Venting of Pressurized Gases over Solids

DOE-HDBK-3010-94

5.0 Surface Contamination; Contaminated, Combustible Solids

5.2.2.3

V en tin g of P ressurized G ases over S olid s

No directly applicable data were uncovered. The entrainment of loose surface contamination

is a function of the characteristics of the flow over the particulate material that may be lying

on the surface, the particles, and the surface. However, as noted above, the combustible

material substrate will not typically provide a rigid surface for venting gases to act upon. As

noted in subsection 5.3.3.2.2 for impact/vibration releases from non-brittle materials, flexing

of the substrate is the primary mechanism for aerodynamic entrainment. The ARF x RF

value given for that phenomena (i.e., 1E-3) is essentially identical to the next most applicable

phenomena, release from powders due to accelerated flow parallel to the surface as discussed

in subsection 4.4.2.2.2 (ARF x RF = 1.5E-3). Accordingly, the ARF and RF of 1E-3 and

1.0 are assessed to be bounding.

5.2.3

F ree-F all S p ill an d I mp action S tres s

Loss/dislodgement of surface contamination during the free-fall spill of contaminated,

combustible materials would not appear to generate any significant stress upon the surface.

5.2.3.1

F ree-F all S p ill

No applicable data were uncovered. In many cases the combustible materials are light and

have high surface area to mass ratios (e.g. paper, cardboard, plastic sheets and wrapping)

and thus would generate little force during impact with surfaces. For such materials, no

significant suspension of surface contamination is postulated. In the case of material with

appreciable mass, the dislodgement of surface contamination upon impact would appear

unlikely but would be bounded by the bounding ARF and RF described in subsection

5.3.3.2.2 for the suspension of surface contamination by vibration-shock.

5.2.3.2

I mp act

A distinction is made for impact releases as to whether the base material is packaged or

unpackaged. For unpackaged materials with appreciable mass that generate significant forces

upon impact with a surface (forces adequate to result in dislodgement of the surface

contamination), the bounding ARF and RF for the suspension of surface contamination from

shock, 1E-3 and 1.0, described in subsection 5.3.3.2.2 are assessed to be bounding.

For the situation where the combustible material is packaged in a reasonably robust container

(e.g., drum) that fails due to impact, the bounding ARF and RF assigned are 1E-3 and 0.1.

This value is the same as that assigned to suspension of powder in a can due to debris impact

(subsection 4.4.3.3.2), which bounds this phenomena.

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