The three controls you already know, written so a barrier calculation has a place to start.
For RSO · vault designers · staff·7 min
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You will be able to
01Cut dose with time, inverse square, and transmission B.
02Count TVLs rather than millimetres of lead.
03Build a weekly workload from W, U and T.
Chapter 01
Three knobs
Dose rate times time, times the square of reference over actual distance, times transmission. Stand twice as far, take a quarter. Halve the time, take a half. Add a tenth-value layer, take a tenth. You will use all three in a hot lab before you ever pour a wall.
Distance is the cheapest shielding.
Simulation
Time, distance, and shielding — Change the numbers; the scene follows.
A tenth-value layer is the thickness that leaves ten percent. Two leave one percent. Primary barriers see the useful beam; secondary walls see scatter and leakage. Never borrow a TVL from a different energy or a different material.
Simulation
Thickness from HVL / TVL — Change the numbers; the scene follows.
Workload W, use factor U, occupancy T. The product sizes the weekly dose at a point, before transmission. A maze buys TVLs with extra scatters instead of extra lead. The door is where the last gap is closed with lead and borated polyethylene.
Simulation
Workload, use and occupancy WUT — Change the numbers; the scene follows.
Variables
W = 48 Gy/week
Keep thisOccupancy of a stair is not occupancy of a desk.