Prior to implementation of the above plan, DOE recommended that several small areas with high
activity be excised. These "hot" spots were excised, resulting in a 17 percent reduction in average
TRU activity in one small area and a 46 percent reduction in another; one spot increased 6 percent.
Small-area excision continued for several days with significant results; the action plan then returned
to the plan devised in the 27 May meeting. When the 2,000 yd target volume was reached, the
excision process was halted in the jfig/Quince area until soil removal from other islands was
completed, including about 15,000 yd® from Pearl. Soil excision on the basis of the "highest first"
continued in the Fig/Quince area until the Dome wasfilled to design capacity.
The average indicated TRU activity in the Fig/Quince area was significantly reduced by soil removal
but was not reduced below 160 pCi/g in every square. With reference to the same 47 Squares
mentioned earlier, the average TRU activity following the final Hft was about 145 pCi/g. Fifteen
squares had indicated TRU greater than 160 pCi/g, with an average of about 240 pCi/g. The highest
TRU value was about 700 pCi/g at 0-BL-0.
6.10.4 Follow-up Actions
Final soil removal from the Fig/Quince area was followed by backblading to smooth out the
hummocks. A few days later, on 6 August 1979, four members of the DOE/ERSP staff, accompanied
by one member from RADCON, conducted a detailed survey of the Fig/Quince area with portable
instruments to locate and pick "hot" particles as a last cleanup step. Very few particles were
located; however, numerous pieces of contaminated metallic debris were found and transported to
the Dome by bucket loader. Meanwhile, soil profile samples had been collected and analyzed from
the vicinity of the 1310 bunker in search of a source of clean soil to use as a cover to be placed over
the Fig/Quince area. The soil just north of the bunker was determinedto be suitable and was used to
eover Fig/Quince to a depth of one foot.
Upon completion of the Cactus Dome (Figure 6-27) and demobilization of all construction facilities,
the entire north end of Yvonne was surveyed by IMP on a 25-m grid.
Chapter7.
Final results are reported in
6.11 DOSE ASSESSMENT AND THE FISSION PRODUCT DATA BASE (by William Robison, LLNL)
6.11.1
Relationship Between Data Base and Dose Assessment
A major purpose for developing the Fission Product Data Base (FPDB) as part of the Enewetak
Radiological Survey Project (ERSP) was to supply an adequate data base after the cleanup activities
to update the estimated radiological doses to a returning population. The dose assessments for
alternate living patterns at Enewetak Atoll served as the basis of the recommendations of the
Department of Energy (DOE) and the Department of Interior (DOI) for the resettlement of the atoll
In addition, the Enewetak people and their legal counsel may use the assessment as the basis for
their decisions on their preferences for the use of the atolL
The dose assessments, therefore, played a crucial role in the practical and political decisions for
resettlement of the atoll. These assessments are, however, only as good as the data upon which they
are based. The data base developed is as thorough as time and money would allow.
Previous assessments showed that the terrestrial food chain for locally grown food crops is the most
Significant potential exposure pathway. The second most significant pathway is external gamma
exposure. Estimation of the magnitude of the exposure through the terrestrial food chain required a
detailed knowledge of the concentration of the key radionuclides in the soil on the islands in the
northern half of the atoll A detailed survey of the soil concentrations would not have been required
if the common local foods such as coconut, breadfruit, Pandanus fruit, papaya, squash, etc., were
available for analysis.
A direct analysis of these foods would have provided the information needed
for the dose assessment. However, in absence of these edible foods, concentration ratios were used
{i.e., the radionuclide concentration in the edible food divided by the radionuclide concentration in
the soil, both in pCi/g) for each specific radionuclide, along with the average concentration in the
198