An Experimental Study on the Uptake Factor of Tungsten Oxide Particles Resulting from an Accidentally Dropped Storage Container

Abstract

A test procedure was developed and verified to measure the airborne concentrations of particles of different sizes (0.5–20 μm) within the vicinity of a dropped container when a significant portion of the tungsten oxide powder (simulating uranium oxide) is ejected from the container. Tests were carried out in a full-scale stainless steel environmental chamber with an interior volume of 24.1 m³. Thirty-two drop tests were performed, covering variations in dropping height, room air movement, landing scenario, and lid condition. Assuming a breathing rate of 1.2 m³/hr, the uptake factor during the first 10 min was calculated to be between 1.13 × 10⁻⁹ and 1.03 × 10⁻⁷ in reference to the amount loaded; or between 6.44 × 10⁻⁸ and 3.55 × 10⁻⁴ in reference to the amount spilled. Results provide previously unavailable data for estimating the exposure and associated risk to building occupants in the case of an accidental dropping of heavy powder containers. The test data show that for spills larger than 0.004 g, the power-law correlation between the spill uptake factor and the spilled mass (i.e., SUF = 2.5 × 10⁻⁵ × Spill_Mass^−0.667) established from the test data is smaller and a more accurate estimate than the constant value of 10^–3 assumed in the Department of Energy Nuclear Material Packaging Manual. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplementary resource: an online supplementary table of all cumulative uptake amounts at 10 min for all test data.]

Keywords:

• dropped storage container
• tungsten oxide particles
• uptake factor