Fact Sheet - Enewetak Operation 

April 1980 

Defense Nuclear Agency 

Washington, D.C. 20305 
DEFENSE NUCLEAR AGENCY 

WASHING TON, D.C. 20305 

April 1980 

Subject: Fact Sheet - Enewetak Operation 

In April 1980 the Department of Defense (DoD) will return Enewetak Atoll to. 

its People. This event will mark the end of the largest radiological cleanup 

operation ever conducted and will fulfill a moral obligation i_ncurred by the United 

States thirty-three years ago. This paper summarizes these events from the 

perspective of DoD. 

Enewetak is the northwestern atoll in the Marshall lslands--which themselves 

are one of the major island groups in Micronesia and in the Trust Territory of the 

Pacific Islands (TTPI). Enewetak lies some 2400 nautical miles west-southwest of 

Honolulu. The atoll is formed by a coral reef, oval in shape, which surrounds a 

lagoon stretching some 23 miles in a general north-south direction and 17 miles 

east-west. Rising from the reef at intervals along its circumference are some 40 

low, sandy islands--most of them quite small. 

The People of Enewetak--who have lived on the atoll for centuries, and who 

are different in many ways from other Marshall lslanders--subdivide into two 

groups: the dri-Enewetak, whose home is the largest southern island of the atol I 

(Enewetak); and the dri-Enjebi, whose home is the largest island in the north 

(Enjebi). 

Enewetak's role in the nuclear age began shortly after World War II, when the 

imperatives of national security required the establishment of several proving 

grounds for the testing of nuclear weapons. Enewetak was one of the principal 

sites selected for this testing, particularly for the higher-yield thermonuclear 

devices that were then in the conceptual stage. The People of Enewetak--then 

numbering about 150--were relocated in 1947 to a much smaller atoll, 

Ujelang, some 125 miles to the southwest. A large scientific and military task 

force, under the joint direction of the Atomic Energy Commission (AEC--now the 

Department of Energy (DoE)) and DoD, established its headquarters on the southern 

islands of Enewetak Atoll. Between 1948 and 1958, 43 nuclear tests were carried 

out on the atoll. The great majority were conducted in the northeastern quadrant, 

to keep the base camps in the south free of contamination. Some of the "ground 

zeros" were on the islands themselves, some were on the reef, some were in the 

lagoon, and one was in the ocean nearby. The tests were detonated in the air, on 

towers, on the surface of islands and reefs, on barges, and underwater. The nuclear 

weapons developed through this decade-long test program have been major 

elements in the mechanism of deterrence which has ensured the security of the 

free world and the absence of nuclear war for succeeding decades. 

In 1958 the U.S. ceased nuclear testing on Enewetak, in response to a 

trilateral US-UK-USSR testing moratorium. t-fowever, radioactive debris and 

fission products from the detonations and the resulting fallout contaminated most 

of the northern islands to varying degrees. The southern islands, which had been 

used as a base for the scientific task force, remained relatively uncontaminated. 
From 1958 until ·1976 DoD retained custody of the atoll, and a small caretaker 

force remained on Enewetok Island in the south. The atoll was occasionally used 

for DoD programs not involving nuclear testing. During this period, in 1972, the 

U.S. Government decided that future notional requirements in this port of the 

world could be met without use of Enewetok; and Ambassador Franklin Haydn 

Williams announced that the atoll would be returned to the TTPI Government, for 

subsequent return to the people--who by this time hod not seen their homeland for 

25 years. The announcement also committed the U.S. Government to cleanup and 

rehabilitation of Enewetak. 

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Planning for the radiological cleanup and rehabilitation programs was intensive and complex. It extended from 1972 until 1977, and involved major actions by 

numerous departments and agencies in the Executive Branch, by the Congress, and 

by the People of Enewetak. The hallmark of the entire effort was total 

involvement by the People of Enewetak in all major decisions. 

The major milestones of the planning effort--each of which required many 

months or even years of work--were: ~onduct of a detailed radiological survey of 

the otol I, its islands, and the lagoon by the AEC; conduct of a comprehensive 

engineering survey of the structures and debris on the atoll by the Defense Nuclear 

Agency (DNA); preliminary planning of resettlement options with the People of 

Enewetok; development and study of cleanup options, and selection of a preferred 

course of action, by on AEC Task Group; assignment of responsibilities to 

Executive Branch Deportments, as follows: AEC for radiological characterization, 

DoD for radiological cleanup and operational support, and Deportment of the 

Interior (Doi) for rehabilitation and resettlement; development of a detailed Moster 

Pion for rehabilitation and resettlement by the People of Enewetok, assisted by 

Doi, DoD, and AEC; development, issuance, and resulting action on an Environmental Impact Statement (EIS); development of disposal/containment options for 

radioactive soil and debris, and selection or a preferred plan; presentation of issues 

to the Congress, and ultimate Congressional authorization and appropriation; 

development by DNA of a Concept Plan (CONPLAN) governing the cleanup, and its 

approval by the Joint Chiefs of Staff; assignment of individual responsibilities to 

Army, Novy, and Air Force; and development by DNA of a detailed Operation Pion 

(OPLAN) governing all facets of the cleanup operation. 

At an early juncture in this planning process the Defense Nuclear Agency was 

designated the DoD Project Manager for the Enewetok operation. 

A key decision in this process was that operations would be concurrent rather 

than sequential. The normal, conservative approach would have been to conduct 

the operation in three sequential phases: first, the detailed on-site radiological 

characterization by AEC (DoE); second, the cleanup by DoD, based upon the 

radiological characterization developed in the first phase; and third, the rehabilitation (homebuilding, crop planting, etc.) and resettlement by Doi, once the DoD 

cleanup had been completed. To save time and money, the planners decided on a 

much riskier concurrent approach, in which all three phases would be carried out 

simultaneously. Because support costs are a dominant portion of overall expense, 

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... 

this approach shortened the project by several years and saved tens of millions of 

dollars. 

