Table 5-9. SAFe for Various ITP Materials and Polydisperse (s g = 2.5) Particle Size Distributions (in AMAD)

DOE-HDBK-1184-2004

NOTE: In Table 5-8, A and Z for organic and rust are based on the sum of the

elements of the empirical formula. ∆ for organic and rust are an average

of a range of values from the Handbook of Chemistry and Physics (CRC,

1973). A and Z for hydrides are based on the metal only, since hydrogen

is a minor contribution. ∆ for hydrides are taken from Richardson, 1999

and Cheng, 1999a. Hydrogen in tritium-labeled compounds has been

represented as protium only, as this has a minor effect on the ratio A/(Z∆).

Functional representations (curve-fits) of numerically calculated SAF data (for

monodisperse physical particle sizes), as a function of particle size, were further

derived. These representations are a refinement of those by Kropf (1998), and

more accurately fit the data at small particle sizes.

From the functional representations of SAFs for monodisperse physical particle

sizes, SAFs for polydisperse AMAD particle size distributions were calculated using

the methodology adapted from Kropf (1998) and Cheng (1999a). The resulting

values are given in Tables 5-9 and 5-10.

Table 5-9. SAFe for Various ITP Materials and Polydisperse (s g = 2.5) Particle Size

Distributions (in AMAD)

A/( Z∆)

SAF e vs. Particle Size [AMAD(m), s g=2.5]

Base Material*

0.5

Organic [∼(CH2)n]

1.944

0.305 0.474

0.707

0.841

0.925

Rust [∼FeO(OH)]

0.690

0.231 0.381

0.614

0.768

0.879

Ti H2

0.558

0.215 0.362

0.594

0.753

0.871

Zr H2

0.351

0.180 0.312

0.541

0.714

0.852

Hf H2

0.212

0.142 0.260

0.490

0.680

0.842

* Variable amounts of elemental hydrogen are isotopically tritium.

Table 5-10. SAFβ for Various ITP Materials and Polydisperse (s g = 2.5)

Particle Size Distributions (in AMAD)

A/( Z∆)

SAFβ vs. Particle Size [AMAD(m), σ g=2.5]

Base Material*

0.5

Organic [∼(CH2)n]

1.944

0.205

0.333 0.535 0.677

0.789

Rust [∼FeO(OH)]

0.690

0.140

0.244 0.439 0.602

0.745

Ti H2

0.558

0.133

0.231 0.423 0.590

0.739

Zr H2

0.351

0.104

0.191 0.380 0.555

0.719

Hf H2

0.212

0.077

0.154 0.343 0.529

0.707

* Variable amounts of elemental hydrogen are isotopically tritium.

Other published computations of self-absorption factors (Richardson, 1999; Traub,

1999) largely confirm the results above. Traub (1999) states that bremsstrahlung

photons, created when beta particles are self-absorbed, are not expected to be a

significant contribution to dose from tritiated particulates.