ENS 46931
ENS Event | |
|---|---|
01:00 Mar 31, 2011 | |
| Title | Agreement State Report - Extremity Overexposure During Laboratory Work |
| Event Description | The following information was provided via e-mail from the Washington State Department of Health, Office of Radiation Protection:
A Nuclear Medicine technologist received an overexposure to her extremity dosimeter for March 2011 while working in the basement of the Magnusen Health Sciences Building on the UW Campus. The Extremity Dose was reported as 56,440 mrem. During the month of March, she performed several cell-labeling procedures involving 75mCi, 111mCi, and 108mCi amounts of Y-90. There were also several labeling procedures involving the use of I-131 during the same time frame. However, because the whole body badge showed no significant exposure, it is believed the majority of the exposure came from the technologist's work with Y-90. Licensee: University of Washington City and State: Seattle, WA License Number: WN-C001-1 Type of License: Broad A Date and time of Event: March 1 - March 30, 2011 Location of Event: UW Magnusen Health Sciences Building Investigation is ongoing. Washington Report #WA-11-030
On 6 June 2011, the department [Washington Division of Radiation Protection] received notification via letter from the University of Washington (UW) that an employee, had received an extremity dose to the left hand of 56,440 mrem from Yttrium 90 for the month of March 2011. The department [Washington Division of Radiation Protection] was notified that the employee retired in May 2011. An incident number WA-11-030 was assigned to the event. UW informed the technician of the overexposure and she agreed to meet to discuss the incident. On 15 June 2011, a Health Physicist from the Department of Health met with the UW RSO, a UW Health Physicist, and the technician to discuss the incident. The Y-90 comes in bulk and must be divided into smaller aliquots based on the desired dose for cell labeling. These aliquots must be handled several times during the cell labeling procedure by the technician. The small size of the aliquot tubes made it too difficult to use tongs or other devices that might have lessened their exposure during these parts of the procedures. Most of this work was done in a hood behind shielding so that the whole body dose remained normal. Because the technician is right-handed, she would most often hold the tube containing the Y-90 in the left hand so she could use their right hand to add reagents or pipette the Y-90 solution into another tube. Although the exposure to the right hand did not exceed the annual limit, it was also unusually high for the month of March, 10.85 REM. The technician stated that there was no spill or other unusual occurrence during the month of March. It is highly unusual to do multiple labeling procedures in a one month period and March 2011 is the only time she has done three in one month. The amounts received, 75mCi, 111mCi, and 108 mCi were also larger than average. There were also several procedures involving the use of large doses, up to 1 Ci, of I-131 in March. However, this was not out of the ordinary for the technician so it is believed to be more likely that the multiple labeling procedures involving Y-90 contributed to exceeding the annual exposure limit to the left hand. Although, the technician is required to do surveys of the lab, the lab only has access to a GM detector and the area readings in the lab are often higher than background because of the large quantities of nuclides on hand. It is difficult for the technician to determine if contamination exists because of these high area readings. No swipe surveys are done by the technician. Swipe surveys are done by the radiation safety office staff. The last survey in which swipes were taken was January 2011. No contamination was noted at that time. The dose reconstruction was done to verify that the technician could in fact have received the reported dose given the time frame the technician was working with the Y-90. The dose reconstruction was also done to eliminate the possibility that the dose recorded by the ring dosimeter could have been caused by the ring being contaminated by Y-90 and that contamination remaining on the dosimeter. It was concluded by the UW RSO and the department [Washington Division of Radiation Protection] that handling these amounts of Y-90 could result in a dose of 56.4 REM in a very short period of time. Therefore, it is the conclusion of this investigation that the reported exposure is real. As a result of this investigation, the technician has been informed that she cannot work in an environment which would further contribute to her 2011 radiation dose. Because she is retired and no longer employed as a radiation worker at any facility, this should not be a hardship. It was determined that although the technician received an exposure above the legal limit, it is unlikely to result in any adverse health effects and no medical intervention is warranted. The Y-90 labeling has been halted at UW. No other person has done a labeling of this kind since the technician's retirement. No further work of this kind will take place at UW until a complete reworking of the procedures is completed and submitted to the Department, and their own RSC, for approval. This incident is closed. R4DO (Campbell) and FSME EO (Zelac) have been notified. |
| Where | |
|---|---|
| University Of Washington Seattle, Washington (NRC Region 4) | |
| License number: | WN-C001-1 |
| Organization: | Wa Division Of Radiation Protection |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+1627.57 h67.815 days <br />9.688 weeks <br />2.229 months <br />) | |
| Opened: | Kelee Attebery 20:34 Jun 6, 2011 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jul 19, 2011 |
| 46931 - NRC Website | |
University Of Washington with Agreement State | |
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