Because of the isolation and lac~ of facilities at Enewetak, any productive 

effort in any of the three phases required establishment and maintenance on the 

atoll of such supporting infrastructure as: an electrical power generation and 

distribution system; a fresh water distillation, storage, and distribution system; a 

complete airhead for air transportation; cargo-handling piers; regular sealift and 

airlift to and from the atoll; a tank farm for receipt, storage, and distribution of 

various types of fuel; living and messing accommodations for about 1,000 individuals; large-capacity refrigeration facilities for storage of food; extensive 

medical facilities up to the operating-room level; satellite and high-frequency 

long-haul communications; an inter-island communication network; an extensive 

fleet of Navy landing craft and boats for inter-island water transportation, backed 

up by major boat maintenance facilities; vehicles for land transportation; helicopters and associated maintenance facilities for medical evacuation and other 

emergency use; underwater demolition and ordnance disposal capabilities; a large 

maintenance and repair facility for heavy construction equipment (bulldozers, 

graders, rock crusher:s, frontloaders, trucks, backhoes, cranes, etc.); a postal 

system; austere recreation facilities; etc. 

Many of the early planning decisions addressed the problems of radiological 

contamination. It was recognized that a distinction had to be made between two 

types of soil contamination, "transuranics" and "suburanics." Transuranics are 

elements above uranium in the atomic table, such as plutonium. They typically 

have very long half-lives, e.g., 24,000 years in the case of plutonium. Suburanics, 

such as strontium-90 and cesium-137, have much shorter half-lives. These two, for 

example, are 28 and 30 years, respectively. The AEC's radiological survey had • 

disclosed that, except on the island of Runit, most high transuranic concentrations 

were in the top few centimeters of soil. This was not the case with suburanics, 

which, because of their water solubility, were distributed to considerable depth. 

Since the near-surface transuranics had the greatest potential for ingestion or 

inhalation through resuspension, and since their threat was long-term, it was 

recognized that the cleanup would have to deal with them. Excision of soi! 

contaminated with suburanics, however, was simply not practicable. To do so 

would require such extensive soil removal as to render the island useless for 

habitation or subsistence agriculture. However, by the same token, cleanup of 

suburani.cs was less essential because contamination levels were declining measurably year by year. Thus it was determined that, insofar as contaminated soil was 

concerned, the radiological cleanup would address transuranics. 

Another key decision concerned the method for disposing of, or containing, 

contaminated debris and soil. Various options were developed and analyzed: 

lagoon-dumping, ocean-dumping, spreading over the surface of Runit, etc. The 

method selected--after extensive debate on the EIS--incorporated the following 

elements: 

o All contaminated debris and soil on all islands would be transported 

by boat to the island of Runit. 

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o The contaminated soil would be mixed with cement and formed into a 

concrete matrix, which would fill the crater on the north end of Runit formed by 

the "Cactus" nuclear detonation. 

o The contaminated debris would be encapsulated in this concrete 

matrix. 

o The dome-like mound formed over Cactus crater would be covered 

with a concrete cap to remove any resuspension and inhalation threat. 

• 

o Since the entire island of Ruhit would remain quarantined indefinitely because of residual sub-surface contamination in its soil, presence of the capped, 

encapsulated contamination at the north end of the island should pose no future 

problems for the People of Enewetak. 

In 1975 the Congress authorized the Enewetak Radiological Cleanup and 

Rehabilitation Project, and funds were appropriated in 1976. Congressional 

guidance was as follows: 

o The radiological cleanup was to be accomplished by the Military 

Services. 

o A total of $20 million was appropriated in FY 1977 Military 

Construction (MilCon) funds. 

o DoD was directed to draw other needed resources, without reimbursement, from the Military Services' construction and support forces, their 

subsistence, equipment, material, supplies, and transportation. 

o DoD was further directed to employ all feasible economies in the 

project, consistent with meeting radiation standards established by AEC (DoE). 

o The People of Enewetak were required to agree that appropriation of 

the $20 million MilCon funds would constitute the total commitment of the U.S. 

Government for the cleanup of Enewetak Atoll. 

During development of the Master Plan with the People of Enewetak, 

probably the most important decision involved choice of residence islands. Since 

residence islands would be the site of most subsistence agriculture, as well as living 

and sleeping quarters and community centers, great care had to be taken to ensure 

that the living patterns and locations selected would not permit the people to 

accumulate lifetime body burdens of radioactivity at levels thought by medical 

science to cause any significant increase in the risk of adverse health effects. 

From the start it was clear that the dri-Enewetak could return safely to their home 

island of Enewetak in the south. The three large southern islands of Enewetak, 

Medren, and Japtan, which had been the base comp for the 4,000-man scientific 

task force during the test period, had remained essentially uncontaminated by the 

testing and had served as headquarters for the caretaker force subsequently. The 

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·" level of residual contamination on these islands was generally less than that of 

most· locations in the United States. At the outset it was hoped that the dri-Enjebi 

could return to their home island of Enjebi in the north. However, upon analyzing 

the results of the radiological survey, AEC (DoE) decided in 1974 that residual 

levels of suburonics in the soil of Enjebi would be such that the lifetime body 

burden accumulated by people eating-crops grown in the Enjebi soil might exceed 

levels then considered acceptable. Accordingly, the Master Plan developed by the 

People of Enewetak and the U.S. Government in 197S called for both the driEnewetak and the dri-Enjebi--then numbering about 4SO in total--to reside on 

Enewetak, Medren, and Japtan in the south. Because of the relatively short haltlives of the principal suburanics in the ·north, it was recognized that eventual 

return to Enjebi would be possible. 

