Residual radionuclides in soil

DOE-STD-1128-98

DOE Order 5400.5, Ch. 2 (DOE, 1993c) also provides the following guidelines for

(1) residual concentrations of radionuclides in soil, (2) concentrations of airborne

radon decay products, (3) external gamma radiation, (4) surface contamination, and

(5) radionuclide concentrations in air or water:

-- Residual radionuclides in soil - Generic guidelines for thorium and radium

(226Ra, 228Ra, 230Th, and 232Th) are 5 pCi/g averaged over the first 15 cm of soil

below the surface and 15 pCi/g averaged over 15-cm-thick layers of soil more

than 15 cm below the surface. For other radionuclides in soil (e.g., plutonium),

specific guidelines should be derived from the basic dose limit by means of an

environmental pathway analysis using specific property data where available.

Residual concentrations of radioactive material in soil are defined as those in

excess of background concentrations averaged over an area of 100 m2.

-- Airborne radon decay products - Applicable generic guidelines are found in

40 CFR 192 (EPA, 1992b). In any occupied or habitable building, the objective

of remedial action should be, and a reasonable effort should be made to

achieve, an annual average (or equivalent) radon decay product concentration

(including background) not to exceed 0.02 WL. Remedial actions by DOE are

not required to comply with this guideline when there is reasonable assurance

that residual radioactive material is not the source of the radon concentration.

-- External gamma radiation - The average level of gamma radiation inside a

building or habitable structure on a site to be released without restrictions

should not exceed the background level by more than 20 R/h.

-- Surface contamination - The DOE guidelines on transuranic surface

contamination levels are given in a DOE memorandum dated November 17,

1995, "Application of DOE 5400.5 requirements for release and control of

property containing residual radioactive materials," the guideline values are as

follows:

Guidelines

Removable Contamination

20 dpm/100 cm2

Total (Fixed plus Removable Contamination)

500 dpm/100 cm2

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