Release Estimation cont'd

DOE-HDBK-3010-94

7.0 Application Examples; Dissolving Operations Examples

The key question in matching phenomena is whether or not the release will act

predominantly as a free-fall spill of liquid or, for a vessel leak, as a depressurization

of liquid via a failure under the liquid surface level. The only pressure acting on the

liquid is its own static head, since the vessel itself is under a slight vacuum. The

static head of the liquid can be determined from the equation:

Psh = H* *g

(7-4)

where:

Psh = static head pressure (Pa),

H = height of fluid (m),

= fluid density (kg/m3), and

g = acceleration due to gravity (9.8 m/sec2)

The 30-liter slab vessel has a height of 0.75 m (2.5 ft), with 20 cm of freeboard

during operation. This leaves a liquid height of 0.55 m (1.8 ft). The 64% nitric acid

solution has a density of ~ 1400 kg/m3. These values yield a static pressure head at

the bottom of the vessel of 7550 Pa (~ 1 psi). At this low pressure, the

depressurization spray effect will be immaterial.

The density of the solutions in the oxide dissolution glovebox exceeds 1.2 g/cm at all

points in the process, so the spill is modelled as that of a concentrated, heavy metal

solution. The ARF and RF assigned for a free-fall spill of a concentrated heavy

metal solution of less than 3 m are 2E-5 and 1.0 (subsection 3.2.3.1). The initial

respirable source term is:

1322 g * 1.0 * 2E-5 * 1.0 = 3E-2 g

This source term would be generated within glovebox confinement. Although

subsection 3.2.3.1 discusses applying the spill ARF equation only to fall heights

greater than 3 m, it can be used for smaller distances. The equation for bounding

ARF is:

*H3*g/vsoln2)0.55

(7-5, 3-13)

ARF = 8.9E-10 (

air

where:

ARF = airborne release fraction,

air = density of air (1.18E-3 g/cm ),

H = spill height, (cm),

g = acceleration of gravity (981 cm/sec2), and

vsoln = solution viscosity (poise).

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