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| Entered date | Event description | |
|---|---|---|
| ENS 49238 | 5 August 2013 15:52:00 | The State of Nebraska submitted the following information via email: The licensee uses fixed industrial gauges for measuring levels in fly ash hoppers at the station's precipitator building. The industrial fixed gauges contain a Cesium 137 sealed source. The Cesium 137 sources were originally installed in April, 1984, and at the time contained 50 millicuries per source. The sources were manufactured and installed by Kay Ray Inc. The gauge that experienced the event was Kay Ray Gauge, Housing Model #7080 and housing serial number 16784H. The source capsule manufacture was Amersham model no. CDC 800 and K-R Ref. Number serial number 15095 V. In accordance with their license conditions two of the station's chemists were securing the Unit #5's precipitator sources in preparation for an inspection of the precipitator. The 'external' source closure mechanism for Unit #5 precipitator's 5FA-3E & 4E hoppers did not operate as designed and the shutter did not close when the handle on the floor was operated. The radiation sources, which are part of a hopper level sensor, are mounted between two fly ash hoppers 20 feet off the floor. The source closure mechanisms are connected to a handle located at the floor level by a flexible cable. These closure cables are secured to the structures so that when the handles are operated the control cables slide inside a sheath. On the 5FA-3E & 4E source, the shutter closure cable became loose up at the source which allowed the whole cable to slide back and forth when the handle was operated to try and close the shutter. This type of failure has been seen in the past and is easily fixed by tightening the screw which secures the end of the cable to the structure. This required a scaffold to be built up to the source level. A contractor came on site at 12:30 pm (CDT) on 8/5/2013 and erected a scaffold so repairs could be made. |
| ENS 46058 | 30 June 2010 16:04:00 | The following report was received via fax from the State of Nebraska: The licensee uses fixed industrial gauges for measuring densities in flyash hoppers at the Stations precipitator building. The Industrial gauges contain a Cesium 137 sealed source. The Cesium 137 sources were originally installed in 1984 and at the time contained 50 millicuries per source. The sources were manufactured and installed by Kay Ray Inc. The gauge housing Model No. is 7080. The licensee was performing the semi-annual 'Shutter Function Test' on Unit #4's precipitator sources. The 'external' source closure mechanism for the 4FA-1B & 2B hoppers did not operate as designed and the shutter did not close when the handle on the floor was operated. The external closure cable had detached from the cable clamp on the side of the hopper. In this condition, when the shutter closure mechanism was moved, the cable that operates the source shutter mechanism 20 feet above the floor, bent instead of sliding the cable to the closed position. No personnel were exposed to radiation during this event. This was the fourth similar event at the licensee's plant (March 25, 27, May 6, & June 30, 2010). On June 17, a NE DHHS (Nebraska Department of Health and Human Services), Radioactive Material inspector performed a follow-up investigation on-site. At this plant, OPPD (Omaha Public Power District) has 58 installed operating nuclear fixed gauges. At the time of the investigation, OPPD had replaced 20 of the old shutter cables with a new redesigned direct replacement cable. OPPD plans to replace all of the 58 shutter cables when they fail to operate or as time permits. |
| ENS 45907 | 6 May 2010 16:19:00 | The following information was received from the State of Nebraska via facsimile: The licensee uses fixed industrial gauges for measuring densities in fly ash hoppers at the station's precipitator building. The industrial gauges contain a Cesium 137 sealed source. The Cesium 137 sources were originally installed in 1975 and at the time contained 50 millicuries per source. The sources were manufactured and installed by Kay Ray Inc. The gauges are Model No. 7700-50. The licensee was attempting to close the shutter on the fixed gauge prior to performing maintenance. One of the external closure cables was found to be slightly bound up and only partially closed the internal source shutter. The cable closure was reopened, which reopened the source shutter up at the sealed source. Closure was tried again. This time the cable, which connects the handle at the floor to the sealed source shutter mechanism 20 feet above, bent instead of sliding the cable to the closed position. This event happened at 1346 (CDT) and was reported to the station's Shift Supervisor who in turn contacted the plant electricians to make repairs so the precipitator tag-out could continue. By 1353, the cable had been closed and the lab contacted to perform a survey to verify the source shutter was in the closed position. No personnel were exposed to radiation during this event. |