3.0 Occupational Dose Limits and Contamination Standards

3.1 Occupational Dose Limits

It is UNR policy to maintain human radiation exposure levels to "As Low As Reasonably Achievable" (ALARA). In any area accessible to any person, radiation levels shall not exceed 0.002 rem (0.02 mSv) in one hour or 0.05 rem (0.5 mSv) in one year at 30 cm from the source of radiation or from any surface that the radiation penetrates.

UNR annual limits for radiation exposure:

  • Total effective dose equivalent: 5000 mrem (0.05 Sv)
  • Skin and extremities: 50000 mrem (0.50 Sv)
  • Lens of eye: 15000 mrem (0.15 Sv)
  • Declared pregnant worker: 500 mrem (0.005 Sv)
  • Minors: 500 mrem (0.005 Sv)
  • General public: 100 mrem (0.001 Sv)

UNR administrative limits are 10% of the annual limits excluding the general public and declared pregnant worker limits. The administrative limits for the general public and declared pregnant worker limits are the same as the regulatory occupational limits.

3.2 Contamination Standards

The administrative permissible levels of contamination are listed below. It is UNR’s policy however, to maintain contamination levels as low as reasonably achievable. These values reflect the net activity determined by wipe tests. Contamination above background level will normally be required to be decontaminated according to ALARA principles.

Administrative Permissible Levels of Contamination for alpha, beta and gamma emitters
Area Alpha emitter/100 cm2 Beta and gamma emitter/100 cm2
Uncontrolled 11 dpm 100 dpm
Controlled 22 dpm 550 dpm
Restricted 110 dpm 1100 dpm