ENS 53072
ENS Event | |
|---|---|
19:30 Nov 14, 2017 | |
| Title | Agreement State Report - Contamination Found During Source Exchange |
| Event Description | On 11/14/2017, during a source exchange, a radiation technician discovered contamination on an High Dose Rate [HDR] device located inside a pig container. The device was located inside the vault. The Radiation Safety Officer [RSO] isolated and roped off the area to prevent unauthorized entry and contacted the vendor: Varian. The vendor is expected to arrive tomorrow to continue the investigation.
Device: Varian HDR 600333 Source: IR-192 Activity: 11 Curies Oregon Event Report ID: 17-0071
The following report was received via e-mail: The radiation technician who found the contamination is the Varian field service engineer (FSE) who performed the HDR source exchange. The decayed Ir-192 source was removed from the HDR and placed into a transport container. The new container with the new Ir-192 source was surveyed and a contamination wipe performed with all readings within normal range for a new source. The new source wire was wiped and no contamination found and it was loaded into the HDR. A dose rate survey was performed around the afterloader and the new transport container to confirm the source transfer was successful. However, the measurement inside the empty container indicated a dose rate of 35 microSv/hr (background in the vault given at 0.1 microSv/hr). The Varian RSO was called at this time (11:30 AM PT). The FSE placed the lid onto the new transport container and the dose rate dropped to 2.4 microSv/hr. Per company procedure, the new Ir-192 source was unloaded from the HDR and placed back into the new transport container and a confirmation survey and wipe performed on the HDR to ensure no contamination was transferred into the machine. The FSE then performed a contamination wipe on the new source wire and found the count rate at 6.35 cps with a background of 0.62 cps. This was a second indication of contamination. The FSE was instructed by the Varian RSO to leave the room and secure it. The FSE was surveyed by the facility AMP [Authorized Medical Physicist] upon exit to ensure no spread of contamination. The Varian RSO then contacted Oregon Radiation Protection Services [RPS] to report the event as well as the source manufacturer, Alpha-Omega Services, Inc. (AOS) to plan a response. The Varian RSO and AOS RSO came to the Oregon site on November 15th. Oregon RPS also responded and observed the procedure by the Varian RSO to clear any contamination from the HDR vault. No contamination was found outside the new transport container. The new transport container was prepared and shipped by the AOS RSO for return to their licensed facility in Louisiana, the Louisiana Agreement State agency was notified by Oregon RPS of the event. Oregon RPS requested a copy of the AOS investigation report stating what radionuclide is identified in this contamination event and potential source of the contamination. The Varian FSE indicated that similar contamination events, 'four (including this one) since 2013 where a hot particle has been found' in the container of AOS shipments containing HDR sealed sources of Ir-192. Notified the R4DO (Hay) and NMSS (via e-mail).
The following report was received via e-mail: On November 14, 2017, a contracted Varian field service engineer (FSE) was at the licensee's facility performing a routine Ir-192 source exchange on a Varisource IX High Dose Rate brachytherapy afterloader (HDR), serial number H600333. The 'old' sealed source (Source #1) was removed from the HDR and placed in the 'old' shielded transport safe (Safe #1). The 'new' shielded transport safe (Safe #2) was wiped and surveyed and no unusual readings noted. The 'new' sealed source (Source #2=Varian model VS2000, 11 mCi, Ir-192, serial number 02-01-9216-001-110117-11206-32) was removed from Safe #2, wiped and surveyed with no issues and placed into the HDR. The FSE surveyed the HDR and inside the unloaded Safe #2 and found a dose rate of 35 uSv (3.5 mrem) per hour inside the container. The FSE stopped work and immediately phoned the Varian RSO. Per the RSO instructions, the FSE replaced the lid on Safe #2 and took another dose reading outside and found a maximum of 2.4 uSv (240 urem) per hour. An exterior wipe of the 'new' container was at background which was 0.62 cps indicating contamination was inside the container. Per Varian procedure, the FSE then removed Source #2 from the HDR and