ENS 52242
ENS Event | |
|---|---|
14:08 Sep 15, 2016 | |
| Title | Potential Unanalyzed Condition Based on Identified Non-Conforming Conditions |
| Event Description | During performance of an extent of condition evaluation of protection for Technical Specification (TS) equipment from the damaging effects of tornadoes, Arkansas Nuclear One, Unit 1, identified non-conforming conditions in the plant design such that specific TS equipment on Unit 1 is considered not [to] be adequately protected from tornado missiles. The reportable condition is postulated by tornado missiles entering vital switchgear rooms 99 and 100 and striking vital switchgears in the rooms. A tornado could generate multiple missiles capable of striking the Unit 1 vital switchgear and rendering both safety related AC electrical trains inoperable.
This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) for any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety, and per 10 CFR 50.72(b)(3)(v) for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (A) safe shutdown capability, (B) residual heat removal capability, or (D) accident mitigation. This condition was identified as part of an on-going extent of condition review of potential tornado missile related site impacts. Licensee Event Report (LER) 50-313/2016-002-00 was recently submitted addressing previously identified tornado missile vulnerabilities at the Unit 1 plant. Enforcement discretion per Enforcement Guidance Memorandum EGM 15-002 has been implemented and required actions taken. Corrective actions will be documented in a follow-on licensee event report. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-2.83 h-0.118 days <br />-0.0168 weeks <br />-0.00388 months <br />) | |
| Opened: | Don Walls 11:18 Sep 15, 2016 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Sep 15, 2016 |
| 52242 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (90 %) |
| After | Power Operation (90 %) |