In addition to identifying the three large southern islands as the location for 

residence and subsistence agriculture, the Master Pion also outlined virtually all 

other major aspects of the future life-style of the People of Enewetak ofter return 

to their atoll. For example, in it the people set forth their property boundaries, 

the desired location of each family's home, the house designs they hod selected, the 

location and configuration of the community centers, their decision not to have 

electrical power in their homes, their option for individual water catchment 

systems rather than a distillation plant, etc. 

The planning documents identified the desired utilization of each island as 

either residential, agricultural, or food-gathering. The acceptability of each island 

for the desired use depended upon the residual radiation levels, as follows: 

o Islands whose soil met the tightest standard for amount of residual 

tronsuranics could be used for residence (including subsistence agriculture), provided suburanic levels were acceptable. 

o Islands whose soil met an intermediate standard of residual transuranics could be used for agriculture (e.g., coconut trees for copra production). 

o Islands whose soi I met a lesser, but st i II acceptable, standard for 

residual transuranic contamination couid safely be visited for food-gathering 

(fishing, bird's egg gathering, etc.). 

o Only one island of the 40, Runit, had such extensive sub-surface 

contamination that cleanup to meet any of the three standards was not feasible. 

With the agreement of the People of Enewetak, Runit was to be quarantined 

·indefinitely. 

o The lagoon was safe for all purposes, including fishing, for which the 

People of Enewetak would normally use it. 

The radiological cleanup itself consisted of three phases spanning 3S months. 

Phase I, Mobilization, commenced on-atoll on IS May 1977 and lasted six months, 

completing on IS November 1977. Phase II, Cleanup, was scheduled for 22 months, 

s 
... terminating on 15 September 1979. Phase Ill, Demobilization, was scheduled for 

seven months, completing on 15 April 1980. Dol's rehabilitation effort was to start 

subsequent to DoD's Mobilization Phase, but was scheduled to complete concurrently with DoD on 15 April 1980. These schedules were established in 1976, during 

preliminary planning, and the entire project has remained on schedule all the way 

through to comp letion. 

Mobilization began in the spring of 1977. The base camp on Enewetak Island, 

which had served as the home of the caretaker force for many years, was expande,,P 

manyfold to accommodate the support forces, the cleanup forces who would clear 

the southern islands of uncontaminated debris, and the Doi contractor who ~ould 

carry out the rehabilitation effort. An advance camp was constructed on the island 

of Lojwa in the northeastern chain. Residual radiation levels on Lojwa were very 

low, and the island was of adequate size to accommodate the cleanup force of 

about 400 men who would clear the northern islands of uncontaminated debris, 

contaminated debris, and soil with the highest levels of transuranic contamination. 

Lojwa also served as the base for the sizeable force which carried out containment 

operations for contaminated material on the island of Runit. 

Throughout the summer and fall of 1977 on-atol I personnel levels rose and 

construction activity increased, until by the end of the Mobilization Phase on 15 

November 1977 the camps on Enewetak and Lojwa were completed and the on-atoll 

force numbered about 900. 

During the planning stages it had been recognized that the People of 

Enewetak--then exiled from their homeland for 25 years--longed to return to their 

atol I as soon as possible; yet the cleanup and rehabilitation efforts would keep 

them away for three more years. To accommodate their desires to the maximum 

extent possible, an "early return" program was established whereby some 50-60 of 

the people could return at the start of the Mobilization Phase and live on Japtan, 

one of the uncontaminated islands in the south. The people selected those who 

would first return to Japtan (generally the older individuals, some of whom might 

not survive for three more years), and the U.S. Government established austere 

temporary housing facilities. The results were highly successful, in that it meant a 

great deal to the people (who rotated residents between Japtan and Ujelang every 

few months), and it created no problems for cleanup and rehabilitation forces 

which could not be worked out. 

The complexity of the radiological environment on Enewetak Atoll required 

DoE to employ highly sophisticated methods in its soil characterization efforts. A 

laboratory complex was established on the atoll, incorporating modern equipment 

and methods for the rapid analysis of many thousands of samples. This made 

possible the timely use of laboratory results in day-to-day planning. Noteworthy 

was the method employed by DoE to identify the plutonium content of soil. 

Plutonium is an emitter of alpha particles, a form of radiation that is not 

penetrating. For example, alpha radiation can be stopped by a few inches of air, or 

a sheet of paper, or tiny particles of soil. Thus it was entirely impractical to 

measure directly for plutonium in the soil by attempting to detect alpha radiation. 

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... Instead, DoE measured the gamma radiation emitted by amenc1um--a daughter 

product of plutonium. Americium results from radioactive decay of plutonium, and 

its gamma emissions are sufficiently energetic to penetrate several inches of soil. 

To accomplish this measurement in the difficult environment on Enewetak, DoE 

designed and built special tracked vehkles which could operate in the soft sands, 

equipped them with boom-mounted, highly sensitive germanium detectors (cooled 

by liquid nitrogen), and installed analysis and counting equipment in the vehicle. 

The vehicle itself was air conditioned to provide a controlled environment for this 

delicate equipment. These mobile measuring systems measured the intensity of 

gamma radiation in the energy spectrum .characteristic of americium. Reading!! 

were taken at every intersection of a SO-meter grid surveyed on each island which 

coarser aerial and in-situ surveys had shown to have significant transuranic 

contamination. At each location of van readings, soil samples from several depths 

were obtained and were analyzed for plutonium-americium ratio by the radiological 

laboratories. In areas of higher or irregular contamination, additional van readings 

and soil samples·were taken at intervals of 25, 12Yz, or 6V,. meters. Sophisticated 

computer programs were developed to produce radiation contour maps of plutonium contamination, which were then used by cleanup teams to guide soil excision. 

