ENS 56923
ENS Event | |
|---|---|
06:00 Dec 11, 2023 | |
| Title | Potential Overexposure |
| Event Description | The following information was received from the Illinois Emergency Management Agency (the Agency) via email.
On Thursday, January 11, 2024, the Agency received written notification from the radiation safety officer (RSO) at a nuclear pharmacy of an elevated dosimetry badge report for a worker in Romeoville, IL. The whole body dose reported would exceed the occupational limits in 32 Ill. Adm. Code 340.210. The information provided indicates the worker received 162,926 mrem during the week of December 11, 2023, which exceeds the annual limit of 5,000 mrem. This is a reportable incident under 32 Ill. Adm. Code 340.1230, and will be reported to NRC and NMED. While an investigation is underway to determine the cause of this overexposure, after speaking with the RSO, it is likely the result of a spill/splash event. If this spill resulted in an occupational exposure in excess of the limits, it is also reportable under 32 Ill. Adm. Code 340.1220(b) and will be reported to the NRC today. In the next week, Agency inspectors will perform a reactionary inspection to inspect the adequacy of the licensee's investigation, compliance with the Agency's regulations, and determine the root cause. NMED Item Number: IL240002
A reactive inspection was conducted on 1/19/24. Reportedly on 12/11/2023, the technician noted a pressure issue within an F-18 synthesis cell. While containing approximately 9.9 Ci of F-18, the technician opened the synthesis cell to diagnose the issue. The magnitude of the resulting whole-body exposure is an unknown component of the reported 162 rem. Extremity badges reported only 447 mrem for this wear period. Movement of the synthesis tubing resulted in an undetermined quantity of F-18 contaminating the upper chest, neck and underarm of the technician. The technician reports feeling `wetness' as a result of the contamination event. Licensee staff estimated 3-5 minutes passed before decontamination efforts were initiated. Initial survey readings on the technician were 12 mR/hour from the neck and chest after shirt and lab coat were removed. No assessment of uptake/intake was performed, nor were any bioassays performed. No medical assessment was performed for blood changes or impacts to the skin. The corporate Radiation Safety Officer (RSO) was not notified until the dosimetry report was returned nearly 30 days later. At the time of the inspection, no medical conditions had emerged that were indicative of radiation exposure. The technician's badge was not evaluated for contamination, simply assumed to be contaminated and sent for reading. The badge did not show evidence of contamination when received by the dosimetry processor - however, that may have been due to decay. The licensee did not cease or limit any work with radioactive materials assigned to the individual. The employee has continued work in 2024, as the elevated exposure was attributed to the 2023 annual limit. Inspectors believe there is some portion of the exposure recorded on the optically stimulated luminescence (OSL) [dosimeter] that was not a true whole-body exposure (resulting from contamination and storage in the bunker). However, the lack of adequate records or timely assessment makes any quantification impossible. While an undetermined fraction of the recorded 162 rem was likely not a whole-body dose to the technician; there are certainly exposure avenues which could have led to at least 5 rem whole body. Until data is presented which indicates otherwise, this matter is being treated as an occupational exposure in excess of the 5 rem limit. While 16 mL containing 9.9 Ci of F-18 was in the synthesis cell, there is no accurate account on the amount of activity deposited on the technician's skin/clothing. (The syringe containing the F-18 was not used and allowed to decay within the cell. No volume or activity assessment performed). The only data allowing an estimate is the initial 12 mR/hour exposure rate, which would be close to 13 microcuries of activity incident to the detector active surface area. I.e., if the badge was surveying 12 mR/hour at one inch, that would equate to approximately 13 microcuries of F-18 incident to the probe. The exposure to the OSL over the mean life of this F-18 is estimated at 20 Rem. No data is available to estimate committed dose. While a VARSKIN+ analysis is pending, initial estimates indicate skin dose is likely less than 10 percent of the occupational limit. If the entirety of the 162-rem exposure was suspected to have come from contamination, the initial contamination of the badge would have needed to exceed 100 microcuries. This would have an exposure rate in excess of 100 mR/hour - inconsistent with the recorded exposure rates. Occupational whole body dose year to date, prior to this incident, was recorded at 974 mrem. Average weekly whole-body dose was 19 mrem. The area was isolated due to the spill and this incident is likely also reportable under 32 Ill. Adm. Code 340.1220(b), equivalent to 10 CFR 20.2202(b). The investigation is still in process. Notified R3DO (Orlikowski), NMSS Event Notifications (Email), and NMSS/MSST Division Director (Williams) |
| Where | |
|---|---|
| Sofie Romeoville, Illinois (NRC Region 3) | |
| License number: | IL-02074-01 |
| Organization: | Illinois Emergency Mgmt. Agency |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+773.2 h32.217 days <br />4.602 weeks <br />1.059 months <br />) | |
| Opened: | Whitney Cox 11:12 Jan 12, 2024 |
| NRC Officer: | Kerby Scales |
| Last Updated: | Jan 25, 2024 |
| 56923 - NRC Website | |
Sofie with Agreement State | |
WEEKMONTHYEARENS 569232023-12-11T06:00:00011 December 2023 06:00:00
[Table view]Agreement State Potential Overexposure ENS 563682023-01-17T06:00:00017 January 2023 06:00:00 Agreement State Occupational Dose Limit Exceeded ENS 555432021-10-25T14:45:00025 October 2021 14:45:00 Agreement State Agreement State - Contaminated Package 2023-12-11T06:00:00 | |