ML19168A010

Curtis-Wright Nuclear Division- Notification Report for Potential Part 21 Update

ML19168A010
Person / Time
Site:	Point Beach, Quad Cities
Issue date:	05/31/2019
From:	Franchuk T Curtiss-Wright Nuclear Division
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Pannier S, 415-4083, NRR/DIRS
References
Download: ML19168A010 (2)

Text

• CURl1SS- Nuclear Division 4600 East Tech Drive WRIGHT Cincinnati, OH 45245 T: 513.528.7900 IF: 513.528.9292 www.curtisswright.com/NuclearDivision May 31, 2019 U.S.. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001

Subject:

Notification Report for Potential Part 21 update.

Dear Sir or Madam:

In reference to the Curtiss-Wright Interim Notification Report dated 10/8/2018 (Event No. ML18289A457/Log No. 2018-24-00) for an EA700-90964 limit switch failure, the following updates are provided.

Curtiss-Wright was notified on August 7th, 2018 by Exelon's Quad Cities Plan~,that a Curtiss-Wright Supplied*Namco Limit Switch, PIN: EA 700-90964 had failed during a planned maintenance test. ,

The switch was 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# ST34603 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 roughly four and a half 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 (See QDC-07067). 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 lubrication.

Note that in subsequent discussions after release of the QDC-07067 report, Namco indicated that their statement on the lack of lubrication was an observation of the switch's current condition, and not the cause of the failure.

References (attached):

Exelon Powerlabs Initial Report QDC-07067 08/08/2018 on failed Switch Exelon Powerlabs 2nd Report QDC-62770 Rl 05/09/2019 on used Switches Namco Report Mechanical Cycle Testing, EA700-90964 Commercial Limit Switch (Final Report- 28May2019)

Initial Report QDC-07067

Conclusions:

Initial Failure occurred roughly four and a half years in service where switch* "binding was due to insufficient (i.e. dried out) lubrication on the moving parts". The shaft 0-ring was sevijrely hardened.from aging, "which could have contributed to binding".

Second Report QDC-62770:

Per Table 1, pg. 3: SN 05, 09, & 02 were installed for 6 years without a failure.

Pages 16 & 17 photos show these 3 switches are without lubrication and had wear patterns between tile slide & the outer housing, similar to the failed switch.

Per pg. 1: CQ1400801 S/N 03 was installed for approximately 9 months.

Page 17 photo shows significant lubrication and the same wear pattern.

The foreign material found in the switches were identified as paint residue (due to wear).

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• CURTISS- Nuclear Division 4600 East Tech Drive WRIGHT Cincinnati, OH 45245 T: 513.528.7900 IF: 513.528.9292 www.curtisswright.com1Nuclear0ivision Shaft 0-Rings on the 6 years in service switches were severely hardened and embrlttled due to aging, while the 9 month switch's 0-Ring was still in good condition, but beginning to show signs of aging as noted by an increase in hardness.

NAMCO Cycle Aging Report:

Report showed the results of Mechanical Cycle Testing on two new switches, which was performed in the same orientation as the Exelon application. The purpose of this test was to prove that with/without lubrication, at the known rate of cydes, these units would not have experienced the amount of wear indications noted in Exelon Powerlabs' reports r~gardless of the amount of lubrication present. One switch was completely lubricated and one was without any lubrication. These were cycled for 4800 cycles and were both functional at the end of testing.

Curtiss-Wright noted that Namco's testing was done at laboratory ambient conditions, and did not account for other external factors such as typical system vibrations and operating temperature present in Quad Cities application.

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 CQ1400801 S/Nj)3 installed for9 months, the 0-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 0-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 faihire does not aP. ear to represent a common mode failure.

m Tim Franchuk Director, Quality Assurance Curtiss-Wright Nuclear Division, Cincinnati Operations 513-201-2176 TFranchuk@CurtissWright.com Page 2 of Z