After each removal of soi I, the area was re-surveyed, new van readings and new 

soil samples were taken, until residual plutonium contamination had reached 

acceptable limits. 

The U.S. forces which accomplished the radiological cleanup and rehabilitation throughout 1978 and 1979 typically were present in about the following groups 

and strengths: 

Joint Task Group Staff (DNA) 35 

Army Element 430 

Navy Element 115 

Air Force Element 75 

Support Contractor 165 

Army & Air Force Exchange System 5 

DoE 5 

Rad-Lab Contractors 10 

Mid-Pacific Research Laboratory 10 

Doi and TTPI 5 

Rehabilitation Contractor IOO 

Micronesian Labor 10 

965 

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The U.S. military forces performed with great effectiveness in this difficult 

environment. Tour lengths on-atoll were about six months for most personnel, one 

year for key individuals. Some were volunteers, but because of the specialized 

nature of most tasks, the majority were assigned from units world-wide having the 

necessary skills. It was arduous, rigorous work in a harsh environment, with 

potentially hazardous conditions always present. The planned workweek was 60 

hours, with many individuals working much more. Temperatures and humidities 

were always high, and for those working in confining anti-contamination clothing, 

short shift lengths had to be established. Living conditions were austere, and 

recreational facilities were extremely limited (and even here there was potentiat 

for danger). In all, over 4,000 U.S. servicemen served on-atoll in the Enewetak 

radiological cleanup; and six lost their lives (two in industrial accidents, two in a 

recreational accident, and two unrelated to the environment). 

The Army element, which was the largest of the Service contingents, came 

principally from the 84th Engineer Battalion in Hawaii. These Army engineers 

performed the bulk of the actual cleanup work, and provided the maintenance 

capability for the heavy construction equipment. The Army also supplied the 

helicopter detachment for medical evacuation, search and rescue, and other 

emergency use. 

The Novy element, which drew large numbers of its personnel from Assault 

.Craft Unit One of the Pacific Fleet, provided all inter-island water transport--a 

task which required some 30 Novy landing craft and boots and extensive maintenance facilities for their support. The Navy also provided the Underwater 

Demolition T earns, the Explosives Ordnance Disposal T earns, and some of the 

technicians for DoE's radiological laboratories. 

The Air Force element, whose personnel come from force-wide units, • 

provided a myriad of support functions: Field Radiation Support Teams for on-site 

radiological safety supervision, communications team, staff for the medical 

facilities, POL (fuels) team, airhead detachment, some laboratory technicians, and 

postal workers. 

Despite the rigorous and austere nature of the assignment, personnel problems were few. Individuals understood and supported the important objectives of 

the radiological cleanup and its notional and international significance. In 

recognition of their unselfish and highly effective efforts, the Secretory of Defense 

awarded- the DoD Humanitarian Service Medal to members of all Services for 

meritorious participation on-atoll in the Enewetak radiological cleanup. 

Throughout every step of planning and every day of execution, the most 

important consideration in the cleanup operation was the radiological safety of 

individuals involved in the operation. In planning, each aspect of the operation was 

designed to minimize the potential for exposure of individuals to ionizing radiation. 

In execution, each operation involving possible radiation exposure was directly 

supervised and closely reviewed by teams or organizations whose sole function was 

radiological safety (rodsafe). Radiation exposurn standards were set conservatively 

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to begin with; and the guiding philosophy was for operations to be conducted so as 

to assure that radiation exposure of individuals was limited to the lowest levels 

practicable within these standards. The goal has been to ensure that any actual 

exposures are so much lower than today's standards that they should not be a cause 

for concern even if future Federal ex-posure standards were to be tightened by a 

factor of ten or more. 

The standard operating procedures for the radiological safety program were 

developed by experts from DoE, Sandia Laboratories, Lawrence Livermore Labora. 

tory, and DNA. The program was implemented in the field by a speciaJJy qualified 

group of Air Force personnel organized into Field Radiation Support Teams. These 

teams were under the supervision of trained radiation safety personnel in the 

Radia tion Control Division of the Joint Task Group (JTG) staff on the atoll. 

Overseeing these organizations and monitoring the overall radiological safety 

program was an on-atoll Radiation Control Committee, which included the JTG 

Deputy Commander, a medical doctor, a DoE representative, and a representative 

from each of the Service elements. Finally, an independent "Radiation Safety 

Audit and Inspection Team'' of experts headed by the Director, Armed Forces 

Radiobiology Researcf1 Institute (AFRRI), and including representatives from DoE 

and the three Services, visited the atoll frequently during the project to ensure the 

radsafe policies and procedures were sound and that actual practices in effect at 

the work sites were effective. 

Personnel assigned to Enewetak Atoll wer.e briefed on the known and potential radiological risks involved in the operation. Upon arrival, all personnel 

received an initial orientation covering the operation and the potential hazards-­

not only those involving radiation, but also sunburn, coral, swimming, fish, and 

others. A sizeable percentage of the servicemen assigned to Enewetak--those who 

lived and worked on the southern islands--had no potential for exposure to 

radiation. The others--those who were engaged in cleanup of radioactive debris 

and soil--underwent additional training covering operations in controlled areas, 

potential risks, and radiological safety procedures. Written standard operating 

procedures outlined the conduct of aJJ operations. 

The most fundamental procedure employed to keep exposure to a minimum 

. was rigid control of access to contaminated islands. Extensive knowledge of the 

radiological environment was available before the cleanup began. Reports of the 

nuclear tests were reviewed to ascertain exactly where each test occurred, and the 

patterns of known or expected radioactive contamination that resulted from it. 

Helicopter surveys were then made to define the existing radiation situation in 

more detail. Finally, DoE conducted a detailed island-by-island survey to identify 

precise radiological contamination contours before the removal of soil and debris 

began. Travel to controlled (contaminated) islands was permitted only for cleanuprelated purposes, and individuals were logged in and out on each occasion. 

