Summary of Task Group Recommendations Enewetak Atoll

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The Atomic Ener ~y Commission agreed to pro~ide radiological and rehabilitation of Enewetak Atoll to the Interior (DOI). A comprehensive survey of the radiological enviromnent of Encwetak 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, Ditision 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 national 4 13pldati- e to the Enewetak v~do~v u l 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 individual 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 SO1l containing Pu can be handled on a basis using the following: 40 to 400 pCi/gm of soil - corrective action determined on a case-by-case basis considering all radiological For comparison vtith population dose guidelines, evaluations were made for the follo~ting conditions: l Dose reductions obtained by diet modification. l Dose reductions achieved by removal of contaminated soil. plus corrective actions: l Plow the village island, and gravel the village area for . Import pandanus and breadfruit from the southern islands (ALVIN-KEITH) for inhabitants of the northern islands to control ingestion of radio nuclides. . Import pandanus, breadfruit, coconut and tacca from the . Import pandanus, breadfruit, coconut, tacca, and domestic meat from the southern islands. Contaminated material is composed of soil, debris and scrap. At some places there is P-u including pieces of Pu metal. Contamination is clistributed 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 cont~rnimted soil. For any disposal there should be no pathway to people; periodic followup surveys are necessary. Disposal of I% in any form is a greater problem, and disposal must protect against exposure for the future. ,, The consensus of the Task Group reflects consideration of a range of options and the benefits of reviews 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 preferable to restricting use of land for living and agriculture, these actions can otherwise adversely affect the environment and for some the effectiveness 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 isl~nds, ALVIN through KEITH, is expected to result in radiation doses ~-vit”hinthe reconmnended 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 agriculmre. Steps to make this isiand completely or partially available in the near term are important from the social Ps well as scientific viewpoint. Predicted radiation doses associated ivith the Task Group recommendation that people live only on the southern islands, ALVIN through KEITH, are give n in the following table. The Bikini Atoll estimates and typical natural background levels in the U.S. are given ior comparison.

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PREDICTED RADIATION DOSE IN REM WITH APOPTION OF TASK Whole Body Bone Marrow k Child Adult Child Adult whole Body Bone ‘;”: Predicted Radiation Dose for Bikini Atoll Dose - Rates in U.S.Measured Terrestrial Gamma *see Option HI, Table 11, of the Task Group report. Dose includes contribution from natural background, about 0.03 Rem/yr, and O. 90 **The dose to bone marrow is about one-third the dose to bone. P. F. Gustafson, Division of Biology and Medicine, “ May 1968. Estimates do not include contribution from natural background.

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T’he Task Group reached t~lc following conclusions: 1. Obserting precautions, the people may safely return after certain actions are taken. Exposures will be somewhat above current levels in the U. S. , but the small risk seems permissible in rel?. tiG:: to the desire of the people to return. 2. To assure exp~sures 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 YVONNE. When Pu contamination on YVONNE is removed, the restriction of travel to that island may be Coconut excepted, growth of animal a~d vegetable sub - - sistence crops to be limited to southern islands ALVIN-KEITH. Subsistent e and commercial coconut may be grown without remedial measures except on A LICE., BELL~, CL4RA, 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 Wells to provide lens water for human consumption or for agricultural use to be di”illed only on the southern islands (ALVIN-KEITH). Water from any well to be assayed for bacterial, salinity, and radioactivity content before approved 3. Enjebi (J.ANET) is a special case, and the people have a strong 1 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 schedul”~ as southern islands. ‘I’he island c.~n 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 from test plantings showed acce~tablv low levels of raclioactititv. impact on the island environment. Concurrent with the Enjebi work, radioactivity levels should be measured in coconut and other food crops grown on PEARL, CLARA, .4 LICE, and BELLE. Produce from YVONNE should be included after removal of plutonium contamination. 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. YVONNE, quarantined by the USAF in 1972, should remain quarantined until plctonium contamination on that island has been cleaned up. An authority responsible for enforcement of the quarantine should be identified and in residence in the .4to11 if people return to the Atoll before cleanup’ is completed. Only general recommendations for cleanup of Pu on ~ONNE can be presented at this time. An accurate picture of this contamination should develop as the decontamination proceeds The area observed to have small pieces of plutonium and the highest soil concentrations is about 30% of the island. A background for plans for the recovery of I% 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 Service group, now part of EPA, protided radiological assistance for cleanup of Bikini -4to11. Similar support should be sought from “EP14 for Enewetak. b. Decontamination of YVOhThTE 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 tmo: Recovery of the pieces of plutonium that have been observed on or near the island surf~ce. Recot-cry of plutonium contaminated soil. Recovery of lutonium in soil at concentrations greater than 400 pCi/g 23?, 240w at any depth these levels are found. Also, recovery of cont~.minated soil sufficient to reduce surface levels to a value weil below 40 pCi/g 2391 240%. After soil removal, all areas should be resurveyed to ensure no pieces or hot spots of plutonium remain. Plutonium contaminated soil on IP.ENE should be handled as on YVOh~E. Pieces of Pu metal are not expected to be found. Test plantings of food crops may be conducted on each of the IIno crops” islands as designated by the Enewetak people. As edible parts of these plants become available, concentrations of significant radionuclides should be measured and compared with the radiological survey predictions. These studie5 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 radio nuclide content should be measured. Radioactivity information will contribute to an understanding of processes operating - or which can bnemade to operate - to reduce the ecological half-life of 9°Sr and 1=7CS below the radioactive half-life on the northern 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 .mpport 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 thereaher. Resurveys of the environmental radiation and radioactivity should be made in the first year of return and repeated, %r example,

