Reference Levels and Derived Reference Levels

DOE-STD-1121-98

equivalent in a year, or 50 rems committed dose equivalent to an organ or tissue other than the eye). In

light of this requirement, there are three distinct situations for internal dosimetry programs:

Adequate technology. In this situation, routine bioassay measurements can show not only

compliance with 10 CFR 835.202, but can be used to assess doses when HE,50 # 100 mrem (the

investigation level). An example of an "adequate technology" situation, that is, where there is

no technology shortfall, is a routine urinalysis program for 3H or a routine in vivo counting

program for 137Cs: in each case, the MDA is less than the DIL.

Technology shortfall for routine bioassay. In this situation, the DIL is less than the MDA for

practical routine bioassay, but special bioassay, triggered by workplace indicators, is available

on short notice that can be used to show compliance with 10 CFR 835.402(d). An example of a

"technology shortfall for routine bioassay" situation is a state-of-the-art internal dosimetry

program for plutonium supplemented by vigorous workplace monitoring and controls.

No practical bioassay. In this situation, no bioassay method is available for the radionuclides

in question, and no bioassay program, either routine or special, can show compliance with 10

CFR 835.202. An example of a "no practical bioassay" situation is routine worker exposure to

the short-lived decay products of radon and thoron, in which no bioassay program can

demonstrate compliance with the limits. In the "no practical bioassay" case, the only recourse

in showing compliance with 10 CFR 835.202 is using representative air monitoring, tracking

worker exposure in DAC-h or working level months (WLM), and performing dose assessments

on the basis of the air monitoring results.

For the short-lived progeny of radon and thoron, worker stay times and measurements of potential

alpha energy concentration (PAEC) can be converted to potential alpha energy exposure (PAEE) in

WLM. Alternatively, worker stay times and radon concentration measurements, with knowledge or

assumption of the equilibrium factor, can be converted to equilibrium equivalent DAC-h or to PAEE in

WLM.

4.2 REFERENCE LEVELS AND DERIVED REFERENCE LEVELS

A reference level is a predetermined value of a quantity that triggers a specified course of action

when exceeded or expected to be exceeded. Reference levels may be dose-based or intake-based.

Derived reference levels are the measurement values for particular bioassay or air sampling results that

correspond to a more general reference level under specifically defined circumstances. Some suggested

reference levels are described below:

Verification Level, LV - The level of unexpected intake or dose at or above which an attempt

should be made to determine if the intake is real. For example, this is the level at which special

follow-up measurements should be obtained to confirm a high routine result. Below this level,

it may be assumed, routine results are valid and default assumptions can be used to calculate

and assign intake and dose.

Investigation Level, IL - The level of intake or dose (specified in the IDG as 100 mrem) at or

above which a bioassay or air monitoring result should be investigated. The intent of this level

is to investigate the circumstances and, to the extent reasonable, to determine actual conditions

and parameters for dose evaluation, rather than use default assumptions. An investigation may