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Index/Radiation protection/RPR-17

RPR-17

Number of tenth-value layers

n = log10(1/B). How many TVLs a barrier must provide.

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ShieldingTenth-value count

Governing equation

n=log⁡10(1/B)n=\log_{10}(1/B)

B∈[1×10−7,1]B \in \left[1\times 10^{-7}, 1\right]

where

B
Transmission B (—)
n
Tenth-value layers (—)

The figure, part by part

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RPR-17 · gauge
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①

Governing law — red

n=log⁡10(1/B)n=\log_{10}(1/B)

B∈[1×10−7,1]B \in \left[1\times 10^{-7}, 1\right]

B=1×10−7B = 1\times 10^{-7}n=7n = 7

②

Domain of the variable — blue

Bmin⁡=1×10−7,Bmax⁡=1B_{\min} = 1\times 10^{-7},\quad B_{\max} = 1

B∈[1×10−7,1]B \in \left[1\times 10^{-7}, 1\right]

B=1×10−7B = 1\times 10^{-7}B=1×10−7B = 1\times 10^{-7}

③

Response curve — green

n=log⁡10(1/B)n=\log_{10}(1/B)

B∈[1×10−7,1]B \in \left[1\times 10^{-7}, 1\right]

B=1×10−7B = 1\times 10^{-7}n=7n = 7

④

Rate of change — amber

dndB\frac{\mathrm{d}n}{\mathrm{d}B}

B∈[1×10−7,1]B \in \left[1\times 10^{-7}, 1\right]

B=0.006B = 0.006n′=−405.4n^{\prime} = -405.4

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-17 — Number of tenth-value layers) is the form associated with Tenth-value count. Working symbols: BB →\rightarrow nn. A transmission of 10^{−3} is three TVLs. Designers often add a first TVL plus (n−1) equilibrium TVLs.

Purpose

Purpose: compute nn from BB in Radiation protection via n=log⁡10(1/B)n=\log_{10}(1/B) n = log10(1/B). How many TVLs a barrier must provide. 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 B=0.001 —B = 0.001\,\mathrm{—}, the governing relation n=log⁡10(1/B)n=\log_{10}(1/B) yields n=3.000 —n = 3.000\,\mathrm{—}. A tiny B and a count of decades of attenuation. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Outputs

  • Tenth-value layers n3.000 —
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RPR-17 · gauge
00:0 / 00:08

Narration of this film

A tiny B and a count of decades of attenuation.

A transmission of 10^{−3} is three TVLs. Designers often add a first TVL plus (n−1) equilibrium TVLs.

Reading speed

Watch on YouTube