Event Notification Report for June 23, 2005

NON-LICENSED SUPERVISOR FAILED RANDOM FITNESS FOR DUTY TEST

A non-licensed employee supervisor tested positive for illegal drugs during a random test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer.

The licensee notified the NRC Resident Inspector.

UNIT 2 AUX FEEDWATER TRAIN SEPARATION NOT MAINTAINED DURING OPERATION

"The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73.

"On 6/23/05 at approximately 08:23 MST, it was identified that the door between the 'A' and 'B' Train Aux Feedwater Pump rooms was open and unattended. The door was immediately closed and secured. This door is required to be maintained secured in the closed position (except for personnel ingress/egress) during Modes 1 through 4 to provide a barrier for protection from fire or internal flooding. Station procedures require compensatory measures to be established when this door is maintained open in Modes 1-4. The compensatory measures include stationing an individual with the responsibility to close the door in the event of internal flooding. Since this compensatory measure was not established, this condition is considered to be reportable as an unanalyzed condition per the criteria of 10CFR50.72(b)(3)(ii)(B).

"Investigation is in progress to determine the duration and reason that this door was inappropriately open."

The licensee notified the NRC Resident Inspector.

UNIT EXPERIENCED AN AUTOMATIC REACTOR SCRAM DUE TO A LOSS OF FEEDWATER FLOW

"On June 23, 2005 at 1348 PDT Columbia Generating Station experienced a Reactor Protection System (RPS) actuation and closure of all Main Steam Isolation Valves (MSIV) while operating at approximately 25% power. Currently, Reactor Pressure Vessel (RPV) level is being controlled using the Reactor Core Isolation Cooling (RCIC) system and RPV pressure is stable at approximately 800 psi. There was no automatic ECCS system injection. At this time, the plant is stable and indications show that the RPS actuation and closure of MSIVs was initiated in response to a valid low RPV water level signals that occurred because of a loss of feedwater flow. Determination of the cause of the loss of feedwater flow is ongoing at this time."

All control rods fully inserted.

The licensee informed the NRC Resident Inspector.

OFFSITE POWER SOURCE DECLARED INOPERABLE DUE TO LOW VOLTAGE

"At 15:49 hours Central Daylight Savings Time, June 23, 2005, entered DOA 6500-12, Low Switchyard Voltage. Bulk Power Operations reported predicted post Unit trip with LOCA switchyard voltage for Unit 2 is 342.5 KV and for Unit 3 is 342.3 KV. This rendered both Unit 2 and Unit 3 offsite electrical power sources inoperable. This predicted voltage is the value required to support Loss Of Coolant Accident (LOCA) loading. Entered applicable Technical Specification required actions for both Units due to both offsite power sources being declared inoperable for Unit 2 and Unit 3.

"As of 1744 hours, restored Unit 2 offsite electrical power source to operable status by performing Transformer 86 Tap Changer adjustment per applicable procedure. TR 86 [transformer 86] supplies Unit 2 offsite electrical power.

"As of 1948 hours, switchyard voltage was restored to operable limits. This restored Unit 3 offsite electrical power source to operable status.

"This notification is provided in accordance with 10CFR50.72(b)(3)(v)(D) to report a 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."

The licensee will notify the NRC Resident Inspector and the state.

* * * UPDATE FROM P. SALGADO TO M. RIPLEY 1258 EDT 07/28/06 * * *

"The purpose of this report is to retract ENS report 41791 (June 23, 2005) for Dresden Nuclear Power Station (DNPS). The report was made following notification from Bulk Power Operations that the predicted post Unit trip with LOCA switchyard voltage rendered both Unit 2 and Unit 3 offsite electrical power sources inoperable. Both offsite electrical power sources were declared inoperable, the appropriate Technical Specification required actions were taken and an ENS notification was made in accordance with 10CFR 50.72(b) (3)(v)(D) for an event that could have prevented fulfillment of a safety function.

"In July 2006, DNPS performed a reanalysis of the June 23, 2005 event. The reanalysis determined that the computer model used to determine the required switchyard voltage for the June 23, 2005 event conservatively assumed that the Reserve Auxiliary Transformers (RATs) were supplying all plant 4 kilovolt (Kv) electrical loads and the second source of offsite power for each unit was based on a post unit trip. During normal plant operation the 4kV electrical loads are split between the RATs and the Unit Auxiliary Transformers (UATs). The reanalysis used the split bus configuration and the actual switchyard voltages at the time of the June 23, 2005 event. The reanalysis concluded that the voltages were greater than required, ensuring that the second source of offsite power for each unit would remain operable following a postulated design basis accident. Therefore, there was no condition present on June 23, 2005, that could have prevented fulfillment of a safety function and this event is not reportable under 10CFR 50.72(b)(3)(v)(D)."

The licensee notified the NRC Resident Inspector. Notified R3 DO (R. Lanksbury)

LICENSEE DECLARED AN UNUSUAL EVENT DUE TO DETECTION OF A FLAMMABLE GAS IN THE GENERAL SERVICES BUILDING

An NOUE was declared at the site at 2327 PDT due to the discovery of flammable gas in the General Services Building (office space) which is attached to the turbine and reactor building. The source and type of gas has not been identified and investigation is ongoing by HAZMAT trained personnel. The highest level of flammability measured is 50% of LEL (Lower Explosive Limit). The building has been evacuated.

The NRC Resident Inspector will be notified and State local and other Gov agencies have been notified.

* * * UPDATE FROM D. FUJIYOSHI TO M. RIPLEY 0527 EDT 06/24/05 * * *

"EAL # 9.3.U.3 - Report or detection of toxic or flammable gases that could enter or have entered within the Protected Area Boundary in amounts that could affect the health of plant personnel or safe plant operation.

"The event has been terminated based on a thorough survey of the building by HAZMAT personnel. The building in question has been determined to be free of any flammable gases.

"Probable source of gas is from a sewage treatment plant. The gas was carried by a stable breeze to the building's air intake. Immediately prior to the event, initial reports of odorous gas from several building occupants was confirmed using portable instrumentation. The highest flammable gas levels were found at a building air intake. Dissipation of gas concentration was accomplished using normal building ventilation."

The NRC Resident Inspector will be notified and State local and other Gov agencies have been notified. Notified R4 DO (R. Bywater), NRR EO (M. Case), IRD Manager (S. Frant), DHS (Ceasar), and FEMA (Sullivan).