The Optimization of Radiation Protection in the Design of the High Temperature Reactor-Pebble-Bed Module

Table 1

Classification of radiation zones for the HTR-PM’s operation.

Number	Name		Dose rate; (mSv/h)	Airborne radioactivity concentration	Residence characteristics
I	Supervised area		0.0005 < d ≤ 0.0025	negligible	40 h per week
II	Controlled area	Conventional work area	0.0025 < d ≤ 0.0075	≤0.1 DAC	Less than 40 h per week
III		Intermittent work area	0.0075 < d ≤ 0.03	≤1 DAC	Usually less than 10 h per week, which accordingly determines the dose rate upper limit
IV		Limited work area	0.03 < d ≤ 3	≤10 DAC	Determined by the staff in charge of radiation protection
V		Chartered work area	d > 3	—	Temporarily chartered

radioactivity concentration is represented by derived air concentration (DAC).