Chapter 1 SUMMARY AND CONCLUSICNS In conducting its assessment of the effectiveness of the Cacths Crater structure in preventing harmful amounts of radioactivity from becoming available for internal or external human exposure, the Committee on Evaluation of Enewetak Radioactivity Containment or a drilling program to obtain cores through the entire depth of finished containment structure, visited Enewetak Atoll to cxamin structure and observe tne drilling operation, reviewed all rele data and reports connected with the cleanup program, and intervi key individuals associated with the program, including those re Sible for radiation measurements and their interpretation. Duri its deliberations, the committee focused on such issues as the nature of the radioactive materials contained within the structure, the poskible changes that might occur to the structure as time passes, the wa which radicactive material now contained in the structure concei might be transported elsewhere, and the radioactive risks to whi the people of Enewetak would be exposed in the most extreme of these hypothetical cases. 1.1 The Containment Structure The committee believes that the Cactus Crater containment stricture and its contents present no credible health hazard to the people Enewetak, either now or in the future. The function of the containment structure, as the committee rc ceives it, is to prevent hazardous human exposure to the radioactive material buried within it, and the committee believes it is phigh unlikely that any sequence of events would prevent the structure performing this function. From Any flushing or spilling of the contenks of the structure into the lagoon or ocean that might occur as a res cracking, settlement, or ~torm damage will not create an Unaccep radioactive hazard. Indeed, even if the entire radioactive contehts containment structure were to fail in any way, it is prudent to tain the physical integrity of the structure in order that it ma continue to prevent direct human access to the radioactive materiBl it contains. Thus, inspection of the dome should take place pericdifaily L “x