Personnel working on these islands were under supervision of the Radiation Control 

Division and under constant surveillance of a Field Radiation Support Team. This 

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team monitored the local radiation environment, sampled the air for airborne 

activity, determined the level of protective equipment needed, and monitored 

personnel for contamination. 

The low gamma radiation levels-found at Enewetak Atoll would not normally 

require a full-scale dosimetry program, however such a program was established. 

All personnel who worked on, or visited, the contaminated northern islands were 

issued film badges on a monthly basis. Because film badges frequently were 

adversely affected by climatic conditions, a supplemental dosimetry system making 

use of thermoluminescent dosimeters (TLDs) was established for personnel working 

on contaminated islands. TLDs had. the additional advantage that they could be 

read on-atoll. Self-reading ionization chambers (pocket dosimeters) were also 

issued, as required, to provide backup dosimetry before TLDs were acquired. 

When earth-moving operations were conducted in contaminated areas, water 

sprinklers were normally rigged to minimize resuspension of the soil. Personnel 

were trained (and directed on-site) habitually to remain upwind of any dustproducing operation. Air samplers were set up downwind to monitor for any 

airborne hazard. These power-operated samplers forced air through filters, which 

were monitored and changed at two-hour intervals, and subjected to laboratory 

analysis. During transit, trucks containing soi I were wet down and covered with 

tarpaulins. Personnel involved in earth-moving operations wore appropriate safety 

gear for the conditions (respirators, protective clothing, etc.). Bioassay procedures 

(nose swipes, fecal analysis, urine analysis) were established on the atoll and used 

as required. Urine samples from personnel who worked for extended periods on 

controlled islands were collected at end of tour and analyzed. 

The effectiveness of this conservative approach toward sampling the radiological environment, and controlling and measuring exposure to it, is borne out by 

the very low radiological exposures that were experienced. 

Exposures to gamma radiation were extremely low level. Of some 12,000 film 

badge readings, about 83% show zero exposure, and the highest valid reading is 

about 0.07 rem.* 

The probability of there having been any internal (inhaled) contamination is 

similarly very low, as shown by the facts that: 

(I) More than 5,000 filters from air samplers were collected during the 

operation, and about one million cubic meters of air were sampled. Over half the 

filters showed no traces of transuranic element activity, over 95% showed less than 

one percent of the maximum permissible concentration (MPC), and none showed 

more than 10% of MPC. 

*The current Federal guideline for allowable exposure for radiation workers is 3 

rem per quarter, or 12 rem per year (reduced to 5 rem per year when certain ageexposure limits have been reached). 

10 
... 

(2) Assays of urine samples of some 2,000 individuals were carried out, 

with no indication of any contamination attributable to activities on the atoll. 

Finally, extensive permanent documentation of individuals involved, their 

assignments, operations, protection levels, exposures, etc., has been carried out. In 

summary, it would be difficult to identify additional radsafe precautions that could 

have been taken. The measured results bear out the effectiveness of the program. 

During the course of the three-year c;leanup operation, numerous changes and 

setbacks occurred which added significantly to the scope of work and the amount 

of effort required. Four of the more significant are summarized below: 

o Throughout the years of planning and into the actual Cleanup Phase, 

all soil-removal estimates had been based upon plutonium-239 and -240 being the 

only significant transuranics present in the soil. In early 1978, as more detailed soil 

characterizations became available, DoE identified that significant amounts of 

plutonium-238 and americium-241 were also present, and recommended that the 

cleanup be based upon "total transuranic" concentrations. DNA accepted this 

recommendation, which significantly improved final islqrd conditions, although it 

correspondingly increased the quantity of soil to be removed. 

o In the planning process, the guidelines for soil cleanup which DoE 

provided to DNA were as fol lows: 

(I) Residence islands were to be cleaned to a level of 40 picocuries of 

plutonium-239/240 per gram of soil (pCi/gm); 

(2) plutonium-239/240 concentrations greater than 400 pCi/gm were 

to be excised wherever found; and 

. (3) case-by-case decisions were to be made by DNA for cleanup of 

plutonium-239/240 concentrations between 40 and 400 pCi/gm. 

In 1978 DoE provided new and expanded radiological guidance to DNA, as follows: 

(I) Residence islands were to be cleaned to the some numerical 

standard as before--40 pCi/gm--but now based on total transuranics; 

(2) agriculture islands were to be cleaned to a transuranic level of 80 

pCi/gm; and 

(3) food-gathering islands were to be cleaned to a transuranic level 

of 160 pCi/gm. 

These more detailed standards permitted soil removal decisions to be based more 

directly on cost-benefit considerations; however, because they were much tighter 

standards, they greatly increased the amount of soil-removal work required. 

o The original pion did not include cleanup of contaminated soil from 

the large island of Enjebi in the north, even though this was the ancestral homeland 

of the dri-Enjebi, and although the transuranic levels in the soil were known to be 

in excess of the standards for a residence island. This situation was not a planning 

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oversight. It had long been considered that the massive effort which would be 

required to improve the transuranic condition of Enjebi would be disproportionate 

to the end result, considering that the levels of suburanics remaining after the 

cleanup were still estimated to be excessive for immediate residential use of the 

island. In 1978, however, as more detailed information became available on the 

overall scope of the soil removal work, it became apparent that significant 

improvement of Enjebi was not beyond reach. DNA made the decision to attempt 

the Enjebi soil cleanup--for if the transuranic condition of the island were not now 

improved it might never be habitable, even after the passage of several half-lives 

of the shorter-lived suburanics. Initially an intermediate goal was set, but as the 

work progressed major innovations were developed in soil measuring, mapping, and 

removal techniques. The residential criterion for transuranics was met, thereby 

making possible the eventual resettlement of the dri-Enjebi to their home. Enjebi 

soil removal was the single most massive effort of the cleanup, and potentially the 

most significant to the returning people. 

o During the three-year duration of the radiological cleanup project, 

four major typhoons and tropical storms hit Enewetak Atoll, causing extensive 

destruction. In particular, two of them did such damage to boats and landing craft 

that extensive repair and replacement efforts were required, and cleanup work was 

slowed for many months. One typhoon required complete evacuation of the atoll. 

