The following information was obtained from the State of
Oklahoma via email:
A well logging source has been lost down hole in Woods County, OK. The source information is Cesium 137, 1.78 Curie, S/N A3128, QSA Global model Y3. The licensee is Thrubit, Oklahoma license OK-32115-01.
The source is at a depth of 4452 [ft.] according to the gamma ray log. Surface location is Section 13-28N 13W, Lat 36.899418, Long -98.555695.
The well operator is Chesapeake.
The licensee has monitored to verify that there is no leakage of radioactivity from a source rupture. Four unsuccessful fishing attempts have been made and the licensee believes that the source is lodged in rubble where it can't be retrieved. The licensee informs DEQ [Oklahoma Dept. of Environmental Quality] they expect to submit a request to abandon the source. The Cesium source is lost as mentioned, but no AmBe or Californium source is lost.
The above is based on telephonic information received from the licensee and is a preliminary report. This information may be modified or updated based on written reports from the licensee or a DEQ investigation.
It is unclear at this time when the source was lost.
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. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf
Although IAEA categorization of this event is typically based on device type, the staff has been made aware of the actual activity of the source, and after calculation determines that it is a Less than Cat 3 event.
Note: the value assigned by device type "Category 3" is different than the calculated value "Less than Cat 3