DEFENSE

NUCLEAR

WA SH I N GT ON ,

AGENCY

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 radiologicql
cleanup
operation ever conducted and will fulfill a moral obligation incurred 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 Islands--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 I7 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
islanders--subdivide
into two
whose home is the largest southern island of the atoll
groups: the dri-Enewetak,
(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
ISO--were
relocated
in 1947 to a much smaller
atoll,
Ujelang, some 125 miles to the southwest.
A large scientific
and mijitary task
force, under the joint direction of the Atomic Energy CorGmission (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 dei’bnated in the air, on
towers, on the surface of islands and reefs, on barges, and underwhter.
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.
However,
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
The atoll was occasionally used
force remained on Enewetak Island in the south.
for DOD programs not involving nuclear testing.
During this period, in 1972, the
U.S. Government
decided that future national
requirements
in this part of the
world could be met without use of Enewetak;
and Ambassador Franklin Haydn
Williams announced that the atoll would be returned to the TTPI Government,
for
subsequent return to the people--w ho by this time had not seen their homeland for
25 years. The announcement also committed
the U.S. Government to cleanup and
rehabilitation
of Enewetak.
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:
conduct of a detailed radiological survey of
the atoll, 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
Enewetak; development and study of cleanup options, and selection of a preferred
course of action,
by an AEC Task Group; assignment
of responsibilities
to
AEC for radiological characterization,
Executive
Branch Departments,
as follows:
DOD for radiological
cleanup and operational
support, and Department
of the
Interior (Dol) for rehabilitation
and resettlement;
development of a detailed Master
Plan for rehabilitation
and resettlement
by the People of Enewetak, assisted by
Dol, 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
Congressional
authorization
and appropriation;
to the Congress, and ultimate
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, Navy, and Air Force; and development by DNA of a detailed Operation Plan
(OPLAN) governing all facets of the cleanup operation.
At an early juncture in this planning process the Defense Nuclear
designated the DOD Project Manager for the Enewetak operation.

Agency was

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 cl’eanup by DOD, based upon the
radiological characterization
developed in the first phase; and third, the rehabilitation (homebuilding,
crop planting, ‘etc.) and resettlement
by Dol, 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,

2

 this approach
dollars.

shortened

the project

by several

years and saved tens of millions

of

Because of the isolation and lack 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 indilarge-capacity
refrigeration
facilities
for storage of food; extensive
viduals;
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 crushers, frontloaders,
trucks, backhoes, cranes, etc.); a postal
system; austere retreat ion faci I i t ies; 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
They typically
elements above uranium in the atomic table, such as plutonium.
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,I?or
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
Excision of soil
recognized
that the cleanup would have to deal with them.
To do so
contaminated
with suburanics, however, was simply not practicable.
would require such extensive
soil removal OS to rendei the island useless for
habitation
or subsistence agriculture.
However, by the same token, cleanup of
suburanics 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 dispo&g pf, 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
by boat to the island of Runit.

debris and soil on all islands would be transported

3

 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
ly because of
encapsulated
problems for

Since the entire island of Runit would remain quarantined indefiniteresidual sub-surface contamination
in its soil, presence of the capped,
contamination
at the north end of the island should pose no future
the People of Enewetak.

In 1975 the Congress authorized
the Enewetak
Rehabilitation
Project,
and funds were appropriated
guidance was as follows:
o

The

radiological

cleanup

Radiological
in 1976.

was to be accomplished

Cleanup and
Congressional

by the Military

Services..

k

Constructio:

bursement,
subsistence,

project,

&!

A total of
(MilCon)‘funds.

$20

million

was

appropriated

in

FY

1977 Military

o DOD was directed to draw other needed resources, without reimfrom the Military
Services’ construction
and support forces, their
.
equipment, material, supplies, and transportation.
__

o DOD was further
consistent with meeting

directed to employ all feasible economies in-the.
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 token 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 *verse
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 camp 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

4

 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 suburanics in the soil of Enjebi would be such that the lifetime
body
burden accumulated
by people eating crops grown in the Enjebi soil inight exceed
levels then considered acceptable.
Accordingly,
the Master Plan developed by the
People of Enewetak and the U.S. Government
in 1975 called for both the driEnewetak
and the dri-Enjebi --then
numbering about 450 in total--to
reside on
Enewetak, Medren, and Japtan in the south. Because of the relatively
short halflives 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 Plan also outlined virtually
all
other major aspects of the future life-style of the People of Enewetak after 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 had 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
The acceptability
of each island
either residential, agricultural,
or food-gathering.
for the desired use depended upon the residual radiation levels, as follows:
o Islands whose soil met the tightest standard for amount of residual
transuranics
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).

