Quality Factor (Neutron) / (Neutron Quality Factor)

Text Box: Quality Factor (Neutron) (Neutron Quality Factor)  If it is more convenient to measure the neutron flux rate than to determine the neutron dose equivalent rate in rems per hour or sieverts per hour, as provided in 10 CFR 20, 1 rem (0.01 Sv) of neutron radiation of unknown energies may, for purposes of the regulations in 10 CFR 20, be assumed to result from a total flux of 25 million neutrons per square centimeter incident upon the body.  If sufficient information exists to estimate the approximate energy distribution of the neutrons, the licensee may use the flux rate per unit dose equivalent or the appropriate Q value from the following table to convert a measured tissue dose in rads to dose equivalent in rems.

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Neutron Energy (MeV)

Quality Factor (Q)a

Flux per unit

Dose equivalent b (neutrons cm-2 rem 1)

Neutron Energy (MeV)

Quality Factor (Q)a

Flux per unit

Dose equivalent b (neutrons cm-2 rem 1)

(Thermal)

2.5 X 10-8

2

980 X 106

5

8

23 X 106

1 X 10-7

2

980 X 106

7

7

24 X 106

1 X 10-6

2

810 X 106

10

6.5

24 X 106

1 X 10-5

2

810 X 106

14

7.5

17 X 106

1 X 10-4

2

840 X 106

20

8

16 X 106

1 X 10-3

2

980 X 106

40

7

14 X 106

1 X 10-2

2.5

1010 X 106

60

5.5

16 X 106

1 X 10-1

7.5

170 X 106

1 X 102

4

20 X 106

5 X 10-1

11

39 X&106

2 X 102

3.5

19 X 106

1

11

27 X 106

3 X 102

3.5

16 X 106

2.5

9

29 X 106

4 X 102

3.5

14 X 106

a Value of quality factor (Q). at the point where the dose equivalent is maximum in a 30-cm diameter cylinder tissue-equivalent phantom.

b Monoenergetic neutrons incident normally on a 30-cm diameter cylinder tissue- equivalent phantom.