ENS 51788
ENS Event | |
|---|---|
04:00 Oct 1, 2015 | |
| Title | Part 21 - Hydraulic Snubber Seal Material Deviation Interim Report |
| Event Description | Anvil Engineered Pipe Supports (EPS) supplied 14 Fig. 200N Configuration 'A' style hydraulic snubbers to the Exelon owned and operated Peach Bottom Atomic Power Station (PBAPS) in 2013. During the course of routine refueling outage activities in October 2015, it was discovered that 9 of these 14 snubbers had no hydraulic fluid in the reservoir. The cause of the hydraulic fluid loss was premature aging of the reservoir piston seal due to vibration induced frictional heat. Subsequent laboratory testing of both replacement and degraded seal material by Exelon Power Labs suggested that a material substitution had been made from the Anvil approved Ethylene Propylene (EP) compound to a different grade of EP rubber.
On February 17, 2016, Anvil determined that a material substitution was made by the seal vendor. A machined seal that was fabricated by the manufacturer was substituted for a seal molded with the approved Anvil compound. Prior to its installation in Fig. 200N/201N Configuration 'A' hydraulic snubbers, the machined seal compound was not tested to establish a service life for the compound. Anvil has bounded the extent of condition to 4 specific seal batches of 4" and 5" Fig. 200N/201N Configuration 'A' reservoir piston seals provided after January 1, 2013. Based on its Part 21 investigation, Anvil has yet to determine that a specific defect exists, based on the demonstrated operability of the snubbers at PBAPS despite severe service conditions beyond their published operational limits, and the compatibility of the EP base polymer with Anvil hydraulic fluids. Anvil is conducting a test campaign to approve and establish a service life for the machined seal compound. This testing will either qualify the machined compound for use at currently published Anvil service conditions (157 degrees F for 25 years with a total lifetime dose not to exceed 2e8 rads), or establish a reduced service life for the snubbers in which a material substitution was made. This testing is being conducted on an assembled reservoir with the substitute machined compound. It will include irradiation of the reservoir to 6.4e7 rads, accelerated temperature aging, and a final radiation exposure to bring the cumulative dose to 2e8 rads. As of 3/14/16, the reservoir specimen had been irradiated to 6.4e7 rads with no effect on the seal. Anvil expects to have this testing complete by May 1, 2016, with a formal evaluation to follow. PBAPS has been notified of the material substitution, and a full accounting of the affected snubbers by serial number, PO number, site, and utility is being assembled. Anvil will notify affected sites when the testing and equivalency evaluation is complete. Please feel free to contact me if you have any questions or require any additional information. Sincerely, Mark R Ward Operations Manager Anvil Engineered Pipe Supports 160 Frenchtown Road North Kingstown, Rl, 02852
The following is a summary of information received from Anvil EPS: Anvil performed qualification testing of the machined compound with satisfactory results. The machined compound is now qualified for a service life equivalent to the published service life of the molded compound when used as a reservoir piston seal for the Fig. 200N/201N Configuration "A". Anvil has determined that a specific defect does not exist and no action by licensees is needed. Fifty-nine (59) total snubbers were shipped to NRC licensees (Farley, Peach Bottom, Oconee, ANO, and Diablo Canyon); Anvil will advise sites. Notified R1DO (Dwyer), R2DO (Ehrhardt), R4DO (Groom) and NRR Part 21 Group. |
| Where | |
|---|---|
| Anvil Engineering Pipe Support North Kingstown, Rhode Island (NRC Region 1) | |
| Organization: | Anvil Engineering Pipe Support |
| Reporting | |
| 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+3970.12 h165.422 days <br />23.632 weeks <br />5.438 months <br />) | |
| Opened: | Mark R. Ward 14:07 Mar 14, 2016 |
| NRC Officer: | Dong Park |
| Last Updated: | Apr 26, 2016 |
| 51788 - NRC Website | |
Anvil Engineering Pipe Support with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect, 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
WEEKMONTHYEARENS 517882015-10-01T04:00:0001 October 2015 04:00:00
[Table view]10 CFR 21.21(d)(3)(i), Failure to Comply or Defect, 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 - Hydraulic Snubber Seal Material Deviation Interim Report 2015-10-01T04:00:00 | |