placed into Safe #2. A wipe was performed of the source wire and the measurement was found to be 6.35 cps, well above background (background noted previously). This wipe was placed into a nitrile glove for analysis. Based on elevated contamination and dose readings, the Varian RSO instructed the FSE to exit the room and leave all tools in the HDR vault. The FSE was then surveyed by the HDR facility Authorized Medical Physicist (AMP) and the vault secured to prevent entry. The Varian RSO contacted the Oregon Agreement State program office, Radiation Protection Services (RPS), to report the event. The Varian RSO then contacted and coordinated a response plan with the source manufacturer, Alpha Omega Services, Inc (AOS). RPS contacted the HOO at 2:35 hours to initially report a potential leaking medical sealed source. On November 15, 2017, the Varian RSO, the Varian FSE, facility RSO, and an inspector with Oregon RPS arrived on site. The Varian RSO and FSE established a radiation control zone and the RSO performed wipes and surveys of the vault and all tools and equipment and ensured Safe #2 plus transport bucket had no exterior contamination while RPS observed the work. No new contamination was found. RPS performed an independent survey and found no contamination. The AOS RSO arrived in the afternoon and performed additional surveys and no contamination was found. That RSO packaged up Safe #2 and transport bucket with contaminated wipe (inside glove) and Source #2 with contaminated wire for shipment back to the AOS manufacturing facility in Louisiana. This shipment occurred that day. The Varian FSE prepared Source #1 for shipment to AOS in the uncontaminated transport container which was also shipped that day. Entry access to the vault was permitted in the afternoon. A new source was ordered for the facility HDR which was installed on November 17th with no issues. On November 21, 2017, Safe #2 was received by the AOS Louisiana facility and surveys/wipes performed. The Varian FSE contamination field wipe taken on November 14th showed activity of 2.91 nCi, Source #2 wire showed activity of 344 nCi, and a contamination wipe taken by AOS personnel at the top of Safe #2 exterior under the metal bracket showed activity of 5.62 uCi. The first two items were further sent off to an independent laboratory on December 6, 2017 to determine nuclide identity. On January 2, 2018, the laboratory reported to AOS that the nuclide was Ir-192. Results showed the Varian FSE field wipe at 942 pCi and Source #2 wire at 562 pCi. AOS reported the lab findings and their full report on January 4, 2018. The report indicated three potential causes (all human error, not following correct procedures) for the contamination: (1) The handling tools used in the hot cell, specifically the manipulator fingers, did not always have their rubber covers replaced between receipt/opening of irradiated targets and the start of sealed source manufacturing in the same cell. (2) Observation of personnel performing contamination wipes on the shielded transport safes after loaded with a sealed source showed that not all surfaces were being wiped, specifically under the top metal bracket. (3) After the loaded transport safes are placed into shipping packages (buckets), they are stored in the same manufacturing facility and when ready to be shipped, personnel perform another contamination wipe but again, not all surfaces were being wiped, specifically the bottom of the bucket and some areas on the lid. Procedural changes for the hot cell and contamination wipes have been implemented by the Louisiana licensee to address the issue. The licensee indicates that separation of manufacturing processes (target opening and sealed source manufacturing) into dedicated cells will be a long-term solution. Notified the R4DO (Deese) and NMSS (via e-mail). |
| Where | |
|---|---|
| St. Vincents Portland, Oregon (NRC Region 4) | |
| License number: | ORE-91014 |
| Organization: | Or Dept Of Health Rad Protection |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+-1.92 h-0.08 days <br />-0.0114 weeks <br />-0.00263 months <br />) | |
| Opened: | Todd Carpenter 17:35 Nov 14, 2017 |
| NRC Officer: | Jeff Herrera |
| Last Updated: | Jan 30, 2018 |
| 53072 - NRC Website | |
St. Vincents with Agreement State | |
WEEKMONTHYEARENS 530722017-11-14T19:30:00014 November 2017 19:30:00
[Table view]Agreement State Agreement State Report - Contamination Found During Source Exchange 2017-11-14T19:30:00 | |