residual
(fishing,

o Islands whose soil met a lesser, but still acceptable,
standard for
transuranic
contamination
could safely be visited
for food-gathering
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 Enewetok,
Runit was to be quarantined
indefinitely.
o The lagoon was safe for all purposes, including
People of Enewetak would normally use it.

fishing,

for which the

The radiological cleanup itself consisted of three phases spanning 35 months.
Phase I, Mobilization,
commenced on-atoll on IS May 1977 and lasted six months,
completing on I5 November 1977. Phase II, Cleanup, was scheduled for 22 months,

5

 terminating
on 15 September 1979. Phase III, Demobilization,
was scheduled for
seven months, completing on I5 April 1980. DoI’s rehabilitation
effort was to start
subsequent to DOD’S Mobilization
Phase, but was scheduled to complete concurrently with DOD on I5 April 1980. These schedules were established in 1976, during
preliminary
planning, and the entire project has remained on schedule all the way
through to completion.
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 expanded
manyfold to accommodate
the support forces, the cleanup forces who would clear
the southern islands of uncontaminated
debris, and the Dol contractor
who would
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-atoll personnel levels rose and
construction
activity
increased, until by the end of the Mobilization
Phase on I5
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 hornetand for 25 years--longed
to return to their
atoll 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 SO-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
reat deal to the people (who rotated residents between Japtan and Ujelang every
3ew 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 0t.msamples.
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.

6

 Instead, DOE measured the gamma radiation
emitted
by americium--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 vehicles 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.
Readings
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, l2H, or 6Y4 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 soil, 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

II5

Air Force Element

75

Support Contractor

165

Army & Air Force Exchange

System

DOE
Rod-Lab

Mid-Pacific

Research

Laboratory

Dol and TTPI
Rehabilitation
Micronesian

5
5
IO

Contractors

IO
5

Contractor
Labor

.

100
’ IO
965

_

 The U.S. military forces performed with great effectiveness
in this difficult
Tour
lengths
on-atoll
were
about
six
months
for
most
personnel, one
environment.
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
it was arduous, rigorous work in a harsh environment,
with
necessary ski Ils.
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 potential
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 Navy 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 Navy landing craft and boats and extensive maintenance facilities
for their support.
The Navy also provided the Underwater
Demolition
Teams, the Explosives Ordnance
Disposal Teams, and some of the
..
technicians for DOE’S radiological laboratories.
The Air Force element,
whose personnel came 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 national
and international
significance.
In
recognition of their unselfish and highly effective
efforts, the Secretary 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
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 (radsafe).
Radiation exposure standards were set conservatively

‘important

 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 exposure
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 Laboratory, and DNA. The program was implemented
in the field by a specially 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
Research
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 were 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
hatards-not only those involving radiation,
but aIso sunburn, coral, swimming,
fish, and
A sizeable percentage
of the servicemen
assigned to Enewetak--those
who
others.
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 all operations.
The most fundamental
procedure
employed
to keep exposure to a minimum
Extensive knowledge of the
was rigid control of access to contaminated
islands.
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 cleanupand individuals
were logged
in and out on each occasion.
related
purposes,
Personnel working on these islands were under supervision
of the Radiation Control
Division and under constant surveillance
of a Field Radiation
Support Team. This

9

 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 dustAir samplers were set up downwind to monitor for any
producing operation.
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 soil 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 anhlysis, 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
similarly very low, as shown by the facts that:

(inhaled)

contamination

is

(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
(MFC), and none showed
more than 10% of MPC.

*The current Federal quideline for allowable exposure for radiation workers is 3
rem per quarter, or I2 rem per year (reduced to 5 rem per year when certain ageexposure limits have been reached).

IO

 (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
cleanup 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
DNA accepted this
concentrations.
cleanup be based upon “total transuranic”
recommendation,
which significantly
‘improved final islqnd conditions, although it
correspondingly increased the quantity of soil to be removed.

provided

o In the planning process, the guidelines
to DNA were as follows:

(I)
plutonium-239/240

Residence islands were to be cleaned
per gram of soil (pCi/gm);

for soil cleanup

which DOE

to a level of 40 picocuries

of
c

(2) plutonium-239/240
to be excised wherever found; and
(3)
plutonium-239/240

concentrations

greater

than 400 pCi/gm

case-by-case decisions were to be made by DNA
concentrations between 40 and 400 pCi/gm.

