ENS 46145
ENS Event | |
|---|---|
10:50 Aug 3, 2010 | |
| Title | Discovery of After-The-Fact Emergency Condition Unusual Event Due to a High Level Water Alarm |
| Event Description | This is a one-hour report for the discovery of a condition that met an emergency action level (EAL) for a Notification of Unusual Event (NOUE) but was not determined classifiable until after conditions meeting the EAL level for the NOUE no longer existed. A detailed review of the conditions that existed at 0650 [EDT], on August 3, 2010 during a planned system drain down of the 2A loop of RHR to the northeast diagonal sump met the criteria for an NOUE: EAL HU1 - Natural and Destructive Phenomena Affecting the Protected Area.
Threshold Value 6 states: 'Exceeding Max Normal Operating Values specified in EOP 31EO-EOP-014-1(2) SC - Secondary Containment Control Table 5 Secondary Containment Operation Water Levels.' At 0650 [EDT] on August 3. 2010 the Hatch Unit 2 crew received a HIGH-HIGH-HIGH alarm which is the Max Normal Level described in 31EO-EOP-014-1(2). This occurred during a planned draindown evolution when a valve (2T45-F004) which is required to transfer water from the sump to radwaste failed to open. At 0656 [EDT] on August 3, 2010 the RHR drain valve (2E11- F069A) was closed discontinuing draining into the northeast diagonal sump. It is estimated that no more than 800 gallons of water was in the system and internal flooding was not a significant concern. However, despite the low safety significance, the EAL threshold criteria was technically met and therefore this report is being made. This event is a one hour report based on the guidance in NUREG-1022 Section 3.1.1 for a condition that met an EAL and the condition for the classification no longer existed at the time of discovery. A courtesy notification will be made to state and local agencies. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Hatch  Georgia (NRC Region 2) | |
| Reporting | |
| Emergency class: | Unusual Event |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+6.7 h0.279 days <br />0.0399 weeks <br />0.00918 months <br />) | |
| Opened: | Bill Duvall 17:32 Aug 3, 2010 |
| NRC Officer: | Vince Klco |
| Last Updated: | Aug 3, 2010 |
| 46145 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 461452010-08-03T10:50:0003 August 2010 10:50:00
[Table view]Other Unspec Reqmnt Discovery of After-The-Fact Emergency Condition Unusual Event Due to a High Level Water Alarm 2010-08-03T10:50:00 | |