Table 1.

Design summary for the radiation barriers, assuming full use at 18 MV and with the workloads described in the text. The “use factor” refers to the fraction of the time the beam is directed at the barrier. For the calculation based on limits per hour, the use factor is taken to be one, and the “duty factor” refers to the fraction of one hour that the beam may be on. The required meters of concrete (or equivalent) is given for the limiting case, using tenth‐value layers as described in the text.

Barrier ID	Location	Barrier type	Area type	Workload period	Limit (μSv)	Use factor	Occup. factor	Duty factor	Trans. factor	Meters o concrete
P1, P2	side walls	1°	uncontrolled	per week	1000	$1/4$	$1/4$		2.69E‐05
				per hour (TBI)	20	1	1	$1/5$	1.40E‐05
				per hour (continuous)	20	1	1	1	2.80E‐06	2.47
P1a, P2a	above 3.2 m	1°	uncontrolled	per week	1000	$1/4$	$1/16$		1.34E‐04	1.76
				per hour	20	1	1	0.025	1.12E‐04
P3	roof	1°	controlled	per hour	1000	1	1	$1/4$	2.57E‐04	1.60
S1	front wall	2°	controlled	per week	100	1	1		1.37E‐03	1.13
S1a	door	2°	controlled	per week	100	1	1		1.37E‐03	1.13
S2	back wall	2°	uncontrolled	per week	20	1	$1/4$		1.13E‐03	1.16
S3,4	side walls	2°	uncontrolled	per week	20	1	$1/4$		2.23E‐03	1.09
S5	roof	2°	uncontrolled	per week	20	1	$1/16$		3.48E‐03
				per hour	20	1	1	$1/4$	2.29E‐03	1.04

TBI = total body irradiation.