ENS 43183
ENS Event | |
|---|---|
12:00 Feb 22, 2005 | |
| Title | Agreement State Report - Misplaced Source Causes Possible Overexposure |
| Event Description | At approximately 0600 on 2/22/07 while loading a well logging source (Gulf Nuclear CSV H90 1 Curie Cs-137 source) into the pig on the truck, the crew unknowingly dropped the source in the motor pool parking lot. The source was picked up by a mechanic at approximately 0900 and he put it in the pocket of his jacket. He did not realize that it was radioactive, but thought it might be a part to something. The mechanic wore the jacket for about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. He visited several businesses including a sandwich shop. He hung the jacket in the break room where it remained for the remainder of the day and over night. On 02/23/07, the mechanic put the jacket back on. The well logging crew returned to the facility at approximately 0600 and discovered that the source was missing when they unpacked their equipment. The crew did not discover the missing source earlier because they did not need to use the source on a job site. The crew immediately started a search for the source. The mechanic produced the source when he heard that it was missing. In total the mechanic wore the jacket about 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> over the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period. This is an estimate based on an interview with the mechanic who was uncertain about the exactness of his recollection for the time he wore the jacket.
The mechanic and a couple of coworkers were taken to a local hospital emergency room and examined. No abnormalities were noted. They are scheduled to return to the emergency room on 2/24/07. Oklahoma continues to investigate. There has been no media interest. The R4 PAO (V. Dricks) was also notified.
Patient received two white blood cell counts, one on 02/23 and the other on 02/24, at Integris Baptist Hospital, Oklahoma City, Oklahoma, and both white blood cell counts were normal. The Doctor does not think the patient received a large dose. Patient is to report back in 1 week for follow-up testing. A blood sample of the patient will be sent to RPA located in London, England for chromosome analysis. R4DO ( Bill Jones) and NMSS EO (Joe Holonich) notified.
The patient visited the hospital emergency room again on 2/24/07. The ER Physician stated there was no sign of radiation effects. Oklahoma is arranging for the exposed individual to see a radiologist and/or oncologist at the OU Health Sciences Center. Blood samples will be drawn and provided to RPA in the UK for chromosome analysis. The state investigation is continuing. R4DO ( Bill Jones) and NMSS EO (Joe Holonich) notified.
The state provided a matrix of dose rate readings taken around the source by the licensee. The state is evaluating the information. The NRC continues to interface with the state on this event. Notified R4 (C. Cain), R4DO (D. Powers) and NMSS EO (S. Wastler).
When the mechanic removed the jacket containing the source, he initially hung it on a bollard (cement & metal post to keep vehicles away from a building) outside the logging company office. It was there all afternoon, the assistant mechanic stated that he was working in that area, so he has the possibility for exposure. The mechanic who was the main exposed person moved the jacket to the company break room at quitting time. There were staff working around the clock Thursday night, so there is a definite possibility staff were near the jacket while it was hanging there. Fortunately, the break room is small (more like a large closet) so most likely they would have gotten coffee and left. We will be interviewing staff this afternoon to try to nail this down. The exposed individual will see a very well-qualified physician, this afternoon. DEQ staff asked him to sign medical releases authorizing release to DEQ and to NRC. A blood sample will be taken and shipped to England for chromosome analysis. DEQ staff will be doing interviews this afternoon with facility staff who were potentially exposed to the source. DEQ staff will use this information to determine who else may warrant medical follow-up. We will also get confirmatory readings on the radiation level of the source with an ion chamber (as opposed to the GM tubes used by the company measures sent earlier). Notified R4 (C. Cain) Email only, R4DO (D. Powers) and NMSS EO (S. Wastler).
