CHP Radiation Protection Principles 4

Question 1

What is the purpose of a derived air concentration (DAC) value in radiation protection?

Accepted Answer

To define the airborne radionuclide concentration that would give a worker 5 rem/year if inhaled for 2,000 hours

Answer

DAC is the airborne radionuclide concentration (Bq/m³ or µCi/mL) that, if inhaled for a full work year (2,000 hours), would result in the 5-rem annual occupational CEDE limit.

Question 2

Which shielding material is most effective for attenuating high-energy gamma radiation?

Accepted Answer

Lead or dense concrete

Answer

High atomic number (Z) and high-density materials like lead and dense concrete provide the greatest photoelectric and Compton attenuation for gamma rays.

Question 3

A health physicist needs to determine the half-value layer (HVL) for a photon source. The HVL is defined as the thickness that:

Accepted Answer

Reduces the dose rate to 50% of its original value

Answer

The HVL is the thickness of a specified material required to reduce the intensity (dose rate) of radiation to half its incident value.

Question 4

Stochastic effects of radiation are characterized by:

Accepted Answer

Probability of occurrence increasing with dose, with no threshold

Answer

Stochastic effects (cancer, hereditary effects) have a probability that increases with dose, but their severity is independent of dose if they occur.

Question 5

A sealed radioactive source must be leak tested at what maximum interval per NRC regulations?

Accepted Answer

Every 6 months

Answer

10 CFR 20 and specific NRC regulations generally require leak testing of sealed sources at intervals not to exceed 6 months.

(CHP) Certified Health Physicist Practice Test

(CHP) Certified Health Physicist Practice Test

CHP Radiation Protection Principles 4