Thermal Stress Bounding Assessments

DOE-HDBK-3010-94

3.0 Liquids; Organic, Combustible Liquids

and salts is explosive release of moisture trapped under the salt during rapid heating of the

material. The ARFs for soil and vegetation covered soil are lower than the ARFs for

stainless steel under comparable conditions but are consistent with the ARFs for asphalt,

which does not conduct heat but may become plastic due to the heat and retain salts from the

evaporation of solution.

3.3.7

T h erm al S tress B ou n d in g A sses s men ts

Based on the experimental results summarized in the preceding sections, a distinction will be

made between volatiles (i.e., iodine) and other radionuclides and between various burning

environments. For volatiles, the bounding ARF and RF are 1.0 and 1.0. For other

radionuclides, the ARF and RF are a function of the burning characteristics.

The experiments summarized in sections 3.3.1 and 3.3.2 (with additional insight obtained

from section 3.3.3) represent a reasonable approximation of quiescent burning, small-scale

pool burning, or the burning of a relatively thin layer, as compared to the underlying layer of

aqueous solution, of organic solvent. A bounding ARF and RF of 1E-2 and 1.0 are believed

to appropriately characterize these conditions. The median ARF and RF are estimated to be

6E-3 and 1.0.

The experiments summarized in sections 3.3.3 and 3.3.4 represent a reasonable

approximation of vigorously burning large pools or solvent burning over aqueous layers,

where the relative sizes of the two layers support significant turbulent disruption of the

aqueous layer. The main distinction is whether the burning proceeds to complete dryness.

When it does not, a bounding ARF and RF are assessed to be 3E-2 and 1.0. When complete

dryness results, a conservative bounding value of ARF is assessed to be 1E-1 (7E-2 rounded

upward), with an RF, in the absence of a measured value, of 1.0. The median ARF is 1E-2

with an average value of 2E-2. The ARF (1.5E-2) reported by Jordan and Lindner

(February 1985) agrees with the median ARF for the other experimental conditions.

Two other conditions relating to large organic fires over specific types of base surfaces are

discussed based on section 3.3.6. The first condition is aqueous solutions or air-dried salts

on a surface that absorbs or holds liquid. Candidate surfaces include those that are porous or

are significantly cracked or pitted. The bounding ARF and RF are 5E-3 and 0.4 respectively

(liquid UNH on sandy soil, 10 m/s) for the actual combustion period. The median values of

ARF and RF are 1E-3 and 0.8 (liquid UNH on vegetation covered sandy soil at 1 m/s) with

average ARF and RF values of 1E-3 and 0.5. The second condition is aqueous solutions or

air-dried salts on a surface that is a strong conductor of heat (i.e., metal). The bounding ARF

and RF are 2E-1 and 0.3 (stainless steel, 10 m/s) for the actual combustion period.

Page 3-49