ENS 47651
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ENS Event | |
|---|---|
19:35 Feb 8, 2012 | |
| Title | Scram Functionality May Be Degraded in a Appendix R Fire |
| Event Description | During BFNP NFPA 805 transition review, it was determined in the vent of an Appendix-R fire, the Reactor Protection System (RPS) function could be rendered not functional. The current Appendix R Safe Shutdown Analysis states: "The safe shutdown function of the Reactor Protection System (RPS) is to initiate reactor scram through actuation of the control rod drives. The RPS includes the RPS motor-generator power supplies and associated control and indicating devices, sensors, relays, bypass circuitry, and switches that initiate rapid insertion of control rods (scram) to shutdown the reactor. The RPS utilizes a fail-safe design so that device failures or a loss of power will result in control rod insertion. The scram function will remain available despite any fire-induced spurious signals that may be generated due to the effects of a postulated fire in any fire area. This system is expected to perform its function automatically, however credit is taken only for manual scram. No additional analysis is needed to ensure the availability of reactor scram in the even of a fire.
Due to lack of physical separation with 120 volt AC lighting circuitry, the RPS system potentially could remain energized due to a postulated hot short circuit during a fire which could potentially prevent the control rods from inserting. Therefore, the fail-safe design of the RPS system would not be maintained. Compensatory actions in the form of fire watches to mitigate this condition are in place in accordance with the BFNP Fire Protection Report. This event is reportable as an 8-hour notification to the NRC in accordance with 10CFR50.73(a)(2)(ii)(B). The NRC Resident Inspector has been notified of this event. This event was entered into the licensee's Corrective Action Program as PER 503304. |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.07 h-0.00292 days <br />-4.166667e-4 weeks <br />-9.5886e-5 months <br />) | |
| Opened: | John Ridinger 19:31 Feb 8, 2012 |
| NRC Officer: | Charles Teal |
| Last Updated: | Feb 8, 2012 |
| 47651 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 542662019-09-11T00:34:00011 September 2019 00:34:00
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