Source Term cont'd - h3010v10300

DOE-HDBK-3010-94

7.0 Application Examples; Liquid Storage and Ion Exchange Examples

Rearranging the equation to solve for pressure gives:

P = [2*(T-C)*SE]/[2*(C-T)*Y + D]

(7-8)

which, upon substitution of the above values, yields a design pressure of ~ 9 MPa

(1300 psi). Internal defects and flaws could cause the vessel to fail locally at

substantially smaller pressure, as was suspected in the Hanford incident, and flange or

gasket failure could occur at lower pressures as well. However, because no relief

valve or rupture disc is installed on the system, a failure pressure of 9 MPa will be

assumed.

The correlation for airborne release fraction for superheats in excess of 100 oC

requires determining the fraction of liquid that flashes. Subsection 3.2.2.3.3 provides

a basic thermodynamic relationship for making this determination for superheated

liquid at temperature T1 and pressure P1 being depressurized to temperature T2 and

pressure P2:

massv/masssh = (Hsh - Hl)/(Hv - Hl)

(7-9, 3-11)

where

massv

= mass of saturated vapor generated by flashing during

depressurization (g),

masssh

= mass of superheated liquid present (g),

Hsh

= enthalpy of superheated liquid at T1 and P1 (cal/g),

= enthalpy of saturated liquid (e.g., liquid at saturation

temperature T2 for pressure P2) (cal/g), and

= enthalpy of saturated vapor (e.g., vapor at saturation

temperature T2 for pressure P2) (cal/g).

The 4% nitric acid solution behaves substantially like water, so the steam tables are

used to estimate enthalpies. At 9 MPa and 303 oC (203 oC superheat), the enthalpy of

superheated liquid is 325 cal/g. Once depressurized (0.1 MPa and 100 oC), the

enthalpies for the flashed vapor and the remaining liquid are 639 cal/g and 100 cal/g,

respectively. Inserting these values into the thermodynamic relationship yields a mass

vapor to total original mass ratio, or MFg, of 0.4. The ARF can then be determined

from the equation

F = 0.33 (MFg)0.91 = 0.15.

(7-10, 3-7)

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