ENS 46179
ENS Event | |
|---|---|
18:40 Aug 16, 2010 | |
| Title | Npdes Limit Was Exceeded for River Temperature Discharge Requirements |
| Event Description | Browns Ferry Nuclear Plant inadvertently exceeded a limitation of its National Pollutant Discharge Elimination System (NPDES) Permit for Tennessee River temperature conditions which was reported to the Alabama Department of Environmental Management (ADEM) at 1340 Central Daylight Time, on August 16, 2010. As such, this is being reported in accordance with 10 CFR 50.72(b)(2)(xi) as 'Any event or situation, related to the health and safety of the public or on-site personnel, or protection of the environment, for which a news release is planned or notification to other government agencies has been or will be made.'
The NPDES Permit requires that when the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ambient average river temperature exceeded 90 degrees Fahrenheit, the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average downstream river temperature may equal but not exceed the upstream value. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average upstream temperature was found to be 90.4 (rounded to 90) degrees Fahrenheit and the downstream temperature was found to be 90.6 (rounded to 91) degrees Fahrenheit. Browns Ferry had been maintaining compliance with the NPDES permit. The departure is thought to be due to a summer storm cooling off the upstream temperature. With the time delay between upstream temperature changes and the ensuing rate at which the downstream temperature changes are observed, the resultant 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average downstream river temperature exceeded the upstream value. Duration of this condition was found to be only several hours. The three Browns Ferry units, which had already been derated to approximately 50 percent rated thermal power in order to maintain compliance with the NPDES Permit river temperature limits, were further derated to achieve compliance with the NPDES Permit. There is no corresponding requirement for written follow-up in accordance with 10 CFR 50.73. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | |
| Time - Person (Reporting Time:+-0.63 h-0.0263 days <br />-0.00375 weeks <br />-8.62974e-4 months <br />) | |
| Opened: | Ricky Givens 18:02 Aug 16, 2010 |
| NRC Officer: | John Knoke |
| Last Updated: | Aug 16, 2010 |
| 46179 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (45 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (45 %) |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (45 %) |
WEEKMONTHYEARENS 569412024-02-01T18:17:0001 February 2024 18:17:00
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