Beta Dose Calculations • External beta dose rate not in ...

Beta Dose Calculations

? External beta dose rate not in contact with skin

? Point Source, 10 mCi, distance of 0.1 m

D

=

27

rad Ci

- m2 - hr

A d2

D

=

27

rad - m2 Ci - hr

10 mCi

(0.1 m)2

Ci

1000

mCi

=

27

rad hr

1

Beta Dose Calculations

? External dose rate in contact with skin

? 50 cm2 area, 10 mCi Source, Emax = 1 MeV ? What is the skin dose rate with no glove?

? With one glove?

? With two gloves?

D

=

Cf

A a

D

=

Cf

10 50

mCi cm2

=

0.2

mCi cm2

Cf

2

CF (rad-cm2/(hr-mCi))

Healy Curves

10

S = 9

70 m 8

200 m 6

1G = 5

4 30 m

2

2G = 3.5

0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Maximum Beta Energy (MeV)

3

Beta Dose

Calculations

? Skin dose rate with no glove?

D

=

0.2

mCi cm2

9

rad - cm2 hr - mCi

= 1.8

rad / hr

? Skin dose rate with one glove?

D

=

0.2

mCi cm2

5

rad - cm2 hr - mCi

= 1.0

rad / hr

? Skin dose rate with two gloves?

D

=

0.2

mCi cm2

3.5

rad - cm2 hr - mCi

= 0.7

rad / hr

4

Gamma Dose

Calculations

? External gamma dose rate

? Cs-137, A = 10 mCi, d = 0.1 m

? What are the deep, eye, and shallow dose equivalent rates?

? First calculate exposure rate

X

=

A d2

X

=

10 mCi

(0.1 m)2

Ci 1000 mCi

=

1 Ci m2

5

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