Event Notification Report for February 16, 2007

TWELVE LOST TRITIUM EXIT SIGNS

The licensee provided the following information via email:

"In February of 2007 PacifiCorp Energy received the NRC letter (NRC Regulatory Issue Summary 2006-25) regarding Tritium exit signs. The receipt of the NRC 2006-25 instruction letter prompted Wyodak plant to do an inventory of Tritium exit signs and review the NRC standards and rules. When reviewing the 10CFR20.2201 rules in regards to missing sources, Wyodak plant subsequently started an investigation and discovery of the now missing Tritium exit signs.

"The following is a brief description of our investigation of missing Tritium exit signs:

"In 1993 a contractor (Montague) was hired to build a new coal handling facility at Wyodak plant that is owned by Black Hills Power and PacifiCorp Energy. An assumption is made that the contractor ordered 22 Tritium self luminating exit signs from Isolite and installed them in the new coal facility. The contractor (Montague) who built the Secondary Crusher Facility is no longer in business to verify any of the assumptions.

"During the facility construction most of the new coal handling facility was being handled by Black Hills Corporation. Later owner / operator lines were finalized and PacifiCorp Energy took over operation of the facility.

"In about 1999 the coal handling operator's control building which was a part of the 1993 facility was torn down. It is believed that two of the 1993 Tritium exit signs were destroyed with the demolition of this building.

"In 2003 Isolite notified PacifiCorp that the 22 self luminating Tritium exit signs purchased in 1993 were about to come to the end of their effective life. This call is what leads us to the assumption that 22 Tritium signs were purchased and installed in 1993. From the Isolite telephone call in 2003 PacifiCorp Energy's Wyodak plant purchased 22 new Tritium exit signs to replace the original 1993 signs. A work order was written to change out the old signs. The work order was never completed.

"From the ongoing investigation we now believe that only 16 of the original 22 Tritium exit signs were installed by the contractor (14 in the coal handling facility and 2 in its control building). It is assumed that 6 of the Tritium exit signs left the plant at the end of the 1993 construction with the contractor.

"We are currently working with Isolite to identify the serial numbers of the missing Tritium exit signs.

"Disposition of the radioactive material:

"6 - Tritium exit signs with 7.5 curries each are assumed to have been taken by the contractor (Montague) in 1993 - lost and not recoverable.

"2 - Tritium exit signs with 7.5 curries each were hauled to trash with the demolition of the coal operators control building in 1999 assumed lost and not recoverable.

"2 - Tritium exit signs with 7.5 curries lost by plant in 2003 assumed to be in a landfill and not recoverable.

"2 - Tritium exit signs with 11.5 curries, S/N's 224944 and 224947 lost by plant somewhere between 1993 and 2007 assumed to be in a landfill and not recoverable..

"Radiation exposure to individuals:

"It is believed that no individual exposure took place or any individual risk was involved.

"Actions taken to recover the material:

"Plant personnel have made a comprehensive search throughout the plant, plant storage and shop areas, plant warehouses, and coal facilities. Plant tried to make contact with the original installation contractor (Montague) but the company has gone out of business. Interviewed employees that might have had any knowledge of the Tritium exit signs. The results of the plant investigation are reported above.

"Actions taken to prevent recurrence.

"Wyodak Plant has completed an inventory of the 1993 and 2003 signs. Maps have been made of Tritium exit signs in use.

"A corporate policy has been initiated on the use and handling of Tritium exit signs. An annual inventory list with model and serial numbers has been created for tracking and inventory purpose. Employees responsible for the ordering, disposal, and installation of Tritium signs will receive annual training on the corporate policy."

THIS MATERIAL EVENT CONTAINS A "LESS THAN CAT 3" LEVEL OF RADIOACTIVE MATERIAL

Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks.

This source is not amongst those sources or devices identified by the IAEA Code of Conduct for the Safety & Security of Radioactive Sources to be of concern from a radiological standpoint. Therefore is it being categorized as a less than Category 3 source

COAL BUNKER FIRE DAMAGED DENSITY GAUGE CONTAINING 50 MILLICURIE CS-137

Subsequent to discussions with NRC Region IV (J. Thompson), the licensee is reporting a fire in one of their coal bunkers in late February 2007 damaged a Texas Nuclear Model 5192 density gauge (S/N B4745) containing 50 milliCurie Cs-137. The gauge was fix mounted in Unit 2 approximately 20 feet above the floor. After the fire was extinguished, a radiological survey of the gauge indicated that the source was still in the gauge. The licensee hired a contractor who removed and disposed of the gauge.