TUE-B - Special Session: Argonne National Laboratory Response to Np-237 Incident Tuesday 09/15/20 2:00 PM - 5:10 PM
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| Chair(s): Stacy Sternberg, Diep Quan McCormick
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TUE-B.1
2:00 PM Incident Description and Initial HP Response HA Hall*, UChicago Argonne, LLC
Abstract: In 2017, Argonne National Laboratory health physics staff responded to an incident resulting from a spill of radioactive solution containing neptunium (Np-237), hydrofluoric acid and nitric acid. The researcher had been working in a fume hood within a radiochemistry laboratory when the solution spilled, contaminating the researcher’s personal protective clothing, exposed and non-exposed areas of the body, and laboratory surfaces and equipment. Argonne National Laboratory will discuss the timeline and background for the incident, which will provide background for later presentations within the special session. The presentation will also discuss the initial health physics response to the personnel contamination incident, initial decontamination efforts, recognition that decontamination methods were unsuccessful, response to changing conditions, and lessons learned.
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TUE-B.2
2:45 PM Hospital Response to a Np-237 Spill M Sreniawski*, Argonne National Laboratory
Abstract: Argonne National Laboratory (Argonne) Health physics personnel responded to a personnel radioactive contamination incident and soon learned that there was possible dermal contact with hydrofluoric acid (HF). 911 was called and the on-site Fire Department responded. The researcher was taken to an offsite medical facility for treatment of HF. Argonne will discuss interactions with the contaminated individual, different decontamination methods used on the individual without causing abrasions to the skin, interactions with hospital staff and understanding their roles and responsibilities, post-hospital response and actions taken for detecting fixed contamination in the dermal layers of the skin, and lessons learned.
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TUE-B.
3:30 PM BREAK
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TUE-B.3
3:40 PM Neptunium-237 Internal Dose Assessment KL Weibel*, Argonne National Laboratory
Abstract: A personnel contamination incident involving neptunium (Np-237), hydrofluoric acid (HF), and nitric acid (HNO3) in solution led to a complicated internal dosimetry assessment involving coinciding intake pathways of inhalation, wound (strong), and injection. Argonne National Laboratory will discuss the challenges faced while completing this dose assessment, such as difficulty obtaining bioassay data and determining whether certain pieces of data were anomalous. The methodology of dose assessment will be discussed, including the use of the IMBA software, the biokinetic models applied, the assumptions made concerning interpretation of the data, and fitting the in vitro bioassay results to an excretion curve. A comparison of the dose assessment results to “rules of thumb” found in literature will be made to demonstrate that the results of the dose assessment were conservative despite the fact that a similar intake has never before occurred. Lessons learned, including changes that were made to the internal dosimetry program, will also be presented.
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TUE-B.4
4:25 PM Skin Dose Assessment RL Morris*, M. H. Chew & Associates, Inc.
; HA Hall, UChicago Argonne, LLC
Abstract: A dose assessment was required to determine the skin dose to a researcher whose skin was contaminated by a solution containing neptunium (Np-237), hydrofluoric acid and nitric acid as a result of a spill. The acidic solution contained Np-237 which is an alpha-emitter, and its decay product, protactinium-233 (Pa-233), which is a beta-emitter. After decontamination, it was apparent that some fraction of the radioactivity was persistent in subcutaneous tissue. The VARSKIN program provides a standard approach for skin dose calculations, but VARSKIN does not calculate dose from alpha emitters. Instead, MCNP6® was used with reasonable or bounding assumptions to determine a “best estimate” skin equivalent dose.
Trademark acknowledgement
MCNP® is a registered trademarks owned by Triad National Security, LLC, manager and operator of Los Alamos National Laboratory.
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