MODEL FOR ESTIMATING Pu TRANSPORT AND DOSE 493 



YDL = yDLS + fURDLF Am TdlF (37) 



dyiiver 



dt 



dVK 

 dt 



dybone 

 dt 



dyTB 

 dt 



= fBL TB -(>^A + >^L)yiiver (38) 



= fBK re - C^A + Xk) yK (39) 



= fBBN TB -(^A + XB)ybone (40) 



= ^BTB TB -(^A + XTB)yTB (41) 



where rg, tgit - rates that plutonium reaches the blood and gastrointestinal tract (GtT), 

 respectively (juCi/day) 

 Am, Hm = plutonium inhalation and ingestion rates, respectively (juCi/day) 



f = fraction of plutonium transferred from one location to another within 

 the body with the subscript notation as follows: URG is upper 

 respiratory tract (URT) to GIT; URB is URT to blood; GITB is GIT to 

 blood; URDLF and URDLS are URT to the fast and slow portions, 

 respectively, of the deep lung; BL, BK, BBN, and BTB are blood to 

 liver, kidney, bone, and total body, respectively 

 Tdlp,Tgit ~ transit times for the fast portion of the deep lung and the GIT (lower 

 large intestine), respectively 

 X = biological elimination rate constant with the subscript notation as 

 follows; DLS is deep lung (slow portion), TB is total body, L is liver, K 

 is kidney, and B is bone (day ~ ^ ) 

 X = In (2)/r, where r is the biological half-time for the organ (days) 

 y = plutonium burden in the organ with the subscript notation either 

 self-evident or identical to that for X except DLF is the fast portion of 

 the deep lung and DL is the total deep lung (/iCi) 



Values of the parameters in Eqs. 33 through 41 can be obtained from Fig. 3 for 

 plutonium. The values for other transuranic elements, if different from plutonium, are 

 given in Table 8. The radioactive half-times for each transuranic nuclide are given in 

 Table 7. 



Task Group on Lung Dynamics Model 



The ICRP Task Group on Lung Dynamics (Morrow et al., 1966) provided a more detailed 

 description of the inhalation pathway and arrived at the model indicated in Fig. 4. A 

 subsequent report [ICRP Publication 19 (International Commission on Radiological 

 Protection, 1972)] provided specific data for applying this model to plutonium and other 

 transuranic elements. The Task Group model treats the respiratory tract as a series of 

 compartments in which the amount initially deposited depends on the particle size and 

 the clearance rate (biological half-time) depends on the type of compound. 



