Source Term

DOE-HDBK-3010-94

7.0 Application Examples; Liquid Storage and Ion Exchange Examples

suppression. If a large amount of resin burns, the heat generated may be sufficient to

initiate resin exotherm reactions in the undamaged columns. This effect is by no

means certain and there are historical incidents where an exotherm in one column was

followed by a fire with no subsequent exotherm in adjacent columns. In the Hanford

exotherm incident, the presence of a significant amount of uncharred resin was

reported after the incident. Finally, the other columns may not be undamaged in the

initial explosion. They may be shattered by shrapnel from the damaged column, in

which case spilled resin may burn, but pressurization of multiple columns is not

possible.

Therefore, depending on how many columns are assumed to be affected by a given

stress, the first potential factor of the damage ratio is 0.33, 0.67, or 1.0. A second

potential factor is, at least for solids, how far the process is into a loading or elution

cycle. For example, if only 2000 g are loaded at the time of an exotherm reaction,

the DR is 2000/6500 = 0.3. If both potential factors are used, they must be defined

together so that "double-counting" does not occur.

In the examples in this handbook, DRs are typically bounded by assuming a value of

1.0 for the sake of simplicity. The above discussion indicates how conservative such

a bound can be. It is important not to lose sight of the fact that the phenomena being

examined are generally unlikely to highly unlikely. By the time a maximum MAR

has been assumed, the DR has been maximized as 1.0, the bounding ARFs and Rfs

of this document have been applied, no leakpath is accounted for, and 95% or greater

meteorology has been used for dispersion, the answer obtained is extreme.

Objectivity must be retained in the evaluation process so that a rote conception does

not distract available resources from areas where greater real gains in safety can be

made. As previously cautioned in this handbook, answers obtained are only as good

as the decisions they lead to.

Source Term

The combustion of polystyrene resin has a combined ARF x RF of 1E-2 (subsection

5.2.1.4.3). The combined ARF x RF for depressurization of superheated liquid is

either 6E-3 or 7E-2 depending on whether the degree of superheat is less than or

greater than 50 oC (subsection 3.2.2.3.3), although higher values can be estimated if

the degree of superheat is in excess of 100 oC. Assuming the properties of water as

expressed in steam tables, a superheat of 50 oC corresponds to 0.76 MPa (110 psia)

and a superheat of 100 oC corresponds to 3.1 MPa (450 psia). Therefore, whether

the largest release mechanism is burning resin or flashing spray depends on the failure

pressure of the ion exchange column.

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