EVENT AND 1.2 DESCRIPTION OF EXPOSED - GROUPS oO carried out, nor was its operating condition Whole Body Gamma Doses known to be satisfactory under the emergency condition prevailing at the time of use. For these reasons the later readings, which were higher than the early survey by an average of 50 percent when corrected to the same times, were used in computing the doses listed. The instruments used for the later measurements “were calibrated just prior to the surveys. Tre Estimatrep Vatters of external dose given in Table 1.1 were calculated from readings of radiation field survey instruments.* Averages of a numberof dose rate measurements on each island at a given time were used. The readIngs were taken in air, approximately threc feet above ground, several days after the inhab30 iol ORIGINAL SOURCE SPECTRUM INFINITE PLANE, SIN AIR I i ' ww { ( | I # 20- 5 ! i 4 ' °e !' < 3 i ‘ \ | t \ 1 l ‘ | t i t —‘ . ! bE = La t ! 1 { t Oo \ { 1 1 1 ( ( ec 1 t I i lu i { 1 ' 2 io \ 1 1 ( ' ; { i ' i ' ‘ i ' t i . \ 1 1 ' 4 ' t 1 1 ‘ ( ‘ ; ' ' ‘ i oy bo o ! Q rod { f ! \ ju 200 | 1 t 400 I i ' ‘ 1 1 t 1]. ! ' ‘ i ; ' ' { 1 1 oa t 7 ‘ ‘ 1 I \ to oo ; ! t 7 ‘ t 660 i [| 1. goo \ i000 \ i \ ' 1 1500 ENERGY (KEV) Fictre 1.2—Distribwtion of inherent energics ef gaunng radrafion from mired fission products, and histugram of degroded cnergies produced by Contutan scattering at level of infinite plane 3 feet in cir above untformly-drstribuied Hants were evacuated. DBefore this time, adequate surveys with well calibrated instriments had not been possible, although readin,rs had been taken with a single survey meter at the tine of However, *Arniv Nuva eatalar ANSP DIE 29, — _ evacuation. prefminary calibration of this instrument had not been ~ ee ee fission products ficid. S002 1b3 1.21 Characteristics of the Gamma Radtation The fallout material, when deposited on the ground, formed a large planar source of radiation. The energydistribution of the radiation reaching an exposed individual was infinenced by its passage through the intervening ar, A knowledse of the energy spectrum of the ra-