Table 6.4. Isotopic Composition of the Plutonium Used in the Extremity Dosimetry Measurements

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

with a 1-quart steel can (nominal wall thickness of 10 mil or 0.25 mm), containing

1 kg of plutonium dioxide with the isotopic composition shown in Table 6.4.

Measurements were made at the various locations with the arm phantom inside

20-mil Neoprene gloves (average thickness 0.021 in., 0.53 mm) and inside 37-mil

(0.94-mm) lead-loaded Neoprene gloves.

The data shown in Table 6.5 are the average dose rates measured by three

TLD-700s with the indicated one standard deviation in the measured values. As

one would expect, the palm and fingers had the highest dose rates, approximately

300 mrad/h; the lowest dose rates of 1 mrad/h were measured at the top of the arm.

Because the plutonium was "infinitely thick" and lower-energy photons were

removed by the shielding provided by the steel can, the dose rates in the lead-

loaded glove were only slightly lower than those in the Neoprene glove. The can

of plutonium was removed, and the gloves dusted with high-exposure plutonium

with an isotopic composition similar to that given in Table 6.4. The arm phantom

was inserted into 20-mil Neoprene and 37-mil lead-loaded Neoprene gloves; the

dose rates measured with TLDs are shown in Table 6.6.

Table 6.4.

Isotopic Composition of the Plutonium Used in the Extremity Dosimetry

Measurements

Isotope

Weight Percent

236

0.000003

238

0.58

239

72.1

240

19.15

241

6.29

242

1.88

241

0.02

As expected, the highest does rates were recorded on the hand, wrist and forearm,

where the most PUO2 dust had accumulated, and the lowest dose rates were on the

upper arm and humerus. For thin dust layers, the dose rates inside the lead-loaded

glove were generally much lower, typically a factor of 4 to 5 times less than the

dose rates inside the Neoprene glove. The lead-loaded glove provided significantly

better shielding for the 60-KeV photons from 241Am and the L x-rays from

plutonium, which were responsible for much of the dose. In these examples, the

dose rates from the contaminated glove were about 10% of those from the 1 kg of

plutonium dioxide inside the steel can. Additional experiments with 25% PuO2-

6-8