4 | 7m me. oo UNCASSFIED Crater Surveys. . “re The eraters formed by the tests on the islands in Operation SANDSTONE . Were not "craters" in the general sense of the term. The detonuition of . . the test weapon did not remove a larye amount of soil and leave a pit of f- lurge proportions. In these cages only a slight saucer~Like depression an immediately in the vicinity of the test remined following the blast, A. The crater involved in these radiological surveys was defined as the ara Me surrounding the ZERO point in which variation of radiation intensitios was independent of the distance from ZERO, “ In this area it was not practical to plot the iso-intensity Lines as was done on the island sur- *" veys. if ZERO point prevented any approach to this crater area until several days on following the test. ex The high intensity of the radiation innediately surrounlin: the Permission was secured to mke the crater survey a mission of 300 mr vA linit. Plans for the crater surveys wore worked out in considerable detail prior to the operation, Each member was carefully briefed ani the hy exact path which was to be follaved was carefully worked out in advance aN so that the muocimimnunber of roadings could be made in a minimum time, a . Monitors started their survey in the vicinity of ZERO point and walked on a previously determined course amy from the center of the area covered & o ~sS by the blast outward to a distance of about 200 yanis, takin: readings “ at 10 yard intervals, t reasonably accurate picture was_obtained of the intensities in the area ~7 r These readings were Liter plotted by RadQps anda covered by the survey. as -& - A : = } Riv een . ‘ i TT ee os Nelo = = ae =. ~ soos ‘ “le . - : co . ee "7 we: Soue“e an —t e a > wea ame wee tan me ° ee ee a. D7 ma 27 Te Ree eh Parr aa 0 Dey 6 ER ey Ahm,