ENS 51024
ENS Event | |
|---|---|
14:00 Apr 29, 2015 | |
| Title | Valve Classified as Item Relied on for Safety Failed to Operate as Designed |
| Event Description | On April 29, 2015 at 1000 [EDT], it was reported to EH&S [Environmental Health and Safety] that the spring loaded valve on the deionized (DI) water line, which supplies rinse water to an in-line gamma monitor in the conversion scrap recovery area, was found to have the spring-return damaged such that the valve would not automatically return to the closed position when released. This valve is listed as IROFS ADUSCRA-102. While production activities had already ceased in preparation for a Special Nuclear Material (SNM) inventory and planned maintenance outage, liquid wastewater processing activities were on-going.
Liquid wastewater processing activities were immediately stopped, and EH&S was notified of the event by phone and the 'Redbook' reporting system (Redbook Issue #68460). At no time was there any actual or potential health and safety consequences to the workers, the public, or the environment. The safety function of this IROFS is to automatically close when released by hand to prevent possible backflow of Uranium-235 containing wastewater into the DI water supply and potentially to an unfavorable geometry tank. During this time, IROFS ADUSCRP-153, a three-way valve that prevents the commingling of wastewater and DI water, remained available and reliable to prevent potential backflow of the wastewater into the DI water supply. Based on available IROFS, this accident sequence was 'Unlikely' (a failure probability of 10E-3), and not 'Highly Unlikely' (a failure probability of 10E-4 or less), and therefore does not meet the performance requirements of 10 CFR 70.61 [which requires that an accident sequence be 'Highly Unlikely']. The actual configuration remained safe at all times, and no external conditions affected the event. A process upset would have to occur to enable a potential backflow condition, and the remaining IROFS would have had to simultaneously fail. Immediate Corrective Actions: As stated above, the process was shut down, and the upstream DI water valve was locked closed. After evaluation and with EH&S approval, maintenance replaced the valve and a functional test was completed. The event was reviewed in the conversion huddle meetings held before the start of each shift, and operations initiated a check to validate the operability of the spring loaded valve after each use until a long term corrective action is in place. Operating Experience is being shared with the site and industry personnel. An Extent of Condition inspection was performed for all safety-significant spring loaded valves. All other valves functioned properly. This event has been entered into the facility Corrective Action Prevention And Learning system (CAPAL) #100267824. |
| Where | |
|---|---|
| Westinghouse Electric Corporation Columbia, South Carolina (NRC Region 2) | |
| License number: | SNM-1107 |
| Reporting | |
| Part 70 App A (B)(2) | |
| Time - Person (Reporting Time:+19.5 h0.813 days <br />0.116 weeks <br />0.0267 months <br />) | |
| Opened: | Carl Snyder 09:30 Apr 30, 2015 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Apr 30, 2015 |
| 51024 - NRC Website | |
Westinghouse Electric Corporation with Part 70 App A (B)(2) | |
WEEKMONTHYEARENS 542982019-09-27T19:15:00027 September 2019 19:15:00
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