Table 6.6. Gamma Dose Rates Measured with an Arm Phantom Placed Inside Gloves Dusted

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

photons have been shielded out, and the spectrum is dominated by higher photon

energies. Note that plutonium metal buttons or cans of plutonium oxide prepared

for storage are self-shielded, and high-energy photons from decay progeny such as

237

U become increasingly important.

Table 6.6.

Gamma Dose Rates Measured with an Arm Phantom Placed Inside Gloves Dusted with

Plutonium Dioxide Powder

Gamma Dose Rates, mrad/h

Position

Neoprene Glove

Lead-Loaded Glove

Palm

10.0 0.4

9.5 16

Back of hand

21.8 1.3

5.4 0.3

Wrist

Inside

22.6 0.7

9.0 0.6

Outside

22.5 0.6

5.8 0.4

Forearm

Inside

34.5 0.2

6.7 0.4

Outside

16.7 0.2

3.6 0.6

Elbow

5.3 0.4

17.5 0.4

Inside

3.7 0.4

11.4 0.1

Outside

4.4 0.3

---

Front

Bottom of humerus

3.5 0.2

3.6 0.4

Lower mid-arm

6.7 0.5

3.4 0.2

Lower mid-humerus

2.1 0.2

2.9 0.3

Upper mid-arm

4.6 0.1

2.3 0.4

Upper mid-humerus

1.0 0.1

1.4 0.3

Top of arm

0.8 0.2

3.7 0.3

Top of humerus

---

1.1 0.3

6.2.2.2 Calculated Photon Dose Rates

It is very difficult to accurately calculate dose rates from plutonium because of the

wide range of photon energies and the relatively low abundance of photons. Most

of the photons are of relatively low energies, usually below 425 keV, which are

easily shielded. For heavily shielded spectra, the high-energy photons from decay

progeny become very important, as well as the high-energy photons from

plutonium, which have very low abundances.

For this reason, there are only a few computer codes that give accurate dose rates

for plutonium. Many computer codes do not calculate the photons from progeny

from radioactive decay. Others do not include the high-energy photons which have

very low abundances, but which become very important for massive shields. One

6-10