ENS 46163
ENS Event | |
|---|---|
13:35 Aug 9, 2010 | |
| Title | Appendix R Safe Shutdown Instructions Do Not Contain Two Required Operator Manual Actions |
| Event Description | The Browns Ferry Nuclear Plant (BFN) 10 CFR 50 Appendix R Safe Shutdown Instructions provide manual actions to limit diesel loading. From the Tennessee Valley Authority's review of the design input calculation, 'Appendix R - Auxiliary Power System Alignments and Diesel Generator Loading,' it was determined that two 4 kV breakers (one in each of two fire scenarios) that should be tripped and/or tripped and isolated during a postulated Appendix R event were not part of the BFN Safe Shutdown Instructions. Without additional operator manual actions to trip and/or trip and isolate the affected breakers, spurious closure of the breakers could overload the credited emergency generator.
Interim actions to trip and/or trip and isolate these breakers for Appendix R Safe Shutdown Instructions are being put in place. This event is reportable within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> under 10CFR50.72 (b)(3)(v)(A) - any event or condition that results in the condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: Shut down the reactor and maintain it in a safe shutdown condition. This event is also reportable within 60 days under 10CFR50.73(a)(2)(v)(A) - as any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to: Shut down the reactor and maintain it in a safe shutdown condition. This condition was self-identified. The condition has been documented in the BFN Corrective Action program as Service Request 228891. Unit 1, 2, and 3 remain at power and are not affected by this event. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
| Time - Person (Reporting Time:+3.68 h0.153 days <br />0.0219 weeks <br />0.00504 months <br />) | |
| Opened: | Todd Bohanan 17:16 Aug 9, 2010 |
| NRC Officer: | Vince Klco |
| Last Updated: | Aug 9, 2010 |
| 46163 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (50 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (50 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (50 %) |