In terms of results achieved, the three-year radiological cleanup was a striking success. The Enewetak forces met all cleanup objectives and exceeded many. 

The following subparagraphs discuss some of the accomplishments: 

o Over 215,000 cubic yards of uncontaminated debris were removed 

from islands and reef areas and disposed of at designated dump sites in the lagoon 

and in shoreline protection. Before any piece of debris could be touched, it had to 

be screened by radiation monitors for several types of possible contamination, and 

then marked as contaminated or uncontaminated. In many cases (e.g., blockhouses 

and bunkers) extensive demolition of uncontaminated structures was required. For 

debris in the reef areas, Navy Underwater Demolition Teams often worked in IO or 

20 feet of water clearing sunken landing craft and other objects. Repeated postcleanup inspections of each of the 40 islands verified them to be completely clear 

of even the smallest scraps of residual debris from World War II and the test 

period. 

o About 16,000 items of World War ·11 ordnance (e.g., unexploded 

artillery projectiles, mortar shells, hand grenades, small arms and ammunition) 

were located by detectors, dug up, and disposed of by Navy Explosive Ordnance 

Disposal T earns. 

o Some 6,000 cubic yards of radiologically contaminated debris were 

identified, transported by landing craft to Runit, and immobilized in concrete in 

Cactus crater. 

o All former dumps, crypts, and burial sites for contaminated debris 

and soi I during the test period, to which reference could be found, were excavated 

and the contents were encapsulated in Cactus crater. One major crypt on Aomon 

island was so extensive and difficult it required over a year to pion and carry out 

its excavation. 

12 
o About 105,000 cubic yards of soil contaminated with transuranics, 

principally isotopes of plutonium and americium, were identified, excised, transported by landing craft to Runit, and mixed with cement to form concrete with 

which Cactus crater was filled. This crater in the reef is about 350 feet in 

diameter and some 30 feet deep. The crater volume below sea level was fi lied by 

the tremie method, in which a concrete slurry is pumped by large hose and pipe to 

the crater floor, and progressively built up. Above the waterline, a soil-cement 

mixture was formed from the contaminated soil. A thick concrete keywall was 

constructed around the circumference, and a dome-shaped concrete cap covered 

the entire crater. · • 

o At the completion of the cleanup, of the 40- islands of Enewetak 

Atoll: 30 qualified as residential and subsistence agriculture islands in terms of 

residual transuranic contamination; seven qualified as agriculture islands; two 

qualified as food-gathering islands; and the last one, Runit, had all identified highlevel concentrations of transuranics removed. It remains quarantined because of 

residual sub-surface contamination. Every island designated in planning documents 

for a particular end-use by the people was Cleaned at least to the level 

corresponding to that use; and for many islands--including, most significantly, 

Enjebi--the cleanup exceeded the planning goals. 

Costs have remained remarkably constant for the duration of the project. 

The effort has been completed within the $20 million MilCon funds originally 

appropriated for the task. When Congressional direction was received to accomplish the cleanup project with military forces without reimbursement, the first 

estimate of total project cost was developed by DNA during the Mobilization Phase 

and was presented to Congress in the spring of 1978. At that time DoD costs were 

estimated at $80 million (including MilCon), Doi costs at $12 million, and DoE costs 

at $4 million, for an overall total of $96 million. Despite inflation, major increases • 

in project scope, unforeseen difficulties, and damage and delay from four severe 

typhoons, current estimates today, more than two years later (and within a few 

weeks of project completion) are: DoD $86 million; Doi $14 million; DoE $4 

million; for a total of $104 million. While this amount represents "value received" 

by the People of Enewetak in terms of cleonup effort, "out of pocket" cost for U.S. 

taxpayers is substandially less, because many of the DoD expenses would have 

accrued had there been no Enewetak cleanup (e.g., pay and subsistence for 

personnel, fuel and spare parts for vehicles). DNA estimates that the cost to the 

taxpayers of the Enewetak cleanup and rehabilitation program has been approximately: DoD $49 million (including MilCon); Doi $14 million; DoE $4 million; for a 

total of $67 million. 

Dol's rehabilitation program has involved the construction of 116 homes for 

the people on the three southern islands of Enewetak, Medren, and Japtan, along 

13 
·" 

with community centers, piers, and other life support elements. Subsistence 

agriculture (breadfruit, pandanus, dwarf coconuts, etc.) has been planted on the 

three southern islands, and some 31,000 coconut trees for commercial and subsistence purposes have been planted tt'!roughout the atoll (20,000 in the south, 11,000 

on the lesser contaminated islands in the northeastern chain). 

As mentioned earlier, a continuing hallmark of the Enewetak cleanup and 

rehabilitation project has been the total and continuing involvement of the People 

of Enewetak in the process. Frequent inspection visits and planning conferences by 

the Enewetak leadership have been held on the atoll, with the Enewetak hereditary 

leaders, the Magistrate, the Planning Council, and others traveling from Ujelang to 

Enewetak for periods of days or weeks. This continuing interaction has resulted 

not only in a feeling of deep involvement by the People of Enewetak, but also in 

accomplishment of the cleanup and rehabilitation in accordance with their desires. 

