ENS 44661: Difference between revisions
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| event date = 10/16/2008 09:07 EST | | event date = 10/16/2008 09:07 EST | ||
| last update date = 11/17/2008 | | last update date = 11/17/2008 | ||
| title = Invalid Actuation | | title = Invalid Actuation of Steam Driven Aux Feed Pump | ||
| event text = On October 16, 2008 during a routine clearance restoration activity, two solenoid-operated steam supply isolation valves on one of the three steam lines to the steam-driven Auxiliary Feedwater Pump (2FWE-P22) unexpectedly opened at Beaver Valley Power Station (BVPS) Unit No.2, admitting steam to and causing this pump to commence rotating. The control room operator monitoring the plant quickly recognized the unwarranted system response and attempted to terminate steam flow to the auxiliary feedwater pump by re-closing the two unexpectedly open steam supply isolation valves from the control room. At the same time, the local operator performing the restoration activity of opening a separate manual upstream steam isolation valve also recognized the unwarranted system response (by hearing too much steam flow through the manual valve) and also terminated steam flow to the pump by re-closing the upstream manual isolation valve. The total time that this pump rotated was less than approximately 30 seconds and the plant computer indicated that no auxiliary feedwater was actually pumped into any of the steam generators. Neither of the other two Auxiliary Feedwater System motor-driven pumps were actuated at BVPS Unit No.2. | | event text = On October 16, 2008 during a routine clearance restoration activity, two solenoid-operated steam supply isolation valves on one of the three steam lines to the steam-driven Auxiliary Feedwater Pump (2FWE-P22) unexpectedly opened at Beaver Valley Power Station (BVPS) Unit No.2, admitting steam to and causing this pump to commence rotating. The control room operator monitoring the plant quickly recognized the unwarranted system response and attempted to terminate steam flow to the auxiliary feedwater pump by re-closing the two unexpectedly open steam supply isolation valves from the control room. At the same time, the local operator performing the restoration activity of opening a separate manual upstream steam isolation valve also recognized the unwarranted system response (by hearing too much steam flow through the manual valve) and also terminated steam flow to the pump by re-closing the upstream manual isolation valve. The total time that this pump rotated was less than approximately 30 seconds and the plant computer indicated that no auxiliary feedwater was actually pumped into any of the steam generators. Neither of the other two Auxiliary Feedwater System motor-driven pumps were actuated at BVPS Unit No.2. | ||
The design for these two solenoid-operated isolation valves are susceptible to briefly popping open if steam is initially introduced too rapidly. These valves fail open with no power and are pilot-operated solenoid-actuated to close. An initial large steam rush can briefly overcome the solenoid force holding the valve shut. This is what occurred on October 16, 2008. Therefore, this brief rotation of the steam-driven Auxiliary Feedwater Pump was not initiated by a valid actuation signal. | The design for these two solenoid-operated isolation valves are susceptible to briefly popping open if steam is initially introduced too rapidly. These valves fail open with no power and are pilot-operated solenoid-actuated to close. An initial large steam rush can briefly overcome the solenoid force holding the valve shut. This is what occurred on October 16, 2008. Therefore, this brief rotation of the steam-driven Auxiliary Feedwater Pump was not initiated by a valid actuation signal. | ||
Latest revision as of 21:13, 1 March 2018
| Where | |
|---|---|
| Beaver Valley Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+763.32 h31.805 days <br />4.544 weeks <br />1.046 months <br />) | |
| Opened: | R. G. Loose 10:26 Nov 17, 2008 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Nov 17, 2008 |
| 44661 - NRC Website
| |