U.S. Nuclear Regulatory Commission

Decontamination Limits for Americium-241

HPPOS-183 PDR-9111210288

Title: Decontamination Limits for Americium-241

See the memorandum from R. E. Cunningham to H. D. Thornburg

dated September 15, 1981. This memo provides appropriate

surface and soil decontamination limits for Am-241. Based

on the total dose from inhalation and ingestion, the soil

concentration limit for Am-241 is calculated to be 30

picocuries per gram (pCi/g) in order not to exceed the 3

millirad per year recommended by the EPA.

Acceptable surface contamination levels for Am-241 are

specified in "Guidelines for Decontamination of Facilities

and Equipment Prior to Release for Unrestricted Use or

Termination of Licenses for Byproduct, Source, or Special

Nuclear Material." The maximum and average levels of fixed

Am-241 contamination permitted on surfaces released for

unrestricted use is 300 and 100 disintegration per minute

per 100 square centimeters (dpm/100 cm2), respectively.

Removable contamination should not exceed 20 dpm/100 cm2.

With respect to soil decontamination limits, the EPA

recommended on November 30, 1977, radiation dose guidelines

for transuranium elements such that no individual will

receive a radiation dose in excess of 1 millirad per year

to the lung and 3 millirad per year to the bone from

exposure to the contaminated soil (42 FR 60956-60959). In

this case, the solubility classification of Am-241 is a W

compound (see ICRP Publication 30) and its existence in

soil will contribute to the inhalation and ingestion

pathways through resuspension of soil in air and uptake

from plants. The critical organ is the bone. Based on the

total dose from inhalation and ingestion, the soil

concentration limit for Am-241 is calculated to be 30 pCi/g

in order not to exceed the 3 millirad per year limit.

Regulatory references: None

Subject codes: 3.6, 7.6, 8.4, 12.4

Applicability: All