ENS 43041
ENS Event | |
|---|---|
11:37 Oct 30, 2006 | |
| Title | Inadvertent Opening of Two Isolation Valves |
| Event Description | This telephone notification to report an invalid actuation is provided in accordance with 10 CFR 50.73(a)(1), which states, 'In the case of an invalid actuation reported under Sec. 50.73(a)(2)(iv), other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. The specific reporting requirement in 10 CFR 50.73(a)(2)(iv)(A), states, 'Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B).' For this report, the affected system was the Unit 2 Train B Containment Spray System.
On October 30, 2006 at approximately 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />, a Main Control Room (MCR) Senior Reactor Operator identified during a panel walk-down that the containment spray header isolation valve, 2CS007B, and the containment spray eductor NaOH tank suction isolation valve, 2CS019B, were open. This was an unexpected condition, which prompted Operations to investigate. A review of the Alarm computer points revealed that the valves opened at 0537 hours0.00622 days <br />0.149 hours <br />8.878968e-4 weeks <br />2.043285e-4 months <br />. The investigation determined that the most probable cause of this occurrence was attributed to, during the performance of maintenance inside of the 2PA10J panel, an Electrical Maintenance Department technician inadvertently making contact with the manual latch causing the actuation of the K643B slave relay that led to repositioning of the out-of-position valves. The following information provides the required details outlined in NUREG 1022 Revision 2: (a) The relay actuation for the 2B Containment Spray valves was not a valid ESF actuation. The actuation was the result of an inadvertent bump of the K643B relay and not the result of a valid ESF signal from the reactor protection system. (b) This report is being made under 10CFR50.73(a)(2)(iv)(A). (c) The specific train and system that actuated was 2B Containment Spray. (d) The train actuation was a partial actuation for three containment spray valves from the K643B slave relay due to an inadvertent bump of the slave relay manual latching mechanism with the following conditions identified: " 2CS007B, 2B containment spray header isolation valve, changed from closed to open. "2CS010B, 2B containment spray NaOH eductor inlet isolation valve, is normally open and did not change position, but received an open signal. "2CS019B, 2B containment spray eductor NaOH tank suction isolation valve, changed from closed to open. The 2B containment spray system was in TEST in preparation for changing from Mode 5 to Mode 4. (e) The containment spray system did not start because the system was in TEST and the containment spray pumps were in lock out while in Mode 5. The three valves functioned as designed. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+961.3 h40.054 days <br />5.722 weeks <br />1.317 months <br />) | |
| Opened: | Javier Sanchez 12:55 Dec 9, 2006 |
| NRC Officer: | John Knoke |
| Last Updated: | Dec 9, 2006 |
| 43041 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 485792012-10-20T05:24:00020 October 2012 05:24:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid Specified System Actuation ENS 430412006-10-30T11:37:00030 October 2006 11:37:00 10 CFR 50.73(a)(1), Submit an LER Inadvertent Opening of Two Isolation Valves 2012-10-20T05:24:00 | |