Computer Codes

DOE-HDBK-1184-2004

Table 5-7. Default assumptions for insoluble tritiated particulate intakes

Mode of Intake

Inhalation

1m AMAD

Particle Size

Geometric Standard Deviation (s g)

2.5

Shape Factor

1.5

Absorption Type

Type S

Weighting Factors

10 CFR Part 835

Biokinetic Model

ICRP 78

NOTE: The default particle size assumption of 1 m AMAD is consistent with 10

CFR Part 835. Dorrian (1995) concluded (through a compilation of

studies) that ICRP 66's choice of 5 m is a "realistic" assumption and 1 m

AMAD is conservative. Therefore, in order to maintain conservatism, 1 m

AMAD is the default assumption within this handbook, although doses

from other particle sizes are evaluated here via LuDEP. However, values

of the various self-absorption factors, dose conversion factors, and air

concentration values are calculated for 5 m and other values of AMAD.

Such values may be used when justified.

5.2.2.5 Computer Codes

The National Radiological Protection Board of Great Britain (NPRB) developed a

computer program, LuDEP, (Version 2.06) "Personal Computer Program for

Calculating Internal Dose Using the ICRP Publication 66 Respiratory Tract Model."

The model is discussed in Section 5.1. ICRP 71 (which defaults to a 1 m AMAD

polydisperse particle size distribution with a material density of 3 g/cm3) also uses

the ICRP 66 Human Respiratory Tract Model to calculate DCF. The DCFs for a 1

m AMAD polydisperse particle size distribution and a material density of 3 g/cm3

listed in ICRP 71 are the same as those calculated with LuDEP.

NOTE: NRPB has developed a successor to LuDEP called IMBA. A version of

this computer program called "IMBA Expert USDOE" will have the

capability to perform bioassay and dose calculations for insoluble tritiated

compounds. However, adjustment for self-absorption of beta particles and

their energy still has to be performed as described in the value to obtain

DCFos.

LuDEP was used at the Mound site to investigate the variability of the DCFs for

ITPs of various particle sizes and material densities, when dissolution rate is taken

as Type S, and an intake is known from air monitoring. LuDEP can also be used to

refine the conclusions of this handbook, and to assess the dose from ITPs of known

particle sizes and material densities or dissolution rates other than Type S.

ITP dose evaluations may be calculated either by using LuDEP directly, or by using

DCFs (organ CDE and CEDE) that are developed in this handbook (or that can be

calculated using LuDEP).