The issue of when the dri-Enjebi may be able to return to their ancestral 

home island of Enjebi in the north is .still unresolved. As noted previously, all 

planning and project execution to date--with the agreement of the People of 

Enewetak--has been based upon the dri-Enjebi residing initially in the south, and 

this is where their homes have been constructed. One of the remaining responsibilities of the U.S. Government is to advise the dri-Enjebi when it will be safe to 

return to their home island. To provide this advice, DoE, Doi, and TTPI have 

collected extensive data on residual suburanic soil contamination in the north, on 

radionuclide uptake by crops, on alternative living and subsistence patterns in the 

north, on the rate of accumulation of radionuclides in the body, and on estimated 

health effects from this accumulation. These data have been analyzed in-depth 

and combined into dose assessments. Separately, the People of Enewetak have 

engaged their own team of eminent scientists and authorities to provide them with 

independent estimates of the above factors and the resulting dose assessments. 

Based upon extensive review of the data provided by both sources, the People of 

Enewetak have expressed their desire for the dri-Enjebi to return at once to their 

home island. The U.S. Government has this request under consideration at the time 

of this writing. 

The remarkable success of the Enewetak radiological cleanup operation has 

been due in large measure to the dedication and commitment of the Military 

· Services in providing the resources to do the job; and to the enthusiasm, initiative, 

and willing efforts of the individual servicemen assigned to the cleanup fo'rce. Also 

notable has been the remarkably effective coordination between the many organizations whose efforts had to be integrated into a smooth-working team on-atoll. 

In summary, the Enewetak Radiological Cleanup and Rehabilltation Program 

was well conceived and well executed, was completed on time and within cost, and 

produced more effective results than anticipated. It marks the fulfillment of a 

moral obligation this country incurred decades ago, and it represents an effort in 

which every American can take great pride. 

14 
Defense Nuclear Agency 

• 

FACT 

Public Affairs Office 

Washington, D. C. 20305 

325-7091 D 

SUBJECT: ENEWETAK RADIATION SAFETY 

The safety of the personnel involved in the cleanup of radioactivity at s 

Enewetak is a matter of prime concern in the planning and execution of ffie 

major effort. In 1947 the people of Enewetak Atoll were relocated to Ujelang 

AtoU so the United States could use Enewetak for nuclear weapons tests. 

19.58. 

Forty-three nuclear detonations took .place at Enewetak between 1948 and H

In 1972 Ambassador Williams announced that the United States was prepared to 

Commission 

clean-up, rehabilitate, 

(now the Department 

and return 

of 

the 

Energy 

Atoll to 

(DoE)) 

its people. 

and Department 

The Atomic 

of Defense 

Energy E

(DoD) were tasked to do the preliminary surveys and planning. DoD was tasked 

to perform the cleanup itself, D?E to provide radiological monitoring and 

survey, 

resettlement. 

and the Department of Interior (Doi) to accomplish rehabilitat·ion and E

In FY 197.5 DoD requested a military construction appropriation to accomplish 

the 

appropriation, 

cleanup using 

and instead 

civilian 

directed 

contractors. 

that project 

Congress 

planning 

did 

be 

not 

revised 

authorize 

to make 

this T

use of military personnel and equipment. 

In the FY 1977 military construction appropriation Congress provided $20 

million as a base amount for the cleanup, stipulating that "aU reasonable 

economies should be realized in the accomplishment of this project through the 

use of military servkes' construction and support forces, their subsistence, 

equipment, material, supplies, and transportation which have been funded to 

support ongoing operations of the military services and would be required for 

normal operations of these forces." 

This directjon from Congress required not only that DoD manage the cleanup 

operation, but that DoD personnel actually perform the cleanup. The Army, 

Navy, and Air Force were accordir.gly tasked to provide personnel and 

equipment to _perform the various jobs required. The Director, Defens·!!t 

Nuclear Agency (DNA), was appointed as the DoD Project Manager. 

The DoE is responsible for providing technical support to the DoD Project 

Manager, for characterizing and defining the radiological environment, for 

establishing the criteria for cleanup levels, and for certifying the radiological 

condition of each island in~he Atoll after the cleanup effort. DoD, however, h~ the responsibility for radiological safety of DoD personnel. 

, 
The cleanup portion of this program, managed by DoD, consists of three 

separate efforts: removal and lagoon-dumping of uncontaminated debris and 

structures; removal and crater-entombment of radiologically contaminated· 

debris and structures; and excision and crater-entombment of some of the 

radiologically contaminated soil that remains on the islands. 

·-

Because of the pattern of ground-zero locations for nuclear detonations, 

radiological contamination today is limited roughly to islands of the northern 

half of the Atoll. Typical radiation exposure rates in the southern islands are 

generally less than those from natural background in tbe U.S. _ 

The primary contam.inants in the soil are long-lived transuranic elements 

(plutonium and americium) and relatively short-lived radioisotopes ceslum-137, 

strontium-90, and cobalt-60. The principal purpose of the contaminated soil 

cleanup program is to reduce the transuranic elements to levels that do not. 

pose long-term hazards to the returning people of Enewetak. Of course, in 

removing soil which contains transuraaj_cs, any other radioisotopes present in 

that volume of soll will also be removed. 

No_! .. all personnel involved in the cleanup operation are subject to radiation 

exposure. Service personnel who have- the potential for being exposed to 

radiation consist only of those who are actually engaged in the removal and 

disposal of the contaminated debris, structures, and soil. Typical duties 

involve operating bulldozers, backhoes, trucks, cranes, cement mixers, boats, 

and monitor equipment. 

The overall philosophy is for operations to be conducted in such a manner as to 

assure that radiation exposure to individuals is limited to the lowest levels 

practicable. The cleanup radiation exposure standards are based on Title 10, 

Code of Federal Regulations, Part 20, as implemented in Department of Army 

Regulation 40-14, Control and Recording Procedures for Occupational Exposure 

to Ionizing Radiation. The limits for exposure in this regulation are .5 rem per 

_year, or 11/4 rem for any ~hree consecutive months. 

