ENS 46846
ENS Event | |
|---|---|
04:00 May 12, 2011 | |
| Title | U-Rings Fabricated with Incorrect Material |
| Event Description | {{#Wiki_filter:The following was received via facsimile:
This report relates to two NP8344E series four-way solenoid valves found to be leaking through the exhaust port in both the energized and de-energized states. Background - On January 21, 2011, ASCO Valve, Inc. (ASCO) was notified by AREVA that a four-way solenoid valve NP8344A75E AC, (serial number F623557002-002) from the Dresden Station was leaking from the exhaust port in both the energized and de-energized states. AREVA reported that Exelon Labs had performed a Fourier Transform Infrared Spectroscopy (FTIR) analysis which indicated the piston U-ring exhibited properties consistent with a Nitrile compound instead of Teflon� coated Ethylene Propylene as required by the ASCO design drawing. The valve itself was not returned to ASCO. At ASCO's request, Exelon returned the U-ring on January 27, 2011. ASCO provided a letter to Dresden Station on February 3, 2011 (Reference A) maintaining the correct U-ring material was installed at the time of shipment and that no additional action was required. The second occurrence involved another four-way solenoid valve, NPK8344A072E DC, (serial number F337837-2), from PSEG Nuclear's Salem station, returned to ASCO on Service RMA 47113 on February 25, 2011. The valve was brought to ASCO where testing confirmed the valve was leaking through the exhaust ports in both the energized and de-energized states. The inspection of parts showed that the U-ring material had become brittle. If the U-ring becomes brittle, it may no longer perform its sealing function. ASCO Investigation Results - The above referenced valves were manufactured in 1992 (Dresden) and 1995 (Salem) respectively. It was determined that both valves used the same piston U-ring, part number 029043-024-S. This U-ring is common to both the 3/8" and 1/2" NPT valve constructions, A review of ASCO's incoming and dedication inspection records indicated that these U-rings were Teflon� coated Ethylene Propylene. The piston U-rings from the Salem and Dresden valves, along with a piston U-ring from ASCO's current stock, were sent to a third party laboratory for a FTIR analysis. The U-rings from both the Salem and Dresden valves were determined by the laboratory to be Nitrile. The U-ring from current stock was determined to be Teflon� coated Ethylene Propylene, as called for by the design drawings, Impact on Performance - The use of a Nitrile piston U-ring could potentially reduce the valve life and result in leakage through the exhaust port. Initial Action - FTIR analysis confirmed that the piston U-ring in ASCO's current stock was Teflon� coated Ethylene Propylene. ASCO records disclosed no prior cases of piston U-rings fabricated with incorrect material. Discussions with the distributor of the U-rings disclosed no other cases of improper material. Corrective Action - The customers that were shipped potentially affected NP8344E valves are being notified of the potential deviation. All variations of NP8344A72E, NP8344A73E, NP8344A74E, NP8344A75E, NP8344850E, NP8344B52E, NP8344B62E, and NP8344B64E manufactured from 1992 through 1995 are recommended to be monitored for leakage. Due to the qualified service life and date of manufacture, it is believed a majority of these valves are no longer in service, Subsequent to 1995, ASCO has implemented a more rigorous lot and batch control to verify the material compound at incoming and dedication inspection. This action further enhanced traceability of resilient materials used in specific production lots. }} |
| Where | |
|---|---|
| Asco Valve Aiken, South Carolina (NRC Region 1) | |
| Organization: | Asco Valve |
| Reporting | |
| 10 CFR 21.21 | |
| Time - Person (Reporting Time:+12.23 h0.51 days <br />0.0728 weeks <br />0.0168 months <br />) | |
| Opened: | Robert Arnone 16:14 May 12, 2011 |
| NRC Officer: | Dong Park |
| Last Updated: | May 12, 2011 |
| 46846 - NRC Website | |
Asco Valve with 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation | |
WEEKMONTHYEARENS 468462011-05-12T04:00:00012 May 2011 04:00:00
[Table view]10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation U-Rings Fabricated with Incorrect Material ENS 466402010-03-18T05:00:00018 March 2010 05:00:00 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation Failure of Actuators Due to Undersized Output Shafts 2011-05-12T04:00:00 | |