The primary exposed individual ('A') has been seen by a physician from the OU Health Sciences Center who has strong radiation protection credentials. The physician's belief is that the patient will probably suffer radiation burns on his abdomen, and possibly on his fingertips. He doesn't expect any other short-term effects. No burns or other effects are visible now. There is no sign of GI tract syndrome. 'A' is going to have follow-up visits with the physician at one week and two weeks, and possibly additional visits. A blood sample has been taken from 'A' and tomorrow it will be shipped to England for chromosome analysis. There was some delay due to international shipping requirements for biohazardous material. DEQ and OU HSC staff worked together this afternoon to take measurements using ion chambers. The measurements showed lower readings than those calculated through inverse square law. We will prepare a detailed report tomorrow and send it. In short, the dose level with the ion chamber case in contact with the source was 3.3 rem/hour, falling off to 139 mrem/hour at one meter. A badge was exposed to the source at one inch for 3 minutes 35 seconds, and is being sent to Landauer for emergency processing, which will give us more information. DEQ staff interviewed additional personnel at the licensee this afternoon, focusing on determining who might have been exposed to excess dose other than 'A.' Tentatively, the most at-risk individual appears to be a coworker who rode with 'A' to lunch. While they were in the cab of a pickup truck, the coworker was sitting in the passenger seat on the opposite side of 'A's' body from the source, and across a sandwich shop booth from 'A' during lunch. After lunch, 'A' and the coworker worked together on a logging truck with the coat (and source) hanging a couple of yards away. They spent most of their time under the truck, which would have provided considerable shielding. Tentatively we think it is conceivable the coworker broke the limit for dose to the public, but doubt there was medically significant exposure. We will do a detailed analysis tomorrow to test this. Notified R4DO (D. Powers) and FSME EO (J. Holonich)
The results for the dosimeter that was exposed to the Cesium source at one inch for 3 minutes 35 seconds were reported from Landauer this afternoon. Deep dose was 16,106 mrem and shallow dose was 15,374 mrem. This works out to about 4.4 R/minute or 264 R/hour skin dose. The package containing the blood sample from 'A' was shipped to England via overnight delivery this afternoon. Results are expected in the first half of next week. The results of the examination of 'A' by an OUHSC radiologist have been received and will be combined with the ER records from the weekend and faxed to the NRC on 02/28/07. The results were not substantially different from the verbal report on 02/26/07 and described in the update on the afternoon of 02/26/07. Notified R4DO (Powers) and FSME EO (Mohseni).
OK DEQ provided corrections to the previous report information. Specifically, the well logging source was originally reported to be a directional source. DEQ states that the source was not a directional source. In addition, the update on 2/27/07 reported a dose rate of 4.4 mrem/minute. This should have been 4.4 Rem/minute. The text of the previous report information has been corrected accordingly. Notified R4DO (Powers) and FSME EO (Davis).
The blood sample for chromosomal analysis has arrived in England and been received in good condition. They advise us they expect results on Tuesday. Notified R4DO (Powers) and FSME EO (Morell).
This morning the DEQ investigators visited the facility. We met with corporate management. They briefed us on their investigation and steps so far. They are doing root cause analysis of the incident. They will be doing several equipment upgrades to reduce exposure and increase certainty in handling sources. As a temporary measure they have removed the sources of the type in the incident (which did not have positive engagement of the source with the handling stick) from service until the handling sticks can be upgraded. They are doing additional staff training and will be seeking to change the safety culture at the company. As a temporary measure, they have a policy that a member of management must be present during all source handling at the shop. We explained our enforcement process to them. We informed management that based on calculations by NRC and DEQ, it appeared that a coworker of 'A' may have exceeded the dose limit for non-radiation workers, with a calculated dose of 140 mrem. We met with the coworker and explained his potential exposure, setting it in context by comparing it to the dose rate from natural background and the dose limits for radiation workers. As a precautionary measure, the company expects to do medical follow-up for this worker's exposure. We met with 'A' to follow up on his visit with a radiologist on Monday. He complained of nervous stress, but stated he had experienced no sensitivity or evidence of burns in the affected areas. We urged him to contact the radiologist immediately if he experienced any of the expected radiation symptoms. We asked 'A' some questions to clarify his interactions when he unknowingly had the source with him off-site. It does not appear that there was anyone off-site who had enough potential exposure to warrant follow-up. Notified R4DO (Powers) and FSME EO (Morell). |
| Where | |
|---|---|
| Ips Oklahoma City, Oklahoma (NRC Region 4) | |
| License number: | 310-0901 |
| Organization: | Ok Deq Rad Management |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+17552.72 h731.363 days <br />104.48 weeks <br />24.044 months <br />) | |
| Opened: | Mike Broderick 20:43 Feb 23, 2007 |
| NRC Officer: | Bill Gott |
| Last Updated: | Mar 1, 2007 |
| 43183 - NRC Website | |
Ips with Agreement State | |
WEEKMONTHYEARENS 431832005-02-22T12:00:00022 February 2005 12:00:00
[Table view]Agreement State Agreement State Report - Misplaced Source Causes Possible Overexposure 2005-02-22T12:00:00 | |