The bask staridard operating procedures for the cleanup radiation safety 

program were developed by a group of experts. from DNA, DoE, Sandia 

Laboratories, and Lawrence Livermore Laboratory. The program is implemented in the field by a specially qualified group of Air Force personnel 

organized into Field Radiation Support Teams. These teams are under the 

supervision of radiation safety experts in the Radiation Control Division of the 

Joint Task Group (JTG) on the Atoll. An on-site Radiation Control 

Committee, which includes the JTG commander, a medical doctor, a DoE 

representative, and a representative from each of the Service elements, 

monitors the overaJl radiological safety program. In addition, an independent 

audit and inspection team of experts headed by the Director, Armed Forces 

Radiobiology Research Institute (AFRRI), and including representatives from 

DoE, the three Services, and AFRRI visits the AtoJJ ·on a periodic basis 

(quarterly, for the past year) to ensure the program is being properly 

implemented. 

2 
The most fundamental procedure employed to keep exposure to a minimum is 

to rigidly control access to the contaminated islands. When personnel do work 

on these islands, it is. under the supervision of the- Radiation Control Division 

and under the constant surveillance of a Field Radiation Support T earn. This 

team monitors the local radiation environment, samples the air for airborne 

activity, determines the level of protective equipment needed, and monitors 

persoMel for contamination. Speclf ic procedures have been formulated to 

provide-detailed day-to-day guidance on safety and other=-i)rocedures pertaining 

to operations that might involve radiological contamination. 

Although the low gamma radiation levels found at Enewetak Atoll would not 

normally require a full-scale dosimetry program, it was decided to establish 

one. All personnel who work on, or visit, the contaminated northern islands 

(the controlled islands) are issued film badges on a monthly basis. Because 

film badges are sometimes adversely affected by the climatic conditions on 

the Atoll, a supplemental dosimetry system was also established for personnel 

working on contaminated islands, making use of thermoluminescent dosimeters 

(TLDs). TLDs have the additional advantage that they can be read on the 

Atoll. In addition, self-reading ionization chambers (pocket dosimeters) are 

also issued, as required, to augment the film badge program. These are read 

on a daily basis. -

When earth-moving operations are to be conducted in contaminated areas, 

water sprinklers are normally rigged to minimize resuspension of the soil. Air 

samplers are set up downwind of the operation to monitor any airborne hazard. 

During transit, trucks containing soil are wet-down and covered with 

tarpaulins. Personnel involved in earth-moving operations wear appropriate 

safety gear for the conditions (respirators, protective clothing, etc.) Bioassay 

procedures (nose swipes, fecal analysis, urine analysis) have been established 

on the Atoll, and are used as required. In addition, urine samples from 

personnel who work on controlled islands are collected at the beginning and 

end of their tour on the A toll. 

The effectiveness of this conservative approach toward sampling the radiological environment and controlling exposure to it is borne out by the very low 

radiological exposures that have been experienced in the first year of 

operations. 

As far as exposure to external gamma radiation is concerned, in the hundreds 

of film badge readings taken to d.ate, the great majority have shown nc 

exposure whatsoever. Tht> highest readings have reached only a small fractior1 

of the permissible monthly exposure. 

As far as internal exposures, our intensNe measurement program has shown no 

evidence of any intake whatsoever. In the thousands of hours of air sampler 

operation, airborne radioactivity has been virtualJy negligible. No indication 

of iflternal expo:".ure has been aetected in analysis of face mask filters. 

Bioassay urine sarr:;::l'."'s on d~parting personnel with a potential for exposure 

have all been negative. 

3 
Personnel assigned to Enewetak are weU briefed on the known and potential 

radiological risks involved in the operation. Upon arrival, all personnel receive 

an initial orientation covering the operation and the potential hazards-.-not 

only radioactive, but also sunburn, coral, fish, and others. Those who are to be 

engaged in cleanup of radioactive materials undergo additional training 

covering operations in a controlled area, potential risks, and radiological 

safety procedures. Further, all operations are conducted under close 

leadership and supervision, and in accordance with the pertinent directives, 

regulations, and standard operating procedures. 

DNA is documenting the operational activities performed on each of the 

northern islands. These records are being developed by the JTG, but are being 

permanently retained at DNA's Field Command in Albuquerque. In addition, a 

central computerized data base is being established at Field Command to 

record the pertinent data on air personnel involved in the cleanup and, for 

those with putentiaJ exposure to radioactive contamination, to record all 

exposures. The data base includes identification of personnel working on each 

northern island each day, level of-protection, personnel dosimetry, and urine 

sample results. The records will be stored permanently, and a computer-based 

ready-retrieval system is being developed. 

Other permanent records are being kept as well. Prior to arriving on the Atoll, 

individuals undergo pre-deployment physical examinations which pay special 

attention to past history of exposure to ionizing radiation and baseline blood 

counts. The results are entered in individual permanent medical records. The 

monthly Ii1m badges from Enewetak are processed by Lexington Blue Grass 

Army Depot, which maintains its own permanent record of the results, and 

sends a copy to the JTG .Radiological Protection Officer for entry in individual 

medical records and to Field Command. Thus any exposure received by an 

individual while on the Atoll will be entered in his own medical record as well 

as into the DNA central data base. Should exposures warrant, whether 

recorded by dosimetry or shown by bioassay results, follow-up examinations 

and tests will be instituted • 

. The Department of Defense is absolutely committed to ensure that all 

personnel involved in the Enewetak cleanup operation are protected from the 

risk of exposure to radiation. The radiation safety program is the result of 

application of the most up-to-date knowledge and use of the latest equipment 

available. Safety is the overriding priority in the operation. 

-30-