ENS 49690
ENS Event | |
|---|---|
20:00 Jan 3, 2014 | |
| Title | Abgts Potentially Inoperable for Both Units Under Worst-Case Conditions |
| Event Description | At 1500 EST on 01/03/2014, TVA determined that during certain conditions, Service Air usage (air used for non-safety related tools/equipment) could result in introducing air into the Auxiliary Building Secondary Containment Enclosure that could, in worst-case conditions, exceed the margin required to maintain the Auxiliary Building Gas Treatment System (ABGTS) operable for Sequoyah Units 1 and 2. ABGTS is required to be operable for both units by Technical Specifications. This is an unanalyzed condition that could prevent both trains of ABGTS from performing [their] safety function[s]. Service air has been isolated to the Auxiliary Building and is under administrative controls until further analysis [is] complete. This is additional information discovered during follow-up evaluation regarding the issue identified in LER 50-327/2013-004. Further analysis will be performed to determine safety significance.
There is 1600 scfm margin in the ABSGTS. The Service Air compressors have an 1850 scfm capacity. The licensee informed the NRC Resident Inspector.
Sequoyah Nuclear Plant, Units 1 and 2, are retracting the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> non-emergency notification January 3, 2014 at 2207 EST (EN# 49690). The notification on January 3, 2014, reported under certain conditions, service air usage could result in the Auxiliary Building Secondary Containment Enclosure (ABSCE), in worst case conditions, exceeding the margin required to maintain the Auxiliary Building Gas Treatment System (ABGTS) operable and prevent both trains of ABGTS from performing its safety function(s). Subsequent engineering analysis concluded acceptable margin was available. Both trains of ABGTS would have remained operable and capable of performing its design function(s) at all times. The engineering analysis results are captured in the licensee's corrective action program. Based on the new analysis, the condition reported in EN #49690 did not result in an unanalyzed condition that significantly degraded plant safety. This event report is being retracted. The NRC Resident Inspector has been briefed on the analysis results and informed of this retraction. Notified R2DO (McCoy). |
| Where | |
|---|---|
Sequoyah  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+2.12 h0.0883 days <br />0.0126 weeks <br />0.0029 months <br />) | |
| Opened: | Robert Camenisch 22:07 Jan 3, 2014 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jan 30, 2014 |
| 49690 - 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 %) |
WEEKMONTHYEARENS 544872020-01-22T03:18:00022 January 2020 03:18:00
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