In 1978 DOE provided

new and expanded radiological

guidance

were

for cleanup of

to DNA, as follows:

(I)
Residence islands were to be cleaned to the same numerical
standard as before--40
pCi/gm--but
now based on total transuranics;

(2)
pCi/gm;

agriculture

islands were to be cleaned

to a transuranic

level of 80

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 plan 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
.

II

 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 mode 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 &i-Enj&i
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
four major typhoons and
destruction.
In particular,
that extensive repair and
slowed for many months.

three-year
duration of the radiological cleanup project,
tropical storms hit Enewetak
Atoll, causing extensive
two of them did such damage to boats and landing craft
replacement efforts were required, and cleanup work was
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 II 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 Teams.
t
.
‘2
.a
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 soil 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 plan and carry out
its excavation.

 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 filled by
the tremie method, in which a concrete slurry is pumped by large hose and pipe to
a soil-cement
the crater floor, and progressively built up. Above the waterline,
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), Dol 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;
Dol $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 cleanup 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); Dol $14 million; DOE $4 million; for a
total of $67 million.
Dolls rehabilitation
the people on the three

program has involved the construction
of II6 homes for
southern islands of Enewetak, Medren, and Japtan, along

I3

 other
life support elements.
Subsistence
with community
centers,
piers, and
.
_
agriculture
(breadfruit,
pondanus, 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 throughout 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 c&i-Enjebi when it will be safe to
return to their home island.
To provide this advice, DOE, Dol, 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 w;‘th
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
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 force.
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.
been

In summary, the Enewetak Radiological
Cleanup and Rehabilitation
Program
was well conceived and well executed, was comple’ted on tim6 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.

I4

_

 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 suburanics in the soil of Enjebi would be such that the lifetime body
burden accumulated by people eating crops grown in the Enjebi soil inight exceed
levels then considered acceptable.
Accordingly,
the Master Plan developed by the
People of Enewetok and the U.S. Government
in 1975 called for both the driEnewetak
and the dri-Enjebi --then
numbering about 450 in total--to
reside on
Enewetak, Medren, and Japtan in the south.
Because of the relatively
short halflives 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 Plan also outlined virtually
all
other major aspects of the future life-style
of the People of Enewetak after 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 had selected, the
location and configuration
of the community
centers, their decision not to hove
electrical
power in their homes, their opt ion for individual
water. catchment
systems rather than o 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, OS follows:
o Islands whose soil met the tightest standard for omount of residual
transuranics
could be used for residence (including subsistence agriculture),
pro.
vided suburanic levels were acceptable.
o Islands whose soil met on intermediate
standard of residual transuranics could be used for agriculture (e.g., coconut trees for copro production).

residual
(fishing,

o Islands whose soil met o lesser, but still acceptable,
standard for
transuranic
contamination
could safely be visited
for food-gathering
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 Enewetok,
Runit wos to be quarantined
indefinitely.
o The lagoon was safe for all purposes,
People of Enewetok would normally use it.

includin3

fishing,

for which the

The radiological cleanup itself consisted of three phases spanning 35 months.
Phase I, Mobilization,
commenced on-atoll on I5 May 1977 and lasted six months,
completing on I5 November 1977. Phase II, Cleanup, was scheduled for 22 months,

5

 terminating
on 15 September 1979. Phase III, Demobilization,
was scheduled for
seven months, completing on I5 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 completion.
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 expanded
manyfold to accommodate
the support forces, the cleanup forces who would clear
the southern islands of uncontaminated
debris, and the Dot contractor
who would
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-atoll personnel levels rose and
construction
activity
increased, until by the end of the Mobilization
Phase on I5
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 hornetand for 25 years--longed
to return to their
atoll as soon as possible; yet the cleanup and rehabilitation
efforts would keep
their desires to the maximum
them away for three more years. To accommodate
extent possible, an “early return” program was established whereby some SO-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
reat deal to the people (who rotated residents between Japtan and Ujelang every
3ew 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 0t.e 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.

6

 Instead, DOE measured the gamma radiation
emitted
by americium--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 vehicles 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.
Readings
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, l2H, or 6% meters.
Sophisticated
computer programs were developed to produce radiation contour mops of plutonium contamination,
which were then used by cleanup teams to guide soil excision.
After each removal of soil, 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 I978 and 1979 typically were present in about the following groups
and strengths:
Joint Task Group Staff (DNA)

35

Army Element

430

Navy Element

II5

Air Force Element

75

Support Contractor

165

Army & Air Force Exchange

System

DOE
Rad-Lab

5
IO

Contractors

Mid-Pacific

Research

Laboratory

Dol and TTPI
Rehabilitation
Micronesian

5

IO
5

Contractor
Labor
965

.

