Summary of Task Group Recommendations Enewetak Atoll

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SUMMARY OF TASK GROCTP RECOMMENDATIONS The Atomic Energy criteria for cleanup Commission agreed to protide radiological and rehabilitation of Enewetak Atoll to the Department of Defense (DOD) and to the Department of the Interior (DOI). A comprehensive survey of the radiological environment of Enewetak was made to serve as a basis for judgments and recommendations. The survey data show that the northern islands have the greater amount of radioactive contamination and there are plutonium problems. The Director, Division of Operational Safety, appointed a Task Group and through it staff liaison representatives of DNA, DOI and EPA were kept informed of progress toward completion of recommendations. Current radiation protection guidance containing numerical standards and radiation protection philosophy of nationai and international standards bodies was used to develop reconu-nended . Population dose to the Enewetak people should be as low as The Federal Radiation Council (FRC) Radiation Protection.* Guides (RPG) for individual and gonadal exposures will be used to evaluate. exposure options. The values should be reduced by 50 percent for indi~dual exposure and 20 percent for gonadal exposure to allow for uncertainties in dose predictions. The guides for cleanup planning become: Whole body and bone marrow O. 25 Rem/yr Gonads 4 Rem in 30 yr

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Cleanup of soil containing Pu can be handled on a case-by-case basis using the following: b. 40 to 400 pCi/gm of soil - corrective action determined on a case-by-case basis considering all radiological DOSE ASSESSMENT .4ND CORRECTIVE ACTION ALTERNATIVES For comparison with population dose guidelines, evaluations were made for the following conditions: . Dose tithout cleanup. l Dose reductions obtained by diet modification. l Dose reductions achieved by removal of contaminated soil. In addition, estimates were made for representative living patterns plus corrective actions: l Plow the village island, and gravel the village area for l Import pandanus and breadfruit from the southern islands (ALVIN-KEITH) “for inhabitants of the northern islands to control ingestion of radio nuclides. l Import pandanus, breadfruit, coconut and tacca from the . Import pandanus, breadfruit, coconut, tacca, and domestic meat from the southern islands. DISPOSAL OF CONTAMINATED MAT ERLAL Contaminated material is composed of soil, debris and scrap. At some places there is Pu including pieces of Pu metal. Contamination is distributed on and below the surface; some is in rad waste burial sites. Fission products and induced radioactivity found on such scrap and debris, particularly scrap metal, should be made unavailable to the returning people. Possible approaches are:

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1. Disposal in water-filled and underwater craters. 2. Land burial where the radiation level of the scrap is not significantly above that on land. 3. Disposal in deep water. Pu excepted, the Task Group has not made recommendations for removal of contaminated soil. For any disposal there should be no pathway to people; periodic followup surveys are necessary. Disposal of F% in any form is a greater problem, and disposal must protect against exposure for the future. OBSERVATIONS AND CONCLUSIONS The consensus of the Task Group reflects consideration of a range of options and the benefits of retiews and comments. Choice of the method which will optimize reduction of exposures is a matter of judgement. Action such as use of imported foods could be effective but is not recommended. Although engineering actions, e. g. , soil removal and replacements may appear to be preferable to restricting use of land for living and agriculture, these actions can otherwise adversely affect the environment and for some the effectivenesss is uncertain. The extent of compliance by the people with restrictions has been considered, and an acceptable level of cooperation is expected so that they may use land where the radiation environment is or can be made acceptable. Return of people to live on the southern islands, ALVIN through KEITH, is expected to result in radiation doses within the recormnended criteria. JANET (Enjebi), which the people desire for a residence island is a special case of the category of islands having radiation and radioactivity levels which preclude living and agriculture. Steps to make this island completely or partially available in the near term are important from the social as well as scientific viewpoint. Predicted radiation doses associated with the Task Group recommendation that people live only on the southern islands, ALVIN through KEITH, are given in the folloting table. The Bikini Atoll estimates and typical natural background levels in the U.S. are given for comparison.

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PREDICTED RADLATION DOSE IN REM WITH ADOPTION OF TASK Maximum Annual Dose ‘:: Whole Body Bone Marrow Child Adult Child Adult Predicted Radiation Dose for Bikini Atoll Whole Body Bone Marrow *See Option 111, Table 11, of the Task Group report. Dose includes contribution from natural background, about O. 03 Rem/yr, and O. 90 **The dose to bone marrow is about one-third the dose to bone. ***Presented in “Additions to Radiological Report on Bikini Atoll, P. F. Gustafson, Divisian of Biology and Medicine, “ May 1968. Estimates do not include contribution from natural background.

