Room Temperature Oxidation/Corrosion cont'd

DOE-HDBK-3010-94

4.0 Solids; Metals

(dry air) 2E-6 g/cm2-hr

unalloyed

(100% RH) 7E-3 g/cm2-hr

(dry air) 7E-8 g/cm2-hr

delta stabilized

(100% RH) 6E-4 g/cm2-hr.

Figure 4-3, also reproduced from Stewart (1963), shows the size distribution of the particles

obtained at various temperatures (only the metal type is specified for one distribution). The

diameter of the particles is given as equivalent spheres indicating that the dimensions are

Geometric Diameter and must be multiplied by the square root of the density of PuO2

(11.46 g/cm3) to approximate the AED. Using distribution A from the figure (i.e., material

airborne under static conditions at all temperatures in air), the RF is between 0.6 and 0.7.

Chatfield (1968) conducted a series of experiments to measure the airborne release in air

flowing at velocities from 10 to 80 cm/s involving both delta-alloy and unalloyed plutonium.

Experiments were performed using both horizontal and vertical glass tubes with exterior

resistance heating. The experimental configuration was such that particles >20 m

were lost prior to sampling. Size distributions of the airborne materials were by Casella

cascade impactors that yield AED. Figures 4-4 and 4-5 reproduce, from the reference, plots

of the rate of release of activity (Ci/cm2-s) as particles 10 m AED and less for both delta-

alloy and unalloyed plutonium in dry and saturated air as a function of the reciprocal of the

absolute temperature. The data are plotted in this fashion to ascertain if the release rate is

linearly proportional to the oxidation rate. Assuming the specific activity for weapons grade

plutonium given by Raabe (November 1978) and Eidson and Kanapilly (February 1983) of

7.4E-2 Ci/g, the author calculates airborne releases to be:

(dry air) 0.1 -- 4E-6 g Pu/cm2-hr

unalloyed

(100% RH) 2 -- 4E-3 g Pu/cm2-hr

(dry air) 0.1 -- 1E-7 g Pu/cm2-hr

delta-alloy

(100% RH) 0.1 -- 4E-3 g Pu/cm2-hr.

The values are close to those from Stewart (1963) above. However, the data from

Stewart were judged to be more consistent. Therefore, the ARRs and RFs assessed to be

bounding for the low release phenomena of room temperature oxidation (corrosion) of

plutonium metal for a short time duration are based on the Stewart data.

g/cm2-hr/0.7 (dry air)

unalloyed metal:

2E-6

g/cm2-h/0.7 (100% RH)

7E-3

g/cm2-hr/0.7 (dry air)

delta-alloy

7E-8

g/cm2-hr/0.7 (100% RH).

6E-4

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