Utah Administrative Code
Topic - Environmental Quality
Title R313 - Waste Management and Radiation Control, Radiation
Rule R313-12 - General Provisions
Section R313-12-20 - Units of Exposure and Dose
Current through Bulletin 2024-06, March 15, 2024
(1) As used in these rules, the unit of EXPOSURE is the coulomb per kilogram (C per kg). One roentgen is equal to 2.58 x 10-4 coulomb per kilogram of air.
(2) As used in these rules, the units of dose are:
(3) As used in these rules, the quality factors for converting absorbed dose to dose equivalent are shown in Table 1.
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TABLE 1 Quality Factors and Absorbed Dose Equivalencies |
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Type of Radiation |
Quality Factor (Q) |
Absorbed Dose Equal to a Unit Dose Equivalent |
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X, gamma, or beta radiation and high-speed electrons |
1 |
1 |
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Alpha particles, multiple-charged particles, fission fragments and heavy particles of unknown charge |
20 |
0.05 |
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Neutrons of unknown energy |
10 |
0.1 |
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High energy protons |
10 |
0.1 |
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For the column in Table 1 labeled "Absorbed Dose Equal to a Unit Dose Equivalent", the absorbed dose in rad is equal to one rem or the absorbed dose in gray is equal to one Sv. |
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(4) If it is more convenient to measure the neutron fluence rate than to determine the neutron dose equivalent rate in sievert per hour or rem per hour, as provided in Subsection R313-12-20(3), 0.01 Sv of neutron radiation of unknown energies may, for purposes of these rules, be assumed to result from a total fluence 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 or registrant may use the fluence rate per unit dose equivalent or the appropriate Q value from Table 2 to convert a measured tissue dose in gray or rad to dose equivalent in sievert or rem.
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TABLE 2 Mean Quality Factors, Q, and Fluence Per Unit Dose Equivalent for Monoenergetic Neutrons |
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Neutron Energy Mev |
Quality Factor Q |
Fluence per Unit Dose Equivalent neutrons cm-2 rem-1 |
Fluence per Unit Dose Equivalent neutrons cm-2 Sv-1 |
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thermal 2.5 x 10-8 |
2 |
980 x 106 |
980 x 108 |
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1 x 10-7 |
2 |
980 x 106 |
980 x 108 |
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1 x 10-6 |
2 |
810 x 106 |
810 x 108 |
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1 x 10-5 |
2 |
810 x 106 |
810 x 108 |
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1 x 10-4 |
2 |
840 x 106 |
840 x 108 |
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1 x 10-3 |
2 |
980 x 106 |
980 x 108 |
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1 x 10-2 |
2.5 |
1010 x 106 |
1010 x 108 |
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1 x 10-1 |
7.5 |
170 x 106 |
170 x 108 |
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5 x 10-1 |
11 |
39 x 106 |
39 x 108 |
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1 |
11 |
27 x 106 |
27 x 108 |
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2.5 |
9 |
29 x 106 |
29 x 108 |
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5 |
8 |
23 x 106 |
23 x 108 |
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7 |
7 |
24 x 106 |
24 x 108 |
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10 |
6.5 |
24 x 106 |
24 x 108 |
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14 |
7.5 |
17 x 106 |
17 x 108 |
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20 |
8 |
16 x 106 |
16 x 108 |
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40 |
7 |
14 x 106 |
14 x 108 |
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60 |
5.5 |
16 x 106 |
16 x 108 |
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1 x 102 |
4 |
20 x 106 |
20 x 108 |
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2 x 102 |
3.5 |
19 x 106 |
19 x 108 |
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3 x 102 |
3.5 |
16 x 106 |
16 x 108 |
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4 x 102 |
3.5 |
14 x 106 |
14 x 108 |
| For the column in Table 2 labeled "Quality Factor", the values of Q are at the point where the dose equivalent is maximum in a 30 cm diameter cylinder tissue-equivalent phantom. | |||
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For the columns in Table 2 labeled "Fluence per Unit Dose Equivalent", the values are for monoenergetic neutrons incident normally on a 30 cm diameter cylinder tissue equivalent phantom. |
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