RPR-10

Use factor U

W_U = W U. Workload aimed at one barrier.

Reading speed

Barrier designNCRP 151 U

Governing equation

W_U=WU

$U \in \left[0.05, 1\right]$

where

W: Isocentre workload (Gy/wk)
U: Use factor U (—)
W_U: Directed workload (Gy/wk)

The figure, part by part

Each numbered marker wears the color of its card. Hover a card to light the marker. Tap a marker to jump to that card. The slider walks a red point along the curve; Animate drawing traces it like a pen.

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①

Governing law — red

W_U=WU

$U \in \left[0.05, 1\right]$

$U = 0.05$ $W_U = 25$

Along the curve

②

Domain of the variable — blue

U_{\min} = 0.05,\quad U_{\max} = 1

$U \in \left[0.05, 1\right]$

$U = 0.05$ $U = 0.05$

Along the curve

③

Response curve — green

W_U=WU

$U \in \left[0.05, 1\right]$

$U = 0.05$ $W_U = 25$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}W_U}{\mathrm{d}U}

$U \in \left[0.05, 1\right]$

$U = 0.056$ $W_U^{\prime} = 500$

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-10 — Use factor U) is the form associated with NCRP 151 U. Working symbols: $W$ , $U$ $\rightarrow$ $W_U$ . NCRP primary: U = 1 floor, 1/4 walls, 1/16 ceiling. Secondary barriers take U = 1 because leakage and scatter are isotropic.

Purpose

Purpose: compute

W_U

from

W

U

in Radiation protection via

W_U=WU

W_U = W U. Workload aimed at one barrier. 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

W = 500.000\,\mathrm{Gy/wk}

U = 0.250\,\mathrm{—}

, the governing relation

W_U=WU

yields

W_U = 125.0\,\mathrm{Gy/wk}

. A linac gantry and a pie-slice of beam-on toward a wall. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Isocentre workload W500 Gy/wkUse factor U U0.25 —

Outputs

Directed workload W_U125.0 Gy/wk

Reading speed

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Narration of this film

A linac gantry and a pie-slice of beam-on toward a wall.

NCRP primary: U = 1 floor, 1/4 walls, 1/16 ceiling. Secondary barriers take U = 1 because leakage and scatter are isotropic.

Reading speed

Watch on YouTube