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 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 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.
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.
Crane will continue to review XOMOX records to determine if any other sites are impacted, which we expect to complete by August 31, 2017.
Should you have any questions regarding this matter, please contact Samson Kay, Manager of Engineering at (630) 226-4983 or Jennifer Bregovy, Manager of Quality and Safety at (630) 226-4949.
The following facilities received these safety related orders: TVA Sequoyah, Pennsylvania Power & Light Susquehanna.
The following information was received via fax:
Crane Nuclear (CNI) has initiate the final phase of the Part 21 research and is currently reviewing over 15,000 documents from the original XOMOX Canada historical archive to determine if any other nuclear sites were impacted by the subject Part 21. The investigation encompasses sales orders spanning from 1968 to 1992. CNI expects to complete the review by 10/30/2017.
Point of Contact: Samson Kay (630-226-4983) or Jennifer Bregovy (630-226-4949)
Notified the R1DO (Cook), R2DO (Lopez), and Part 21 Resources (via e-mail).
- * * UPDATE AT 1627 EDT ON 11/01/17 FROM SAMSON KAY TO S. SANDIN VIA FAX * * *
The following information was provided as an update:
Crane Nuclear (CNI) has completed approximately 40% of the review of the historical archive and will not be able to complete the review by the previously requested 10/30/2017 deadline.
The historical review covers the following scope:
-XOMOX UK DEVON, ENGLAND - Safety-Related and N-Stamped Valves/Parts issued between 1987 - 1993
-XOMOX Canada & XOMOX A&M - Safety-Related Parts from 1979 - 1993
-XOMOX Cincinnati TUFFLINE - Safety-Related and N-Stamped Valves and Parts issued between 1970 -1993
-XOMOX Crane Nuclear - Safety-Related and N-Stamped Valves and Parts issued from 2001 until present.
Note: Parts and valves were no longer supplied by XOMOX as safety-related or nuclear after 1993 until Crane Nuclear acquired XOMOX in June 29, 2001.
The following sites . . . were identified as a safety-related valves effected by this letter. All sites were supplied to customer 'Delaval' which no longer exists. At the current pace of review, CNI expects to complete the review of the historical archive by 1/30/2018.
Delaval supplied valves to these Original Plant Name(s); TVA (doesn't show which plant), Comanche Peak Units 1&2, Columbia, Cleveland Electric, Midland Nuclear Power Plant Units 1&2 and TVA, - Hartsville and Phipps Bend Nuclear Plants both of which were cancelled before completion.
Notified R1DO (McKinley), R2DO (Ehrhardt), R3DO (Duncan), R4DO (Werner) and Part 21/50.55 Reactors via email.
- * * UPDATE AT 1553 EDT ON 01/31/18 FROM JOYCE HAMMAN TO DONG PARK * * *
The following information was provided as an update via fax:
The historical research is complete. Our review of the records from 1973 through 2001 identified 25 valves that were supplied with a stem-sleeve material combination that could 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. Those valves were supplied to:
Northeast Utilities, Millstone; Houston Lighting & Power, South Texas Project; Niagara Mohawk, Nine Mile Point; Transamerican Delavel, Oakland; Power Systems, Rocky Mount; Bechtel Energy Corp., 5 Miles West Wadsworth; Pennsylvania Power & Light, Susquehanna; NY Power Authority, Fitzpatrick; TVA, Sequoyah; Omaha Public Power, Ft. Calhoun.
Notification letters have been sent to some of the affected plants advising them of the condition, and recommending that the sleeve material be replaced with a lower friction Polytetrafluoroethylene (PTFE) material that would significantly reduce the required input operating torque, thereby reducing the risk of failure of the stem material. Crane will complete the notifications to the other sites no later than 2/9/18.
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.
- * * 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.