<OUETORNneesY hour (start of intake at the beginning of the 2nd day after detonation for a duration of four days). Step l. Determine the number of microcuries at time of ingestion to produce 1.0 rad to the lower large intestine. a From Graph Two take the mid point of intake perfod (7end hour)-»31 pe. (Tis is obviously an approximtion since the exact timea of intake during the four-day period will be unknown). Step 2. Determine the activity at time of intake. From equation (2) 31 2 5 Aok 241-2 eo? ~ 120 ~0.27 Ay, = 0.9% yc/hr Since there is assumed a 220 ml/day intake 0.94 x 2h 2200 = 0.010 pe/m) or gm IT. Doses to the Thyroid -The following principal assumptions are used in calculating the doses to the adult thyroid from intake of activity from fallout material: a. The percentages of the isotopes of iodine in mixed fission products are according to Hunter and Palisu.? be. c. Twenty percent of the ingested 731 reaches the thyroid. - The mean energy is 0.22 Mev. : ‘ a. The thyroid weight is 20 grams. (See ZV. Discussion below) e. The percentages of shorter-lived isotopes of iodine that reach the thyroid and their doses are according to reference four. The method of calculation of doses to the thyroid is iliustreted by con puting that amount of intake of fission products at the 48th hour -4h- DOEARCHIVES 53