equipment itself, control gas samples were taken before and after decontamination of the sampling equipment. Equipment was deconteminated
after each shot. Spot checks during Upshot - Knothole indicated decontamination factors exceeding 1,000 which were deemed satisfactory for
close~in samples.
Gas samples were also collected at long-range in the vicinity of
Hawaii using B-3l equipment. Variability, fractionation of gas isotopes
with respect to each other and with respect to particulate debris, and
rainout of tritium were to be studied.
Unfortunately~--as experienced during Ivy and Upshot - Knothole---
many samples, particularly the LRD samples, were compromised because of
cross~contamination in the laboratory, particularly with respect to
tritium. Due to the variation in size of the gas samples to be separated and assayed, two sets of separation equipment were used. Experiments
conducted to determine the amount of holdover contamination in this
equipment revealed that the large gas separation equipment used to assay
the B-31 LRD gas samples and the B-36 Squeegees was not always effectively flushed after one separation.
Redesign of traps and improved methods
of steam flushing, followed by lengthy drying periods, removed the possibility of cross contamination of samples, but only after certain
samples were lost or results were determined as invalid.
In the separation process it was also discovered by the University
of California Radiation Laboratory (UCRL) personnel that tritium activity was being lost through an exchange of tritium in the sample with the
plastic liner (heresite) of the Squeegee sample sphere. The tritium
lost by this mechanism was recovered by treating the inside of the
spheres with three separate rinses of hot, alkaline, potassium permanganate solution. The resultant mixture from each rinse was then processed
and assayed. This result was added to the result obtained by assaying
the water and water vapor in the sphere. Certain B-36 Squeegee samples
in which assay of liner activities was not made are noted in Tables 3.10
through 3.15, and therefore do not represent the total tritium activity
present in the sample.
Most of the values reported in the tables are believed to be rea~
sonably valid. Those values wherein known cross contamination occurred
have been deleted from the presented data.
Couriering of samples from the test site, separation, processing,
and assay of all gas collected washandled by Headquarters, United States
AirForce, Washington 25, D. c.{
Under military contract.
or by agencies responsible
Procedures, instrumentation, and the
processes of gas analysis are described in References 3, 4, and 5, and
no attempt will be made to describe these methods here.
3.2.2
Definition of Units Expressing Results.
In accordance with
past procedures, and in order to standardize results, all activity results are expressed as atoms of a given isotope per unit volume of a
given air sample at a specified temperature and pressure.
ume was defined in terms of moles;
The unit vol-
i.e., 1 equivalent mole air (EMA)
is that volume occupied by 1 mole of air at 70°F and 760~mm pressure.
The approximate volume of 1 mole equivalent air is 0.85 ft.
25