ENS 52178
ENS Event | |
|---|---|
04:59 Aug 14, 2016 | |
| Title | Unusual Event Declared Due to Excessive Reactor Coolant System Leakage |
| Event Description | Prairie Island Unit 1 declared an Unusual Event at 2359 CDT on 8/13/2016 based on Reactor Coolant System (RCS) identified leakage being greater than 25 gpm. The RCS leakage was 40 gpm for three (3) minutes. The RCS leakage was stopped when letdown flow was isolated. Minimum charging flow has been established and Excess Letdown was placed in service. Prairie Island Unit 1 is currently stable and continues to operate at 100 percent power. There was no impact on Prairie Island Unit 2.
CV-31339 (Letdown Line Containment Isolation Valve) failed closed. VC-26-1 (Regenerative Heat Exchanger Letdown Line Outlet Relief to Pressurizer Relief Tank [PRT]) lifted with 40 gallons per minute to the PRT for three (3) Minutes. Operators entered procedure 1C12.1 AOP3, Loss of Letdown Flow to VCT. Letdown was isolated per 1C12.1 AOP3, relief valve VC-26-1 reseated and leakage to the PRT stopped. Charging flow was reduced to one (1) charging pump at minimum speed (16 GPM). Excess letdown was placed in service to maintain pressurizer level between 32 - 34 percent. The cause for CV-31339 closing has not yet been determined. The NRC Resident Inspector has been notified. Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail.
At 0329 CDT the Notice of Unusual Event was terminated based on confirmation that conditions meet all termination criteria. RCS conditions are stable. RCS leakage is less than Technical Specification limits. The current value [of RCS identified leakage] is 0.038 gpm. No classification criteria is currently met. The NRC Resident Inspector has been notified. Notified R3DO (Kozak), NRR EO (Miller), and IRD (Stapleton). Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail. |
| Where | |
|---|---|
Prairie Island  Minnesota (NRC Region 3) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3 h-0.125 days <br />-0.0179 weeks <br />-0.00411 months <br />) | |
| Opened: | Paul Finholm 01:59 Aug 14, 2016 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Aug 14, 2016 |
| 52178 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 565432023-05-27T23:34:00027 May 2023 23:34:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Notification of Unusual Event Due to Multiple Fire Alarms in Containment Not Verified within 15 Minutes ENS 521782016-08-14T04:59:00014 August 2016 04:59:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Excessive Reactor Coolant System Leakage ENS 516092015-12-17T19:18:00017 December 2015 19:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Fire Alarm in Containment Not Verified within 15 Minutes ENS 508662015-03-05T10:06:0005 March 2015 10:06:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unit 2 Declares Unusual Event Due to Inability to Validate a Containment Fire Alarm within 15 Minutes ENS 484642012-10-31T19:18:00031 October 2012 19:18:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event Due to Security Condition ENS 477202012-03-06T12:24:0006 March 2012 12:24:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Due to Unidentified Rcs Leakage Greater than 10 Gpm ENS 475692012-01-05T09:53:0005 January 2012 09:53:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Sodium Hypochlorite Leak Resulted in Airborne Concentrations Potentially Dangerous to Life and Health ENS 443802008-08-03T08:52:0003 August 2008 08:52:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - Hydrazine Leak in Non-Vital Area of the Turbine Building 2023-05-27T23:34:00 | |