.

 The U.S. military forces performed
with great effectiveness
in this difficult
Tour
lengths
on-atoll
were
about
six
months
for
most
personnel, one
environment.
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
it was arduous, rigorous work in a harsh environment,
with
necessary ski Its.
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 potential
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
The Army also supplied the
capability
for the heavy construction
equipment.
helicopter
detachment
for medical
evacuation,
search and rescue, and other
emergency use.
The Navy 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 Navy landing craft and boats and extensive mainThe Navy also provided the Underwater
tenance facilities
for their support.
Demolition
Teams, the Explosives Ordnance
Disposal Teams, and some of the
\
technicians for DOE’S radiological laboratories.
The Air Force element,
whose personnel came from force-wide
units,
Field Radiation Support Teams for on-site
provided a myriad of support functions:
communications
team, staff
for the medical
radiological
safety
supervision,
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 national
and international
significance.
In
recognition of their unselfish and highly effective
efforts, the Secretary of Defense
awarded the DOD Humanitarian
Service Medal to members of all Services for
meritorious participation
on-atoll in the Enewetak radiological cleanup.
Throughout
everi step of planning and every day of?&xecution,
the most
consideration
in the cleanup operation was the radiological
safety of
In planning, each aspect of the operation was
individuals involved in the operation.
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 (radsafe).
Radiation exposure standards were set conservatively

. important

8

 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 exposure 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 Laboratory, and DNA. The program was implemented
in the field by a specially quaIified
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 Croup (JTC) staff on the atoll.
Overseeing
these organizations
and monitoring
the overall
radiological
safety
program was an on-atoll
Radiation
Control Committee,
which included the JTC
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
Research
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 were briefed on the known and potenUpon arrival,
all personnel
tial radiological
risks involved
in the operation.
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 all 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 reqoval
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

9

..

 .

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 soil 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
similarly very low, as shown by the facts that:

(inhaled)

contamination

is

(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 concetiration
(MFC), and none showed
more than 10% of MPC.

+fhent
Federal guideline for allowable exposure for radiation workers is 3
rem per quarter, or I2 rem per year (reduced to 5 rem per year when certain ageexposure limits have been reached).

 (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 individuols 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
cleanup 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 tronsuranic”
concentrations.
DNA accepted this
recommendation,
which significantly
improved final isfqnd conditions, although it
correspondingly increased the quantity of soil to be removed.

provided

o In the planning process,
to DNA were as follows:

(I)
plutonium-239/240

Residence islands were to be cleaned
per gram of soil (pCi/gm);

(2) plutonium-239/240
to be excised wherever found; and
(3)
plutonium-239/240

the guidelines

concentrations

for soil cleanup

to a level of 40 picocuries

greater

than 400 pCi/gm

case-by-case decisions were to be made by DNA
concentrations between 40 and 400 pCi/gm.

In 1978 DOE provided

new and expanded

radiological

which DOE

guidance

of

wire

for cleanup

of

to DNA, as follows:

(I)
Residence islands were to be cleaned to the same 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

pC i/gm; and
(3)

food-gathering

islands were to be cleaned;-+0 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 plan
the large island of Enjebi in the
of the dri-Enjebi,
and although
in excess of the standards for a
.

did not include cleanup of contaminated
soil from
north, even though this was the ancestral homeland
the transuranic
levels in the soil were known to be
residence island. This situation was not a planning

II

 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 lev&
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
Initially an intermediate
goal was set, but as the
of the shorter-lived
suburanics.
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
In particular,
two of them did such damage to boats and landing craft
destruction.
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 II 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 Teams.
i
.
.:t
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 soil 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 plan 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 filled 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), Dol 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
DOD $86 million;
Dol $14 million; DOE $4
weeks of project completion)
are:
million; for a total of $104 million.
While this amount represents “value received”
by the People of Enewetak in terms of cleanup 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); Dol $14 million; DOE $4 million; for a
total of $67 million.
Dol’s rehabilitation
the people on the three

program has involved the construction
of II6 homes for
southern islands of Enewetak,
Medren, and Japtan, along

I3

 .

Subsistence
with community
centers,
Piers, and other life SU DDOr t elements.
agriculture
(breadfruit,
pondanus, 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 throughout 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, Dol, 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 &ith
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 force.
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 Rehabilitation
Program
was well conceived and well executed, was complkted on tim6 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.

I4
.