toproduce 1.0 rad. Step 1. Determine the dose rate on the day of intake of st to produce 1.0 rad to the thyroid. D= _R Where: Ae D = dose (1.0 rad) R «= dose rate on initial day Ae # effective decay constant (radiological and biological) 1.0 =R 0.09 R © 0.09 rads/day Step 2. Determine the number of microcuries of 1131 to produce 0.09 rad/day X(uc)(2.2 x 10°)(60 x 24)(1.6 x 107°) (0.22) = 0.09 (100) (20) X # 0.16 uc to thyroid 1 ingested (0.16) (5) oF= 0.80 pe r731 Step 3. Determine relative doses from I+31 ana yshort according to Graph miree.! At 48th hour, the relative contribution to total dose 132 ana 18°* 46 about1. from I> Therefore, ingestion of 0.4 uc 31 (equivalent) at 48th hour will produce 1.0 rads to thyroid. Step 4. Determine the number of microcuries of fission products required to yield the required 731 activity. At 48th hour, 73+ constitutes about 2.35% of total activity. Therefore, DOE ARCHIVES 0.4 ~ 0.003 * 17 uc of fission products. - 5 -