RPR-30

Stay time

t = H_lim / Ḣ. How long until a dose constraint is met.

Reading speed

ALARAStay time

Governing equation

t=H_{\lim}/\dot H

where

H_{lim}: Dose constraint (µSv)
\dot H: Dose rate (µSv/h)
t: Stay time (min)

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-30 — Stay time) is the form associated with Stay time. Working symbols: $H_{lim}$ , $\dot H$ $\rightarrow$ $t$ . A 20 µSv investigation level at 40 µSv/h is a 30 min stay. Always add a margin for dose-rate gradients and unexpected hold-ups.

Purpose

Purpose: compute

t

from

H_{lim}

\dot H

in Radiation protection via

t=H_{\lim}/\dot H

t = H_lim / Ḣ. How long until a dose constraint is met. 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

H_{lim} = 20.000\,\mathrm{\mu Sv}

\dot H = 40.000\,\mathrm{\mu Sv/h}

, the governing relation

t=H_{\lim}/\dot H

yields

t = 30.0\,\mathrm{min}

. A dose cup filling at rate Ḣ up to H_lim. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Dose constraint H_{lim}20 µSvDose rate \dot H40 µSv/h

Outputs

Stay time t30.0 min

Reading speed

Watch on YouTube

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Narration of this film

A dose cup filling at rate Ḣ up to H_lim.

A 20 µSv investigation level at 40 µSv/h is a 30 min stay. Always add a margin for dose-rate gradients and unexpected hold-ups.

Reading speed

Watch on YouTube