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every other year. 13s Methods of disposal of plutonium contaminated soil and scrap till have to be decided. Pending a decision, it is reco~ended taminated sail and scrap with storage on YVONNE. If 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 s~il, shouId 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.

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The Atomic Sncrgy i criteria for cleanup Commission agreed to pro~ide radiological and rehabilitation of Enewetak Atoll to the Department cf Defense (DOD) and to the Department of the Interior (DOI). A comprehensive survey of the radiological t 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 Dire”ctor, Division of Operational Safety, appointed a Task Group and through it staff liaison representatives of DN”A, DOI and EPA were kept informed of progress toward completion of recorm-nendations. Current radiation protection guidance containing.’ numerical standards and radiation protection philosophy of national and international standards bodies was used to develop recommended . l Population dose to the Enewetak people should be as low as l The Federal Radiation Council (FRC) Radiation Protection Guides (RPG) for individual and gonadal exposures till be 1 used to evaluate exposure options. ‘ The values should be reduced by 50 percent for individual exposure and 20 percent for gonadal exposure to allow for uncertainties in dose predictions. The guides for cleanup planning become: 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: < 40 pCi/gm of soil - corrective action not required. 40 to 400 pCi/gm of soil - corrective action determined on a case-by-case basis considering all radiological For comparison with population dose guidelines, evaluations were made for the follo~ting conditions: l Dose without cleanup. l Dose reductiofis obtained by diet modification. l Dose reductions achieved by removal of contaminated soil. In addition, estimates were made for representative living patterns l Plow the village island, and gravel the village area for . Import pandanus and breadfruit from the southern islands (ALVIN-KEITH) for inhabitants of the northern islands to control ingestion of radio nuclides. . Import pandanus, breadfruit, coconut and tacca from the . Import panclanus, breadfruit, coconut, tacca, and domestic meat from the southern islands. DISPOSAL OF CONT.4MIRT.4TED MA TERLAL 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 peopls. Possible approaches are:

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1. Disposal in water-filled and underwater craters. 2* Land burial where the radiation le~~cl 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 Pu in any form is a greater problem, and disposal must protect against exposure for the future. “, The consensus of the Task Group reflects consideration of a range of options and the benefits of reviews 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 effecti>-e 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 mav use land where the radiation environment is or can be made acceptable. .,.’~. Return of people to live on the southern isl~nds, ALVIN through KEITH, is expected to result in radiation doses \vithin the recommended 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 liting and agriculture. Steps to make this isiand completely or partially available in the near term are important from the social as well as scientific viewpoint. Predicted radiation doses associated itith the Task Group recommendation that people live only on the southern islands, ALVIN through KEITH, are given in the follo~ting 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 AI? QPTION OF TASK Predicted Radiation Dose for Bikini Atoll Whole Body Bone Marrow . *see Option III, Table 11, of the Task …