ENS 46957
ENS Event | |
|---|---|
00:24 Jun 14, 2011 | |
| Title | Automatic Reactor Trip During Startup Physics Testing |
| Event Description | On June 13, 2011 at 1924 CDT, an automatic reactor trip was actuated during Shutdown Bank Insertion for Beginning of Life Physics Testing. Neutron flux lowered from the intermediate range to the point of automatic energization of the Source Range Nuclear Instruments. Energization of the Source Range Nuclear Instruments during this step is anticipated and permissible per the test procedure. When it energized, the N-31 Source Range Nuclear Instrument (Red Channel) failed high which initiated an automatic reactor trip.
All plant systems functioned as required, including the Reactor Protection System. All control rods fully inserted into the core. There was no Emergency Core Cooling System or Auxiliary Feedwater System actuation. No Emergency Diesel Generators were started and power continues to be supplied from off site. The reactor coolant system has forced circulation and the atmospheric steam dumps are currently being used for decay heat removal from the steam generators. There was no radiological release and emergency plan implementation was not required. An investigation of the failure of the N-31 Source Range Nuclear Instrument is in progress There is no known primary to secondary leakage. The licensee notified the NRC Resident Inspector.
At the time of the trip, the reactor was subcritical. This notification is updated to reflect reporting in accordance with 10CFR50.72(b)(3)(iv)(A). An investigation of the failure of the N-31 source range nuclear instrument continues. This event was initially reported by the licensee as a four-hour report in accordance with 10CFR50.72(b)(2)(iv)(B). The licensee notified the NRC Resident Inspector. Notified R3DO (Kozak).
'On June 14, 2011 at 2055 EDT, EN 46957 was amended to state the reactor was subcritical at the time of the trip. Subsequent review of this situation by the licensee resulted in a determination that at the time the test sequence was initiated, the reactor was critical and in MODE 2. Accordingly, this non-emergency report is amended to reflect EN 46957 as originally submitted on 06/13/11 at 2229 CDT. LER 301/2011-004-01 [submitted on July 25, 2011] will be revised accordingly.' The licensee has notified the NRC Resident Inspector. R3DO (Peterson) notified. |
| Where | |
|---|---|
Point Beach  Wisconsin (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| LER: | 05000301/LER-2011-004 |
| Time - Person (Reporting Time:+-0.92 h-0.0383 days <br />-0.00548 weeks <br />-0.00126 months <br />) | |
| Opened: | David Plessas 23:29 Jun 13, 2011 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Oct 12, 2011 |
| 46957 - NRC Website
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WEEKMONTHYEARENS 553902021-07-31T21:46:00031 July 2021 21:46:00
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