Event Notification Report for November 28, 2007

OFFSITE NOTIFICATION OF HIGH TRITIUM LEVELS IN SUMP

"This communication is being made in accordance with 50.72(b)(2)(xi) and the Nuclear Energy Institute (NEI) Industry Ground Water Protection Initiative. Millstone Power Station and other nuclear power stations across the country are participating in this voluntary initiative to develop and improve ground water protection programs at nuclear power stations. This communication provides notification of preliminary sample analysis of water that seeped into the foundation drain sump outside of the Millstone Unit 3 engineered safety features building. This water is pumped to the station yard drain system and discharged to Long Island Sound via a permitted and monitored pathway for the station. Tritium was detected at a concentration of approximately 34,000 picoCuries per liter in a sample of the water from the sump. The NEI reporting threshold for tritium concentrations is 20,000 picoCuries per liter.

"Investigation into the source of the tritium is underway and at the present time the source has not been determined.

"The presence of tritium at this location does not present a health hazard to plant employees or the general public. Samples from several wells closest to the affected sump show no detectable concentrations of tritium. Additional sampling is underway. Based on the known hydrology of the site, public drinking water supplies are not affected.

"The licensee notified the following agencies: CT Department of Environmental Protection, CT Department of Emergency Management and Homeland Security, CT Department of Public Utilities Control, The Town of Waterford, and The Town of East Lyme."

The licensee performed pump maintenance in the sump. At the same time, they performed samples of the water in the sump and found the high tritium concentration in the samples taken.

The licensee notified the NRC Resident Inspector.

REACTOR SCRAM AND ECCS INJECTION

A reactor scram occurred at full power due to either a main turbine trip or loss of feedwater (cause is still under investigation). All rods fully inserted. RCIC started as expected but tripped shortly thereafter on a preliminary indication of low suction pressure. The Digital Feedwater System backup motor driven feedwater pump did not function as required and reactor water level decreased to level 2 (130 inches). High Pressure Core Spray (HPCS) started automatically at level 2 and restored water level. Currently reactor water level is at 188 inches and reactor pressure is at 927 PSI. Decay heat is being removed via the turbine bypass valves. No other significant equipment was out of service at the time of the scram. The scram had no impact on offsite or onsite power availability.

The licensee attempted to restore RCIC a second time and experienced another trip. In addition, the licensee attempted to restore the digital feedwater and was unsuccessful. Feedwater continues to be supplied as needed via the HPCS while the licensee attempts to restore RCIC and Digital Feedwater System.

The licensee notified the NRC Resident Inspector.

HPCI INOPERABLE DUE TO LEVEL SWITCH FAILURE

"On 11/28/2007 at 0230 CST, Browns Ferry Unit 1 received a 'HPCI PUMP SUCT HDR LEVEL LOW' alarm and HPCI automatically transferred its suction from the Condensate Storage Tank (CST) to the Suppression Pool. With the HPCI suction not aligned to its normal source, the HPCI system was declared inoperable. At 0710 CST, trouble shooting identified a level switch malfunction. This switch was removed from service allowing HPCl to be returned to the normal Standby Readiness configuration. The System was declared Operable at 0710 when the system was aligned back to normal suction source.

"This event is reportable under 10CFR 50.72(b)(3)(v)(B) '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: Remove Residual Heat' and 10CFR 50.72(b)(3)(v)(D) '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: mitigate the consequences of an accident.'

"This event also requires a 60 day written report in accordance with 10CFR 50.73(a)(2)(v)(B) and 10CFR 50.73(a)(2)(v)(D)."

The licensee notified the NRC Resident Inspector.

* * * RETRACTION FROM TODD BOHANAN TO HOWIE CROUCH AT 1311 HRS. EST ON 01/25/08 * * *

"ENS Event Number 43809, made on 11/28/2007, is being retracted.

"NRC Notification 43809 was conservatively made to ensure that the eight-hour non-emergency reporting requirements of 10 CFR 50.72 were met pending the evaluation of an atypical system alignment with the High Pressure Coolant Injection (HPCI) [system].

"An evaluation has been performed in response to this event. The evaluation concluded that the HPCI system was capable of performing its intended safety function in this atypical configuration. As such, the circumstances discussed in the report did not result in any condition that could have prevented the fulfillment of the safety function of structures or systems needed to mitigate the consequences of an accident. Thus there would have no impact on nuclear safety. Therefore, this event is not reportable under 10 CFR 50.72(b)(3)(v)(B) or 10 CFR 50.72(b)(3)(v)(D).

"TVA's evaluation of this event is documented in the corrective action program.

"The licensee has notified the NRC Resident Inspector."

Notified R2DO (Desai).