will conclude in late February or early March 2019. Once this data is made available, a final conclusion as to the root cause of the failure can be determined. We therefore request additional time to complete our evaluation and should have our final report issued by March 8th, 2019. Notified R3DO (Peterson) and Part 21/50.55 Reactors E-mail group.
The following information was received via email: In reference to the Curtiss-Wright Interim Notification Report dated 10/8/2018 for an EA700-90964 limit switch failure, the following updates are provided. Curtiss-Wright's investigation is ongoing, with the current focus being the evaluation of in-service switch operating temperatures and results from a recent disassembly/inspection of similar switches (same model but different date codes). Additional inspection of other switches currently in-service at the plant is needed to finish the investigation. Evaluation of these switches is expected to be completed by mid-May. Once this data is made available, a final conclusion as to the root cause of the failure can be determined. We therefore request additional time to complete our evaluation and should have our final report issued by May 31, 2019. Notified R3DO (Hills) and Part 21/50.55 Reactors group (email).
The following information was received via e-mail: ln reference to the Curtiss-Wright Interim Notification Report dated 10/8/2018 (Event No. ML18289A457lLoC No. 2018-24-00) for an EA700-90954 limit switch failure, the following updates are provided. Curtiss-Wright was notified on August 7th, 2018 by Exelon's Quad Cities Plant that a Curtiss-Wright Supplied Namco Limit Switch, PIN: EA 700-90954 had failed during a planned maintenance test. CW Conclusion: Based upon similar wear patterns, the presence of 'significant grease' does not resolve wear pattern issue caused in a shorter period of time, thus the lack of grease can be considered to 'not be a significant credible failure mechanism' (same or no grease between shuttle and housing). Based upon the NAMCO report, the presence or lack of grease has no impact on wear or operability and thus does not affect the safety function. In addition, the CQ14100801 S/N 03 installed for 9 months, the O-Ring measured an 81 durometer hardness (showing aging) but not brittle. The other 3 installed for 6 years were brittle but did not affect operability. Thus the hardness of the O-Rings can be considered to 'not be a significant credible failure mechanism'. All four switches in Report QDC-62770 had paint scrapings caused by wear which was present and operated properly after being in service for an extended period of time. Thus the presence of paint residue due to wear can be considered to 'not be a significant credible failure mechanism'. There have been no other reported failures of this type. The root cause failure mechanism has not been identified, thus this switch failure does not appear to represent a common mode failure. Notified the R3DO (Daley) and Part 21/50.55 Reactors group (via email). |
| Where | |
|---|---|
| Curtiss Wright Cincinnati, Ohio (NRC Region 3) | |
| Organization: | Curtiss Wright |
| Reporting | |
| 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
| Time - Person (Reporting Time:+1498.9 h62.454 days <br />8.922 weeks <br />2.053 months <br />) | |
| Opened: | Tim Franchuk 14:54 Oct 8, 2018 |
| NRC Officer: | Ossy Font |
| Last Updated: | May 31, 2019 |
| 53653 - NRC Website | |
Curtiss Wright with 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
WEEKMONTHYEARENS 536532018-08-07T04:00:0007 August 2018 04:00:00
[Table view]10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 Notification - Namco Limit Switch Failed Test Due to Insufficient Lubrication 2018-08-07T04:00:00 | |