Dose Reconstruction Using Computational Modeling of Handling a Particular Arsenic-73/Arsenic-74 Source

A special work evolution was performed at Los Alamos National Laboratory (LANL) with a particular 73As/74As source but the worker?s extremity dosimeter did not appear to provide appropriate dosimetric information for the tasks performed. This prompted a reconstruction of the dose to the worker?s hands. The computer code MCNP was chosen to model the tasks that the worker performed to evaluate the potential nonuniform hand dose distribution. A model was constructed similar to the worker?s hands to represent the performed handling tasks. The model included the thumb, index finger, middle finger, and the palm. The dose was calculated at the 7 mg cm-2 skin depth. To comply with the Code of Federal Regulations, 10 CFR 835, the 100 cm2 area that received the highest dose must be calculated. It could be determined if the dose received by the worker exceeded any regulatory limit. The computer code VARSKIN was also used to provide results to compare with those from MCNP where applicable.

The results from the MCNP calculations showed that the dose to the worker?s hands did not exceed the regulatory limit of 0.5 Sv (50 rem). The equivalent nonuniform dose was 0.126 Sv (12.6 rem) to the right hand and 0.082 Sv (8.2 rem) to the left hand.