Table 6-4. Isotopic Composition of the Plutonium Used in the Extremity Dosimetry Measurments

DOE-STD-1128-98

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

0.000003

236

238Pu

0.58

239Pu

72.1

240Pu

19.15

241Pu

6.29

242Pu

1.88

241Am

0.02

As expected, the highest dose 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- 75% normal UO2 showed that dose rates

increased as dust loadings increased with use; the dose rates on the hand

and forearm increased to levels of about 30 mrem/h to 20 mrem/h,

respectively.

6-8