ENS 47348
ENS Event | |
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00:50 Oct 18, 2011 | |
Title | Unit 1 Declared an Unusual Event Based on Ammonia Levels Exceeding Osha Limits |
Event Description | Normal Operation of WBN [Watts Bar Nuclear] Unit 1 impeded in the Turbine Building, El. 685, West side of the Unit 1 Main condenser due to Toxic Gas (ammonia) concentrations of 75-79 ppm exceeding the OSHA Permissible Exposure Limit (PEL) of 50 ppm, and the ACGIH [American Conference of Governmental Industrial Hygienists] limit of 25 ppm. WBN Unit 1 returned to approximately 100% RTP on Monday, October 17, 2011, following a maintenance outage. Suspect excessive ammonia concentrations due to condenser vacuum pump continuous drains which may need throttling open to increase drain flow, following Unit startup. (Ammonia is used to treat feedwater for secondary chemistry control). There have been no injuries from this event. NRC Senior Resident [Inspector] has been notified. (Event Class 4.4.A, Toxic Gas, Unusual Event).
The licensee informed both the State and local agencies. Notified FEMA (Blankenship) and DHS (Konopka).
At 0047 EDT on 10/18/2011, the licensee terminated the Notification of Unusual Event condition based on ammonia concentrations having been reduced to approximately 6 ppm. Normal personnel access to the affected area has been restored. Unit 1 remained at 100% power during this event with no changes or challenges to plant operations. During the event there were no additional EAL designators. During the event there were no significant changes in plant conditions. During the event there were no significant changes in plant radiological conditions. During the event there were no offsite protective recommendations made by the licensee. The licensee notified the NRC Resident Inspector and State and local agencies. Notified R2DO (Lesser), NRR EO (Brown), IRD (Morris), DHS (Gates), and FEMA (Blankenship).
This information is being provided to the NRC for a 10CFR50.72(b)(2)(xi) notification. TVA is planning on making a news release to local media affiliates and posting the news release on TVA's website. This news release is in reference to the Notification of Unusual Event (NOUE) Watts Bar Nuclear Plant recently entered and exited for ammonia levels exceeding OSHA limits (reference EN 47348 and update). The licensee notified the NRC Senior Resident Inspector." Notified R2DO (Lesser). |
Where | |
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Watts Bar Tennessee (NRC Region 2) | |
Reporting | |
Emergency class: | Unusual Event |
10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | |
Time - Person (Reporting Time:+-3.28 h-0.137 days <br />-0.0195 weeks <br />-0.00449 months <br />) | |
Opened: | Bill Sprinkle 21:33 Oct 17, 2011 |
NRC Officer: | Steve Sandin |
Last Updated: | Oct 18, 2011 |
47348 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
Watts Bar with 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | |
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ENS 464692010-12-06T13:15:0006 December 2010 13:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification - Osha Contacted Due to Fatality of Contractor Employee ENS 464482010-12-02T21:10:0002 December 2010 21:10:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to an Individual Contamination ENS 430022006-11-21T11:15:00021 November 2006 11:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Unidentified Leakage ENS 414002005-02-10T22:01:00010 February 2005 22:01:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Tritium Sample Exceeding Offsite Dose Calculation Manual (Odcm) Reporting Level ENS 410492004-09-17T09:00:00017 September 2004 09:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Loss of Emergency Siren Capability and Notification of Offsite Agency 2023-11-12T08:00:00 | |