Detection of toxic gases (CO) inside the turbine building.
Source not identified.
Initial Readings were greater than 50 parts per million in turbine building lower elevations.
EALHU5.1
Detected by safety department random sampling.
Turbine building has been evacuated, all personnel have been accounted for with no injures.
Follow-up notification will be made with determination of cause of event.
The unit is currently defueled. The carbon monoxide source is being investigated.
The NRC Resident Inspector as well as state and local authorities were notified.
- * * UPDATE FROM ERIC PICKRELL TO JOE O'HARA AT 1932 EST ON 1/23/08 * * *
Notified J. O'Hara of termination of the declared NOUE. Termination is based on subsequent air monitoring sampling revealing normal Oxygen levels and no detectable Carbon Monoxide levels.
(unknown) Source of abnormal sample readings is not yet determined. Believed to be result of Hydrogen Water Chemistry system purge which was in progress at the time of sampling.
Licensee terminated the declaration of notification of unusual event at 1827 CST following two subsequently satisfactory air samples.
Notified R4DO(Johnson), NRR(Case), and IRD(Blount)
- * UPDATE FROM TIM SCHENK TO JOHN KNOKE AT 1515 EST ON 01/24/08 * *
It has been determined that hazardous levels of toxic gases (Carbon Monoxide) inside the turbine building did not exist at the time of emergency declaration. Actual carbon monoxide levels were less than detectable. Gas sensor cross contamination led to false readings of high carbon monoxide level (60 ppm), when actual gas measurements were reading hydrogen levels of 20 ppm. This level of hydrogen is well below the 40,000 ppm Lower Explosive Limit for hydrogen. The source of the hydrogen readings was attributed to a leaking ventilation rig for the Hydrogen Water Chemistry system during system purge with Nitrogen.
The licensee notified the NRC Resident Inspector. Notified R4DO (C. Johnson).
