MODEL FOR ESTIMATING Pii TRANSPORT AND DOSE 499 



^^ = (0.3) (0.15) (D3 + D4 + D5) Ani - (Xa + Xlv) Ylv (63) 



Xlv = [In (2)/50] exp [-In (2)t/365] (64) 



yp = yLc + yLv (65) 



dy-pLNM 



5^ = fLCTLXLCyLC -(Xa +XTL)yTLNM (66) 



dyiLNR 



dt 



dyALNM 



- flLTLXlLyTLNM -XaYTLNR (67) 



^^ - fLCALXLCyLC -(Xa +XAL)yALNM (68) 



dyALNR 



dt 



- fALAL^ALYALNM - XaYaLNR (69) 



where r, X, y, f, D, and Am are as defined in the ICRP II and Task Group models. The 

 subscripts, where different, are as follows: NPTB refers to the combined nasopharynx and 

 tracheobronchial region, IX refers to that portion of the pulmonary lung with a constant 

 biological half-time, LV refers to the variable half-time portion, and P refers to the 

 combined portions; TLNM and ALNM refer to those portions of the thoracic and 

 abdominal lymph nodes, respectively, in which plutonium is mobile, and TLNR and 

 ALNR refer to the corresponding portions where plutonium is retained indefinitely; LCG 

 refers to transfer from LC to GIT, LG is from liver to GIT, LCB is from LC to blood, 

 TLB is from TLNM to blood, ALB is from ALNM to blood, LB is from liver to blood, KB 

 is from kidney to blood, LCTL is from LC to TLNM, and LCAL is from LC to ALNM. 

 Values of the parameters in the above equations can be taken from Figs. 5 and 6. The 

 equations for GIT, liver, kidney, and bone are identical to the ICRP II and Task Group 

 models, but the parameter values are those indicated in Fig. 6. Stuart et al. (1971) did not 

 give estimates for total body. 



Modifications to the SDB Model 



We (Bloom and Martin, 1976) modified the SDB long-term model to include ingestion 

 and the possibility of transfer from the blood to lungs and to lymph nodes. We also 

 incorporated many of the long-term transfers of the Task Group model. However, we also 

 simplified the model somewhat by removing the variable half-life lung compartment from 

 the SDB model. The resulting model is shown in Fig. 7. In this figure the upper 

 respiratory tract (URT) refers to the nasopharyngeal and tracheobronchial regions, and 

 deep lung (DL) refers to the long-term component of the pulmonary compartment in the 

 Task Group model. 



The equations for our modifications to the SDB model are 



rciT = (D3 + D4 + D5) fuRcAm + foLcXoLyOL + ^LcXLyiiver + H^ (70) 



