Event Notification Report for August 28, 2003

ALERT DECLARED DUE TO REACTOR PROTECTION SYSTEM FAILURE

At 1618 EDT on 08/28/03, an Alert was declared at Sequoyah Unit 1 due to a failure of the Reactor Protection System (RPS) to auto-trip the reactor following a turbine trip. Turbine oil trip testing was in progress when at 1604, the main turbine tripped. The reactor trip breakers were opened by manual operator action approximately 20 seconds after the valid reactor trip signal. Following the trip, all systems operated as required. The main steam isolation valves were manually closed based on indication of steam flow and a throttled steam dump valve. No primary system or steam generator safety valves opened. The unit is currently stable with temperature controlled using atmospheric relief valves. The Auxiliary Feedwater System received an auto-start signal and successfully operated. All control rods were fully inserted into the core. There was no release of radioactive material.

The licensee has initiated an investigation into the cause of the incident.

The NRC Resident Inspector and the State of Tennessee were notified by the licensee. The NRC notified FEMA (Steiner), DOE (Morroni), USDA (Beers-Block), HHS (Williams), DHS (Glick), and DOT/EPA/NRC (Threatt).

The NRC entered monitoring phase of normal mode with Region 2 in the lead at 1735 EDT.

* * * UPDATE ON 08/28/03 AT 2044 EDT, KEVIN WILKES TO NATHAN SANFILIPPO * * *

At 2030 EDT on 08/28/03, the licensee terminated the Alert at Sequoyah Unit 1. The reactor is stable and in Mode 3, Hot Standby. This termination is based upon containment integrity, Emergency Core Cooling System and Engineered Safety Features operability, availability of heat sink, onsite and offsite electrical system and Emergency Diesel Generator operability, radiation monitor operability, availability of technical support personnel, and activation of a forced outage recovery team. Reactor coolant samples were taken, which showed no increase in activity.

The NRC notified FEMA (Austin), DOE (Morroni), USDA (Beers-Block), HHS (Hogan), DHS (Van Buskirk), and DOT/EPA/NRC (White).

The NRC exited monitoring phase of normal mode at 2045 EDT.

* * * UPDATE 1420 EDT FROM ZACHARY KITTS TO S. SANDIN * * *

The following information was provided as an update:

"This provides a follow-up report regarding the prior notification of an Alert on 8/28/03 that included a possible reactor protection system (RPS) failure on Unit 1. The main control room staff responded to a loss of generator load by initiating a manual reactor trip. The Alert was declared at 1618 under EN # 40113. The operators suspected a failure of the automatic RPS because they believed that, based on direct observation of plant conditions at the time, a valid automatic reactor trip signal should have occurred. A subsequent engineering review of plant parameters prior to and after the manual reactor trip determined that no automatic reactor trip signal was required.

"TVA has determined that there was no failure of the turbine protection or reactor protection system. The apparent failure of a pressure switch from the turbine trip oil system in conjunction with the thrust bearing trip components being tested caused the actuation of the Unit 1 generator trip circuitry and the opening of the generator output breakers. The electrical unloading of the generator was followed by rapid closure of the turbine governor valves to control generator speed.

"By design, the generator trip signal does not result in an automatic turbine trip under the conditions experienced. The turbine responded to the generator trip as a loss of load transient. The turbine overspeed protection circuitry (OPC) operated as expected to close the turbine governor valves to prevent an overspeed condition. The turbine protection system contains overspeed trip functions which function independently based on either mechanical or electrical inputs. While the mechanical overspeed protection function was inoperable due to the test in progress, the electrical overspeed trip was available to trip the turbine. The operation of the OPC limited the turbine overspeed transient such that the electrical overspeed trip setpoint was not required.

"For a loss of electric load and/or turbine trip event, the reactor protection system is expected to initiate a reactor trip when either the high reactor coolant system pressure or over temperature differential temperature (OTDT) setpoint is reached. In this event, however the reactor was manually tripped by operator action in response to the generator trip. Subsequent review of the primary system transient response data confirmed that none of the reactor protection system setpoints were exceeded prior to the operator action. The reactor trip breakers opened as expected following the manual trip. The reactor protection system functioned as designed.

"Event investigation will continue with resolution of adverse conditions prior to Unit 1 startup. TVA is providing this follow-up report to update you as to the subsequent information resulting from the investigation."

The licensee informed the NRC Resident Inspector. Notified R2DO(Evans) and NRR EO(Reis).

24-HOUR CONDITION OF LICENSE REPORT INVOLVING POTENTIAL VIOLATION OF MAXIMUM POWER LEVEL

"This 24-hour report is being made as required by Byron Unit 1 License Condition 2.F and Byron Unit 2 License Condition 2.G as a potential violation of the maximum power level (3586.6 MWt) as stated in Unit 1 and Unit 2 License Condition 2.C(1).

"On August 28, 2003 at 17:43 CST Byron Station was notified by the ultrasonic flow measurement vendor via letter that there were discrepancies in the ultrasonic flow measurements used in the calorimetric calculation for reactor power. As part of an ongoing testing plan, ultrasonic flow measurements were being taken on the main feedwater system piping header on Byron Unit 1 and were compared to the results from the ultrasonic flow measurement devices on the four individual feedwater lines. Based on the results of the data analysis, and noted signal abnormalities, it was determined that Byron Unit 1 has potentially exceeded its licensed thermal power limit by approximately 1.5%.

"Based on the results of the testing on Unit 1, the ultrasonic flow measurements on Byron Unit 2 were also investigated. Similar signal abnormalities were identified on one of the four ultrasonic flow measurement devices installed on the individual feedwater lines on Unit 2. Subsequent evaluation indicates that Byron Unit 2 also has potentially exceeded its licensed thermal power limit by approximately 0.6%.

"The power level on both units was reduced to less than 100% power consistent with feedwater flow as measured directly by the venturis without using the correction factors from the ultrasonic flowmeters.

"Additional actions regarding investigation of the condition, determination of root cause and corrective action, and determination of the potential actual overpower will be included in the 30-day license event report."

The licensee informed the NRC Resident Inspector.

LOSS OF POWER TO EMERGENCY OPERATIONS FACILITY

"The Emergency Operations Facility (EOF) for Grand Gulf was lost when power was removed from the facility and the EOF diesel generator failed to start. Power had to be removed due to the loss of one phase of the local power supply. Actual plant operations are not affected. The power phase problem and failure of the EOF diesel generator to start are being investigated at this time. The Backup EOF is available if needed."

The licensee notified the NRC Resident Inspector.

* * * UPDATED ON 09/02/03 AT 1841 EDT FROM CARL EHRHARDT TO NATHAN SANFILIPPO * * *

As of 09/02/03, power to the Grand Gulf Emergency Operations Facility (EOF) has been restored.

The NRC Resident Inspector will be notified. Notified R4DO Charles Marschall.

FITNESS FOR DUTY

"At 0700 a non-licensed contract supervisor failed a for cause fitness-for-duty test. The individual tested positive for alcohol, and the results of the drug portion of the test have not yet been received.

"Immediate Corrective Action: The individual's unescorted site access was denied at 0717 CST on August 28, 2003, and appropriate notifications have been completed in accordance with the station's Fitness-For-Duty Program.

"Safety Significance: None. There is no reason to believe there have been any adverse consequences from this event. The employee had been cleared for unescorted access; however, had never obtained his badge for access to the protected area of the site. This event is not considered to have impacted operation of the plant in any way.

"The licensee informed the NRC Resident Inspector.

"Contact the Headquarters Operations Officer for additional details."