Table 5 -6. Categories and Performance Criteria for Uranium Bioassay

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

magnitude would not be detected if it occurred immediately after a bioassay measurement and if it were

eliminated from the body at such a rate that nothing was detected during the next scheduled

measurement. The dose resulting from such an intake would be the MDD for that particular measurement

technique and frequency.

Estimates of MDD in terms of CEDE should be documented for each measurement technique,

Minimum Detectable Activity (MDA), and frequency. The MDA is defined in ANSI/HPS N13.30 (ICRP

Publication 1996) as a measure of the detection limit. Analytical radiobioassay laboratories should meet the

Acceptable MDAs (AMDAs) recommended in ANSI N13.30 as a minimum. The AMDAs for U bioassay

are shown in Table 5-6.

Table 5 -6. Categories and Performance Criteria for Uranium Bioassay

Direct Bioassay

AMDA(a)

CATEGORY

NUCLIDE

234

U, 235U,

238

Alpha (Urine)

0.1 pCi/L

Isotope specific measurements

Mass determination

Uranium (natural)

5 g/L

(a)

Note: The "Acceptable MDAs (AMDAs)" were removed from later drafts of the ANSI standard due to possible

misinterpretation of the word "acceptable". The AMDAs have been replaced with test ranges for externally

conducted quality control tests that take into consideration the need to be several times MDA or more before

reasonably low coefficients of variation can be obtained for individual sample measurements. In this way, bias as

well as precision can be estimated from reasonably small samples within each test category.

Retention functions specific to the various chemical forms and particle size distributions found in the

facility should be used. Examples of MDD tabulations can be found in La Bone et al. (1993) and

Carbaugh et al. (1994). In establishing MDD tables, it is important to consider dose contributions from all

appropriate radionuclides in any mixture, rather than just the dose contribution from the bioassay

indicator nuclide.

The minimum frequency for routine bioassay programs is interrelated to action levels, as specified in

Table 5-7 (ANSI/HPS 1995). Special bioassays are taken as needed.

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