PAGS ¢£ AneGNVUULDS UW ASoLcibU/is O N W O/NAKR BIKINI ATOLL. ERDA HAS THE CAPABILITY, USING PORTABLE AND VERY SENSITIVE RADIATION M&ASURING EQUIPMENT MOUNTED IN HELICOPTERS, OF RAPIDLY SURVEYING LARGE LAND AREAS. THIS CAPABILITY WAS USED AT ENEWETAK IN LAT& 1972 PRELIMINARY TO AND IN SUPPORT OF THE DETAILED GROUND SURVEY WHICH WAS INITIATED SOON THEREAFTER AND CONTINUED TO FEBRUARY 1973. THE AERIAL SURVEY PERMITTED US TO PLAN IN ADVANCE THE WORK OF THE GROUND PARTIES AND CONCENTRATE THE MEASURIiNG AND SAMPLING EFFORT ON AREAS OF GREATEST CONCERN, WITHOUT AN AERIAL SURVEY OF BIKINI AND ENYU ISLANDS, WE WERE OBLIGED TO COMMIT CONSIDERABLY GREATER EFFORT TO THE GROUND SURVEY THAN MIGHT OTHERWISE HAVE BEEN REQUIRED, IN FACT, THE JUNE 1975 SURVEY, IN THE FIELD EFFORT ALONE, AMOUNTED TO ABOUT 50 MAN-WEEKS. IT PROVIDED, FOR THOSSs TWO ISLANDS, INFORMATION ON EXTERNAL GAMMA DOS& WHICH ON THE BASIS OF COMPLETENESS, ACCURACY AND RESOLUTION IS COMPARABLE TO THE BEST OF THE ENEWETAK SURVEY. IT WILL PROVIDE, AT THe CONCLUSION OF THE ANALYTICAL PHASE LATER THIS YeAR, ISCTOPIC DISTRIBUTION INFORMATION (IN SOILS, WATER PAGE 3 RHEGNVOO0S3 UNCLASSIFIED/IN O N W D/NARR AND BIOTA) WHICH AGAIN IS COMPARABLE TO THE BEST OF ThE ENEWrTAK SURVEY. YOU INDICATED TO MZ THAT A QUESTION HAD BEEN RAISED ABOUT PRESUMED UNCERTAINTIES REGARDING DOSE TO THYKOID DUE TO UPTAKE, IMPLYING THAT WE DO NOT HAVE SUFFICIENT iNFORMATION ABOUT WHICh RADIONUCLIDES ARE PRESEwl AT BIKINI AND ENYU. AMONG FALLOUT CONSTITUENTS, CERTAIN RADIOACTIVE ISOTOPES OF IODINE ARE OVERWHELMINGLY MORE SIGNIFICANT TO THE THYROID THAN ALL OF THE OTHER ISOTOPES. THESE ISOTOPES OF IODINE HAVs SUCH SHORT HALF LIVES AS TO BE AT INSIGNIFICANT LEVELS AFTER THE PASSAGE OF ONLY A FEW MONTHS TIME. THE& LAST NUCLEAR TEST AT BIXINI OCCURRED IN 1958 (OVER 200 MONTHS AGO). I STRESS THAT WE HAVE FOR BIKINI ATOLL WHAT Wi CONSIDER ADECUATE SUKVEY DATA FOR BIKINI AND ENYU ISLANDS ONLY. THIS IS DELIBERATE, FOR THESE ARE THE ISLANDS- WHICH ARE OR SOON WILL BE INHABITED. WE HAVE SUFFICIENT INFORMATION ABOUT THE OTHER ISLANDS TO PrkMIT THEIR LIMITED USE AS PRESCRIBED IN THE 1966 RESETTLEMENT RECOMMENDATIONS. OUR PURPOSE IN BRINGING THE AERIAL SURViY CAPABILITY TO BIKINI ATOLL WILL BE TO OBTAIN MORE COMPLET. INFORMATION ABOUT THE REMAINING LAND