ENS 44986
ENS Event | |
|---|---|
07:00 Feb 3, 2009 | |
| Title | Agreement State Report - Potential Overexposure to the Lungs |
| Event Description | The following report was received from the state of Washington via e-mail:
On February 9 2009, a worker was sent for a lung count at the Battelle (Pacific Northwest National Laboratory) lung counter for a bioassay measurement. The lung count was ordered due to the worker working in an area where airborne contamination levels could cause more then 2.5 DAC-hrs (with respiratory protection factors applied), and greater then 520 DAC-hrs assuming no respiratory protection was worn in one day. The reason for requiring this count was to ensure that measures used to protect the workers were functioning properly. The workers first lung count detected approximately 0.2 nCi of Am-241. Assuming the exposure was from 10 days prior, the intake was approximately 1.9 nCi Am-241. The annual limit of intake for Am-241 is 6 nCi (1micron AMAD particle size). The estimated dose was about 1/3 of the annual limit, or 16 REM CDE (Annual limit 50 REM). The worker had previous whole body exposure, but this added amount did not cause a limit to be exceeded. On March 25, 2009 the licensee informed the Washington State Department of Health [DOH] that further testing by Battelle caused a revision to the original calculated dose and the new calculated dose would exceed the 50 REM CDE limit. The date of exposure (February 3, 2009) was assumed by the licensee, based on air sample data and the use of respiratory protection that may not have provided adequate coverage (use of filtering respirator instead of supplied air). On February 3, the worker was in a containment in which air sample results were about 1e-8 microCi/ml gross alpha activity concentration for several hours and was wearing a Powered Air Purifying Respirator (PAPR, protection factor of 1000). Bioassay results (fecal) from one other worker who was also in the containment showed a small amount of activity, and a dose was assigned to this second worker that did not exceed the legal limit. The second workers lung count was less than detection limits. The cause is still unknown. Contributing factors: High airborne activity, loss of respiratory protection. DOH is conducting an investigation of this incident. Corrective action : Curtailment of work in containment, training on removal of anti contamination clothing and respirator, investigation of respiratory protection failure. There was no media coverage of this incident. Activity and isotope(s) involved: Am-241, Pu-240/241 Overexposures: (number of workers/members of public; dose estimate; body part receiving dose; consequence): There was one potential overexposed worker, no members of the public were exposed, estimated dose to the worker is about 100 REM CDE and 5 REM CEDE. This value will change following further measurements, investigation and calculations. Worker was removed from the restricted area, work in the area where the intake was assumed to occur was stopped, pending the outcome of further investigation. Washington State Incident Number: WA-09-013
On June 22, 2009 the licensee informed the Washington State Department of Health that the Committed Effective Dose Equivalent (CEDE) for the worker was 6.8 cSv (6.8 REM) and the Committed Dose Equivalent (CDE) was 120 cSv (120 REM) to the bone surface. The workers Deep Dose Equivalent (DDE) from his dosimetry for the first quarter 2009 was 0.3mSv (30 mRem). The dose calculation was completed by a consultant for the licensee. Intake was calculated using methodology of ICRP 30, modified for clearance function. Intake for Am-241 was calculated from lung deposition and calculated clearance rates. Intake of Plutonium (Pu) was inferred from excreta bioassay results and assumed ratios of Am-241 to Pu. Dose was calculated using CINDY code version 1.2. The particle size was considered, and a 1micron Activity Median Aerodynamic Diameter (AMAD) was chosen as the best fit. The total calculated intakes are: Am-241 153 Bq (4.14 nCi), Pu239/240 89.9 Bq (2.43 nCi),Pu 238 16.8 Bq (0.455 nCi). The exact cause of the incident is unknown. The assumed cause is a failure of the respiratory protection system. The licensees corrective actions to prevent reoccurrence are to test each worker with a challenge gas prior to high risk work, increased engineering controls to mitigate airborne contaminants, specific training using phosphorescent powder and black lights for workers, more frequent bioassay samples, inclusion of nasal smears for immediate detection of intakes, use of supplied air respirators over air filtering respirators for high risk work, and training for workers, managers and health physics staff. Note that work was resumed in the area, and no further exposures have occurred. Worker was removed from the restricted area, work in the area where the intake was assumed to occur was stopped, changes to operations and training methods, changes to engineering controls, changes to testing of respirators prior to use. Contributing factors [are] high airborne activity, [and] loss of respiratory protection. DOH has completed an investigation of this incident. There was no media coverage of this incident. There was one overexposed worker. No members of the public were exposed. Estimated dose to the worker was 120 REM CDE and 6.8 REM CEDE. Notified the R4DO (Pick) and FSME EO (McIntosh). |
| Where | |
|---|---|
| Perma-Fix Northwest Richland, Washington (NRC Region 4) | |
| License number: | WN-I0508-1 |
| Organization: | Wa Division Of Radiation Protection |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+1662.35 h69.265 days <br />9.895 weeks <br />2.277 months <br />) | |
| Opened: | Sean Murphy 12:21 Apr 13, 2009 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jul 1, 2009 |
| 44986 - NRC Website | |
Perma-Fix Northwest with Agreement State | |
WEEKMONTHYEARENS 449862009-02-03T07:00:0003 February 2009 07:00:00
[Table view]Agreement State Agreement State Report - Potential Overexposure to the Lungs 2009-02-03T07:00:00 | |