Agtendix C Svmbols, comstants and equations used to calculate the Cs - i37m. total body dose equivalent during the uptake interval and the committed dose equivalent The following definitions, symbols, constants and equations describe che mathematical model used to calculate the dose equivalent and che committed dose equivalent. Intermediate steps can be used to determine urine activity concen- trations or daily ingestion rates. The equations were developed with the assumption that the body burden as determined from whole body counting, would be the measured quantity from the bioassay program. Three intervals of monotonically increasing, but constant and continuous uptake throughout an interval were assumed. Consequently, the equations must be repeated 3 times in orcer to obtain the total dose equivalent during the uptake interval. 137 Cs, For . . the uptake interval corresponds to the number of days out of the resi- dence period that an individual maintained the proposed daily activity ingestion rate. Mathematical Model Symdols, Definitions and Units of Physical Quantities Ne = the number of atoms of species of concern present at time zero in compartment i, atoms, Ne = the instantaneous number of atoms of species of concern present at time t in compartment i, atoms, P, = atom intake rate into compartment i from blood, atoms day ' RK. = the instantaneous fraction of atoms removed from compartment i per unit time by physiological mechanisms, day, 31