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Safe Management of Wastes from Health Care Activities, 1999, WHO

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ANNEX 3 - Clearance levels for radioactive waste

The material in this annex has been produced by the International Atomic Energy Agency and is based on extracts from the following two publications, used with permission:

IAEA (1996). Clearance levels for radionuclides in solid materials. Vienna, International Atomic Energy Agency (TECDOC 855).

IAEA (1998). Clearance of materials resulting from the use of radio-nuclides in medicine, industry and research. Vienna, International Atomic Energy Agency (in press).

Table A3.1 Generic clearance levels for solid waste

Radionuclide

Clearance level (Bq/g) for moderate quantities

H-3

1 × 106

C-14

1 × 104

Na-22

1 × 101

Na-24

1 × 101

P-32

1 × 103

S-35

1 × 105

Cl-36

1 × 104

K-42

1 × 102

Ca-45

1 × 104

Ca-47

1 × 101

Cr-51

1 × 103

Fe-59

1 × 101

Co-57

1 × 102

Co-58

1 × 101

Ga-67

1 × 102

Se-75

1 × 102

Sr-85

1 × 102

Sr-89

1 × 103

Y-90

1 × 103

Mo-99

1 × 102

Tc-99

1 × 104

Tc-99m

1 × 102

In-111

1 × 102

I-123

1 × 102

I-125

1 × 103

I-131

1 × 102

Pm-147

1 × 104

Er-169

1 × 104

Au-198

1 × 102

Hg-197

1 × 102

Hg-203

1 × 102

Tl-201

1 × 102

Ra-226

1 × 101

Th-232

1 × 100

Note: The generic clearance levels in Table A3.1 are given for moderate quantities of waste (i.e. less than 3 tonnes of cleared waste per year and per facility). They are identical to the exemption levels of the international basic safety standards for protection against ionizing radiation and for the safety of radiation sources (IAEA, 1996). Clearance levels for large quantities are one-tenth of the levels in Table A3.1.

Table A3.2 Liquid discharge rates to sewers, rivers, or other large water bodies

Radionuclide

Annual release rate
(Bq/year)

Monthly release rate
(Bq/month)

Daily release rate
(Bq/day)

H-3

109

108

107

C-14

107

106

105

Na-22

102

10

1

Na-24

105

104

103

P-32

103

102

10

S-35

106

105

104

Cl-36

107

106

105

Ca-45

107

106

105

Ca-47

105

104

103

Fe-59

103

102

10

Co-57

106

105

104

Co-58

105

104

103

Ga-67

105

104

103

Sr-85

103

102

103

Sr-89

106

105

104

Y-90

107

106

105

Mo-99

105

104

103

Tc-99

107

106

105

Tc-99m

106

105

104

In-111

105

104

103

I-123

106

105

104

I-125

105

104

103

I-131

105

104

103

Pm-146

107

106

105

Er-169

107

106

105

Au-198

105

104

103

Hg-197

106

105

104

Hg-203

104

103

102

Tl-201

105

104

103

Ra-226

103

102

10

Th-232

103

102

10

Note 1: Table A3.2 provides annual release rates below which water-miscible liquid waste may be unconditionally discharged with normal wastewater by a pipe to a sewer, river, or other large water body. Since it would not necessarily be appropriate for the whole discharge to be made over a very short time, both monthly and daily limits have also been included. These are based on 1/10 and 1/100 of the annual limits respectively.

Note 2: The derivation of clearance levels for liquid releases is described elsewhere (IAEA, 1998). For discharge to sewers, two extreme possible scenarios were considered:

- no radioactive material is retained in sewage sludge but all is discharged to the water body in liquid form;

- all radioactive material discharged is retained in the sewage sludge at the sewage treatment works.

Radiation doses were calculated for both cases, and the more restrictive levels were used to derive the values in Table A3.2, after being divided by a conservative factor of 1000. This factor is intended to reflect the fact that:

- the models in the reference document (IAEA, 1998) were developed for application in temperate European and North American conditions, and the assumptions of diet, agriculture, and lifestyle may not be universally valid; and

- these models did not consider the transfer of radionuclides to terrestrial foodchains as a result of irrigation or use of sewage sludge in agriculture.

Note 3: Activity from patients' discharges, after diagnostic or therapeutic use of radionuclides, should also be considered. This may be achieved by comparing discharges with the clearance levels.

Note 4: For other radionuclides and higher levels of activity, any discharge made should be specifically authorized by the regulatory authority after assessment of all the relevant conditions.

Note 5: In reality, more than one radionuclide will often be involved. To determine whether a mixture of radionuclides is at or below the clearance level, a simple ratio expression can be used:

where

Ci is the concentration of radionuclide i in the material being considered (Bq/g)
CLi is the clearance level of radionuclide i in the material (Bq/g)
n is the number of radionuclides in the mixture.

Table A3.3 Gaseous releases into the open air

Radionuclide

Annual release rate
(Bq/year)

Monthly release rate
(Bq/month)

Daily release rate
(Bq/day)

H-3

108

107

106

C-14

107

106

105

Na-22

103

102

10

Na-24

106

105

104

P-32

105

104

103

S-35

105

104

103

Cl-36

104

103

102

K-42

107

106

105

Ca-45

105

104

103

Ca-47

106

105

104

Cr-51

106

104

103

Fe-59

105

104

103

Co-57

106

105

104

Co-58

106

105

104

Ga-67

107

106

105

Se-75

105

104

103

Sr-85

105

104

103

Sr-89

105

104

103

Y-90

107

106

105

Mo-99

106

105

104

Tc-99

104

103

102

Tc-99m

108

107

106

In-111

106

105

104

I-123

107

106

105

I-125

105

104

103

I-131

105

104

103

Xe-127

108

107

106

Xe-133

109

108

107

Pm-147

107

106

105

Er-169

107

106

105

Au-198

106

105

104

Hg-197

107

106

105

Hg-203

105

104

103

Tl-201

107

106

105

Ra-226

103

102

10

Th-232

102

10

1

Note 1: Table A3.3 provides annual release rates below which gaseous waste may be unconditionally discharged via ventilation systems (e.g. from laboratory fume cupboards) or other means to the open air. This may be done only in such a way and and in such a position as to prevent the gas from re-entering any building. Since it would not necessarily be appropriate for the entire discharge to be made over a very short time, monthly and daily limits have also been included; these are based on 1/10 and 1/100 of the annual limits respectively.

Note 2: The derivation of clearance levels for gaseous releases is described elsewhere (IAEA, 1998). It assumes that a person lives 20m from the release point and obtains all crop-based foods from an area at least 100m from the release point and all animal products from an area at least 800m from the release point. Values in Table A3.3 were then based on radiation doses calculated from the summation of inhalation, injection, and external exposure pathways. The values in the table include a conservative factor of 1000 to reflect the fact that the models in the reference document (IAEA, 1998) were developed for temperate European and North American conditions and may differ for countries with significantly different diets, agriculture, and lifestyles.

Note 3: For other radionuclides and higher levels of activity, any discharge should be specifically authorized by the regulatory authority after assessment of all the relevant conditions.

Reference

IAEA (1996). International basic safety standards for protection against ionizing radiation and for the safety of radiation sources. Vienna, International Atomic Energy Agency (Safety Series, No. 115).


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