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The Task Group reached the folloting conclusions: 1. Observing precautions, the people may safely certain actions are taken. Exposures will be above current levels in the U. S. , but the small risk seems permissible in relation to the desire of the people to return. 2* To assure exposures that will be as low as practicable: Villages and residences to be located on ELMER, FRED, DAVID, or other southern islands (ALVIN-KEITH). Travel and visits may be unrestricted to all islands except YV ONNE. When 1% contamination on YVONNE is removed, the restriction of travel to that island may be Coconut excepted, growth of sistence crops to be limited Subsistence and commercial animal and vegetable sub - to southern islands ALViN-KEITR. coconut mav be grown without remedial measures except on ALICE, B“ELL~, CLARA, DAISY, IRENE, JANET, and YVONNE. Fishing permitted anywhere. Wild birds and eggs may be collected anywhere. Coconut crabs may be collected only on the southern islands Wells to provide lens water for human consumption or for agricultu-ral use to be drilled only on the south-em islands (ALVIN-KEITH). Water from any well to be assayed for bacterial, salinity, and radioactivity content before approved 3. Enjebi (JANET) is a special case, and the people have a strong desire to live there. Three ground zeroes were on Enjebi and high yield events were fired nearby, with the result that this was the most heavily contaminated of the larger islands. The Task Group has been unable to determine a reliable, feasible way to bring exposures within the acceptable criteria and permit

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resettlement of Enjebi on the same schedule as southern islands. The island can be resettled sometime in the future when radionuclide ingestion is no longer a problem. To develop the facts, test plantings with and without soil removal may be made. Construction and agriculture would be deferred until produce frcm test plantings showed acceptably low levels of radioactivity. Test plantings without soil removal would have least adverse impac: on the island environment. 4. Concurrent with the Enjebi work, radioactivity levels should be measured in coconut and other food crops grown on PEARL, CLARA, ALICE, and BELLE. Produce from YVONNE should be included after removal of plutonium contamination. 5. All radioactive scrap metal and contaminated debris now or later identified should be removed. This includes three locations on SALLY and one on ELMER where buried contaminated debris should be exhumed and removed. 6. YVONNE, quarantined by the USAF in 1972, should remain quarantined until plutonium contamination on that island has been cleaned up. An authority responsible for enforcement of the quarantine should be identified and in residence in the Atoll if people return to the Atoll before cleanup is completed. 7. Only general recommendations for cleanup of Pu on lWONNE can be presented at this time. An accurate picture of this contamination should develop as the decontamination proceed a The area observed .to have small pieces of plutonium and the highest soil concentrations is about 3070 of the island. A background for plans for the recovery of Pu will require: a. Assembly of a team of experts to interpret field radiation and radioactivity measurements, advise on cleanup actions and provide necessary health physics support. A public Health Ser-zice group, now part of EPA, provided radiological assistance for cleanup of Bikini Atoll. Similar support should be sought from EPA for Enewetak. b. Decontamination of YVONNE is seen as an iterative process. This amounts to a search for and removal of the higher plutonium levels in soil.

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objectives of the cleanup are two: Recovery of the pieces of plutonium that have been observed on or near the island surface. Recovery of plutonium contaminated soil. d. Recovery of lutonium in soil at concentrations greater than 400 pCi/g 23~~ 240Pu at any depth these levels are found. Also, recovery of contaminated soil sufficient to reduce surface levels to a value well below 40 pCi/g 239> 240Pu. After soil removal, all areas should be resurveyed to ensure no pieces or hot spots of plutonium remain. Plutonium contaminated soil on IRENE should be handled as on YVONNE. Pieces of Pu metal are not expected to be found. Test plantings of food crops may be conducted on each of the “no crops “ islands as designated by the Enewetak people. As edible parts of these plants become available, concentrations of significant radio nuclides should be measured and compared with the radiological survey predictions. These studies will indicate times at which planting of subsistence and commercial crops can be safely resumed. Lens water sampling and analysis should be conducted, samples to be taken over a period of at least 12 calendar months. Bacterial content, salinity, and radionuclide content should be measured. Radioactivity information till contribute to an understanding of processes operating - or which can be made to operate - to reduce the ecological half-life of 9°Sr and 137CS below the radioactive half-life on the norkhern islands, especially JANET. A comprehensive air sampling program should be conducted over a period of 12 consecutive months under conditions closely approximating human habitation and expected soil disturbance to provide information on radioactivity levels in air. This program could be conducted coincident with and support cleanup. Base-line surveys of body burdens and urine content of 137CS and 9°Sr should be made for the Enewetak people prior to return to Enewetak Atoll, and periodically thereafter. Resurveys of the environxnental radiation and radioactivity should be made in the first year of return and repeated, for example,

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every other year. 13. Methods of disposal of plutonium contaminated soil and scrap will have to be decided. Pending a decision, it is recomrriended that cleanup should accomplish the recovery of plutonium contaminated soil and scrap with storage on YVONNE. H disposal is deferred for further study, such study should be initiated 14. The cleanup, with particular attention to removal and disposal of contaminated scrap, debris, and soil, should be documented in detail in a final report by those responsible in the field. 15. Advantage would be taken of experience gained during cleanup of Bikini Atoll. No objection should be made to employment of Enewetak people during cleanup.