Chapter 1 SUMMARY AND CONCLUSIONS In conducting its assessment of the effectiveness of the Cactus Crater structure in preventing harmful amounts of radioactivity from becoming available for internal or external human exposure, the Committee on Evaluation of Enewetak Radicactivity Containment organized a drilling program to obtain cores through the entire depth of the . finished containment structure, visited Enewetak Atoll to examine the structure and observe the drilling operation, reviewed all relevant ’ data and reports connected with the cleanup program, and interviewed ' key individuals associated with the program, including those responsible for radiation measurements and their interpretation. During its deliberations, the committee focused on such issues as the nature of the radioactive materials contained within the structure, the possible changes that might occur to the structure as time passes, the ways in which radioactive material now contained in the structure conceivably might be transported elsewhere, and the radioactive risks to which the people of Enewetak would be exposed in the most extreme of these hypothetical cases. 1.1 ‘ The Containment Structure The comnittee believes that the Cactus Crater containment structure and its contents present no credible health hazard to the peovle of Enewetak, either now or in the future. The function of the containment structure, as the committee per- ceives it, is to prevent hazardous human exposure to the radioactive material buried within it, and the committee believes it is highly unlikely that any sequence of events would prevent the structure from performing this function. Any flushing or spilling of the contents of ‘the structure into the lagoon or ocean that might occur as a result of cracking, settlement, or storm damage will not create an unacceptable radicactive hazard. Indeed, even if the entire radioactive contents of the containment structure were to find its way into the lagoon, no unacceptable hazard would result. Although no significant radioactive hazard would be created if the containment structure were to fail in any way, it is prudent to main- - tain the physical integrity of the structure ™% order that it may continue to prevent direct human access to the radioactive material it contains. ‘Thus, inspection of the dome should take place periodically 1 3004319