RPR-22

Derived air concentration

DAC = ALI / 2400 m³, f = C/DAC. One DAC-year is one ALI.

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InternalICRP DAC

Governing equation

\mathrm{DAC}=\mathrm{ALI}/2400,\quad f=C/\mathrm{DAC}

$C \in \left[0.1, 1\times 10^{5}\right]$

where

C: Air concentration (Bq/m³)
ALI: Annual limit on intake (MBq)
DAC: Derived air concentration (Bq/m³)
f: DAC fraction (—)

The figure, part by part

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①

Governing law — red

\mathrm{DAC}=\mathrm{ALI}/2400,\quad f=C/\mathrm{DAC}

$C \in \left[0.1, 1\times 10^{5}\right]$

$C = 0.1$ $DAC = 2.4\times 10^{-4}$

Along the curve

②

Domain of the variable — blue

C_{\min} = 0.1,\quad C_{\max} = 1\times 10^{5}

$C \in \left[0.1, 1\times 10^{5}\right]$

$C = 0.1$ $C = 0.1$

Along the curve

③

Response curve — green

\mathrm{DAC}=\mathrm{ALI}/2400,\quad f=C/\mathrm{DAC}

$C \in \left[0.1, 1\times 10^{5}\right]$

$C = 0.1$ $DAC = 2.4\times 10^{-4}$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}DAC}{\mathrm{d}C}

$C \in \left[0.1, 1\times 10^{5}\right]$

$C = 629$ $DAC^{\prime} = 0.002$

Along the curve

Lecture brief

Historical brief

Inverse-square, half-value layer, ICRP weighting and ALARA are the protection craft since the 1920s commissions. The lab computes transmission, equivalent dose and a shielding snapshot. This sheet (RPR-22 — Derived air concentration) is the form associated with ICRP DAC. Working symbols: $C$ , $ALI$ $\rightarrow$ $DAC$ , $f$ . 2400 m³ = 1.2 m³/h × 2000 working hours. A DAC is an airborne concentration that would deliver the ALI if breathed for a working year.

Purpose

Purpose: compute

DAC

f

from

C

ALI

in Radiation protection via

\mathrm{DAC}=\mathrm{ALI}/2400,\quad f=C/\mathrm{DAC}

DAC = ALI / 2400 m³, f = C/DAC. One DAC-year is one ALI. Use it when a real radiation protection question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

C = 50.000\,\mathrm{Bq/m^{3}}

ALI = 1.000\,\mathrm{MBq}

, the governing relation

\mathrm{DAC}=\mathrm{ALI}/2400,\quad f=C/\mathrm{DAC}

yields

DAC = 416.7\,\mathrm{Bq/m^{3}}

f = 0.120\,\mathrm{—}

. A room air concentration next to a DAC line. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Air concentration C50 Bq/m³Annual limit on intake ALI1 MBq

Outputs

Derived air concentration DAC416.7 Bq/m³
DAC fraction f0.120 —

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Narration of this film

A room air concentration next to a DAC line.

2400 m³ = 1.2 m³/h × 2000 working hours. A DAC is an airborne concentration that would deliver the ALI if breathed for a working year.

Reading speed

Watch on YouTube