ENS 52857: Difference between revisions
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| emergency class = Non Emergency | | emergency class = Non Emergency | ||
| notification date = 07/13/2017 17:59 | | notification date = 07/13/2017 17:59 | ||
| retracted = Yes | |||
| notification by = Samson Kay | | notification by = Samson Kay | ||
| NRC officer = Dong Hwa Park | | NRC officer = Dong Hwa Park | ||
| event date = 06/05/2017 CDT | | event date = 06/05/2017 CDT | ||
| last update date = | | last update date = 03/21/2018 | ||
| title = Part 21 - Defective Safety Related Valves | | title = Part 21 - Defective Safety Related Valves | ||
| event text = The following was excerpted from a letter by Crane Nuclear, Inc.: | | event text = The following was excerpted from a letter by Crane Nuclear, Inc.: | ||
The plug valve designs provided for XOMOX model figure numbers 037AX, 067EG, and 037. These valves have been identified as used in nuclear and/or safety related applications. | The plug valve designs provided for XOMOX model figure numbers 037AX, 067EG, and 037. These valves have been identified as used in nuclear and/or safety related applications. | ||
The stem for the Subject valve models was identified as being undersized based on allowable yield stress analysis of the stem while in torsion. The high stress condition was due to the high torque required to seat/unseat the plug when installed with a Ultra High Molecular Weight Polyethylene (UHMWPE) sleeve material. High friction factor inherent with this material causes torsional stress to exceed the upper limit of yield strength of the valve which could result in fatigue/yielding of the stem, thus preventing the valve from opening and closing while in service. Historical research performed thus far has not identified any notifications from the customer(s) regarding stem failure of the subject valves, indicating that the valves may still be in operation with no performance related or operating issues. | The stem for the Subject valve models was identified as being undersized based on allowable yield stress analysis of the stem while in torsion. The high stress condition was due to the high torque required to seat/unseat the plug when installed with a Ultra High Molecular Weight Polyethylene (UHMWPE) sleeve material. High friction factor inherent with this material causes torsional stress to exceed the upper limit of yield strength of the valve which could result in fatigue/yielding of the stem, thus preventing the valve from opening and closing while in service. Historical research performed thus far has not identified any notifications from the customer(s) regarding stem failure of the subject valves, indicating that the valves may still be in operation with no performance related or operating issues. | ||
The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be | The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be token to complete the action. | ||
Notifications letters have been sent to the affected plants advising them of the condition, and recommending that the sleeve material be replaced with a lower friction Polytetrafluorethylene (PTFE) material that would significantly reduce the required input operating torque, thereby reducing the risk of failure of the stem material. | Notifications letters have been sent to the affected plants advising them of the condition, and recommending that the sleeve material be replaced with a lower friction Polytetrafluorethylene (PTFE) material that would significantly reduce the required input operating torque, thereby reducing the risk of failure of the stem material. | ||
XOMOX has been advised to modify design calculations to provide a larger margin for allowable yield strength of the stem material to ensure the stem is properly sized when Ultra High Molecular Weight Polyethylene (UHMWPE) sleeve material is used. | XOMOX has been advised to modify design calculations to provide a larger margin for allowable yield strength of the stem material to ensure the stem is properly sized when Ultra High Molecular Weight Polyethylene (UHMWPE) sleeve material is used. | ||
| Line 50: | Line 51: | ||
Should you have any questions regarding this matter, please contact me, Joyce Hamman, Director, Safety & Quality at (678) 451-2280, Burt Anderson, Site Leader, at (630) 226-4990, or Samson Kay, Engineering Manager at (630) 226-4983. | Should you have any questions regarding this matter, please contact me, Joyce Hamman, Director, Safety & Quality at (678) 451-2280, Burt Anderson, Site Leader, at (630) 226-4990, or Samson Kay, Engineering Manager at (630) 226-4983. | ||
Notified R1DO (Janda), R2DO (Heisserer), R3DO (Dickson), R4DO (Deese) and Part 21/50.55 Reactors via email. | Notified R1DO (Janda), R2DO (Heisserer), R3DO (Dickson), R4DO (Deese) and Part 21/50.55 Reactors via email. | ||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/ | * * * RETRACTION AT 1308 EDT ON 03/21/18 FROM SAMSON KAY TO DONG PARK * * * | ||
The following information was provided as an update via fax: | |||
Crane reviewed diagnostic testing of 106 XOMOX plug valves for the purpose of validating the assumed torque values specified by XOMOX guidance. From the review of the diagnostic testing, we determined that on average, the actual torque required to stroke the valve (also referred to as the 'break torque') was approximately 56%-67% lower than the calculated value based on the UHMWPE sleeve material for valves with a 150 lbs. pressure class. Statistical analysis confirmed that the test results were within a 95% confidence interval. Consequently, a conservative factor of at least 56% can be applied to the published XOMOX torque value when evaluating stem stress. Applying this factor to the valves previously identified under this Part 21 confirmed that stress limits are below the material allowable for yield strength. This conclusion is supported by operating history (e.g., no reported stem failures) in the field. | |||
Based on these findings, Crane Nuclear, confirms that a condition adverse to quality and safety does not exist and that a Part 21 no longer applies. CNI, requests this Part 21 to be retracted. | |||
Should you have any questions regarding this matter, please contact me, Joyce Hamman, Director, Safety & Quality at (678) 451-2280, Burt Anderson, Site Leader, at (630) 226-4990, or Samson Kay, Engineering Manager at (630) 226-4983. | |||
Notified R1DO (McKinley), R2DO (Sandal), R3DO (Duncan), R4DO (Groom) and Part 21/50.55 Reactors via email. | |||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180322en.html#en52857 | |||
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Revision as of 08:30, 22 March 2018
| Where | |
|---|---|
| Crane Nuclear, Inc. Bolingbrook, Illinois (NRC Region 3) | |
| Organization: | Crane Nuclear, Inc. |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+924.98 h38.541 days <br />5.506 weeks <br />1.267 months <br />) | |
| Opened: | Samson Kay 17:59 Jul 13, 2017 |
| NRC Officer: | Dong Park |
| Last Updated: | Mar 21, 2018 |
| 52857 - NRC Website | |