Porous materials, such as wooden boats, canvas truck tarpaulins, rope, and rubber, were
simply stored until the radioactivity decayed to an acceptable level.
Maximum permissible contamination levels were stated as advisory limits for the control
of contamination under average conditions and listed 2 mr/hr as satisfactory for the interior
surfaces of aircraft, vehicles, and small boats. Seven milliroentgens per hour was considered
applicable for the exterior surfaces of the same transportation, and 20 mr/hr was considered
applicable for distant exterior surfaces such as tail surfaces, bumpers, and keels of the aforementioned craft.
All readings were made with side-window type Geiger counter instruments containing
counter tubes with walls not substantially in excess of 30 mg/cm? and with the beta shield open.
When possible, the surface of the probe was held from 1 to 6 in. from the surface that was
under observation.
A check point was established at the boat landing on Parry Island. When landing craft with
vehicular or other mobile equipment discharged their loads, check-point personnel monitored
the equipment. If the reading was below the permissible contamination limit, the equipmei:t
was moved on to its destination. If the reading was above the contamination limit, the equipment was moved to the decontamination area for storage or decontamination.
Other check points were established aboard the Bairoko and at the airstrip on Parry Island.
Aircraft departing on missions into highly contaminated areas had their interiors lined with
paper. When required, paper liners were removed andinteriors were cleaned by brushes and
industrial type vacuum cleaners.
6.3
RESULTS
The extent of contamination from Operation Castle detonations caused a quick revision of
maximum permissible contamination levels. From the outset, background levels aboard ship
and on the islands of Bikini exceeded the permissible contamination levels. Emergency personnel and equipment levels were established at 15 mr/hr.
Because the ships were so quickly contaminated, before washdown systems became opera-
tional, 4€AVV \created the largest mass decontamination practice in history. All major ships
and the small boats anchored in the lagoon required decontamination. Decontamination procedures were initiated aboard ship shortly after cessaticn of fall-out. These procedures were
generally water methods in which a vigorous washdown by meansof fire hose was used on the
top surfaces. In general, this action removed about 80 per cent of the contamination except in
the case of the wooden flight deck of the Bairoko.
57
eh
Small boats (LCM and LCT)that were left at the Enyu anchorage at the time of thet BkAvo
andthe revised|KoMépdetonations became heavily contaminated and were decontaminated by
strong hose washing of water and a mixture of boiler compound and lye. These caustics were
used to remove paint and iron rust and were an excellent supplement to strong hose washing.
Heavy water flushing and repainting were requirements following decontamination. In dry dock,
steam was utilized to remove grease and oil from bearing surfaces. As was to be expected, the
most difficult itemsto be decontaminated were canvas covers, tarpaulins, rope, and fabric
bumpers. In most cases these items were simply removed and allowed to decay. Versene
scrubbing was attempted on the large canvas “bathtub” on the flight deck of the Bairoko with
little success, This treatment tended to solubilize the radioactive particles, causing a spread
and increase of intensity.
Other than decontamination of marine equipment, i.e., ships, boats, buoys, anchors,etc.,
little decontamination was attempted at Bikini. Construction and technical equipment was
washed and isolated at the time of shipment to Eniwetok. The standard practice wasto isolate
items such astrailers, trucks, bulldozers, and cranes within a 10 mr/hr zone and then to clean
the transport vessel after the removal of the equipment at Eniwetok.
At Eniwetok the decontamination area soon becamefilled with an assortment of items that
varied from personal luggage to heavy cranes. At one time more than 1200 items were awaiting
decontamination. A standard practice of flushing, scrubbing, steaming, and storing was applied
to the majority of metal items. Wooden, plastic, rubber, and fabric materials were stored