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Radiation Safety and Cleanup Preparations
197
readable. To alleviate this problem, an assistance visit to Enewetak by
LBDA representatives led to the suggestion of sealing the film badges
inside two plastic bags, with a small packet of desiccant in the inner bag.
This method reduced, but did not eliminate, the film damage problem.
Another solution was the addition of U.S. Navy TLDs as supplemental
dosimeters. Since these were hermetically sealed devices, intended for use
underwater by Navy divers, the TLDs were unaffected by the Enewetak
heat and humidity. In addition, they could be read on atoll. Beginning in
May 1978, they were issued to and wornin parallel with film badgesbyall
workers on radiologically controlled islands. TLDs also replaced selfreading pocket dosimeters as the dosimetric device for visitors.
Where film badges were damaged or lost, and in those cases in which
supplemental dosimetry was not used, administrative doses were
computed based on actual occupancy data and island background dose
rates. This method was approved by the Army Surgeon General in
accordance with AR 40-14.38
One of the most important aspects of the Enewetak radsafe precautions
was the air sampling program. Two ofthe principal functions of the air
sampling program were to provide a basis for the FRST to establish
respiratory protection levels and to provide documentation of airborne
radionuclide levels in work environments. NBS Handbook 69 and
\OCFR20 establish a maximum permissible concentration (MPC) in air for
insoluble plutonium of 40 pCi per cubic meter (pCi/m3)of air in restricted
radiation areas based on an occupancy of 40 hours per week. Since
‘‘occupancy’’ on Enewetak’s controlled islands theoretically could be as
high as 60 hours per week, this MPC was adjusted downward
proportionately to 27 pCi/m3. On Lojwa, the forward base camp, the MPC
was adjusted for a 168-hour week (24 hours a day for 7 days a week). At
Enewetak Atoll, action levels were established at 10 percent and 50 percent
of the adjusted limits, or 2.7 pCi/m3 and 13.5 pCi/m3 for controlled
islands. Whenthefirst action level was reached (based on air samplerfilter
readings), nasal swipes were taken from all personnel in the area who were
not wearing respiratory protection, and the RPO was informed. If the 0.5
MPC action level was reached, nasal swipes were taken, respiratory
protection was required if work was to continue, and the air sampler filter
was expeditiously transferred to the Rad Lab for analysis.39
The workhorse for air sampling throughoutthe project were the Roots-
Tecumseh MI02 gasoline-engine-driven air samplers (Figure 4-9). These
were procured as surplus and salvage items from the DOE Nevada Test
Site and shipped to the atoll. Keeping sufficient numbers of these air
samplers functional to support operations proved to be such a problem,
due to their age, the salt-spray environment, andthedifficulty in obtaining