Radionuclides in Soil

The following is a listing of the USNRC’s “Interim Screening Values of Common Radionuclides for Soil Surface Contamination Levels”, as they appeared in the December 7, 1999 edition of the Federal Register (64 FR 68395).  The values shown below are in units of “picocuries per gram”.  (For radionuclides followed by a “+C”, the screening value assumes the progeny in that decay series are in equilibrium with the parent.)

Actinium

• Ac-227 – 0.5
• Ac-227+C – 0.5

Americium

• Am-241 – 2.1

Calcium

• Ca-45 – 57

Carbon

• C-14 – 12

Cesium

• Cs-134 – 5.7
• Cs-137 – 11

Chlorine

• Cl-36 – 0.36

Cobalt

• Co-57 – 150
• Co-60 – 3.8

Curium

• Cm-242 – 160
• Cm-243 – 3.2

Europium

• Eu-152 – 8.7
• Eu-154 – 8.0

Hydrogen

• H-3 – 110

Iodine

• I-129 – 0.5

Iridium

• Ir-192 – 41

Iron

• Fe-55 – 10,000

Lead

• Pb-210 – 0.9

Manganese

• Mn-54 – 15

Nickel

• Ni-59 – 5,500
• Ni-63 – 2,100

Niobium

• Nb-94 – 5.8

Plutonium

• Pu-238 – 2.5
• Pu-239 – 2.3
• Pu-241 – 72

Protactinium

• Pa-231 – 0.3
• Pa-231+C – 0.3

Radium

• Ra-226 – 0.7
• Ra-226+C – 0.6

Scandium

• Sc-46 – 15

Sodium

• Na-22 – 4.3

Strontium

• Sr-90 – 1.7

Sulfur

• S-35 – 270

Technetium

• Tc-99 – 19

Thorium

• Th-228 – 4.7
• Th-228+C – 4.7
• Th-230 – 1.8
• Th-230+C – 0.6
• Th-232 – 1.1
• Th-232+C – 1.1

Uranium

• U-234 – 13
• U-235 – 8.0
• U-235+C – 0.29
• U-238 – 14
• U-238+C – 0.5