Resin Exotherm cont'd

DOE-HDBK-3010-94

7.0 Application Examples; Liquid Storage and Ion Exchange Examples

The appropriateness of this assumption will be considered again after a source term

has been developed.

Precedents within DOE for source term estimation have used the model of a thermal

explosion. The closest attempts at a specific model have generally assumed some

release correlation with the TNT equivalent of the physical explosion. One example

considered plutonium disassociating from resin and recombining with nitrate in

solution to have the same essential effect as oxidizing reactions. The heat of reaction

(~ 210 cal/g) was used to estimate a TNT equivalent by assuming some small

percentage of resin reacting, as only a small amount of reaction is believed necessary

to generate significant pressure. This method estimated TNT equivalents around 45 g

of TNT, which is the same value estimated for the 1976 resin exotherm incident at

Hanford (0.1 lb TNT). The Hanford event resulted in ductile failure of the metal

resin column, blowout of both the window above the column and the window in front

of the column, and numerous glove failures.

A second example simply assumed the 0.1 lb value based on the observation that the

column being examined had less structural strength than the Hanford column. This

example estimated the mass of plutonium airborne by use of a mass ratio (grams inert

material/grams TNT) in correlations from Halverson and Mishima (1986) based on

the Steindler-Seefelt data discussed in this handbook. There are two potential

problems with such an approach. First, as noted in this handbook, as the mass ratio

becomes large, the undefined physical configuration of material to explosive becomes

the dominant factor for estimating release as only a small fraction of the material may

be subject to the relevant shock effects. Secondly, any method that focuses solely on

TNT equivalent scales for release is overlooking two other release mechanisms

associated with a thermal explosion. Resin may burn before, during, and after the

explosion, and the generation of significant pressure will result in release from

flashing spray of superheated liquids at the moment of column failure.

MAR

The source term for the ion exchange exotherm is a function of MAR distribution as

damage ratios are variable and there are competing release mechanisms for solid and

liquid phases with no constant ratio of plutonium between the phases. At the start of

a load cycle, only trace holdup plutonium is in the resin beds. Then solution at a

maximum plutonium inlet concentration of ~ 7 g/l passes through the beds. At the

completion of a flowsheet loading cycle, almost 6000 g of plutonium are absorbed in

the beds with a maximum of 6500 g allowed. The majority of this material is

absorbed on the first two of the three ion exchange columns. During the subsequent

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