Radiation protection and chemistry controls
Radiation protection and chemistry controls
This domain tests dose control, contamination control, and chemistry parameters that protect systems and workers. Expect practical questions on time, distance, shielding, survey meters, and sampling.
Core rules
- Apply ALARA: reduce time, increase distance, and use shielding. Dose is dose rate multiplied by time; a high dose-rate area can be entered briefly only with a planned dose estimate and approval.
- Know your dosimetry and survey instrument. Check battery, scale, and response before use; do not use a meter outside its energy or range.
- Control contamination at the source with dress, step-off pads, bagging, and surveys. A clean area is not clean because it looks clean.
- Chemistry limits control corrosion and activity transport. Monitor pH, conductivity, chloride, dissolved oxygen, and boron where applicable; act on trends before limits.
Worked example
A valve job takes 30 minutes in a 100 mR/h field. Estimated dose is 100 mR/h times 0.5 h, or 50 mrem. Add shielding that lowers the field to 25 mR/h: 25 times 0.5 equals 12.5 mrem. If the dose budget is 20 mrem, the shielded job is acceptable with the planned time; the unshielded job is not.
Traps
Confusing mR/h with mrem; forgetting background; using the wrong meter scale; and treating a chemistry result as valid without a representative sample.